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{{Short description|Organic compound (CH₃CH₂OH)}}
{{Other uses|Ethanol (disambiguation)}}
{{For|ethanol as a drug or medicine|Alcohol (drug)|Alcohols (medicine)}}
{{merge from|Alcohol and cortisol|date=January 2012}}
{{Distinguish|Ethenol|Ethynol}}
{{Redirect-distinguish|Grain alcohol|Neutral grain spirit}}
{{Pp-move-indef|small=yes}} {{pp-move-indef|small=yes}}
{{Use dmy dates|date=December 2017}}

{{Chembox {{Chembox
| Watchedfields = changed | Verifiedfields = changed
| Watchedfields = changed
| verifiedrevid = 407816911
| verifiedrevid = 477167117
| ImageFileL1 = Ethanol-2D-flat.png
| ImageFileL1 = Ethanol-2D-flat.svg
| ImageFileL1_Ref = {{chemboximage|correct|??}}
| ImageNameL1 = Full structural formula of ethanol
| ImageSizeL1 = 131
| ImageClassL1 = skin-invert
| ImageNameL1 = Full structural formula of ethanol
| ImageFileR1 = Ethanol-2D-skeletal.svg | ImageFileR1 = Ethanol-2D-skeletal.svg
| ImageNameR1 = Skeletal formula of ethanol
| ImageFileR1_Ref = {{chemboximage|correct|??}}
| ImageClassR1 = skin-invert
| ImageSizeR1 = 111
| ImageFileL2 = Ethanol-3D-balls.png
| ImageNameR1 = Skeletal formula of ethanol
| ImageNameL2 = Ball-and-stick model of ethanol
| ImageFileL2 = Ethanol-3D-balls.png
| ImageFileR2 = Ethanol-3D-vdW.png
| ImageFileL2_Ref = {{chemboximage|correct|??}}
| ImageNameR2 = Space-filling model of ethanol
| ImageSizeL2 = 131
| ImageFile3 = Sample of Absolute Ethanol.jpg
| ImageNameL2 = Ball-and-stick model of ethanol
| ImageCaption3 = Absolute ethanol
| ImageFileR2 = Ethanol-3D-vdW.png
| PIN = Ethanol<ref name=iupac2013>{{cite book | title = Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book) | publisher = The ] | date = 2014 | location = Cambridge, UK | page = 30 | doi = 10.1039/9781849733069-00001 | isbn = 978-0-85404-182-4}}</ref>
| ImageFileR2_Ref = {{chemboximage|correct|??}}
| pronounce = {{IPAc-en|ˈ|ɛ|θ|ə|n|ɒ|l}}
| ImageSizeR2 = 111
| OtherNames = {{ubl|Absolute alcohol|Alcohol|Cologne spirit|Drinking alcohol|Ethylic alcohol|EtOH|Ethyl alcohol|Ethyl hydroxide|Ethylene hydrate|Ethylol|Grain alcohol|Hydroxyethane|Methylcarbinol}}
| ImageNameR2 = Space-filling model of ethanol
| Section2 = {{Chembox Properties
| SystematicName = Ethanol<ref name="Pubchem">{{cite web|title = Ethanol – Compound Summary|url = http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=702|work = The PubChem Project|location = USA|publisher = National Center for Biotechnology Information}}</ref>
|C=2 | H=6 | O=1
| OtherNames = Absolute alcohol<br />
|Appearance = Colourless liquid
Alcohol <br />
|Odor = wine-like, pungent<ref>{{cite web |title=Ethanol |url=https://pubchem.ncbi.nlm.nih.gov/compound/Ethanol |website=PubChem |access-date=29 December 2022}}</ref>
Drinking alcohol<br />
|Density = 0.78945 g/cm<sup>3</sup> (at 20 °C)<ref name=crc2>{{RubberBible92nd|page=3.246}}</ref>
Ethyl alcohol<br />
|MeltingPtC = −114.14 ± 0.03<ref name="crc2" />
Ethyl hydrate<br />
|BoilingPtC = 78.23 ± 0.09<ref name="crc2" />
Ethyl hydroxide<br />
|Solubility = ]
Ethylic alcohol<br />
|RefractIndex = 1.3611<ref name="crc2" />
Ethylol<br />
|LogP = −0.18
Grain alcohol<br />
|VaporPressure = 5.95 kPa (at 20&nbsp;°C)
Hydroxyethane<br />
|pKa = 15.9 (H<sub>2</sub>O), 29.8 (DMSO)<ref>{{cite journal | vauthors = Ballinger P, Long FA | doi = 10.1021/ja01489a008|title=Acid Ionization Constants of Alcohols. II. Acidities of Some Substituted Methanols and Related Compounds1,2|year=1960|journal=Journal of the American Chemical Society|volume=82|issue=4|pages=795–798|issn = 0002-7863 }}</ref><ref>{{cite journal | vauthors = Arnett EM, Venkatasubramaniam KG | doi = 10.1021/jo00158a001|journal=J. Org. Chem.|title=Thermochemical acidities in three superbase systems|year=1983|volume=48|issue=10|pages=1569–1578}}</ref>
Methylcarbinol
|Viscosity = 1.2 mPa·s (at 20&nbsp;°C), 1.074 mPa·s (at 25&nbsp;°C)<ref name=crc92>{{Cite book| editor-last = Lide | editor-first = David R. | name-list-style = vanc | title=CRC Handbook of Chemistry and Physics|url={{google books |plainurl=y |id=pYPRBQAAQBAJ|page=6}}|edition=92|year=2012|publisher=CRC Press/Taylor and Francis|location=Boca Raton, FL|pages=6–232}}</ref>
| Section1 = {{Chembox Identifiers
|Dipole = 1.69 D<ref name=crc89>{{Cite book | editor-last = Lide | editor-first = David R. | name-list-style = vanc | title=CRC Handbook of Chemistry and Physics|url={{google books |plainurl=y |id=KACWPwAACAAJ}}|edition=89|year=2008|publisher=CRC Press|location=Boca Raton, FL|pages=9–55}}</ref>
| CASNo = 64-17-5
|MagSus = −33.60·10<sup>−6</sup> cm<sup>3</sup>/mol
| CASNo_Ref = {{cascite|correct|CAS}}
}}
| PubChem = 702
| Section1 = {{Chembox Identifiers
| PubChem_Ref = {{Pubchemcite|correct|PubChem}}
|IUPHAR_ligand = 2299
| ChemSpiderID = 682
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} |CASNo_Ref = {{cascite|correct|CAS}}
|CASNo = 64-17-5
| UNII = 3K9958V90M
| UNII_Ref = {{fdacite|correct|FDA}} |UNII_Ref = {{fdacite|correct|FDA}}
|UNII = 3K9958V90M
| EINECS = 200-578-6
| UNNumber = 1170 |SMILES = OCC
| DrugBank_Ref = {{drugbankcite|correct|drugbank}} |ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
|ChemSpiderID = 682
| DrugBank = DB00898
|DrugBank_Ref = {{drugbankcite|correct|drugbank}}
| KEGG = D00068
|DrugBank = DB00898
| KEGG_Ref = {{keggcite|correct|kegg}}
|KEGG = C00469
| MeSHName = Ethanol
|PubChem = 702
| ChEBI_Ref = {{ebicite|correct|EBI}}
| ChEBI = 16236 |ChEBI = 16236
|ChEBI_Ref = {{ebicite|correct|EBI}}
| ChEMBL = 545
|ChEMBL = 545
| ChEMBL_Ref = {{ebicite|correct|EBI}}
|ChEMBL_Ref = {{ebicite|correct|EBI}}
| RTECS = KQ6300000
|Gmelin = 787
| ATCCode_prefix = D01
|Beilstein = 1718733
| ATCCode_suffix = AE06
|StdInChI = 1S/C2H6O/c1-2-3/h3H,2H2,1H3
| ATC_Supplemental = {{ATC|D08|AX08}}, {{ATC|V03|AB16}}, {{ATC|V03|AZ01}}
|StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| Beilstein = 1718733
|InChI = 1/C2H6O/c1-2-3/h3H,2H2,1H3
| Gmelin = 787
|StdInChIKey = LFQSCWFLJHTTHZ-UHFFFAOYSA-N
| 3DMet = B01253
|StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| SMILES = CCO
|InChIKey = LFQSCWFLJHTTHZ-UHFFFAOYAB
| StdInChI = 1S/C2H6O/c1-2-3/h3H,2H2,1H3
|3DMet = B01253
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
|UNNumber = UN 1170
| InChI = 1/C2H6O/c1-2-3/h3H,2H2,1H3
| StdInChIKey = LFQSCWFLJHTTHZ-UHFFFAOYSA-N
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| InChIKey = LFQSCWFLJHTTHZ-UHFFFAOYAB}}
| Section2 = {{Chembox Properties
| C = 2
| H = 6
| O = 1
| ExactMass = 46.041864814 g mol<sup>−1</sup>
| Appearance = Colorless liquid
| Density = 0.789 g/cm<sup>3</sup>
| MeltingPtC = −114
| BoilingPtC = 78
| LogP = -0.18
| VaporPressure = 5.95 kPa (at 20 °C)
| pKa = 15.9<ref>Ballinger, P., Long, F.A., ''J. Am. Chem. Soc.'', '''1960''', ''82'', 795.</ref>
| pKb = -1.9
| RefractIndex = 1.36
| Viscosity = 0.0012 Pa s (at 20 °C)
| Dipole = 1.69 D
}} }}
| Section3 = {{Chembox Pharmacology | Section7 = {{Chembox Hazards
|ExternalSDS = <ref name="sigmaaldrichMSDS">{{cite web| url = https://www.sigmaaldrich.com/CH/en/sds/sial/459836| title = MSDS Ethanol| access-date = 2023-01-12}}</ref>
| AdminRoutes = Intramuscular<br />
|GHSPictograms = {{GHS02}} {{GHS07}}
Intravenous<br />
|GHSSignalWord = Danger
Oral<br />
|HPhrases = {{H-phrases|225|319|360D}}
Topical
|PPhrases = {{P-phrases|210|233|240|241|242|305+351+338}}
| Metabolism = Hepatic
|NFPA-H = 2
| ] - Low-Moderate
|NFPA-F = 3
|NFPA-R = 0
|FlashPt = 14 °C (Absolute)<ref>{{Cite web|title=Ethanol|url=https://webwiser.nlm.nih.gov/substance?substanceId=18&identifier=Ethanol&identifierType=name&menuItemId=32&catId=58|access-date=2021-06-25|website=webwiser.nlm.nih.gov|language=en}}</ref>
|LD50 = {{ubl|7060{{nbsp}}mg/kg (oral, rat)|3450{{nbsp}}mg/kg (mouse)}} <ref>{{Cite web|title=Ethyl Alcohol|date=2 November 2018 |url=https://www.cdc.gov/niosh/idlh/64175.html|access-date=2023-12-23|language=en}}</ref>
|PEL = TWA 1000 ppm (1900{{nbsp}}mg/m<sup>3</sup>)<ref name=PGCH>{{PGCH|0262}}</ref>
|IDLH = 3300 ppm <ref>{{Cite web|title=Ethyl Alcohol|url=https://www.cdc.gov/niosh/npg/npgd0262.html|access-date=2023-12-23|language=en}}</ref>
|REL = TWA 1000 ppm (1900{{nbsp}}mg/m<sup>3</sup>)<ref name="PGCH" />
}} }}
| Section4 = {{Chembox Hazards | Section9 = {{Chembox Related
|OtherCompounds = {{ubl|]|]}}
| EUIndex = 603-002-00-5
| EUClass = {{Hazchem F}}
| RPhrases = {{R11}}
| SPhrases = {{S2}}, {{S7}}, {{S16}}
| NFPA-H = 2
| NFPA-F = 3
| NFPA-R = 0
| FlashPt = 13–14 °C
| Autoignition = 362 °C
| LD50 = 5628 mg kg<sup>−1</sup> (oral, rat)
}} }}
}} }}


'''Ethanol''' (also called '''ethyl alcohol''', '''grain alcohol''', '''drinking alcohol''', or simply '''alcohol''') is an ] with the ] {{chem2|CH3CH2OH}}. It is an ], with its formula also written as {{chem2|C2H5OH}}, {{chem2|C2H6O}} or EtOH, where Et stands for ]. Ethanol is a ], ], colorless liquid with a characteristic ]-like odor and ] taste.<ref>{{cite web |url=https://pubchem.ncbi.nlm.nih.gov/compound/Ethanol |title=Ethanol |series=PubChem |publisher=National Library of Medicine |access-date=28 September 2021}}</ref><ref>{{cite web |url=https://www.nj.gov/health/eoh/rtkweb/documents/fs/0844.pdf |title=Ethyl Alcohol |series=Hazardous Substance Fact Sheet |publisher=New Jersey Department of Health |access-date=28 September 2021}}</ref> In nature, grape-sugar breaks up by the action of fermentation into alcohol or carbonic acid, without anything being added.<ref>{{Cite book |last=Black |title=Encyclopædia Britannica, Vol. 1 |date=1875 |publisher=Adam and Charles Black |location=Edinburgh |pages=470}}</ref> As a ] ], it is the active ingredient in ]s, and the second most consumed drug globally behind ].<ref name="u385">{{cite journal | last1=Song | first1=Frank | last2=Walker | first2=Matthew P. | title=Sleep, alcohol, and caffeine in financial traders | journal=PLOS ONE | volume=18 | issue=11 | date=2023-11-08 | issn=1932-6203 | pmid=37939019 | pmc=10631622 | doi=10.1371/journal.pone.0291675 | doi-access=free | page=e0291675| bibcode=2023PLoSO..1891675S }}</ref>
'''Ethanol''', also called '''ethyl alcohol''', '''pure alcohol''', '''grain alcohol''', or '''drinking alcohol''', is a ], ], colorless liquid. It is a ] and one of the oldest ]. Best known as the type of ] found in ], it is also used in ], as a ], and as a ]. In common usage, it is often referred to simply as '''alcohol''' or ''']'''.


Ethanol is naturally produced by the ] process of ]s by ]s or via ] processes such as ] hydration. Historically it was used as a ], and has modern medical applications as an ], ], solvent for some medications, and ] for ] and ].<ref name="Powell1996">{{cite book |title=The Origins and Ancient History of Wine |series=Food and Nutrition in History and Anthropology |edition=1 |volume=11 |chapter=9: Wine and the vine in ancient Mesopotamia: the cuneiform evidence |pages=96–124 |author=Powell MA |veditors=McGovern PE, Fleming SJ, Katz SH |publisher=Taylor & Francis |location=Amsterdam |year=2004 |isbn=978-0-203-39283-6 |issn=0275-5769 |chapter-url=https://books.google.com/books?id=aXX2UcT_yw8C&q=Wine+and+the+vine+in+ancient+Mesopotamia:+the+cuneiform+evidence&pg=PA97 |access-date=2010-09-15}}</ref><ref name="Schnelle">{{cite journal |last=Schnelle |first=Norbert |date=August 1965 |title=Alcohol Given Intravenously for General Anesthesia |url=https://www.sciencedirect.com/science/article/abs/pii/S0039610916376502 |journal=Surgical Clinics of North America |volume=45 |issue=4 |pages=1041–1049 |doi=10.1016/S0039-6109(16)37650-2 |pmid=14312998 |access-date=December 30, 2022}}</ref> It is used as a chemical ] and in the ] of organic compounds, and as a ] for lamps, stoves, and internal combustion engines. Ethanol also can be dehydrated to make ethylene, an important chemical feedstock. As of 2023, world production of ethanol fuel was {{convert|29,590,000,000|usgal|GL|abbr=off}}, coming mostly from the U.S. (51%) and Brazil (26%).<ref name=":0">{{cite web |title=2008 World Fuel Ethanol Production |url=https://ethanolrfa.org/markets-and-statistics/annual-ethanol-production |access-date=21 June 2024 |publisher=Renewable Fuels Association |location=Ellisville, Missouri}}</ref>
Ethanol is a 2-carbon alcohol with the ] CH<sub>3</sub>CH<sub>2</sub>OH. Its ] is ]<sub>2</sub>]<sub>6</sub>]. An alternative notation is CH<sub>3</sub>–CH<sub>2</sub>–OH, which indicates that the carbon of a methyl group (CH<sub>3</sub>–) is attached to the carbon of a methylene group (–CH<sub>2</sub>–), which is attached to the oxygen of a ]. It is a constitutional ] of ]. Ethanol is often abbreviated as '''EtOH''', using the common organic chemistry notation of representing the ethyl group (C<sub>2</sub>H<sub>5</sub>) with '''Et'''.


== Name ==
The ] of sugar into ethanol is one of the earliest ] employed by humanity. The intoxicating effects of ethanol consumption have been known since ancient times. In modern times, ethanol intended for industrial use is also produced from ].<ref name=myers>{{Cite book|author=Myers, Richard L.; Myers, Rusty L.|title=The 100 most important chemical compounds: a reference guide|year=2007|publisher=Greenwood Press|location=Westport, Conn.|isbn=0313337586|page=122|url=http://books.google.com/?id=0AnJU-hralEC&pg=PA122}}</ref> Ethanol has widespread use as a solvent of substances intended for human contact or consumption, including scents, flavorings, colorings, and medicines. In chemistry, it is both an essential solvent and a feedstock for the synthesis of other products. It has a long history as a fuel for heat and light, and more recently as a fuel for ]s.
''Ethanol'' is the ] ] by the ] for a compound consisting of an ] with two carbon ]s (prefix "eth-"), having a single bond between them (infix "-an-") and an attached −OH ] (suffix "-ol").<ref name="Pubchem">{{cite web|title = Ethanol – Compound Summary|url = https://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=702|website = The PubChem Project|location = Bethesda, MD|publisher = National Center for Biotechnology Information}}</ref>


The "eth-" prefix and the qualifier "ethyl" in "ethyl alcohol" originally came from the name "ethyl" assigned in 1834 to the group {{chem|C|2|H|5}}− by ]. He coined the word from the ] name ''Aether'' of the compound {{chem|C|2|H|5}}−O−{{chem|C|2|H|5}} (commonly called "ether" in ], more specifically called "]").<ref>{{cite journal | last = Liebig | first = Justus | name-list-style = vanc | year = 1834 | title = Ueber die Constitution des Aethers und seiner Verbindungen | trans-title = On the constitution of ether and its compounds | language = de | doi = 10.1002/andp.18341072202 | journal = Annalen der Pharmacie | volume = 9 | issue = 22 | pages = 1–39 | quote = From page 18: "''Bezeichnen wir die Kohlenwasserstoffverbindung 4C + 10H als das Radikal des Aethers mit E<sub>2</sub> und nennen es Ethyl'', ..." (Let us designate the hydrocarbon compound 4C + 10H as the radical of ether with E<sub>2</sub> and name it ethyl ...). | bibcode = 1834AnP...107..337L | url = https://zenodo.org/record/1423568 }}</ref> According to the '']'', ''Ethyl'' is a contraction of the Ancient Greek ] (''{{transliteration|grc|aithḗr}}'', "upper air") and the Greek word ] (''{{transliteration|grc|hýlē}}'', "wood, raw material", hence "matter, substance").<ref>{{OEtymD|ethyl}}</ref> ''Ethanol'' was coined as a result of a resolution on naming alcohols and phenols that was adopted at the International Conference on ] that was held in April 1892 in ], Switzerland.<ref>For a report on the 1892 International Conference on Chemical Nomenclature, see:
''Ethanol'' is the ] defined by the ] for a molecule with two carbon atoms (prefix "eth-"), having a single bond between them (suffix "-ane"), and an attached -OH group (suffix "-ol").<ref name="Pubchem">{{cite web|url = http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=702}}</ref> ] redirects here; such usage almost always refers to a part of this sub-grouping inside a larger molecule.
* {{cite journal| last = Armstrong | first = Henry | name-list-style = vanc |year=1892|url={{google books |plainurl=y |id=LHkCAAAAIAAJ|page=56}} |title=The International Conference on Chemical Nomenclature|journal=Nature|volume=46|pages=56–59|doi=10.1038/046056c0|issue=1177|bibcode=1892Natur..46...56A|doi-access=free}}
* Armstrong's report is reprinted with the resolutions in English in: {{cite journal| last = Armstrong | first = Henry | name-list-style = vanc |year=1892|url={{google books |plainurl=y |id=RogMAQAAIAAJ|page=398}}|title=The International Conference on Chemical Nomenclature|journal=The Journal of Analytical and Applied Chemistry|volume=6|issue=1177|pages= 390–400 (398)|quote= The alcohols and the phenols will be called after the name of the hydrocarbon from which they are derived, terminated with the suffix ''ol'' (ex. pentanol, pentynol, etc.) | bibcode = 1892Natur..46...56A | doi = 10.1038/046056c0 |doi-access= free}}</ref>


The term ''alcohol'' now refers to a wider class of substances in chemistry nomenclature, but in common parlance it remains the name of ethanol. It is a medieval loan from ] {{nowrap|'']''}}, a powdered ore of ] used since antiquity as a cosmetic, and retained that meaning in ].<ref>{{cite book|last=Multhauf|first=Robert P.|author-link=Robert P. Multhauf|year=1966|title=The Origins of Chemistry|location=London|publisher=Oldbourne|isbn=9782881245947}} p. 205; ]; ]</ref> The use of 'alcohol' for ethanol (in full, "alcohol of wine") was first recorded in 1753. Before the late 18th century the term ''alcohol'' generally referred to any sublimated substance.<ref>{{cite book|last1=Berthelot|first1=Marcellin|author1-link=Marcellin Berthelot|last2=Houdas|first2=Octave V.|year=1893|title=La Chimie au Moyen Âge|volume=I |location=Paris|publisher=Imprimerie nationale |page=136}}</ref>
==History==
{{details|Distilled beverage}}
<!--]-->
Ethanol has been used by humans since prehistory as the intoxicating ingredient of ]s. Dried residue on 9,000-year-old pottery found in China imply that ] people consumed alcoholic beverages.<ref name="Roach">{{cite journal|author=Roach, J.|date=July 18, 2005|url=http://news.nationalgeographic.com/news/2005/07/0718_050718_ancientbeer.html|title= 9,000-Year-Old Beer Re-Created From Chinese Recipe|journal=National Geographic News|accessdate=2007-09-03}}</ref>


== Uses ==
Although ] was well known by the early Greeks and Arabs, the first recorded production of alcohol from distilled wine was by the ] alchemists in the 12th century.<ref name="Forbes">Forbes, Robert James(1948) ''A short history of the art of distillation'', p.89</ref> The first to mention absolute alcohol, in contrast with alcohol-water mixtures, was ].<ref name="Forbes" />
=== Recreational drug ===
{{Main|Alcohol (drug)}}
As a ] ], ethanol is one of the most commonly consumed ]s.<ref>{{Cite web|title=Alcohol use and safe drinking: MedlinePlus Medical Encyclopedia|url=https://medlineplus.gov/ency/article/001944.htm|access-date=2023-03-11|website=medlineplus.gov|language=en}}</ref> Despite alcohol's psychoactive, addictive, and ] properties, it is readily available and legal for sale in many countries. There are laws regulating the sale, exportation/importation, taxation, manufacturing, consumption, and possession of alcoholic beverages. The most common regulation is prohibition for minors.


In mammals, ethanol is primarily ] in the ] and ] by ADH enzymes.<ref name="Farrés">{{cite journal | vauthors = Farrés J, Moreno A, Crosas B, Peralba JM, Allali-Hassani A, Hjelmqvist L, Jörnvall H, Parés X | display-authors = 6 | title = Alcohol dehydrogenase of class IV (&sigma;&sigma;-ADH) from human stomach. cDNA sequence and structure/function relationships | journal = European Journal of Biochemistry | volume = 224 | issue = 2 | pages = 549–557 | date = September 1994 | pmid = 7925371 | doi = 10.1111/j.1432-1033.1994.00549.x | doi-access = free }}</ref> These enzymes catalyze the ] of ethanol into ] (ethanal):<ref>{{cite journal | vauthors = Edenberg HJ, McClintick JN | title = Alcohol Dehydrogenases, Aldehyde Dehydrogenases, and Alcohol Use Disorders: A Critical Review | journal = Alcoholism: Clinical and Experimental Research | volume = 42 | issue = 12 | pages = 2281–2297 | date = December 2018 | pmid = 30320893 | doi = 10.1111/acer.13904 | pmc = 6286250 }}</ref>
In 1796, Johann Tobias Lowitz obtained pure ethanol by filtering distilled ethanol through ]. ] described ethanol as a compound of carbon, hydrogen, and oxygen, and in 1808 ] determined ethanol’s chemical formula.<ref>{{cite web|title = Alcohol|url = http://www.1911encyclopedia.org/Alcohol|work = 1911 Encyclopædia Britannica|publisher = LoveToKnow}}</ref> Fifty years later, ] published the structural formula of ethanol. It is one of the first structural formulas determined.<ref name=Couper>{{cite journal|author=Couper AS|year=1858|title=On a new chemical theory|journal=Philosophical magazine|format=online reprint|volume=16|issue=104–16|url=http://web.lemoyne.edu/~giunta/couper/couper.html|accessdate=2007-09-03}}</ref>


:CH<sub>3</sub>CH<sub>2</sub>OH + NAD<sup>+</sup> → CH<sub>3</sub>CHO + ] + H<sup>+</sup>
Ethanol was first prepared synthetically in 1826 through the independent efforts of Henry Hennel in Great Britain and S.G. Sérullas in
France. In 1828, ] prepared ethanol by ] hydration of ], a process similar to current industrial ethanol synthesis.<ref name=Hennell>{{cite journal|author=Hennell, H.|year=1828|title=On the mutual action of sulfuric acid and alcohol, and on the nature of the process by which ether is formed|journal=Philosophical Transactions|volume=118|doi=10.1098/rstl.1828.0021|page=365}}</ref>


When present in significant concentrations, this metabolism of ethanol is additionally aided by the ] enzyme ] in humans, while trace amounts are also metabolized by ].<ref>{{cite book |author1=Heit, C. |author2=Dong, H. |author3=Chen, Y. |author4=Thompson, D.C. |author5=Dietrich, R.A. |author6=Vasiliou, V.K. |title=Cytochrome P450 2E1: Its Role in Disease and Drug Metabolism |chapter=The Role of CYP2E1 in Alcohol Metabolism and Sensitivity in the Central Nervous System |series=Subcellular Biochemistry |date=2013 |volume=67 |pages=235–237 |doi=10.1007/978-94-007-5881-0_8 |pmid=23400924 |pmc=4314297 |isbn=978-94-007-5880-3 }}</ref> The resulting intermediate, acetaldehyde, is a known carcinogen, and poses significantly greater toxicity in humans than ethanol itself. Many of the symptoms typically associated with alcohol intoxication—as well as many of the health hazards typically associated with the long-term consumption of ethanol—can be attributed to acetaldehyde toxicity in humans.<ref>{{cite web |title=Alcohol Metabolism: An Update |url=https://pubs.niaaa.nih.gov/publications/aa72/aa72.htm |website=NIAA Publications |publisher=National Institute of Health |access-date=10 March 2021 |archive-date=28 February 2021 |archive-url=https://web.archive.org/web/20210228215303/https://pubs.niaaa.nih.gov/publications/AA72/AA72.htm |url-status=dead }}</ref>
Ethanol was used as lamp fuel in the United States as early as 1840, but a tax levied on industrial alcohol during the ] made this use uneconomical. The tax was repealed in 1906.<ref name=siegel>{{cite news|url=http://www.npr.org/templates/story/story.php?storyId=7426827|title=Ethanol, Once Bypassed, Now Surging Ahead|author=Siegel, Robert |publisher=NPR|date=2007-02-15|accessdate=2007-09-22}}</ref> Original ] automobiles ran on ethanol until 1908.<ref name=dipardo>{{cite web|url=http://tonto.eia.doe.gov/FTPROOT/features/biomass.pdf|title=Outlook for Biomass Ethanol Production and Demand|publisher=United States Department of Energy|author=DiPardo, Joseph |accessdate =2007-09-22|format=PDF}}</ref> With the advent of ] in 1920, ethanol fuel sellers were accused of being allied with ]rs,<ref name=siegel/> and ethanol fuel fell into disuse until late in the 20th century. {{Dubious|date=May 2011}}


The subsequent oxidation of acetaldehyde into ] is performed by ] (ALDH) enzymes. A mutation in the ALDH2 gene that encodes for an inactive or dysfunctional form of this enzyme affects roughly 50 % of east Asian populations, contributing to the characteristic ] that can cause temporary reddening of the skin as well as a number of related, and often unpleasant, symptoms of acetaldehyde toxicity.<ref name="Eng et al.">{{cite journal|vauthors=Eng MY, Luczak SE, Wall TL|date=2007|title=ALDH2, ADH1B, and ADH1C genotypes in Asians: a literature review|journal=Alcohol Research & Health|volume=30|issue=1|pages=22–27|pmc=3860439|pmid=17718397}}</ref> This mutation is typically accompanied by another mutation in the ADH enzyme ] in roughly 80 % of east Asians, which improves the catalytic efficiency of converting ethanol into acetaldehyde.<ref name="Eng et al." />
==Physical properties==
]
Ethanol is a volatile, colorless liquid that has a slight odor.<ref>{{cite web|url=http://www.odour.unsw.edu.au/odorous-compounds.html|title=Odorous Compounds – Odour Descriptions of Chemicals with Odours|publisher=Atmospheric Emissions & Odour Laboratory, Centre for Water & Waste Technology, School of Civil & Environmental Engineering, University of New South Wales|date=24 April 2008|accessdate=16 January 2011}}</ref> It burns with a smokeless blue flame that is not always visible in normal light.


=== Medical ===
The physical properties of ethanol stem primarily from the presence of its ] group and the shortness of its carbon chain. Ethanol’s hydroxyl group is able to participate in hydrogen bonding, rendering it more viscous and less volatile than less polar organic compounds of similar molecular weight.
{{Main|Alcohol (medicine)}}
Ethanol is the oldest known ], used as an oral ] during surgery in ancient ] and in ].<ref name="Powell1996" /><ref name="Schnelle" /> Mild intoxication starts at a ] of 0.03-0.05 % and induces ] at 0.4%.<ref>{{cite web |url=https://www.medicalsecretsmd.com/post/natural-old-school-anesthesia-ancient-opium-alcohol-marijuana |title=3 Natural, Ancient Anesthetics No One Talks About: Opium, Alcohol, Marijuana |last=Kaveh |first=Anthony |website=Dr. Anthony Kaveh, MD |access-date=December 30, 2022}}</ref> This use carries the high risk of deadly ], ] and vomiting, which led to use of alternatives in antiquity, such as ] and ], and later diethyl ether, starting in the 1840s.<ref name= Grattan>Grattan, N. "Treatment of Uterine Haemorrhage". ''Provincial Medicine and Surgical Journal''. Vol. 1, No. 6 (Nov. 7, 1840), p. 107.</ref>


Ethanol is used as an ] in medical wipes and ] gels for its bactericidal and anti-fungal effects.<ref>{{cite journal |last1=Pohorecky |first1=Larissa A. |last2=Brick |first2=John |title=Pharmacology of ethanol |journal=Pharmacology & Therapeutics |date=January 1988 |volume=36 |issue=2–3 |pages=335–427 |doi=10.1016/0163-7258(88)90109-X |pmid=3279433 }}</ref> Ethanol kills ]s by dissolving their membrane ] and ] their ]s, and is effective against most ], ] and ]es. It is ineffective against bacterial ], which can be treated with ].<ref>{{cite journal | vauthors = McDonnell G, Russell AD | title = Antiseptics and disinfectants: activity, action, and resistance | journal = Clinical Microbiology Reviews | volume = 12 | issue = 1 | pages = 147–179 | date = January 1999 | pmid = 9880479 | pmc = 88911 | doi = 10.1128/CMR.12.1.147 }}</ref>
===Solvent properties===
Ethanol is a versatile solvent, ] with water and with many organic solvents, including ], ], ], ], ], ], ], ], ], ], and ].<ref name=crc/><ref name=merck/> It is also miscible with light aliphatic hydrocarbons, such as ] and ], and with aliphatic chlorides such as ] and ].<ref name=merck>{{cite book|author=Windholz, Martha|title=The Merck index: an encyclopedia of chemicals and drugs|publisher=Merck|location=Rahway, N.J., U.S.A|year=1976|isbn=0-911910-26-3|edition=9th}}</ref>


A solution of 70% ethanol is more effective than pure ethanol because ethanol relies on water molecules for optimal antimicrobial activity. Absolute ethanol may inactivate microbes without destroying them because the alcohol is unable to fully permeate the microbe's membrane.<ref>{{Cite web|url=https://www.cdc.gov/infectioncontrol/guidelines/disinfection/disinfection-methods/chemical.html|title=Chemical Disinfectants {{!}} Disinfection & Sterilization Guidelines {{!}} Guidelines Library {{!}} Infection Control {{!}} CDC|website=www.cdc.gov|language=en-us|access-date=2018-01-29}}</ref><ref>{{Cite web|url=https://www.researchgate.net/post/Why_is_70_ethanol_used_for_wiping_microbiological_working_areas|title=Why is 70% ethanol used for wiping microbiological working areas?|website=ResearchGate|language=en|access-date=2018-01-29}}</ref> Ethanol can also be used as a disinfectant and antiseptic by inducing cell dehydration through disruption of the osmotic balance across the cell membrane, causing water to leave the cell, leading to cell death.<ref>{{cite web |title=Ethanol |url=https://www.drugbank.ca/drugs/DB00898 |website=www.drugbank.ca |access-date=28 January 2019}}</ref>
Ethanol’s miscibility with water contrasts with the immiscibility of longer-chain alcohols (five or more carbon atoms), whose water miscibility decreases sharply as the number of carbons increases.<ref name="m_and_b"/> The miscibility of ethanol with ]s is limited to alkanes up to ], mixtures with ] and higher alkanes show a miscibility gap below a certain temperature (about 13 °C for dodecane<ref>{{cite journal|author=Dahlmann U, Schneider GM|title=(Liquid + liquid) phase equilibria and critical curves of (ethanol + dodecane or tetradecane or hexadecane or 2,2,4,4,6,8,8-heptamethylnonane) from 0.1 MPa to 120.0 MPa|journal=J Chem Thermodyn.|volume=21|page=997|year=1989|doi=10.1016/0021-9614(89)90160-2|issue=9}}</ref>). The miscibility gap tends to get wider with higher alkanes and the temperature for complete miscibility increases.


Ethanol may be administered as an ] to ]<ref>{{cite journal|last1=Scalley|first1=Robert | name-list-style = vanc |title=Treatment of Ethylene Glycol Poisoning|journal=American Family Physician|date=September 2002|volume=66|issue=5|pages=807–813|pmid=12322772 |url=https://www.aafp.org/afp/2002/0901/p807.html|access-date=15 January 2018}}</ref> and ].<ref name=EM2016>{{cite journal|last1=Beauchamp|first1=GA|last2=Valento|first2=M|title=Toxic Alcohol Ingestion: Prompt Recognition And Management In The Emergency Department.|journal=Emergency Medicine Practice|date=September 2016|volume=18|issue=9|pages=1–20|pmid=27538060}}</ref> It does so by acting as a ] against ] and ] for ] (ADH).<ref>{{Cite journal |last1=Sasanami |first1=Misa |last2=Yamada |first2=Taihei |last3=Obara |first3=Takafumi |last4=Nakao |first4=Atsunori |last5=Naito |first5=Hiromichi |title=Oral Ethanol Treatment for Ethylene Glycol Intoxication |journal=Cureus |year=2020 |volume=12 |issue=12 |pages=e12268 |doi=10.7759/cureus.12268 |doi-access=free |issn=2168-8184 |pmc=7827791 |pmid=33510981}}</ref> Though it has more side effects, ethanol is less expensive and more readily available than ] in the role.<ref>{{Cite journal |last1=Anseeuw |first1=Kurt |last2=Sabbe |first2=Marc B. |last3=Legrand |first3=Annemie |date=April 2008 |title=Methanol poisoning: the duality between 'fast and cheap' and 'slow and expensive' |url=https://pubmed.ncbi.nlm.nih.gov/18446077/ |journal=European Journal of Emergency Medicine|volume=15 |issue=2 |pages=107–109 |doi=10.1097/MEJ.0b013e3282f3c13b |issn=0969-9546 |pmid=18446077|s2cid=23861841 }}</ref>
Ethanol-water mixtures have less volume than the sum of their individual components at the given fractions. Mixing equal volumes of ethanol and water results in only 1.92 volumes of mixture.<ref name=crc>{{cite book|editor=Lide, D. R. |title=CRC Handbook of Chemistry and Physics 81st edition|publisher=CRC press|year=2000|isbn = 0849304814}}</ref><ref name=ChemTech>{{cite encyclopedia|chapter=Ethanol|title=]|year=1991|page=813|volume=9}}</ref> Mixing ethanol and water is ]. At 298&nbsp;K, up to 777&nbsp;J/mol<ref>{{cite journal|author=Costigan MJ, Hodges LJ, Marsh KN, Stokes RH, Tuxford CW|title=The Isothermal Displacement Calorimeter: Design Modifications for Measuring Exothermic Enthalpies of Mixing|journal=Aust. J. Chem.|volume=33|issue=10|page=2103| year = 1980| doi = 10.1071/CH9802103}}</ref> are set free.


Ethanol is used to dissolve many water-insoluble medications and related compounds. Liquid preparations of ], ], and mouth washes, for example, may contain up to 25% ethanol<ref>{{Cite web | url = https://www.mssny.org/App_Themes/MSSNY/pdf/AlcoholContent.pdf | title = Alcohol Content in Common Preparations | publisher = Medical Society of the State of New York | access-date = October 8, 2019 | archive-date = 29 April 2021 | archive-url = https://web.archive.org/web/20210429232655/https://www.mssny.org/App_Themes/MSSNY/pdf/AlcoholContent.pdf | url-status = dead }}</ref> and may need to be avoided in individuals with adverse reactions to ethanol such as ].<ref name="Ann Allergy Asthma Immunol 2013">{{cite journal | vauthors = Adams KE, Rans TS | title = Adverse reactions to alcohol and alcoholic beverages | journal = Annals of Allergy, Asthma & Immunology | volume = 111 | issue = 6 | pages = 439–445 | date = December 2013 | pmid = 24267355 | doi = 10.1016/j.anai.2013.09.016 }}</ref> Ethanol is present mainly as an antimicrobial preservative in over 700 liquid preparations of medicine including ], ]s, ], ], ], ], ] and ] ].<ref>{{cite journal | vauthors = Zuccotti GV, Fabiano V | title = Safety issues with ethanol as an excipient in drugs intended for pediatric use | journal = Expert Opinion on Drug Safety | volume = 10 | issue = 4 | pages = 499–502 | date = July 2011 | pmid = 21417862 | doi = 10.1517/14740338.2011.565328 | s2cid = 41876817 }}</ref>
Mixtures of ethanol and water form an ] at about 89 mole-% ethanol and 11 mole-% water<ref>{{cite journal|author=Lei Z, Wang H, Zhou R, Duan Z|title= Influence of salt added to solvent on extractive distillation|journal=Chem Eng J.|volume=87|page=149|year=2002| doi= 10.1016/S1385-8947(01)00211-X|issue=2}}</ref> or a mixture of about 96 volume percent ethanol and 4% water at normal pressure and T&nbsp;= 351&nbsp;K. This azeotropic composition is strongly temperature- and pressure-dependent and vanishes at temperatures below 303&nbsp;K.<ref>{{cite journal|author=Pemberton RC, Mash CJ|title=Thermodynamic properties of aqueous non-electrolyte mixtures II. Vapour pressures and excess Gibbs energies for water + ethanol at 303.15 to 363.15 K determined by an accurate static method|journal=J Chem Thermodyn.|volume=10|page=867|year=1978|doi=10.1016/0021-9614(78)90160-X|issue=9}}</ref>


Some medicinal solutions of ethanol are also known as ]s.


=== Energy source ===
]
{{See also|Food vs. fuel}}
Hydrogen bonding causes pure ethanol to be ] to the extent that it readily absorbs water from the air. The polar nature of the hydroxyl group causes ethanol to dissolve many ionic compounds, notably ] and ]s, ], ], ], ], and ].<ref name=merck/> ] and ]s are slightly soluble in ethanol.<ref name=merck/> Because the ethanol molecule also has a nonpolar end, it will also dissolve nonpolar substances, including most ]s<ref name="merckoils">''Merck Index of Chemicals and Drugs'', 9th ed.; monographs 6575 through 6669</ref> and numerous flavoring, coloring, and medicinal agents.
{{Main|Ethanol fuel}}
[[File:Corn vs Ethanol production.webp|thumb|upright=1.36|center|Corn vs ethanol production in the United States
{{legend|#FFD932|Total corn production (]s) (left)}}
{{legend|B51700|Corn used for ] (bushels) (left)}}
{{legend-line|#313131 solid 3px|Percent of corn used for Ethanol (right)}}
]]


{| class="wikitable" style="float:right; margin-left:1em;"
The addition of even a few percent of ethanol to water sharply reduces the ] of water. This property partially explains the “]” phenomenon. When wine is swirled in a glass, ethanol evaporates quickly from the thin film of wine on the wall of the glass. As the wine’s ethanol content decreases, its surface tension increases and the thin film “beads up” and runs down the glass in channels rather than as a smooth sheet.
|+] (]) of some fuels compared with ethanol.
|-
!Fuel type|| MJ/L|| MJ/kg|| ]
|-
|]|| ||~19.5||
|-
|]||17.9||19.9||108.7<ref name="Fuel 89 (2010) 2713-2720">{{cite journal|doi=10.1016/j.fuel.2010.01.032|title = Impact of alcohol–gasoline fuel blends on the performance and combustion characteristics of an SI engine | year = 2010 | last1 = Eyidogan | first1 = Muharrem | last2 = Ozsezen | first2 = Ahmet Necati | last3 = Canakci | first3 = Mustafa | last4 = Turkcan | first4 = Ali | name-list-style = vanc | journal = Fuel | volume = 89 | issue = 10 | pages = 2713–2720 |bibcode = 2010Fuel...89.2713E }}</ref>
|-
|]||21.2<ref name="Thomas">{{cite web |last=Thomas |first=George | url = http://www.eere.energy.gov/hydrogenandfuelcells/pdfs/storage.pdf |title=Overview of Storage Development DOE Hydrogen Program |url-status=dead |archive-url=https://web.archive.org/web/20070221185632/http://www1.eere.energy.gov/hydrogenandfuelcells/pdfs/storage.pdf |archive-date=21 February 2007 |location=Livermore, California |publisher=Sandia National Laboratories |year=2000}}</ref>||26.8<ref name="Thomas" />
||108.6<ref name="Fuel 89 (2010) 2713-2720" />
|-
|]<br />(85% ethanol, 15% gasoline)||25.2||33.2||105
|-
|]||25.3||~55||
|-
|] (])<br />(60% ] + 40% ])||26.8||50||
|-
|]<br />(high-octane gasoline, not jet fuel)||33.5||46.8||100/130 (lean/rich)
|-
|]<br />(90% gasoline + 10% ethanol)||33.7||47.1||93/94
|-
| Regular gasoline/petrol||34.8||44.4<ref>{{cite news|url=http://www1.eere.energy.gov/hydrogenandfuelcells/pdfs/storage.pdf| last = Thomas | first = George | name-list-style = vanc |title=Overview of Storage Development DOE Hydrogen Program |publisher=Sandia National Laboratories|year=2000|access-date=1 August 2009}}</ref>||min. 91
|-
| Premium gasoline/petrol|| || ||max. 104
|-
|]||38.6||45.4||25
|-
|], extruded||50||23||
|}


The largest single use of ethanol is as an engine ] and ]. ] in particular relies heavily upon the use of ethanol as an engine fuel, due in part to its role as one of the world's leading producers of ethanol.<ref>{{cite web|title=Availability of Sources of E85|url=http://www.cleanairtrust.org/Sources-Availability-E85.html|website=Clean Air Trust|access-date=27 July 2015}}</ref><ref>{{cite web|title=Fuel ethanol production worldwide|url=https://www.statista.com/statistics/281606/ethanol-production-in-selected-countries/|website=Statista|access-date=2 June 2021}}</ref> ] sold in Brazil contains at least 25% ] ethanol. Hydrous ethanol (about 95% ethanol and 5% water) can be used as fuel in more than 90% of new gasoline-fueled cars sold in the country.
Mixtures of ethanol and water that contain more than about 50% ethanol are ] and easily ignited. ] is a widely used measure of how much ethanol (i.e., alcohol) such a mixture contains. In the 18th century, proof was determined by adding a liquor (such as ]) to gunpowder. If the gunpowder still burned, that was considered to be “100 degrees proof” that it was “good” liquor — hence it was called “100 degrees proof”.


The US and many other countries primarily use E10 (10% ethanol, sometimes known as gasohol) and E85 (85% ethanol) ethanol/gasoline mixtures. Over time, it is believed that a material portion of the ≈{{convert|150|e9USgal|m3|adj=on}} per year market for gasoline will begin to be replaced with fuel ethanol.<ref name="rfa1">{{cite web |date=20 November 2006 |title=First Commercial U.S. Cellulosic Ethanol Biorefinery Announced |url=http://www.ethanolmarket.com/PressReleaseRFA102006.html |access-date=31 May 2011 |publisher=Renewable Fuels Association}}</ref>
Ethanol-water solutions that contain less than 50% ethanol may also be flammable if the solution is first heated. Some cooking methods call for ] to be added to a hot pan, causing it to flash boil into a vapor, which is then ignited to burn off excess alcohol.


] ethanol for laboratory use]]
Ethanol is slightly more refractive than water, having a ] of 1.36242 (at λ=589.3&nbsp;nm and 18.35 °C).<ref name="crc"/>


Australian law limits the use of pure ethanol from ] waste to 10 % in automobiles. Older cars (and vintage cars designed to use a slower burning fuel) should have the engine valves upgraded or replaced.<ref>{{cite web | url = http://www.mtfca.com.au | title = Model T Ford Club Australia (Inc.) | last = Green | first = Ray | name-list-style = vanc | access-date = 24 June 2011 | url-status=dead | archive-url = https://web.archive.org/web/20140114075515/http://mtfca.com.au/ | archive-date = 14 January 2014 | df = dmy-all }}</ref>
==Production==
]
Ethanol is produced both as a ], through the hydration of ethylene and, via biological processes, by ] sugars with ].<ref name="Mills-Ecklund">Mills, G.A.; Ecklund, E.E. "{{cite journal|author=Mills GA, Ecklund EE|title=Alcohols as Components of Transportation Fuels|journal=Annual Review of Energy|volume=12|page=47|year=1987|doi=10.1146/annurev.eg.12.110187.000403}}</ref> Which process is more economical depends on prevailing prices of petroleum and grain feed stocks.


According to an industry ], ethanol as a fuel reduces harmful ] of carbon monoxide, particulate matter, ], and other ozone-forming pollutants.<ref>{{cite web | url = http://www.ethanol.org/index.php?id=34&parentid=8#Environment | title = Ethanol 101 | publisher = American Coalition for Ethanol | access-date = 26 March 2011 | archive-date = 14 November 2020 | archive-url = https://web.archive.org/web/20201114003907/https://ethanol.org/index.php?id=34&parentid=8#Environment | url-status = dead }}</ref> ] analyzed greenhouse gas emissions of many different engine and fuel combinations, and found that ]/petrodiesel blend (]) showed a reduction of 8%, conventional ] ethanol blend a reduction of 17% and ] 64%, compared with pure gasoline.<ref>{{cite book | chapter-url = http://www.energyfuturecoalition.org/biofuels/benefits_env_public_health.htm | chapter = The Biofuels FAQs | archive-url = https://web.archive.org/web/20110219052041/http://www.energyfuturecoalition.org/biofuels/benefits_env_public_health.htm | archive-date = 19 February 2011 | title = The Biofuels Source Book | author = Energy Future Coalition | publisher = ] }}</ref> Ethanol has a much greater research octane number (RON) than gasoline, meaning it is less prone to pre-ignition, allowing for better ignition advance which means more torque, and efficiency in addition to the lower carbon emissions.<ref>{{Cite journal|last1=Malaquias|first1=Augusto César Teixeira|last2=Netto|first2=Nilton Antonio Diniz|last3=Filho|first3=Fernando Antonio Rodrigues|last4=da Costa|first4=Roberto Berlini Rodrigues|last5=Langeani|first5=Marcos|last6=Baêta|first6=José Guilherme Coelho|date=2019-11-18|title=The misleading total replacement of internal combustion engines by electric motors and a study of the Brazilian ethanol importance for the sustainable future of mobility: a review|journal=Journal of the Brazilian Society of Mechanical Sciences and Engineering|language=en|volume=41|issue=12|pages=567|doi=10.1007/s40430-019-2076-1|issn=1806-3691|doi-access=free}}</ref>
===Ethylene hydration===
Ethanol for use as an industrial feedstock or solvent (sometimes referred to as synthetic ethanol) is made from ] feed stocks, primarily by the ]-] hydration of ethylene, represented by the ]
:] + H<sub>2</sub>O → CH<sub>3</sub>CH<sub>2</sub>OH


Ethanol ] in an ] yields many of the products of incomplete combustion produced by gasoline and significantly larger amounts of ] and related species such as acetaldehyde.<ref>{{cite web | url = https://www.arb.ca.gov/bluebook/bb10/hea/hea-39037_05.htm | author = California Air Resources Board | title = Definition of a Low Emission Motor Vehicle in Compliance with the Mandates of Health and Safety Code Section 39037.05, second release | date = October 1989 | access-date = 18 February 2018 | archive-url = https://web.archive.org/web/20180218150535/https://www.arb.ca.gov/bluebook/bb10/hea/hea-39037_05.htm | archive-date = 18 February 2018 | url-status = dead }}</ref> This leads to a significantly larger photochemical reactivity and more ].<ref>{{cite book | vauthors = Lowi A, Carter WP | date = March 1990 | title = A Method for Evaluating the Atmospheric Ozone Impact of Actual Vehicle emissions | work = S.A.E. Technical Paper | location = Warrendale, Pennsylvania }}</ref> This data has been assembled into The Clean Fuels Report comparison of fuel emissions<ref>{{cite web | vauthors = Jones TT | year = 2008 | url = http://www.researchandmarkets.com/reports/598475 | title = The Clean Fuels Report: A Quantitative Comparison Of Motor (engine) Fuels, Related Pollution and Technologies | archive-url = https://archive.today/20120909174028/http://www.researchandmarkets.com/reports/598475 | archive-date = 9 September 2012 | url-status=dead | website = researchandmarkets.com }}</ref> and show that ethanol exhaust generates 2.14&nbsp;times as much ozone as gasoline exhaust.<ref>{{cite book | url = {{google books |plainurl=y |id=Qg1qDQAAQBAJ|page=60}} | title = Electro-rheological Fluids and Magneto-rheological Suspensions | work = Proceedings of the 12th International Conference | location = Philadelphia | date = 16–20 August 2010 | last = Tao | first = Rongjia | name-list-style = vanc | publisher =World Scientific | isbn = 9789814340229 }}</ref> When this is added into the custom ''Localized Pollution Index'' of The Clean Fuels Report, the local pollution of ethanol (pollution that contributes to smog) is rated 1.7, where gasoline is 1.0 and higher numbers signify greater pollution.<ref>{{Cite news|url=https://www.scientificamerican.com/article/reduce-air-pollution-do-not-rely-on-ethanol/|title=Want to Reduce Air Pollution? Don't Rely on Ethanol Necessarily|last=Biello|first=David | name-list-style = vanc |work=Scientific American|access-date=11 July 2017|language=en}}</ref> The ] formalized this issue in 2008 by recognizing control standards for formaldehydes as an emissions control group, much like the conventional ] and reactive organic gases (ROGs).<ref>{{cite web|title = Adoption of the Airborne Toxic Control Measure to Reduce Formaldehyde Emissions from Composite Wood Products|url = http://www.wdma.com/TechnicalCenter/GreenZone/CARB/tabid/111/Default.aspx|archive-url = https://web.archive.org/web/20100309071022/http://www.wdma.com/TechnicalCenter/GreenZone/CARB/tabid/111/Default.aspx|archive-date = 9 March 2010|date=30 July 2008|location = Chicago & Washington, DC|publisher = Window and Door Manufacturers Association}}</ref>
The catalyst is most commonly ],<ref name=r_and_c>{{cite book|last1=Roberts|first1=John D.|last2=Caserio|first2=Marjorie C.|authorlink1=John D. Roberts|authorlink2=Marjorie Constance Caserio|year=1977|publisher=W. A. Benjamin, Inc|title=Basic Principles of Organic Chemistry|isbn=0-8053-8329-8}}</ref> ] onto a porous support such as ] or ]. This catalyst was first used for large-scale ethanol production by the ] in 1947.<ref name="ECT4 820">{{cite encyclopedia|chapter=Ethanol|title=Encyclopedia of chemical technology|year=1991|page=82|volume=9}}</ref> The reaction is carried out with an excess of high pressure steam at 300 °C. In the U.S., this process was used on an industrial scale by ] and others; but now only ] uses it commercially.


More than 20% of Brazilian cars are able to use 100% ethanol as fuel, which includes ethanol-only engines and ] engines.<ref>{{cite web|url = http://economia.estadao.com.br/noticias/geral,tecnologia-flex-em-automoveis-atrai-estrangeiros,178105|title = Tecnologia flex atrai estrangeiros|publisher = Agência Estado|language=pt-BR}}</ref> Flex-fuel engines in Brazil are able to work with all ethanol, all gasoline or any mixture of both. In the United States, flex-fuel vehicles can run on 0% to 85% ethanol (15% gasoline) since higher ethanol blends are not yet allowed or efficient. Brazil supports this fleet of ethanol-burning automobiles with large national infrastructure that produces ethanol from domestically grown sugarcane.
In an older process, first practiced on the industrial scale in 1930 by Union Carbide,<ref name="ECT4 817">{{cite book|author=Lodgsdon, J.E|chapter=Ethanol|editor=Howe-Grant, Mary; Kirk, Raymond E.; Othmer, Donald F.; Kroschwitz, Jacqueline I.|title=Encyclopedia of chemical technology|publisher=Wiley|location=New York|year=1991|isbn=0-471-52669-X|edition=4th|volume=9|page=817}}</ref> but now almost entirely obsolete, ethylene was hydrated indirectly by reacting it with concentrated ] to produce ], which was ] to yield ethanol and regenerate the sulfuric acid:<ref name=s_and_h/>
:C<sub>2</sub>H<sub>4</sub> + ] → ]
:] + ] → CH<sub>3</sub>CH<sub>2</sub>OH + ]


Ethanol's high ] with water makes it unsuitable for shipping through modern ] like liquid hydrocarbons.<ref name="HornKrupp2009">{{Cite book|first1=Miriam |last1=Horn|first2=Fred |last2=Krupp | name-list-style = vanc |title=Earth: The Sequel: The Race to Reinvent Energy and Stop Global Warming|journal=Physics Today|volume=62|issue=4|pages=63–65|url={{google books |plainurl=y |id=vjs7GtArBNoC|lage=85}}|date=16 March 2009|isbn=978-0-393-06810-8|bibcode=2009PhT....62d..63K|doi=10.1063/1.3120901|s2cid=153892198 }}</ref> Mechanics have seen increased cases of damage to small engines (in particular, the ]) and attribute the damage to the increased water retention by ethanol in fuel.<ref><!-- http://www.msnbc.msn.com/id/25936782/ -->{{Webarchive|url=https://web.archive.org/web/20200923224041/http://www.nbcnews.com/id/25936782/ |date=23 September 2020 }}, ''NBC News'', 8 January 2008</ref>
===Fermentation===
{{Main|Ethanol fermentation}}


Ethanol was commonly used as fuel in early ] ] (liquid-propelled) vehicles, in conjunction with an ] such as liquid oxygen. The German A-4 ballistic rocket of ] (better known by its propaganda name {{Nowrap|]}}),<ref name="Ignition">{{Cite book |last= Clark |first= John. D. |author-link= John Drury Clark |url= https://archive.org/details/ignitioninformal0000clar |title= Ignition! an informal history of liquid rocket propellants |others= Foreword by Isaac Asimov |date= 1972 |publisher= Rutgers University Press |isbn= 978-0-8135-0725-5 |page= |url-access= registration}}</ref> which is credited as having begun the space age, used ethanol as the main constituent of {{nowrap|'']''}}. Under such nomenclature, the ethanol was mixed with 25% water to reduce the combustion chamber temperature.<ref>{{cite web |url= http://daviddarling.info/encyclopedia/V/V-2.html|title=The Internet Encyclopedia of Science: V-2 |last= Darling |first= David |name-list-style= vanc |access-date= 27 July 2024}}</ref><ref name="braeunig">{{Cite web |title=Basics of Space Flight: Rocket Propellants |url=http://braeunig.us/space/propel.htm|access-date= 11 March 2023 |website=braeunig.us}}</ref> The {{Nowrap|V-2's}} design team helped develop U.S. rockets following World War&nbsp;II, including the ethanol-fueled ], which launched the first U.S. astronaut on ].<ref>{{cite web |title= A Brief History of Rocketry |url= http://science.ksc.nasa.gov/history/rocket-history.txt |work= NASA Historical Archive |archive-url= https://web.archive.org/web/20060805203537/http://science.ksc.nasa.gov/history/rocket-history.txt |archive-date= 5 August 2006 |url-status= dead}}</ref><ref>{{Cite book |last1= Kuettner |first1= Joachim P. |author-link= Joachim Kuettner |url= https://ntrs.nasa.gov/citations/19630012071 |title= Mercury Project Summary Including Results of the Fourth Manned Orbital Flight: May 15 and 16, 1963 |last2= Bertram |first2= Emil |date= October 1963 |page= 70 |chapter= Mercury-Redstone Launch-Vehicle development and performance |id= NASA-SP-45 |chapter-url= https://ntrs.nasa.gov/api/citations/19630012071/downloads/19630012071.pdf#page=78 |via= ]}}</ref> Alcohols fell into general disuse as more energy-dense rocket fuels were developed,<ref name="braeunig" /> although ethanol was used in recent experimental ] ].<ref name="sdc20100426">{{cite web |url= http://www.space.com/businesstechnology/rocket-racing-tulsa-demonstration-100426.html |title= Rocket Racing League Unveils New Flying Hot Rod |first= Denise |last= Chow |name-list-style= vanc |website= ] |date= 26 April 2010 |access-date= 27 July 2024 |archive-url= https://web.archive.org/web/20140308035740/https://www.space.com/8290-rocket-racing-league-unveils-flying-hot-rod.html |archive-date= 8 March 2014 |url-status= live }}</ref>
Ethanol for use in ]s, and the vast majority of ethanol for use as fuel,{{fact|date=February 2012}} is produced by fermentation. When certain species of ] (e.g., '']'') ] ] they produce ethanol and carbon dioxide. The chemical equations below summarize the conversion:
:] → 2 CH<sub>3</sub>CH<sub>2</sub>OH + 2 CO<sub>2</sub>
:] + H<sub>2</sub>O → 4 CH<sub>3</sub>CH<sub>2</sub>OH + 4 CO<sub>2</sub>


Commercial fuel cells operate on reformed natural gas, ] or methanol. Ethanol is an attractive alternative due to its wide availability, low cost, high purity and low toxicity. There is a wide range of fuel cell concepts that have entered trials including ]s, auto-thermal reforming systems and thermally integrated systems. The majority of work is being conducted at a research level although there are a number of organizations at the beginning of the commercialization of ethanol fuel cells.<ref>{{cite journal | vauthors = Badwal SP, Giddey S, Kulkarni A, Goel J, Basu S | title = Direct ethanol fuel cells for transport and stationary applications – A comprehensive review|journal=Applied Energy|date=May 2015|volume=145|pages=80–103|doi=10.1016/j.apenergy.2015.02.002|doi-access=free| bibcode = 2015ApEn..145...80B}}</ref>
Fermentation is the process of culturing yeast under favorable thermal conditions to produce alcohol. This process is carried out at around 35–40 °C. Toxicity of ethanol to yeast limits the ethanol concentration obtainable by brewing; higher concentrations, therefore, are usually obtained by ] or ]. The most ethanol-tolerant strains of yeast can survive up to approximately 15% ethanol by volume.<ref name="mosttolerant">{{cite journal|author=Morais PB, Rosa CA, Linardi VR, Carazza F, Nonato EA|title=Production of fuel alcohol by Saccharomyces strains from tropical habitats|journal=Biotechnology Letters|volume=18|page=1351|year=1996|doi=10.1007/BF00129969|issue=11}}</ref>


Ethanol fireplaces can be used for home heating or for decoration. Ethanol can also be used as stove fuel for cooking.<ref>{{cite news|title=Can Ethanol Fireplaces Be Cozy? |first=Debra Jo |last=Immergut |date=3 December 2015 |url=https://www.wsj.com/articles/one-fire-please-hold-the-soot-1449170833|access-date=2 March 2016|work=The Wall Street Journal}}</ref><ref>{{cite journal |vauthors=Rajvanshi AK, Patil SM, Mendonca B |title = Low-concentration ethanol stove for rural areas in India |journal=Energy for Sustainable Development |volume=11 |issue=1 |date=March 2007 |pages = 94–99 |doi = 10.1016/S0973-0826(08)60568-2 |bibcode = 2007ESusD..11...94R |url=https://www.sciencedirect.com/science/article/pii/S0973082608605682 |citeseerx = 10.1.1.142.5846}}</ref>
To produce ethanol from starchy materials such as ]s, the ] must first be converted into sugars. In brewing ], this has traditionally been accomplished by allowing the grain to germinate, or ], which produces the ] ]. When the malted grain is ], the amylase converts the remaining starches into sugars. For fuel ethanol, the hydrolysis of starch into ] can be accomplished more rapidly by treatment with dilute sulfuric acid, ] produced amylase, or some combination of the two.<ref name=hydrolysis>Badger, P.C. "." p. 17–21. In: J. Janick and A. Whipkey (eds.), Trends in new crops and new uses. ASHS Press, 2002, Alexandria, VA. Retrieved on September 2, 2007.</ref>


====Cellulosic ethanol==== === Other uses===
{{more citations needed section|date=November 2024}}
{{Main|Cellulosic ethanol}}
Ethanol is an important industrial ingredient. It has widespread use as a precursor for other organic compounds such as ethyl ]s, ethyl ]s, diethyl ether, acetic acid, and ethyl ]s. It is considered a universal ], as its ] structure allows for the dissolving of both ], ] and ], ] compounds. As ethanol also has a low ], it is easy to remove from a solution that has been used to dissolve other compounds, making it a popular extracting agent for botanical oils. ] extraction methods often use ethanol as an extraction solvent,<ref>{{Cite web|url=https://www.cannabisbusinesstimes.com/article/your-guide-to-ethanol-extraction/|title=Your Guide to Ethanol Extraction|website=Cannabis Business Times|language=en|access-date=2019-04-09}}</ref> and also as a post-processing solvent to remove oils, waxes, and ] from solution in a process known as ].


Ethanol is found in ]s, tinctures, markers, and personal care products such as mouthwashes, perfumes and deodorants. ] ] from aqueous solution in the presence of alcohol, and ethanol precipitation is used for this reason in the purification of ] and ]. Because of its low ] of {{cvt|-114|C|F}} and low toxicity, ethanol is sometimes used in laboratories (with ] or other coolants) as a ] to keep vessels at temperatures below the freezing point of water. For the same reason, it is also used as the active fluid in ]s.
Sugars for ] can be obtained from ].<ref>{{cite journal|author=Taherzadeh MJ, Karimi K|title=Acid-based hydrolysis processes for ethanol from lignocellulosic materials: A review|journal=BioResources|volume=2|page=472|year=2007|url=http://www.ncsu.edu/bioresources/BioRes_02/BioRes_02_3_472_499_Taherzadeh_K_BioEthanol_Review.pdf}}</ref><ref>{{cite journal|author=Taherzadeh MJ, Karimi K|title=Enzymatic-based hydrolysis processes for ethanol from lignocellulosic materials: A review|journal=BioResources|volume=2|page=707|year=2007|url=http://www.ncsu.edu/bioresources/BioRes_02/BioRes_02_4_707_738_Taherzadeh_K_EnzymeBased_Ethanol_Review.pdf}}</ref> Until recently, however, the cost of the ] enzymes capable of hydrolyzing cellulose has been prohibitive. The Canadian firm ] brought the first cellulose-based ethanol plant on-stream in 2004.<ref name=Ritter>{{cite journal|author=Ritter SK|title=Biomass or Bust|journal=Chemical & Engineering News|volume=82|page=31|issue=22|year=2004|url=http://pubs.acs.org/email/cen/html/060804150713.html}}</ref> Its primary consumer so far has been the Canadian government, which, along with the ], has invested heavily in the commercialization of cellulosic ethanol. Deployment of this technology could turn a number of cellulose-containing agricultural by-products, such as ]s, ], and ], into renewable energy resources. Other enzyme companies are developing genetically engineered fungi that produce large volumes of cellulase, ], and hemicellulase enzymes. These would convert agricultural residues such as ], wheat straw, and sugar cane bagasse and energy crops such as ] into fermentable sugars.<ref>{{cite web|author=Clines, Tom|title=Brew Better Ethanol|publisher=Popular Science Online|month=July|year=2006|url=http://www.popsci.com/popsci/energy/6756226d360ab010vgnvcm1000004eecbccdrcrd.html}}</ref>


== Chemistry ==
Cellulose-bearing materials typically also contain other ]s, including ]. When undergoing hydrolysis, hemicellulose decomposes into mostly five-carbon sugars such as ]. ''S. cerevisiae'', the yeast most commonly used for ethanol production, cannot metabolize xylose. Other yeasts and bacteria are under investigation to ferment xylose and other ]s into ethanol.<!--<ref></ref> --><ref>{{cite web|url=http://www.metabolicengineering.gov/me2001/2001Kompala.pdf|title=Maximizing Ethanol Production by Engineered Pentose-Fermenting ''Zymononas mobilis''|author=Kompala, Dhinakar S.|publisher=Department of Chemical Engineering, University of Colorado at Boulder|accessdate=May 21, 2007|format=PDF}}</ref>
{{more citations needed section|date=November 2024}}
{{Further|Ethanol (data page)}}


Ethanol is a 2-carbon ]. Its ] is CH<sub>3</sub>CH<sub>2</sub>OH. The structure of the molecule of ethanol is {{chem2|CH3\sCH2\sOH}} (an ] linked to a ]), which indicates that the carbon of a ] (CH<sub>3</sub>−) is attached to the carbon of a ] (−CH<sub>2</sub>–), which is attached to the oxygen of a hydroxyl group (−OH). It is a constitutional ] of ]. Ethanol is sometimes abbreviated as '''EtOH''', using the common organic chemistry notation of representing the ethyl group (C<sub>2</sub>H<sub>5</sub>−) with '''Et'''.
On January 14, 2008, ] announced a partnership with Coskata, Inc. The goal is to produce cellulosic ethanol cheaply, with an eventual goal of US$1 per US gallon ($0.30/L) for the fuel. The partnership plans to begin producing the fuel in large quantity by the end of 2008. In June 2009, this goal is still ahead of the firm. By 2011 a full-scale plant will come on line, capable of producing {{convert|50|e6USgal|m3}} to {{convert|100|e6USgal|m3}} of ethanol a year (200–400 ]/]).<ref>{{cite web|author=Mick, Jason|title=Cellulosic Ethanol Promises $1 per Gallon Fuel From Waste|date=2008-01-14|work=DailyTech.com|url=http://www.dailytech.com/Cellulosic+Ethanol+Promises+1+per+Gallon+Fuel+From+Waste/article10320.htm|accessdate=2008-01-15}}</ref>


=== Physical properties ===
===Prospective technologies===<!--potentially misleading, US-oriented, and newsy - overall inappropriate possibly-->
], ]]] ]
The ] ''] ljungdahlii'', discovered in commercial chicken wastes, can produce ethanol from single-carbon sources including ], a mixture of ] and ] that can be generated from the partial ] of either ]s or ]. Use of these bacteria to produce ethanol from synthesis gas has progressed to the pilot plant stage at the ] facility in ], ].<ref>{{cite web|url=ht tp://www.brienergy.com/|title=Providing for a Sustainable Energy Future|publisher=Bioengineering Resources, inc|accessdate=May 21, 2007}}</ref> The BRI technology has been purchased by ].


Ethanol is a volatile, colorless liquid that has a slight odor. It burns with a smokeless blue flame that is not always visible in normal light. The physical properties of ethanol stem primarily from the presence of its hydroxyl group and the shortness of its carbon chain. Ethanol's hydroxyl group is able to participate in hydrogen bonding, rendering it more viscous and less volatile than less polar organic compounds of similar molecular weight, such as ].{{cn|date=November 2024}} Ethanol's ] for combustion in air is 2082 °C or 3779 °F.<ref name="chemss">{{cite news |url=http://www.che.msstate.edu/pdfs/fuel_cell_curriculum/me_mods/ME_Combustion_And_Air_Pollution_Module_1.doc |title=Flame Temperature Analysis and NOx Emissions for Different Fuels |publisher=Mississippi State Department of Chemical Engineering}}</ref>
The ] ] when genetically engineered with cow rumen genes and enzymes can produce ethanol from corn stower.<ref></ref>


Ethanol is slightly more refractive than water, having a ] of 1.36242 (at λ=589.3&nbsp;nm and {{convert|18.35|C|F|disp=or}}).<ref name="crc" /> The ] for ethanol is {{nowrap|150 ± 20 ]}}.<ref>{{Cite web |date=2023 |title=Ethanol |url=https://webbook.nist.gov/cgi/inchi/InChI%3D1S/C2H6O/c1-2-3/h3H%2C2H2%2C1H3 |access-date=2023-12-23 |website=NIST Chemistry WebBook, SRD 69}}</ref>
Another prospective technology is the closed-loop ethanol plant.<ref name="clAlc">{{cite journal|url=http://www.renewableenergyaccess.com/rea/news/story?id=46414|title= Closed-Loop Ethanol Plant to Start Production|date=November 2, 2006|publisher=www.renewableenergyaccess.com|accessdate=2007-09-03}}</ref> Ethanol produced from corn has a number of critics who suggest that it is primarily just recycled fossil fuels because of the energy required to grow the grain and convert it into ethanol. There is also the issue of competition with use of corn for food production. However, the closed-loop ethanol plant attempts to address this criticism. In a closed-loop plant, renewable energy for distillation comes from ], produced from cattle that have been fed the ] by-products from grain ethanol production. The concentrated compost nutrients from manure are then used to fertilize the soil and grow the next crop of grain to start the cycle again. Such a process is expected to lower the fossil fuel consumption used during conversion to ethanol by 75%.<ref name="Rapier-1">Rapier, R. (June 26, 2006) R-Squared Energy Blog</ref>


=== Solvent properties ===
An alternative technology allows for the production of ] from distillers grain as an additional value product.<ref>{{cite web|title=Biodiesel from distiller's grain|url=http://www.license.umn.edu/Products/Biodiesel-and-Enriched-Animal-Feed-from-Dry-Distillers-Grains-with-Solubles-Created-in-Ethanol-Production__Z04005.aspx|publisher=University of Minnesota|accessdate=31 May 2011}}</ref> Though in an early stage of research, there is some development of alternative production methods that use feed stocks such as municipal waste or recycled products, rice hulls, sugarcane bagasse, small diameter trees, wood chips, and switchgrass.<ref>{{cite news|url=http://www.ens-newswire.com/ens/apr2007/2007-04-12-02.asp|title=Air Pollution Rules Relaxed for U.S. Ethanol Producers|date=April 12, 2007|publisher=Environmental News Service|accessdate=2009-06-26}}</ref>
Ethanol is a versatile solvent, ] with water and with many organic solvents, including ], ], ], ], ], diethyl ether, ethylene glycol, ], ], ], and ]. Its main use as a solvent is in making tincture of iodine, cough syrups, etc.<ref name="crc" /><ref name="merck" /> It is also miscible with light aliphatic hydrocarbons, such as ] and ], and with aliphatic chlorides such as ] and ].<ref name="merck">{{cite book | last = Windholz | first = Martha | name-list-style = vanc |title=The Merck index: an encyclopedia of chemicals and drugs|publisher=Merck|location=Rahway, NJ|year=1976|isbn=978-0-911910-26-1|edition=9th}}{{page needed|date=February 2014}}</ref>


Ethanol's miscibility with water contrasts with the immiscibility of longer-chain alcohols (five or more carbon atoms), whose water miscibility decreases sharply as the number of carbons increases.<ref name="m_and_b">{{cite book | last1 = Morrison | first1 = Robert Thornton | last2 = Boyd | first2 = Robert Neilson | name-list-style = vanc |title=Organic Chemistry| url = https://archive.org/details/organicchemistry00morrrich | url-access = registration |edition=2nd|year=1972|publisher=Allyn and Bacon, inc.|isbn=978-0-205-08452-4}}{{page needed|date=February 2014}}</ref> The miscibility of ethanol with ]s is limited to alkanes up to ]: mixtures with ] and higher alkanes show a ] below a certain temperature (about 13&nbsp;°C for dodecane<ref>{{cite journal|vauthors=Dahlmann U, Schneider GM |title=(Liquid + liquid) phase equilibria and critical curves of (ethanol + dodecane or tetradecane or hexadecane or 2,2,4,4,6,8,8-heptamethylnonane) from 0.1 MPa to 120.0 MPa|journal=J Chem Thermodyn|volume=21|pages=997–1004|year=1989|doi=10.1016/0021-9614(89)90160-2|issue=9|bibcode=1989JChTh..21..997D }}</ref>). The miscibility gap tends to get wider with higher alkanes, and the temperature for complete miscibility increases.
===Testing===
]
Breweries and ] plants employ two methods for measuring ethanol concentration. Infrared ethanol sensors measure the vibrational frequency of dissolved ethanol using the CH band at 2900&nbsp;cm<sup>−1</sup>. This method uses a relatively inexpensive solid state sensor that compares the CH band with a reference band to calculate the ethanol content. The calculation makes use of the ]. Alternatively, by measuring the density of the starting material and the density of the product, using a ], the change in specific gravity during fermentation indicates the alcohol content. This inexpensive and indirect method has a long history in the beer brewing industry.


Ethanol-water mixtures have less volume than the sum of their individual components at the given fractions. Mixing equal volumes of ethanol and water results in only 1.92 volumes of mixture.<ref name="crc">{{cite book | editor-last = Lide | editor-first = D. R. | name-list-style = vanc |title=CRC Handbook of Chemistry and Physics 81st edition|publisher=CRC press|year=2000|isbn = 978-0-8493-0481-1}}</ref><ref name="ChemTech">{{cite encyclopedia|chapter=Ethanol|title=Encyclopedia of chemical technology|year=1991|page=813|volume=9|title-link=#Encyc Chem}}</ref> Mixing ethanol and water is ], with up to 777&nbsp;J/mol<ref>{{cite journal|vauthors=Costigan MJ, Hodges LJ, Marsh KN, Stokes RH, Tuxford CW |title=The Isothermal Displacement Calorimeter: Design Modifications for Measuring Exothermic Enthalpies of Mixing|journal=Aust. J. Chem.|volume=33|issue=10|page=2103| year = 1980| doi = 10.1071/CH9802103|bibcode=1982AuJCh..35.1971I}}</ref> being released at 298&nbsp;K.
===Purification===
{{Main|Ethanol purification}}
Ethylene hydration or brewing produces an ethanol–water mixture. For most industrial and fuel uses, the ethanol must be purified. ] can concentrate ethanol to 95.6% by volume (89.5 mole%). This mixture is an ] with a boiling point of 78.1 °C, and cannot be further purified by distillation.


]
Common methods for obtaining absolute ethanol include desiccation using adsorbents such as starch, corn grits, or ]s, which adsorb water preferentially, as well as ] and ]. Most ethanol fuel refineries use an adsorbent or zeolite to desiccate the ethanol stream.


Hydrogen bonding causes pure ethanol to be ] to the extent that it readily absorbs water from the air. The polar nature of the hydroxyl group causes ethanol to dissolve many ionic compounds, notably ] and ]s, ], ], ], ], and ].<ref name="merck" /> ] and ]s are slightly soluble in ethanol.<ref name="merck" /> Because the ethanol molecule also has a nonpolar end, it will also dissolve nonpolar substances, including most ]s<ref name="merckoils">''Merck Index of Chemicals and Drugs'', 9th ed.; monographs 6575 through 6669</ref> and numerous flavoring, coloring, and medicinal agents.
In another method to obtain absolute alcohol, a small quantity of ] is added to ] and the mixture is then distilled. Absolute alcohol is obtained in the third fraction, which distills over at 78.3 °C (351.4 K).<ref name="m_and_b">{{cite book|author=Morrison, Robert Thornton; Boyd, Robert Neilson|title=Organic Chemistry|edition=2nd|year=1972|publisher=Allyn and Bacon, inc.|isbn=0205084524}}</ref> Because a small amount of the benzene used remains in the solution, absolute alcohol produced by this method is not suitable for consumption, as benzene is ].<ref>{{cite journal|author=Snyder R, Kalf GF|title=A perspective on benzene leukemogenesis|journal=Crit. Rev. Toxicol.|volume=24|page=177|year=1994|pmid=7945890|doi=10.3109/10408449409021605|issue=3}}</ref>


The addition of even a few percent of ethanol to water sharply reduces the ] of water. This property partially explains the "]" phenomenon. When wine is swirled in a glass, ethanol evaporates quickly from the thin film of wine on the wall of the glass. As the wine's ethanol content decreases, its surface tension increases and the thin film "beads up" and runs down the glass in channels rather than as a smooth sheet.
There is also an absolute alcohol production process by ] using ]. Alcohol produced by this method is known as spectroscopic alcohol—so called because the absence of benzene makes it suitable as a solvent in ].


=== Azeotrope with water ===
===Grades of ethanol===
At atmospheric pressure, mixtures of ethanol and water form an ] at about 89.4&nbsp;] ethanol (95.6% ethanol by mass,<ref name=NIST-SR1828>{{Cite web |last=National Institute of Standards and Technology |title=Standard Reference Material 1828: Ethanol-Water Solutions |url=https://tsapps.nist.gov/srmext/certificates/archives/1828.pdf}}</ref> 97% ]), with a boiling point of 351.3&nbsp;K (78.1&nbsp;°C).<ref name=PembertonMash>{{cite journal|vauthors=Pemberton RC, Mash CJ |title=Thermodynamic properties of aqueous non-electrolyte mixtures II. Vapour pressures and excess Gibbs energies for water + ethanol at 303.15 to 363.15 K determined by an accurate static method|journal=J Chem Thermodyn|volume=10|pages=867–888|year=1978|doi=10.1016/0021-9614(78)90160-X|issue=9|bibcode=1978JChTh..10..867P }}</ref> At lower pressure, the composition of the ethanol-water azeotrope shifts to more ethanol-rich mixtures.<ref name="Beebe1942">{{cite journal |last1=Beebe |first1=A. H. |last2=Coulter |first2=K. E. |last3=Lindsay |first3=R. A. |last4=Baker |first4=E. M. |title=Equilibria in Ethanol-Water System at Pressures Less Than Atmospheric |journal=Industrial & Engineering Chemistry |date=December 1942 |volume=34 |issue=12 |pages=1501–1504 |doi=10.1021/ie50396a019}}</ref> The minimum-pressure azeotrope has an ethanol fraction of 100%<ref name="Beebe1942"/> and a boiling point of 306&nbsp;K (33&nbsp;°C),<ref name=PembertonMash/> corresponding to a pressure of roughly 70&nbsp;] (9.333&nbsp;kPa).<ref name=PressureSwingDistillation>{{Cite web |title=6.4 Pressure swing distillation {{!}} Hyper-TVT: on line Thermische VerfahrensTechnik |work=Institute of Process Engineering {{!}} ETH Zurich |date=10 November 2003 |access-date=12 October 2024 |url= https://www.hyper-tvt.ethz.ch/distillation-azeotrope-pressure_swing.html |language=en}}</ref> Below this pressure, there is no azeotrope, and it is possible to distill absolute ethanol from an ethanol-water mixture.<ref name=PressureSwingDistillation/>
====Denatured alcohol====
{{Main|Denatured alcohol}}


=== Flammability ===
Pure ethanol and alcoholic beverages are heavily taxed, but ethanol has many uses that do not involve consumption by humans. To relieve the tax burden on these uses, most jurisdictions waive the tax when an agent has been added to the ethanol to render it unfit to drink. These include ] such as ] and toxins such as methanol, ], and ]. Products of this kind are called ''denatured alcohol.''<ref>{{cite web|url=http://www.procurement.umich.edu/Contracts/Denatured_Alchohol.pdf|title=U-M Program to Reduce the Consumption of Tax-free Alcohol; Denatured Alcohol a Safer, Less Expensive Alternative|publisher=University of Michigan|accessdate=2007-09-29|format=PDF}}</ref><ref>Great Britain (2005). ''.'' Statutory Instrument 2005 No. 1524.</ref>
An ethanol–water solution will catch fire if heated above a temperature called its ] and an ignition source is then applied to it.<ref name="flash point">{{cite web |url=http://www.nttworldwide.com/tech2212.htm |title=Flash Point and Fire Point |website=Nttworldwide.com |url-status=dead |archive-url=https://web.archive.org/web/20101214222420/http://www.nttworldwide.com/tech2212.htm |archive-date=14 December 2010 |df=dmy }}</ref> For 20% alcohol by mass (about 25% by volume), this will occur at about {{convert|25|°C|°F}}. The flash point of pure ethanol is {{convert|13|°C|°F}},<ref name="NFPA 325">{{cite book |title=NFPA 325: Guide to Fire Hazard Properties of Flammable Liquids, Gases, and Volatile Solids |date=1 January 1994 |publisher=National Fire Protection Association (NFPA) |location=Quincy, Massachusetts |url=https://standards.globalspec.com/std/638448/NFPA%20325}}</ref> but may be influenced very slightly by atmospheric composition such as pressure and humidity. Ethanol mixtures can ignite below average room temperature. Ethanol is considered a flammable liquid (Class 3 Hazardous Material) in concentrations above 2.35% by mass (3.0% by volume; 6 ]).<ref name="49 CFR 173.120">{{cite web |title=49 CFR §&nbsp;173.120 – Class 3 – Definitions. |publisher=Legal Information Institute |url=https://www.law.cornell.edu/cfr/text/49/173.120 |quote=a flammable liquid (Class 3) means a liquid having a flash point of not more than 60 °C (140 °F)}}</ref><ref name="Martínez et al" /><ref name="49 CFR 172.101">{{cite web |title=49 CFR §&nbsp;172.101 – Purpose and use of hazardous materials table. |publisher=Legal Information Institute, Cornell University |url=https://www.law.cornell.edu/cfr/text/49/172.101 |quote= Hazardous materials descriptions and proper shipping names: Ethanol or Ethyl alcohol or Ethanol solutions or Ethyl alcohol solutions; Hazard class or Division: 3; Identification Numbers: UN1170; PG: II; Label Codes: 3;}}</ref> Dishes using burning alcohol for culinary effects are called ].
<!-- Mass % and volume % (ABV) are not the same. You must convert weight percent to volume percent to compare the values in the table below to common beer and wine values (which are labeled ABV, or "alcohol by volume"). For example, 5 wt% ethanol in water is approximately 6.3 vol% ethanol in water. -->


{| class="wikitable mw-collapsible mw-collapsed" style="white-space: nowrap; text-align: center;"
====Absolute ethanol====
|+ Flash points of ethanol–water mixtures<ref name="Ha et al">{{cite journal |last1=Ha |first1=Dong-Myeong |last2=Park |first2=Sang Hun |last3=Lee |first3=Sungjin |title=The Measurement of Flash Point of Water-Methanol and Water-Ethanol Systems Using Seta Flash Closed Cup Tester |journal=Fire Science and Engineering |date=April 2015 |volume=29 |issue=2 |pages=39–43 |doi=10.7731/KIFSE.2015.29.2.039 |url=https://www.researchgate.net/publication/277973979 |quote=Page 4, Table 3}}</ref><ref name="Martínez et al">{{cite journal |last1=Martínez |first1=P. J. |last2=Rus |first2=E. |last3=Compaña |first3=J. M. |title=Flash Point Determination of Binary Mixtures of Alcohols, Ketones and Water |journal=Departamento de Ingeniería Química, Facultad de Ciencias |url=https://engage.aiche.org/HigherLogic/System/DownloadDocumentFile.ashx?DocumentFileKey=e53a8ccc-48b1-4e3b-b59f-bb579cc5132b&ssopc=1 |at=p. 3, Table 4}}</ref><ref name="eng">{{cite web |url=http://www.engineeringtoolbox.com/ethanol-water-d_989.html |title=Flash points of ethanol-based water solutions |access-date=23 June 2011 |website=Engineeringtoolbox.com}}</ref>
Absolute or anhydrous alcohol refers to ethanol with a low water content. There are various grades with maximum water contents ranging from 1% to ppm levels. Absolute alcohol is not intended for human consumption. If ] is used to remove water, it will contain trace amounts of the material separation agent (e.g. benzene).<ref>August Bernthsen, Raj K. Bansal , (2003) ISBN 81-224-1459-1 p. 402</ref> Absolute ethanol is used as a solvent for laboratory and industrial applications, where water will react with other chemicals, and as fuel alcohol. Spectroscopic ethanol is an absolute ethanol with a low absorbance in ] and visible light, fit for use as a solvent in ].<ref>Gary D. Christian Analytical chemistry, Vol. 1, Wiley, 2003 ISBN 0-471-21472-8</ref>
! rowspan="2" | Ethanol<br /> ], %

! colspan="2" | Temperature
Pure ethanol is classed as 200 ] in the USA, equivalent to 175 degrees proof in the UK system.<ref>, Tata McGraw-Hill, 2007 ISBN 0-07-065573-1 p. 268</ref>

====Rectified spirits====
Rectified spirit, an azeotropic composition containing 4% water, is used instead of anhydrous ethanol for various purposes. Wine spirits are about 188 ]. The impurities are different from those in 190 proof laboratory ethanol.<ref>{{cite journal|journal=Appl Microbiol.|year=1968|volume=16|issue=7|page=1067|pmc=547590|title=Sugar and Alcohol Stabilization of Yeast in Sweet Wine|author = Ralph E. Kunkee and Maynard A. Amerine}}</ref>

==Reactions==
{{Details|Alcohol}}
Ethanol is classified as a primary alcohol, meaning that the carbon its hydroxyl group attaches to has at least two hydrogen atoms attached to it as well. Many ethanol reactions occur at its ] group.

===Ester formation===
In the presence of acid catalysts, ethanol reacts with ]s to produce ethyl ]s and water:
:] + HOCH<sub>2</sub>CH<sub>3</sub> → ] + H<sub>2</sub>O
This reaction, which is conducted on large scale industrially, requires the removal of the water from the reaction mixture as it is formed. Esters react in the presence of an acid or base to give back the alcohol and a salt. This reaction is known as ] because it is used in the preparation of soap. Ethanol can also form esters with inorganic acids. ] and ] are prepared by treating ethanol with sulfur trioxide and ] respectively. ] is a useful ethylating agent in ]. ], prepared from the reaction of ethanol with ] and sulfuric acid, was formerly a widely used ].

===Dehydration===
Strong acid desiccants cause the dehydration of ethanol to form ] and other byproducts. If the dehydration temperature exceeds around 160 °C, ] will be the main product. Millions of kilograms of diethyl ether are produced annually using ] catalyst:
:2 CH<sub>3</sub>CH<sub>2</sub>OH → CH<sub>3</sub>CH<sub>2</sub>OCH<sub>2</sub>CH<sub>3</sub> + H<sub>2</sub>O (on 120 °C)

===Combustion===
Complete ] of ethanol forms ] and ] vapor:
:C<sub>2</sub>H<sub>5</sub>OH (l) + 3 O<sub>2</sub> (g) → 2 CO<sub>2</sub> (g) + 3 H<sub>2</sub>O (g); (ΔH<sub>c</sub> = −1371 kJ/mol<ref>{{cite journal|title=Heats of Formation of Simple Organic Molecules|author=Frederick D. Rossini|journal=Ind. Eng. Chem.|year=1937|volume=29|page=1424|doi=10.1021/ie50336a024|issue=12}}</ref>) specific heat = 2.44 kJ/(kg·K)

===Acid-base chemistry===
Ethanol is a neutral molecule and the ] of a solution of ethanol in water is nearly 7.00. Ethanol can be quantitatively converted to its ], the ] ion (CH<sub>3</sub>CH<sub>2</sub>O<sup>−</sup>), by reaction with an ] such as ]:<ref name=m_and_b/>
:2 CH<sub>3</sub>CH<sub>2</sub>OH + 2 Na → 2 CH<sub>3</sub>CH<sub>2</sub>ONa + H<sub>2</sub>
or a very strong base such as ]:
:CH<sub>3</sub>CH<sub>2</sub>OH + NaH → CH<sub>3</sub>CH<sub>2</sub>ONa + H<sub>2</sub>
The acidity of water and ethanol are nearly the same, as indicated by their ] of 15.7 and 16 respectively. Thus, sodium ethoxide and ] exist in an equilbrium that is closely balanced:
:CH<sub>3</sub>CH<sub>2</sub>OH + NaOH {{eqm}} CH<sub>3</sub>CH<sub>2</sub>ONa + H<sub>2</sub>O

===Halogenation===
Ethanol is not used industrially as a precursor to ethyl halides, but the reactions are illustrative. Ethanol reacts with ]s to produce ] such as ] and ] via an ]:
:CH<sub>3</sub>CH<sub>2</sub>OH + ] → CH<sub>3</sub>CH<sub>2</sub>Cl + H<sub>2</sub>O
These reactions require a catalyst such as ].<ref name="s_and_h">{{cite book|author=]; ]|title=Introduction to Organic Chemistry|year=1976|publisher=MacMillan|isbn=0-02-418010-6}}</ref>
HBr requires ] with a ] catalyst.<ref name=s_and_h/> Ethyl halides can, in principle, also be produced by treating ethanol with more specialized ], such as ] or ].<ref name=m_and_b/><ref name=s_and_h/>
:CH<sub>3</sub>CH<sub>2</sub>OH + SOCl<sub>2</sub> → CH<sub>3</sub>CH<sub>2</sub>Cl + SO<sub>2</sub> + HCl

Upon treatment with halogens in the presence of base, ethanol gives the corresponding ] (CHX<sub>3</sub>, where X = Cl, Br, I). This conversion is called the ].<ref>Chakrabartty, in Trahanovsky, ''Oxidation in Organic Chemistry'', pp 343–370, Academic Press, New York, '''1978'''</ref> "
An intermediate in the reaction with chlorine is the ] called ]:
:4 Cl<sub>2</sub> + CH<sub>3</sub>CH<sub>2</sub>OH → CCl<sub>3</sub>CHO + 5 HCl

===Oxidation===
Ethanol can be oxidized to ] and further oxidized to ], depending on the reagents and conditions.<ref name="s_and_h"/> This oxidation is of no importance industrially, but in the human body, these oxidation reactions are catalyzed by the ] ]. The oxidation product of ethanol, acetic acid, is a nutrient for humans, being a precursor to ], where the acetyl group can be spent as energy or used for biosynthesis.

==Uses==
===As a fuel===
{|class=wikitable style="float:right; margin-left:1em;"
|- |-
! °C
!colspan=4|] of some fuels compared with ethanol:<ref name=TEDB> from the ] of the ]</ref>
! °F
|- |-
| 1 || {{convert|84.5|°C|°F|disp=table}}<ref name="Martínez et al" />
!Fuel type|| MJ/L|| MJ/kg|| ]
|- |-
| 2 || {{convert|64|°C|°F|disp=table}}<ref name="Martínez et al" />
|]||||~19.5||
|- |-
| 2.35 || {{convert|60|°C|°F|disp=table}}<ref name="Martínez et al" /><ref name="49 CFR 173.120" />
|]||17.9||19.9||108.7<ref name='Fuel 89 (2010) 2713-2720'>{{cite journal|doi=10.1016/j.fuel.2010.01.032|title = Impact of alcohol–gasoline fuel blends on the performance and combustion characteristics of an SI engine|year=2010|last1=Eyidogan|first1=Muharrem|last2=Ozsezen|first2=Ahmet Necati|last3=Canakci|first3=Mustafa|last4=Turkcan|first4=Ali|journal=Fuel|volume=89|issue=10|pages=2713–2720}}</ref>
|- |-
| 3 || {{convert|51.5|°C|°F|disp=table}}<ref name="Martínez et al" />
|]||21.2<ref name=Thomas>Thomas, George: {{PDF||99.6&nbsp;KB}}. Livermore, CA. Sandia National Laboratories. 2000.</ref>||26.8<ref name=Thomas />
||108.6<ref name='Fuel 89 (2010) 2713-2720'/>
|- |-
| 5 || {{convert|43|°C|°F|disp=table}}<ref name="Ha et al" />
|]<br />(85% ethanol, 15% gasoline)||25.2||33.2||105
|- |-
| 6 || {{convert|39.5|°C|°F|disp=table}}<ref name="Martínez et al" />
|]||25.3||~55||
|- |-
| 10 || {{convert|31|°C|°F|disp=table}}<ref name="Ha et al" />
|] (])<br />(60% ] + 40% ])||26.8||50.||
|- |-
| 20 || {{convert|25|°C|°F|disp=table}}<ref name="Martínez et al" />
|]<br />(high-octane gasoline, not jet fuel)||33.5||46.8||100/130 (lean/rich)
|- |-
| 30 || {{convert|24|°C|°F|disp=table}}<ref name="Ha et al" />
|]<br />(90% gasoline + 10% ethanol)||33.7||47.1||93/94
|- |-
| 50 || {{convert|20|°C|°F|disp=table}}<ref name="Ha et al" /><ref name="Martínez et al" />
|Regular gasoline||34.8||44.4<ref>{{cite news|url=http://www1.eere.energy.gov/hydrogenandfuelcells/pdfs/storage.pdf|author=Thomas, George|title=Overview of Storage Development DOE Hydrogen Program |publisher=Sandia National Laboratories|year=2000|accessdate=2009-08-01}}</ref>||min. 91
|- |-
| 70 || {{convert|16|°C|°F|disp=table}}<ref name="Ha et al" />
|Premium gasoline||||||max. 104
|- |-
| 80 || {{convert|15.8|°C|°F|disp=table}}<ref name="Martínez et al" />
|]||38.6||45.4||25
|- |-
| 90 || {{convert|14|°C|°F|disp=table}}<ref name="Ha et al" />
|], extruded||50||23||
|-
| 100 || {{convert|12.5|°C|°F|disp=table}}<ref name="Ha et al" /><ref name="Martínez et al" /><ref name="NFPA 325" />
|} |}
{{Main|Ethanol fuel}}


== Natural occurrence ==
The largest single use of ethanol is as a motor ] and ]. More than any other major country, ] relies on ethanol as a motor fuel. ] sold in Brazil contains at least 25% ] ethanol. Hydrous ethanol (about 95% ethanol and 5% water) can be used as fuel in more than 90% of new cars sold in the country. Brazilian ethanol is produced from ] and noted for high ].<ref name="WaPo-Brazil">Reel, M. (August 19, 2006) , '']''.</ref> The US uses Gasohol (max 10% ethanol) and E85 (85% ethanol) ethanol/gasoline mixtures.
Ethanol is a byproduct of the metabolic process of yeast. As such, ethanol will be present in any yeast habitat. Ethanol can commonly be found in overripe fruit.<ref>{{cite journal | vauthors = Dudley R | title = Ethanol, fruit ripening, and the historical origins of human alcoholism in primate frugivory | journal = Integrative and Comparative Biology | volume = 44 | issue = 4 | pages = 315–323 | date = August 2004 | pmid = 21676715 | doi = 10.1093/icb/44.4.315 | doi-access = free }}</ref> Ethanol produced by symbiotic yeast can be found in ] blossoms. Although some animal species, such as the ], exhibit ethanol-seeking behaviors, most show no interest or avoidance of food sources containing ethanol.<ref>{{cite web|title=Fact or Fiction?: Animals Like to Get Drunk| last = Graber | first = Cynthia | name-list-style = vanc |year=2008|url=http://www.scientificamerican.com/article.cfm?id=animals-like-to-get-drunk|website=Scientific American|access-date=23 July 2010}}</ref> Ethanol is also produced during the germination of many plants as a result of natural ].<ref>{{cite journal|doi=10.1007/BF02922229 | last1 =Leblová | first1 = Sylva | last2 = Sinecká | first2 = Eva | last3 = Vaníčková | first3 = Věra | name-list-style = vanc |title=Pyruvate metabolism in germinating seeds during natural anaerobiosis|year=1974|journal=Biologia Plantarum|volume=16|issue=6|pages=406–411| s2cid =34605254 }}</ref>
] grade ethanol for laboratory use.]]
Ethanol may also be utilized as a ], and is currently in ] ].<ref name=sdc20100426>
, by Denise Chow, '']'', 2010-04-26. Retrieved 2010-04-27.</ref>


Ethanol has been detected in ], forming an icy coating around dust grains in ]s.<ref>{{cite journal|doi=10.1016/j.chemphys.2007.02.018|title=One possible origin of ethanol in interstellar medium: Photochemistry of mixed CO<sub>2</sub>–C<sub>2</sub>H<sub>6</sub> films at 11 K. A FTIR study | vauthors = Schriver A, Schriver-Mazzuoli L, Ehrenfreund P, d'Hendecourt L |journal=Chemical Physics|volume=334|issue=1–3|year=2007|pages=128–137|bibcode = 2007CP....334..128S}}</ref>
Australian law limits of the use of pure Ethanol sourced from Sugarcane waste to up to 10% in automobiles. It has been recommended that older cars (and vintage cars designed to use a slower burning fuel) have their valves upgraded or replaced.<ref>{{cite web|url=http://www.mtfca.com.au|title=Model T Ford Club Australia (Inc.)|last=Green|first=Ray|accessdate=24 June 2011}}</ref>
Minute quantity amounts (average 196 ]) of endogenous ethanol and acetaldehyde were found in the exhaled breath of healthy volunteers.<ref>{{cite journal | vauthors = Turner C, Spanel P, Smith D | title = A longitudinal study of ethanol and acetaldehyde in the exhaled breath of healthy volunteers using selected-ion flow-tube mass spectrometry | journal = Rapid Communications in Mass Spectrometry | volume = 20 | issue = 1 | pages = 61–68 | year = 2006 | pmid = 16312013 | doi = 10.1002/rcm.2275 | bibcode = 2006RCMS...20...61T }}</ref> ], also known as gut fermentation syndrome, is a rare medical condition in which intoxicating quantities of ethanol are produced through ] ] within the ].<ref>{{cite web|url=https://www.npr.org/blogs/thesalt/2013/09/17/223345977/auto-brewery-syndrome-apparently-you-can-make-beer-in-your-gut|title=Auto-Brewery Syndrome: Apparently, You Can Make Beer In Your Gut| first = Michaeleen | last = Doucleff | name-list-style = vanc |publisher=NPR|date=17 September 2013}}</ref>


== Production ==
Ethanol as a fuel reduces harmful ] of carbon monoxide, particulate matter, ], and other ozone-forming pollutants.<ref> ]</ref> ] analyzed the greenhouse gas emissions of many different engine and fuel combinations. Comparing ethanol blends with gasoline alone, they showed reductions of 8% with the ]/petrodiesel blend known as ], 17% with the conventional ] ethanol blend, and that using ] lowers emissions 64%.<ref> The Biofuels Source Book, Energy Future Coalition, ]</ref>
]


Ethanol is produced both as a ], through the hydration of ] and, via biological processes, by fermenting ]s with ].<ref name="Mills-Ecklund">{{cite journal|vauthors=Mills GA, Ecklund EE |title=Alcohols as Components of Transportation Fuels|journal=]|volume=12|pages=47–80|year=1987|doi=10.1146/annurev.eg.12.110187.000403|doi-access=free}}</ref> Which process is more economical depends on prevailing prices of ] and grain feed stocks.
Ethanol combustion in an internal combustion engine yields many of the products of incomplete combustion produced by gasoline and significantly larger amounts of ] and related species such as acetaldehyde.<ref>California Air Resources Board, Definition of a Low Emission Motor Vehicle in Compliance with the Mandates of Health and Safety Code Section 39037.05, second release, October 1989</ref> This leads to a significantly larger photochemical reactivity that generates much more ].<ref>Lowi, A. and Carter, W.P.L.; A Method for Evaluating the Atmospheric Ozone Impact of Actual Vehicle emissions, S.A.E. Technical Paper, Warrendale, PA; March 1990</ref> These data have been assembled into The Clean Fuels Report comparison of fuel emissions<ref>Jones, T.T.M. (2008)</ref> and show that ethanol exhaust generates 2.14 times as much ozone as does gasoline exhaust.{{citation needed|date=March 2011}} When this is added into the custom ''Localised Pollution Index (LPI)'' of The Clean Fuels Report the local pollution (pollution that contributes to smog) is 1.7 on a scale where gasoline is 1.0 and higher numbers signify greater pollution. The ] formalized this issue in 2008 by recognizing control standards for formaldehydes as an emissions control group, much like the conventional ] and Reactive Organic Gases (ROGs).<ref>{{cite web|title = Adoption of the Airborne Toxic Control Measure to Reduce Formaldehyde Emissions from Composite Wood Products|url = https://www.wdma.com/TechnicalCenter/GreenZone/CARB/tabid/111/Default.aspx|location = USA|publisher = Window and Door Manufacturers Association}}</ref>


=== Sources ===
] where the fuel is available commercially.]]
World production of ethanol in 2006 was {{convert|51|GL|usgal}}, with 69% of the world supply coming from Brazil and the U.S.<ref name=":0" /> Brazilian ethanol is produced from sugarcane, which has relatively high yields (830% more fuel than the fossil fuels used to produce it) compared to some other ]s.<ref name="WaPo-Brazil">{{cite news |date=19 August 2006 |title=Brazil's Road to Energy Independence |newspaper=] |url=https://www.washingtonpost.com/wp-dyn/content/article/2006/08/19/AR2006081900842.html |vauthors=Reel M}}</ref> Sugarcane not only has a greater concentration of sucrose than corn (by about 30%), but is also much easier to extract. The ] generated by the process is not discarded, but burned by power plants to produce electricity. Bagasse burning accounts for around 9% of the electricity produced in Brazil.<ref>{{Cite journal |last1=Rossi |first1=Liane M. |last2=Gallo |first2=Jean Marcel R. |last3=Mattoso |first3=Luiz H. C. |last4=Buckeridge |first4=Marcos S. |last5=Licence |first5=Peter |last6=Allen |first6=David T. |date=2021-03-29 |title=Ethanol from Sugarcane and the Brazilian Biomass-Based Energy and Chemicals Sector |journal=ACS Sustainable Chemistry & Engineering |language=en |volume=9 |issue=12 |pages=4293–4295 |doi=10.1021/acssuschemeng.1c01678 |s2cid=233676614 |issn=2168-0485|doi-access=free }}</ref>
World production of ethanol in 2006 was {{convert|51|GL|usgal}}, with 69% of the world supply coming from Brazil and the United States.<ref>{{cite web|title = 2008 World Fuel Ethanol Production|url = http://www.ethanolrfa.org/pages/statistics/#E|location = USA|publisher = Renewable Fuels Association}}</ref> More than 20% of Brazilian cars are able to use 100% ethanol as fuel, which includes ethanol-only engines and ] engines.<ref>{{cite web|url=http://www.estadao.com.br/economia/not_eco178105,0.htm|title=Tecnologia flex atrai estrangeiros|publisher=Agência Estado}}</ref> Flex-fuel engines in Brazil are able to work with all ethanol, all gasoline or any mixture of both. In the US flex-fuel vehicles can run on 0% to 85% ethanol (15% gasoline) since higher ethanol blends are not yet allowed or efficient. Brazil supports this population of ethanol-burning automobiles with large national infrastructure that produces ethanol from domestically grown ]. ] not only has a greater concentration of sucrose than corn (by about 30%), but is also much easier to extract. The ] generated by the process is not wasted, but is used in power plants as a surprisingly efficient fuel to produce electricity.{{Citation needed|date=January 2010}}


In the 1970s most industrial ethanol in the U.S. was made as a petrochemical, but in the 1980s the U.S. introduced subsidies for ].<ref name="WittcoffReuben2004">{{cite book |last1=Wittcoff |first1=Harold A. |url={{google books |plainurl=y |id=4KHzc-nYPNsC|page=136}} |title=Industrial Organic Chemicals |last2=Reuben |first2=Bryan G. |last3=Plotkin |first3=Jeffery S. |publisher=John Wiley & Sons |year=2004 |isbn=978-0-471-44385-8 |pages=136– |name-list-style=vanc}}</ref> According to the Renewable Fuels Association, as of 30 October 2007, 131 grain ethanol bio-refineries in the U.S. have the capacity to produce {{convert|7|e9USgal|m3|abbr=on}} of ethanol per year. An additional 72 construction projects underway (in the U.S.) can add {{convert|6.4|e9USgal|m3}} of new capacity in the next 18 months.<ref name="rfa1" />
] "fueled by clean burning ethanol" owned by ].]]
The United States fuel ethanol industry is based largely on ]. According to the Renewable Fuels Association, as of October 30, 2007, 131 grain ethanol bio-refineries in the United States have the capacity to produce {{convert|7.0|e9USgal|m3}} of ethanol per year. An additional 72 construction projects underway (in the U.S.) can add {{convert|6.4|e9USgal|m3}} of new capacity in the next 18 months. Over time, it is believed that a material portion of the ≈{{convert|150|e9USgal|m3|adj=on}} per year market for gasoline will begin to be replaced with fuel ethanol.<ref name="rfa1">{{cite web|url=http://www.ethanolmarket.com/PressReleaseRFA102006.html|title=First Commercial U.S. Cellulosic Ethanol Biorefinery Announced|date=2006-11-20|publisher=Renewable Fuels Association|accessdate=May 31, 2011}}</ref>
] vehicle running on ], a "flex-fuel" blend in ], ].]]


In India ethanol is made from sugarcane.<ref>{{Cite book |last=Swami |first=V. N. |publisher=Vidyabharti Publication |year=2020 |location=], Maharashtra, India |page=119 |language=mr |script-title=mr:विद्याभराती जिल्हा मध्यवर्ती सहकारी बँक भारती परीक्षा मार्गदर्शक |trans-title=Vidyabharti District Co-operative Bank recruitment examination guide (Bank clerk grade examination)}}</ref> ] is another potential source of ethanol, and is suitable for growing in dryland conditions. The ] is investigating the possibility of growing sorghum as a source of fuel, food, and animal feed in arid parts of ] and ].<ref>{{Cite web |title=Sweet sorghum for food, feed and fuel |date=January 2008 |website=New Agriculturalist |url=http://resourcespace.icrisat.ac.in/filestore/8/4/0_6c06c9b61b19c20/840_be710da94740b90.pdf|access-date=2023-03-11|archive-url=https://web.archive.org/web/20150904014010/http://resourcespace.icrisat.ac.in/filestore/8/4/0_6c06c9b61b19c20/840_be710da94740b90.pdf |archive-date=4 September 2015 }}</ref> Sweet sorghum has one-third the water requirement of sugarcane over the same time period. It also requires about 22% less water than corn. The world's first sweet sorghum ethanol distillery began commercial production in 2007 in ], ].<ref> {{Webarchive|url=https://web.archive.org/web/20140223044045/http://exploreit.icrisat.org/sites/default/files/uploads/1378281395_DevelopingASweetSorghum_2013.pdf |date=23 February 2014 }}. ], 2013</ref>
One problem with ethanol is its high ] with water, which means that it cannot be efficiently shipped through modern ], like liquid hydrocarbons, over long distances.<ref>W. Horn and F. Krupp. Earth: The Sequel: The Race to Reinvent Energy and Stop Global Warming. 2006, 85</ref> Mechanics also have seen increased cases of damage to small engines, in particular, the carburetor, attributable to the increased water retention by ethanol in fuel.<ref>, msnbc.com, 8 January 2008</ref>


Ethanol has been produced in the laboratory by converting ] via biological and ] reactions.<ref>{{cite journal | vauthors = Liew F, Henstra AM, Köpke M, Winzer K, Simpson SD, Minton NP | title = Metabolic engineering of Clostridium autoethanogenum for selective alcohol production | journal = Metabolic Engineering | volume = 40 | pages = 104–114 | date = March 2017 | pmid = 28111249 | doi = 10.1016/j.ymben.2017.01.007 | pmc=5367853}}</ref><ref>{{Cite news|url=https://newscenter.lbl.gov/2017/09/18/solar-fuel-system-recycles-co2-for-ethanol-ethylene/|title=Solar-to-Fuel System Recycles CO2 for Ethanol and Ethylene|date=18 September 2017|work=News Center|access-date=19 September 2017|language=en-US}}</ref>
===Alcoholic beverages===
{{Main|Alcoholic beverage}}
Ethanol is the principal psychoactive constituent in ]s, with ] effects on the ]. It has a complex mode of action and affects multiple systems in the brain, the most notable one being its agonistic action on the ]s.<ref>{{cite journal|author=Chastain G|title=Alcohol, neurotransmitter systems, and behavior|journal=The Journal of general psychology|volume=133|page=329|year=2006|pmid=17128954|doi=10.3200/GENP.133.4.329-335|issue=4}}</ref> Similar psychoactives include those that also interact with ]s, such as ] (GHB).<ref name="boggan2"/> Ethanol is metabolized by the body as an energy-providing nutrient, as it metabolizes into ], an intermediate common with glucose and ] metabolism that can be used for energy in the ] or for biosynthesis.


{{block indent|CO<sub>2</sub> + {{chem|H|2|O}} → {{chem|CH|3|C|H|2|O}}H + side products}}
Alcoholic beverages vary considerably in ethanol content and in foodstuffs they are produced from. Most alcoholic beverages can be broadly classified as ]s, beverages made by the action of yeast on sugary foodstuffs, or ]s, beverages whose preparation involves concentrating the ethanol in fermented beverages by ]. The ethanol content of a beverage is usually measured in terms of the volume fraction of ethanol in the beverage, expressed either as a percentage or in ] units.


=== Hydration ===
Fermented beverages can be broadly classified by the foodstuff they are fermented from. ]s are made from ]s or other ]y materials, ]s and ]s from ]s, and ]s from ]. Cultures around the world have made fermented beverages from numerous other foodstuffs, and local and national names for various fermented beverages abound.
Ethanol can be produced from petrochemical feed stocks, primarily by the ]-] ] of ethylene. It is often referred to as synthetic ethanol.


:{{chem2| C2H4 + H2O -> C2H5OH }}
Distilled beverages are made by distilling fermented beverages. Broad categories of distilled beverages include ]s, distilled from fermented cereal grains; ], distilled from fermented fruit juices; and ], distilled from fermented ] or ] juice. ] and similar ] can be distilled from any fermented material (grain, tomatoes or ]es are most common); these spirits are so thoroughly distilled that no tastes from the particular starting material remain. Numerous other spirits and liqueurs are prepared by infusing flavors from ]s, ]s, and ]s into distilled spirits. A traditional example is ], which is created by infusing ] berries into a neutral grain alcohol.


The catalyst is most commonly ],<ref name="r_and_c">{{cite book|last1=Roberts|first1=John D.|last2=Caserio|first2=Marjorie C.|name-list-style=vanc|author-link1=John D. Roberts|author-link2=Marjorie Constance Caserio|year=1977|publisher=W. A. Benjamin |title=Basic Principles of Organic Chemistry|isbn=978-0-8053-8329-4|url=https://archive.org/details/basicprincipleso1977obe}}{{page needed|date=February 2014}}</ref><ref name="ullmann" /> ] onto a porous support such as ] or ]. This catalyst was first used for large-scale ethanol production by the ] in 1947.<ref name="ECT4 820">{{cite encyclopedia|chapter=Ethanol|title=Encyclopedia of chemical technology|year=1991|page=82|volume=9}}</ref> The reaction is carried out in the presence of high pressure steam at {{convert|300|C|F}} where a 5:3 ethylene to steam ratio is maintained.<ref> {{Webarchive|url=https://web.archive.org/web/20150113175914/http://www.essentialchemicalindustry.org/chemicals/ethanol.html |date=13 January 2015 }}. ''Essential Chemical Industry''.</ref><ref>{{cite web|last=Harrison |first=Tim |date=May 2014 |url=http://www.chemlabs.bris.ac.uk/outreach/resources/Catalysis%20Web%20Pages%20for%20PreUniversity%20students%20V1_0.pdf |title=Catalysis Web Pages for Pre-University Students V1_0 |archive-url=https://web.archive.org/web/20210305074612/http://www.chemlabs.bris.ac.uk/outreach/resources/Catalysis%20Web%20Pages%20for%20PreUniversity%20students%20V1_0.pdf |archive-date=5 March 2021 |website=Bristol ChemLabs, School of Chemistry |publisher=University of Bristol}}</ref> This process was used on an industrial scale by ] Corporation and others. It is no longer practiced in the US as fermentation ethanol produced from corn is more economical.<ref>{{Cite web |last=Tullo |first=Alexander |date=2021-08-26 |title=Last synthetic ethanol plant in US to close |url=https://cen.acs.org/energy/biofuels/Last-synthetic-ethanol-plant-US/99/i31 |access-date=2022-11-22 |website=cen.acs.org}}</ref>
In a few beverages, ethanol is concentrated by means other than distillation. ] is traditionally made by ], by which water is frozen out of fermented ], leaving a more ethanol-rich liquid behind. ] (also known by the ] term ''Eisbier'' or '']'') is also freeze-distilled, with ] as the base beverage. ]s are prepared by adding brandy or some other distilled spirit to partially fermented wine. This kills the yeast and conserves some of the ] in grape juice; such beverages not only are more ethanol-rich but are often sweeter than other wines.


In an older process, first practiced on the industrial scale in 1930 by Union Carbide<ref name="ECT4 817">{{cite book| vauthors = Lodgsdon JE | chapter=Ethanol|editor1-last=Howe-Grant |editor1-first=Mary |editor2-last=Kirk |editor2-first=Raymond E. |editor3-last=Othmer |editor3-first=Donald F. |editor4-last=Kroschwitz |editor4-first=Jacqueline I. |title=Encyclopedia of chemical technology |publisher=Wiley|location=New York|year=1991|isbn=978-0-471-52669-8|edition=4th|volume=9|page=817}}</ref> but now almost entirely obsolete, ethylene was hydrated indirectly by reacting it with concentrated ] to produce ], which was ] to yield ethanol and regenerate the sulfuric acid:<ref name="s_and_h" />
Alcoholic beverages are sometimes used in cooking, not only for their inherent flavors but also because the alcohol dissolves hydrophobic flavor compounds, which water cannot.


:{{chem2| C2H4 + H2SO4 -> C2H5HSO4 }}
Just as industrial ethanol is used as feedstock for the production of industrial acetic acid, alcoholic beverages are made into culinary/household ]: ] and ] are both named for their respective source alcohols, whereas ] is derived from beer.
:{{chem2| C2H5HSO4 + H2O -> H2SO4 + C2H5OH }}


===Feedstock=== === Fermentation ===
{{more citations needed section|date=November 2024}}
{{Main|Chemical derivatives of ethanol}}
{{Main|Ethanol fermentation|Cellulosic ethanol}}
{{See also|Yeast in winemaking}}
Ethanol in ]s and fuel is produced by fermentation. Certain species of yeast (e.g., '']'') metabolize sugar (namely ]s), producing ethanol and carbon dioxide. The chemical equations below summarize the conversion:


{{block indent|] → 2 {{chem|CH|3|C|H|2|O}}H + 2 CO<sub>2</sub>}}
Ethanol is an important industrial ingredient and has widespread use as a base chemical for other organic compounds. These include ethyl ]s, ethyl ]s, diethyl ether, acetic acid, ethyl ]s, and to a lesser extent ].
{{block indent|] + {{chem|H|2|O}} → 4 {{chem|CH|3|C|H|2|O}}H + 4 CO<sub>2</sub>}}


Fermentation is the process of culturing yeast under favorable thermal conditions to produce alcohol. This process is carried out at around {{convert|35|-|40|C|F}}. Toxicity of ethanol to yeast limits the ethanol concentration obtainable by brewing; higher concentrations, therefore, are obtained by ] or ]. The most ethanol-tolerant yeast strains can survive up to approximately 18% ethanol by volume.
===Antiseptic===
Ethanol is used in medical wipes and in most common antibacterial ] gels at a concentration of about 62% v/v as an ]. Ethanol kills organisms by ] their ]s and dissolving their ]s and is effective against most ] and ], and many ]es, but is ineffective against bacterial ]s.<ref>{{cite journal|author=McDonnell G, Russell AD|title=Antiseptics and disinfectants: activity, action, and resistance|journal=Clin. Microbiol. Rev.|volume=12|page=147|year=1999|pmid=9880479|pmc=88911|issue=1}}</ref>


To produce ethanol from starchy materials such as ]s, the ] must first be converted into sugars. In brewing ], this has traditionally been accomplished by allowing the grain to germinate, or ], which produces the ] ]. When the malted grain is ], the amylase converts the remaining starches into sugars.
===Treatment for poisoning by other alcohols {{anchor|Antidote for methanol poisoning}}===
Ethanol is sometimes used to treat poisoning by other, more toxic alcohols, in particular ]<ref name=cambridge>{{cite web|url=http://www-clinpharm.medschl.cam.ac.uk/pages/teaching/topics/poison/poison9.html|title=Methanol Poisoning|publisher=Cambridge University School of Clinical Medicine|accessdate=2007-09-04}}</ref> and ]. Ethanol ] with other alcohols for the ] enzyme, lessening metabolism into toxic ] and ] derivatives,<ref>{{cite journal|author=Barceloux DG, Bond GR, Krenzelok EP, Cooper H, Vale JA|title=American Academy of Clinical Toxicology practice guidelines on the treatment of methanol poisoning|journal=J. Toxicol. Clin. Toxicol.|volume=40|page=415|year=2002|pmid=12216995|doi=10.1081/CLT-120006745|issue=4}}</ref> and reducing one of the more serious toxic effect of the glycols to ] in the ].


Sugars for ] can be obtained from ]. Deployment of this technology could turn a number of cellulose-containing agricultural by-products, such as ]s, ], and ], into renewable energy resources. Other agricultural residues such as sugarcane bagasse and energy crops such as ] may also be fermentable sugar sources.<ref>{{cite web | last = Clines | first = Tom | name-list-style = vanc |title=Brew Better Ethanol|publisher=Popular Science Online|date=July 2006|url=http://www.popsci.com/popsci/energy/6756226d360ab010vgnvcm1000004eecbccdrcrd.html|archive-url=https://web.archive.org/web/20071103083747/http://www.popsci.com/popsci/energy/6756226d360ab010vgnvcm1000004eecbccdrcrd.html|archive-date=3 November 2007}}</ref>
===Solvent===
Ethanol is ] with ] and is a good general purpose ]. It is found in ]s, ]s, markers, and personal care products such as perfumes and deodorants. It may also be used as a solvent in cooking, such as in ].


===Historical uses=== === Testing ===
]
Before the development of modern medicines, ethanol was used for a variety of medical purposes. It has been known to be used as a ] (as hinted at by the maxim ''"]"''), as medicine for ] and as an ].{{Citation needed|date=May 2010}}
] of liquid ethanol]]


Breweries and ] plants employ two methods for measuring ethanol concentration. Infrared ethanol sensors measure the vibrational frequency of dissolved ethanol using the C−H band at 2900&nbsp;cm{{sup|−1}}. This method uses a relatively inexpensive solid-state sensor that compares the C−H band with a reference band to calculate the ethanol content. The calculation makes use of the ]. Alternatively, by measuring the density of the starting material and the density of the product, using a ], the change in specific gravity during fermentation indicates the alcohol content. This inexpensive and indirect method has a long history in the beer brewing industry.
Ethanol was commonly used as fuel in early ] ] (liquid propelled) vehicles, in conjunction with an ] such as liquid oxygen. The German ] of ], credited with beginning the space age, used ethanol, mixed with 25% of water to reduce the combustion chamber temperature.<ref>{{cite web|url=http://daviddarling.info/encyclopedia/V/V-2.html|title=The Internet Encyclopedia of Science: V-2|author=David Darling}}</ref><ref name=braeunig>Braeunig, Robert A. (Website). Rocket & Space Technology, 2006. Retrieved on 2007-08-23.</ref> The V-2's design team helped develop U.S. rockets following World War II, including the ethanol-fueled ], which launched the first U.S. satellite.<ref> NASA Historical Archive, via science.ksc.nasa.gov.</ref> Alcohols fell into general disuse as more efficient rocket fuels were developed.<ref name="braeunig" />


==Pharmacology== == Purification ==
Ethylene hydration or brewing produces an ethanol–water mixture. For most industrial and fuel uses, the ethanol must be purified. ] at atmospheric pressure can concentrate ethanol to 95.6% by weight (89.5 mole%). This mixture is an azeotrope with a boiling point of {{convert|78.1|C|F}}, and ''cannot'' be further purified by distillation. Addition of an entraining agent, such as benzene, ], or ], allows a new ternary azeotrope comprising the ethanol, water, and the entraining agent to be formed. This lower-boiling ternary azeotrope is removed preferentially, leading to water-free ethanol.<ref name="ullmann">{{cite book | first1 = Naim | last1 = Kosaric | first2 = Zdravko | last2 = Duvnjak | first3 = Adalbert | last3 = Farkas | first4 = Hermann | last4 = Sahm | first5 = Stephanie | last5 = Bringer-Meyer | first6 = Otto | last6 = Goebel | first7 = Dieter | last7 = Mayer | name-list-style = vanc | chapter = Ethanol | title = Ullmann's Encyclopedia of Industrial Chemistry | pages = 1–72 | year = 2011 | publisher = Wiley-VCH | location = Weinheim | doi = 10.1002/14356007.a09_587.pub2 | isbn = 978-3-527-30673-2 }}{{subscription required}}</ref>
Ethanol binds to ], ], ], and ]s.<ref name='CINMHA 1'>{{cite web|url=http://thebrain.mcgill.ca/flash/i/i_03/i_03_m/i_03_m_par/i_03_m_par_alcool.html |title=The Brain from Top to Bottom – Alcohol (Intermediate, Molecular) |accessdate=2010-02-13 |work=Canadian Institute of Neurosciences, Mental Health and Addiction |publisher=]}}</ref>


Apart from distillation, ethanol may be dried by addition of a ], such as ], cellulose, or ]. The desiccants can be dried and reused.<ref name="ullmann" /> ]s can be used to selectively absorb the water from the 95.6% ethanol solution.<ref>{{Cite book|url={{google books |plainurl=y |id= 4iEhAQAAMAAJ}}|title=Advances in Cereal Science and Technology|last=Chemists|first=American Association of Cereal|date=1986|publisher=American Association of Cereal Chemists, Incorporated|isbn=978-0-913250-45-7|language=en}}</ref> Molecular sieves of pore-size 3&nbsp;], a type of ], effectively sequester water molecules while excluding ethanol molecules. Heating the wet sieves drives out the water, allowing regeneration of their desiccant capability.<ref>{{citation |url= https://www.bio.umass.edu/microscopy/mol_sieves.htm |title= Molecular Sieve Information |author= Dale Callaham }}</ref>
The removal of ethanol through oxidation by ] in the ] from the human body is limited. Hence, the removal of a large concentration of alcohol from ] may follow ]. This means that alcohol leaves the body at a constant rate, rather than having an elimination ].


Membranes can also be used to separate ethanol and water. Membrane-based separations are not subject to the limitations of the water-ethanol azeotrope because the separations are not based on vapor-liquid equilibria. Membranes are often used in the so-called hybrid membrane distillation process. This process uses a pre-concentration distillation column as the first separating step. The further separation is then accomplished with a membrane operated either in vapor permeation or pervaporation mode. Vapor permeation uses a vapor membrane feed and pervaporation uses a liquid membrane feed.
Also, the rate-limiting steps for one substance may be in common with other substances. For instance, the blood alcohol concentration can be used to modify the biochemistry of ] and ]. Methanol itself is not highly toxic, but its metabolites ] and ] are; therefore, to reduce the concentration of these harmful metabolites, ethanol can be ingested to reduce the rate of methanol metabolism due to shared rate-limiting steps. ] poisoning can be treated in the same way.


A variety of other techniques have been discussed, including the following:<ref name="ullmann" />
==Drug effects==
* Salting using ] to exploit its insolubility will cause a phase separation with ethanol and water. This offers a very small potassium carbonate impurity to the alcohol that can be removed by distillation. This method is very useful in purification of ethanol by distillation, as ethanol forms an ] with water.
* Direct ] to ethanol under ambient conditions using ]s on a carbon nanospike film as the catalyst;<ref>{{cite journal | last1=Song | first1=Yang | last2=Peng | first2=Rui | last3=Hensley | first3=Dale K. | last4=Bonnesen | first4=Peter V. | last5=Liang | first5=Liangbo | last6=Wu | first6=Zili | last7=Meyer | first7=Harry M. | last8=Chi | first8=Miaofang | last9=Ma | first9=Cheng | last10=Sumpter | first10=Bobby G. | last11=Rondinone | first11=Adam J. | name-list-style = vanc | date=2016 | title=High-Selectivity Electrochemical Conversion of CO2 to Ethanol using a Copper Nanoparticle/N-Doped Graphene Electrode| journal=] | issue=Preprint | doi=10.1002/slct.201601169 | volume=1 | pages=6055–6061| doi-access=free }}</ref>
* Extraction of ethanol from grain mash by ];
* ];
* ] is also used to concentrate fermented alcoholic solutions, such as traditionally made ];
* ].<ref>{{cite journal | doi = 10.1016/j.renene.2011.09.027 | title = Production of anhydrous ethanol using various PSA (Pressure Swing Adsorption) processes in pilot plant | year = 2012 | last1 = Jeong | first1 = Jun-Seong | last2 = Jeon | first2 = Hyungjin | last3 = Ko | first3 = Kyung-mo | last4 = Chung | first4 = Bongwoo | last5 = Choi | first5 = Gi-Wook | name-list-style = vanc | journal = Renewable Energy | volume = 42 | pages = 41–45| bibcode = 2012REne...42...41J }}</ref>


=== Grades of ethanol ===
Pure ethanol will irritate the skin and eyes.<ref>http://www.nfpa.org/Assets/files/AboutTheCodes/704/CLA-AAA_ROPminutes_01-10.pdf</ref> Nausea, ] and intoxication are symptoms of ingestion. Long-term use by ingestion can result in serious liver damage.<ref name="msdset">{{cite web|url=http://msds.chem.ox.ac.uk/ET/ethyl_alcohol.html |title=Safety data for ethyl alcohol |publisher=Msds.chem.ox.ac.uk |date=2008-05-09 |accessdate=2011-01-03}}</ref>
{{Further|Denatured alcohol}}
Atmospheric concentrations above one in a thousand are above the European Union ]s.<ref name="msdset"/>
Pure ethanol and alcoholic beverages are heavily ] as psychoactive drugs, but ethanol has many uses that do not involve its consumption. To relieve the tax burden on these uses, most jurisdictions waive the tax when an agent has been added to the ethanol to render it unfit to drink. These include ] such as ] and toxins such as methanol, ], and pyridine. Products of this kind are called ''denatured alcohol.''<ref>{{cite web|url=http://www.procurement.umich.edu/Contracts/Denatured_Alchohol.pdf|title=U-M Program to Reduce the Consumption of Tax-free Alcohol; Denatured Alcohol a Safer, Less Expensive Alternative|publisher=University of Michigan|access-date=29 September 2007|url-status=dead|archive-url=https://web.archive.org/web/20071127095510/http://www.procurement.umich.edu/Contracts/Denatured_Alchohol.pdf|archive-date=27 November 2007|df=dmy-all}}</ref><ref>Great Britain (2005). '' {{Webarchive|url=https://web.archive.org/web/20091209162605/http://www.opsi.gov.uk/si/si2005/20051524.htm |date=9 December 2009 }}.'' Statutory Instrument 2005 No. 1524.</ref>


Absolute or anhydrous alcohol refers to ethanol with a low water content. There are various grades with maximum water contents ranging from 1% to a few parts per million (ppm). If ] is used to remove water, it will contain trace amounts of the material separation agent (e.g. benzene).<ref>{{cite book|first1=Raj K. |last1=Bansal |last2=Bernthsen |first2=August | name-list-style = vanc |title=A Textbook of Organic Chemistry|url={{google books |plainurl=y |id=1B6ijcTkD5EC|page=402}}|year=2003|publisher=New Age International Limited|isbn=978-81-224-1459-2|pages=402–}}</ref> Absolute alcohol is not intended for human consumption. Absolute ethanol is used as a solvent for laboratory and industrial applications, where water will react with other chemicals, and as fuel alcohol. Spectroscopic ethanol is an absolute ethanol with a low absorbance in ] and visible light, fit for use as a solvent in ].<ref>{{cite book | last1 = Christian | first1 = Gary D. | name-list-style = vanc | chapter = Solvents for Spectrometry | title = Analytical chemistry | date = 2004 | publisher = John Wiley & Sons | location = Hoboken, NJ | isbn = 978-0-471-21472-4 | edition = 6th | volume = 1 | page = | chapter-url = https://archive.org/details/analyticalchemis00chri_0/page/473 }}</ref> Pure ethanol is classed as 200 ] in the US, equivalent to 175 degrees proof in the UK system.<ref name="Andrews2007">{{cite book|first=Sudhir |last=Andrews | name-list-style = vanc |title=Textbook Of Food & Bevrge Mgmt|url={{google books |plainurl=y |id=HfHtaq1GWUcC&|page=268}}|date=1 August 2007|publisher=Tata McGraw-Hill Education|isbn=978-0-07-065573-7|pages=268–}}</ref> Rectified spirit, an azeotropic composition of 96% ethanol containing 4% water, is used instead of anhydrous ethanol for various purposes. Spirits of wine are about 94% ethanol (188 proof). The impurities are different from those in 95% (190 proof) laboratory ethanol.<ref>{{cite journal | vauthors = Kunkee RE, Amerine MA | title = Sugar and alcohol stabilization of yeast in sweet wine | journal = Applied Microbiology | volume = 16 | issue = 7 | pages = 1067–1075 | date = July 1968 | doi = 10.1128/AEM.16.7.1067-1075.1968 | pmid = 5664123 | pmc = 547590 }}</ref>
===Short-term===
{{Main|Short-term effects of alcohol}}


== Reactions ==
{|class=wikitable style="float:right; width:25em; margin-left: 1em"
{{more citations needed section|date=November 2024}}
! BAC (g/L)|| BAC <br />(% v/v)|| Symptoms<ref name="Pohorecky & Brick">{{cite journal|author=Pohorecky LA, Brick J|title=Pharmacology of ethanol|journal=Pharmacol. Ther.|volume=36|page=335|year=1988|pmid=3279433|doi=10.1016/0163-7258(88)90109-X|issue=2–3}}</ref>
{{Further|Alcohol (chemistry)}}
|-
| 0.5||0.05%||Euphoria, talkativeness, relaxation
|-
| 1||0.1 %||Central nervous system depression, nausea, possible vomiting, impaired motor and sensory function, impaired cognition
|-
| >1.4|| >0.14%||Decreased blood flow to brain
|-
| 3||0.3%||Stupefaction, possible unconsciousness
|-
| 4||0.4%||Possible death
|-
| >5.5|| >0.55%||Death
|}


Ethanol is classified as a primary alcohol, meaning that the carbon that its hydroxyl group attaches to has at least two hydrogen atoms attached to it as well. Many ethanol reactions occur at its hydroxyl group.
====Effects on the central nervous system====
Ethanol is a central nervous system depressant and has significant psychoactive effects in sublethal doses; for specifics, see ]. Based on its abilities to change the ], ethanol is considered a ].<ref>{{MedlinePlus|001944|Alcohol Use}}</ref> Death from ethyl alcohol consumption is possible when blood alcohol level reaches 0.4%. A blood level of 0.5% or more is commonly fatal. Levels of even less than 0.1% can cause ], with unconsciousness often occurring at 0.3–0.4%.<ref name=yost/>


=== Ester formation ===
The amount of ethanol in the body is typically quantified by ] (BAC), which is here taken as weight of ethanol per unit volume of blood. The table at right summarizes the symptoms of ethanol consumption. Small doses of ethanol, in general, produce euphoria and relaxation; people experiencing these symptoms tend to become talkative and less inhibited, and may exhibit poor judgment. At higher dosages (BAC > 1 g/L), ethanol acts as a ] ], producing at progressively higher dosages, impaired sensory and motor function, slowed cognition, stupefaction, unconsciousness, and possible death.
In the presence of acid catalysts, ethanol reacts with ]s to produce ethyl esters and water:
:] + HOCH<sub>2</sub>CH<sub>3</sub> → ] + H<sub>2</sub>O
This reaction, which is conducted on large scale industrially, requires the removal of the water from the reaction mixture as it is formed. Esters react in the presence of an acid or base to give back the alcohol and a salt. This reaction is known as ] because it is used in the preparation of soap. Ethanol can also form esters with inorganic acids. ] and ] are prepared by treating ethanol with sulfur trioxide and ] respectively. Diethyl sulfate is a useful ethylating agent in ]. ], prepared from the reaction of ethanol with ] and sulfuric acid, was formerly used as a ].


=== Dehydration ===
Ethanol acts in the central nervous system by binding to the ] receptor, increasing the effects of the inhibitory ] ] (i.e., it is a ]).<ref name="pmid17591544">{{cite journal|author = Santhakumar V, Wallner M, Otis TS|title = Ethanol acts directly on extrasynaptic subtypes of GABAA receptors to increase tonic inhibition|journal = Alcohol| volume = 41 |issue = 3|pages = 211–21|year = 2007|pmid = 17591544|pmc = 2040048|doi = 10.1016/j.alcohol.2007.04.011|url =}}</ref>
In the presence of acid catalysts, alcohols can be converted to alkenes such as ethanol to ethylene. Typically ]s such as ] are used.<ref name="UllmannEthylene">{{cite book |first1=Heinz |last1=Zimmermann |first2=Roland |last2=Walz |chapter=Ethylene |title=Ullmann's Encyclopedia of Industrial Chemistry |publisher=Wiley-VCH |location=Weinheim |year=2008 |doi=10.1002/14356007.a10_045.pub3|isbn=978-3-527-30673-2 }}</ref>
:CH<sub>3</sub>CH<sub>2</sub>OH → H<sub>2</sub>C=CH<sub>2</sub> + H<sub>2</sub>O


Since water is removed from the same molecule, the reaction is known as ]. Intramolecular dehydration of an alcohol requires a high temperature and the presence of an acid catalyst such as sulfuric acid.<ref>{{Cite web |date=2016-02-09 |title=14.4: Dehydration Reactions of Alcohols |url=https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Map%3A_Organic_Chemistry_(Wade)/14%3A_Reactions_of_Alcohols/14.04%3A_Dehydration_Reactions_of_Alcohols |access-date=2022-05-09 |website=Chemistry LibreTexts|language=en}}</ref> Ethylene produced from sugar-derived ethanol (primarily in Brazil) competes with ethylene produced from petrochemical feedstocks such as naphtha and ethane.{{cn|date=November 2024}} At a lower temperature than that of intramolecular dehydration, ] may occur producing a symmetrical ether. This is a ]. In the following example, diethyl ether is produced from ethanol:
Prolonged heavy consumption of alcohol can cause significant permanent damage to the brain and other organs. See ].
:2 CH<sub>3</sub>CH<sub>2</sub>OH → CH<sub>3</sub>CH<sub>2</sub>OCH<sub>2</sub>CH<sub>3</sub> + H<sub>2</sub>O<ref>{{Cite web |date=2013-10-02 |title=Alkenes from Dehydration of Alcohols |url=https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Supplemental_Modules_(Organic_Chemistry)/Alkenes/Synthesis_of_Alkenes/Alkenes_from_Dehydration_of_Alcohols |access-date=2022-05-09 |website=Chemistry LibreTexts |language=en}}</ref>


=== Combustion ===
In USA, about half of the deaths in car accidents occur in alcohol-related crashes.<ref>{{cite journal|author=Hingson R, Winter M|title=Epidemiology and consequences of drinking and driving|journal=Alcohol research & health : the journal of the National Institute on Alcohol Abuse and Alcoholism|volume=27|page=63|year=2003|pmid=15301401|issue=1}}</ref> The risk of a fatal ] increases exponentially with the level of alcohol in the driver's blood.<ref>{{cite journal|author=Naranjo CA, Bremner KE|title=Behavioural correlates of alcohol intoxication|journal=]|volume=88|page=25|year=1993|pmid=8448514|doi=10.1111/j.1360-0443.1993.tb02761.x|issue=1}}</ref> Most ] laws governing the acceptable levels in the blood while driving or operating heavy machinery set typical upper limits of ] (BAC) between 0.05% and 0.08%.{{Citation needed|date=May 2010}}
Complete combustion of ethanol forms carbon dioxide and water:
:C<sub>2</sub>H<sub>5</sub>OH (l) + 3 O<sub>2</sub> (g) → 2 CO<sub>2</sub> (g) + 3 H<sub>2</sub>O (l); −Δ<sub>c</sub>''H'' = 1371&nbsp;kJ/mol<ref>{{cite journal|title=Heats of Formation of Simple Organic Molecules | last = Rossini | first = Frederick D. | name-list-style = vanc |journal=Ind. Eng. Chem.|year=1937|volume=29|pages=1424–1430|doi=10.1021/ie50336a024|issue=12}}</ref> = 29.8&nbsp;kJ/g = 327&nbsp;kcal/mol = 7.1&nbsp;kcal/g


:C<sub>2</sub>H<sub>5</sub>OH (l) + 3 O<sub>2</sub> (g) → 2 CO<sub>2</sub> (g) + 3 H<sub>2</sub>O (g); −Δ<sub>c</sub>''H'' = 1236&nbsp;kJ/mol = 26.8&nbsp;kJ/g = 295.4&nbsp;kcal/mol = 6.41 kcal/g<ref>Calculated from heats of formation from CRC Handbook of Chemistry and Physics, 49th Edition, 1968–1969.</ref>
Discontinuing consumption of alcohol after several years of heavy drinking can also be fatal. Alcohol withdrawal can cause anxiety, autonomic dysfunction, seizures, and hallucinations. ] is a condition that requires people with a long history of heavy drinking to undertake an ] regimen.


Specific heat = 2.44 kJ/(kg·K)
====Effects on metabolism====
{{Main|Ethanol metabolism|Alcohol dehydrogenase}}
Ethanol within the human body is converted into acetaldehyde by ] and then into the ] in ] by ]. ] is the final product of both carbohydrate and fat metabolism, where the acetyl can be further used to produce energy or for biosynthesis. As such, ethanol is a nutrient. However, the product of the first step of this breakdown, acetaldehyde,<ref name=boggan1>{{cite web|url=http://chemcases.com/alcohol/alc-06.htm|accessdate=2007-09-29|author=Boggan, Bill |title=Metabolism of Ethyl Alcohol in the Body|publisher=Chemases.com}}</ref> is more toxic than ethanol. Acetaldehyde is linked to most of the clinical effects of alcohol. It has been shown to increase the risk of developing cirrhosis of the liver,<ref name=boggan2>{{cite web|url=http://chemcases.com/alcohol/alc-07.htm|accessdate=2007-09-29|author=Dr. Bill Boggan|title=Effects of Ethyl Alcohol on Organ Function|publisher=Chemases.com}}</ref> multiple forms of cancer, and ].


====Drug interactions==== === Acid-base chemistry ===
Ethanol is a neutral molecule and the ] of a solution of ethanol in water is nearly 7.00. Ethanol can be quantitatively converted to its ], the ] ion (CH<sub>3</sub>CH<sub>2</sub>O<sup>−</sup>), by reaction with an ] such as ]:<ref name="m_and_b" />
Ethanol can intensify the sedation caused by other ] ] drugs such as ]s, ]s, ]s, ]s, and ].<ref name=yost>{{cite journal|url=http://my.lecom.edu/library/internetresources/journal%20articles/Acute%20Care%20for%20Alcohol%20Intoxication.pdf|title=Acute care for alcohol intoxication|publisher=Postgraduate Medicine Online|author=David A. Yost, MD|volume=112|issue=6|year=2002|accessdate=2007-09-29}}</ref>
:2 CH<sub>3</sub>CH<sub>2</sub>OH + 2 Na → 2 CH<sub>3</sub>CH<sub>2</sub>ONa + H<sub>2</sub>
or a very strong base such as ]:
:CH<sub>3</sub>CH<sub>2</sub>OH + NaH → CH<sub>3</sub>CH<sub>2</sub>ONa + H<sub>2</sub>
The acidities of water and ethanol are nearly the same, as indicated by their ] of 15.7 and 16 respectively. Thus, sodium ethoxide and sodium hydroxide exist in an equilibrium that is closely balanced:
:CH<sub>3</sub>CH<sub>2</sub>OH + NaOH {{eqm}} CH<sub>3</sub>CH<sub>2</sub>ONa + H<sub>2</sub>O


====Magnitude of effects==== === Halogenation ===
Ethanol is not used industrially as a precursor to ethyl halides, but the reactions are illustrative. Ethanol reacts with ]s to produce ] such as ] and ] via an ]:
:CH<sub>3</sub>CH<sub>2</sub>OH + ] → CH<sub>3</sub>CH<sub>2</sub>Cl + H<sub>2</sub>O
HCl requires a catalyst such as ].<ref name="s_and_h">{{cite book | first1 = Andrew | last1 = Streitwieser | first2 = Clayton H. | last2 = Heathcock | name-list-style = vanc | author-link1 = Andrew Streitwieser | author-link2 = Clayton Heathcock | title = Introduction to Organic Chemistry| url = https://archive.org/details/introductiontoor00stre | url-access = registration |year=1976|publisher=MacMillan|isbn=978-0-02-418010-0}}</ref>
HBr requires ] with a sulfuric acid catalyst.<ref name="s_and_h" /> Ethyl halides can, in principle, also be produced by treating ethanol with more specialized ], such as ] or ].<ref name="m_and_b" /><ref name="s_and_h" />
:CH<sub>3</sub>CH<sub>2</sub>OH + SOCl<sub>2</sub> → CH<sub>3</sub>CH<sub>2</sub>Cl + SO<sub>2</sub> + HCl


Upon treatment with halogens in the presence of base, ethanol gives the corresponding ] (CHX<sub>3</sub>, where X = Cl, Br, I). This conversion is called the ].<ref>{{cite book | vauthors = Chakrabartty SK | veditors = Trahanovsky WS | title = Oxidation in Organic Chemistry | pages = 343–370 | publisher = Academic Press | location = New York | year = 1978 }}</ref>
Some individuals have less effective forms of one or both of the metabolizing enzymes, and can experience more severe symptoms from ethanol consumption than others. However, those having acquired ] have a greater quantity of these enzymes, and metabolize ethanol more rapidly.<ref>{{cite journal|author=Agarwal DP, Goedde HW|title=Pharmacogenetics of alcohol metabolism and alcoholism|journal=Pharmacogenetics|volume=2|page=48|year=1992|pmid=1302043|doi=10.1097/00008571-199204000-00002|issue=2}}</ref>
An intermediate in the reaction with chlorine is the ] called ], which forms ] upon reaction with water:<ref name=Ull>{{cite book | last1 = Reinhard | first1 = Jira | first2 = Erwin | last2 = Kopp | first3 = Blaine C. | last3 = McKusick | first4 = Gerhard | last4 = Röderer | first5 = Axel | last5 = Bosch | first6 = Gerald | last6 = Fleischmann | name-list-style = vanc | chapter = Chloroacetaldehydes | title = Ullmann's Encyclopedia of Industrial Chemistry | year = 2007 | publisher = Wiley-VCH | location = Weinheim | doi = 10.1002/14356007.a06_527.pub2 | isbn = 978-3-527-30673-2 }}</ref>
:4 Cl<sub>2</sub> + CH<sub>3</sub>CH<sub>2</sub>OH → CCl<sub>3</sub>CHO + 5 HCl
:CCl<sub>3</sub>CHO + H<sub>2</sub>O → CCl<sub>3</sub>C(OH)<sub>2</sub>H


===Long-term=== === Oxidation ===
Ethanol can be oxidized to acetaldehyde and further oxidized to acetic acid, depending on the reagents and conditions.<ref name="s_and_h" /> This oxidation is of no importance industrially, but in the human body, these oxidation reactions are catalyzed by the enzyme ]. The oxidation product of ethanol, acetic acid, is a nutrient for humans, being a precursor to ], where the acetyl group can be spent as energy or used for biosynthesis.
{{Main|Long-term effects of alcohol}}


====Birth defects==== === Metabolism ===
Ethanol is similar to ] such as proteins, fats, and carbohydrates in that it provides calories. When consumed and metabolized, it contributes 7&nbsp;kilocalories per gram via ].<ref>{{Cite journal|last=Cederbaum|first=Arthur I|title=Alcohol Metabolism|date=2012-11-16|journal=Clinics in Liver Disease|volume=16|issue=4|pages=667–685|doi=10.1016/j.cld.2012.08.002|issn=1089-3261|pmc=3484320|pmid=23101976}}</ref>
Ethanol is classified as a ]. See ].


====Other effects==== == Safety ==
{{See also|Alcohol (chemistry)#Toxicity}}
Frequent drinking of alcoholic beverages has been shown to be a major contributing factor in cases of elevated blood levels of ].<ref>{{cite web|url=http://americanheart.org/presenter.jhtml?identifier=4778|title=Triglycerides
Ethanol is very flammable and should not be used around an open flame.
|accessdate =2007-09-04|publisher=American Heart Association}}</ref>


Pure ethanol will irritate the skin and eyes.<ref> {{Webarchive|url=https://web.archive.org/web/20210416230440/https://www.nfpa.org/Assets/files/AboutTheCodes/704/CLA-AAA_ROPminutes_01-10.pdf |date=16 April 2021 }}. Technical Committee on Classification and Properties of Hazardous Chemical Data (12–13 January 2010).</ref> Nausea, ], and intoxication are symptoms of ingestion. Long-term use by ingestion can result in serious liver damage.<ref name="msdset">{{cite web |url=http://msds.chem.ox.ac.uk/ET/ethyl_alcohol.html |title=Safety data for ethyl alcohol |publisher=University of Oxford |date=9 May 2008 |access-date=3 January 2011 |archive-date=14 July 2011 |archive-url=https://web.archive.org/web/20110714040451/http://msds.chem.ox.ac.uk/ET/ethyl_alcohol.html |url-status=dead }}</ref> Atmospheric concentrations above one part per thousand are above the European Union ]s.<ref name="msdset" />
Ethanol is not a ].<ref>{{cite web|url=http://fscimage.fishersci.com/msds/89308.htm |title=Fisher Scientific anydrous ethanol MSDS |publisher=Fscimage.fishersci.com |date= |accessdate=2011-05-31}}</ref><ref name=aacr>{{cite web|url=http://www.aacr.org/PDF_files/2004Prevention/Program/2004_Prevention_Abstracts.pdf|title=Animal Models for Carcinogenesis and Chemoprevention, abstract #C42: Effects of Chronic Ethanol Intake on Cyclin D1 Levels and Altered Foci in Diethylnitrosamine-initiated Rats|author=Chavez, Pollyanna R.; Wang, Xiang-Dong; Meyer, Jean|publisher=USDA|accessdate=2007-10-24|format=PDF}}</ref> However, the first metabolic product of ethanol, ], is toxic, ]ic, and carcinogenic.


==Natural occurrence== == History ==
{{Further|Liquor}}<!--
Ethanol is a byproduct of the metabolic process of yeast. As such ethanol will be present in any yeast habitat. Ethanol can commonly be found in overripe fruit.<ref>{{cite journal|title= Ethanol, Fruit Ripening, and the Historical Origins of Human Alcoholism in Primate Frugivory|author=Robert Dudley|journal=Integrative Comparative Biology|volume=44|pages=315–323|year=2004|url=http://icb.oxfordjournals.org/cgi/reprint/44/4/315.pdf|accessdate=2010-07-23|doi= 10.1093/icb/44.4.315|issue= 4}}</ref> Ethanol produced by symbiotic yeast can be found in ] blossoms. Although some species such as the ] exhibit ethanol seeking behaviors, most show no interest or avoidance of food sources containing ethanol.<ref>{{cite web|title= Fact or Fiction?: Animals Like to Get Drunk|author=Cynthia Graber |year=2008|url=http://www.scientificamerican.com/article.cfm?id=animals-like-to-get-drunk|publisher=Scientific American|accessdate=2010-07-23}}</ref> Ethanol is also produced during the germination of many plants as a result of natural ].<ref>{{cite journal|doi=10.1007/BF02922229|author=Sylva Leblová, Eva Sinecká and Věra Vaníčková|title=Pyruvate metabolism in germinating seeds during natural anaerobiosis|year=1974|journal=Biologia Plantarum|volume=16|issue=6|pages=406–411|url=http://www.springerlink.com/content/9m775m527k2t1810/|accessdate=2010-07-23}}</ref> Ethanol has been detected in ], forming an icy coating around dust grains in ]s.<ref>{{cite journal|doi=10.1016/j.chemphys.2007.02.018|title=One possible origin of ethanol in interstellar medium: Photochemistry of mixed CO2–C2H6 films at 11 K. A FTIR study|author=A. Schriver, L. Schriver-Mazzuoli, P. Ehrenfreund and L. d’Hendecourt|journal=Chemical Physics|volume=334|issue=1–3|year= 2007|pages=128–137|url=http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TFM-4N68NMT-2&_user=10&_coverDate=04/20/2007&_rdoc=1&_fmt=high&_orig=search&_sort=d&_docanchor=&view=c&_searchStrId=1410911507&_rerunOrigin=google&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=5a8312d85b559afe8d56454167e8886a|accessdate=2010-07-23}}</ref>
]-->


The fermentation of sugar into ethanol is one of the earliest ] employed by humans. Ethanol has historically been identified variously as spirit of wine or ardent spirits,<ref>{{Cite book|last=Ottley|first=William Campbell|url=https://books.google.com/books?id=wYcwvwyk2RAC|title=A dictionary of chemistry and of mineralogy as connected with it|date=1826|publisher=Murray|language=en}}</ref> and as ] or aqua vita. The intoxicating effects of its consumption have been known since ancient times. Ethanol has been used by humans since prehistory as the intoxicating ingredient of alcoholic beverages. Dried residue on 9,000-year-old pottery found in China suggests that ] people consumed alcoholic beverages.<ref name="Roach">{{cite journal | vauthors = Roach J |date=18 July 2005|url=http://news.nationalgeographic.com/news/2005/07/0718_050718_ancientbeer.html|archive-url=https://web.archive.org/web/20050722030635/http://news.nationalgeographic.com/news/2005/07/0718_050718_ancientbeer.html|url-status=dead|archive-date=22 July 2005|title=9,000-Year-Old Beer Re-Created From Chinese Recipe|journal=National Geographic News|access-date=3 September 2007}}</ref>
==See also==
{{Portal|Pharmacy and Pharmacology}}
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The inflammable nature of the exhalations of wine was already known to ancient natural philosophers such as ] (384–322 BCE), ] ({{circa|371}}–287 BCE), and ] (23/24–79 CE).<ref>{{harvnb|Berthelot|Houdas|1893|loc=vol. I, p. 137}}.</ref> However, this did not immediately lead to the isolation of ethanol, despite the development of more advanced distillation techniques in second- and third-century ].<ref>{{harvnb|Berthelot|Houdas|1893|loc=vol. I, pp. 138-139}}.</ref> An important recognition, first found in one of the writings attributed to ] (ninth century CE), was that by ] to boiling wine, which increases the wine's ], the flammability of the resulting vapors may be enhanced.<ref>{{cite book|last1=al-Hassan|first1=Ahmad Y.|author-link=Ahmad Y. al-Hassan|year=2009|chapter=Alcohol and the Distillation of Wine in Arabic Sources from the 8th Century|title=Studies in al-Kimya': Critical Issues in Latin and Arabic Alchemy and Chemistry|location=Hildesheim|publisher=Georg Olms Verlag|pages=283–298}} (same content also available on {{Webarchive|url=https://web.archive.org/web/20151229003135/http://www.history-science-technology.com/notes/notes7.html |date=29 December 2015 }}).</ref> The distillation of wine is attested in Arabic works attributed to ] ({{circa|801}}–873 CE) and to ] ({{circa|872}}–950), and in the 28th book of ]'s (Latin: Abulcasis, 936–1013) ''Kitāb al-Taṣrīf'' (later translated into Latin as ''Liber servatoris'').<ref>{{harvnb|al-Hassan|2009}} (same content also available on {{Webarchive|url=https://web.archive.org/web/20151229003135/http://www.history-science-technology.com/notes/notes7.html |date=29 December 2015 }}); cf. {{harvnb|Berthelot|Houdas|1893|loc=vol. I, pp. 141, 143}}. Sometimes, sulfur was also added to the wine (see {{harvnb|Berthelot|Houdas|1893|loc=vol. I, p. 143}}).</ref> In the twelfth century, recipes for the production of ''aqua ardens'' ("burning water", i.e., ethanol) by distilling wine with salt started to appear in a number of Latin works, and by the end of the thirteenth century it had become a widely known substance among Western European chemists.<ref>{{harvnb|Multhauf|1966|pp=204–206}}.</ref>
==References==
{{Reflist|30em}}


The works of ] (1223–1296) describe a method for concentrating ethanol involving repeated fractional distillation through a water-cooled ], by which an ethanol purity of 90% could be obtained.<ref>{{cite book|last1=Holmyard|first1=Eric John|author1-link=Eric John Holmyard|date=1957|title=Alchemy|location=Harmondsworth|publisher=Penguin Books|isbn=978-0-486-26298-7}} pp. 51–52.</ref> The medicinal properties of ethanol were studied by ] (1240–1311 CE) and ] ({{circa|1310}}–1366), the latter of whom regarded it as a life-preserving substance able to prevent all diseases (the ''aqua vitae'' or "water of life", also called by John the '']'' of wine).<ref>{{cite book|last=Principe|first=Lawrence M.|author-link=Lawrence M. Principe|year=2013|title=The Secrets of Alchemy|location=Chicago|publisher=The University of Chicago Press|isbn=978-0-226-10379-2}} pp. 69-71.</ref> In ], archaeological evidence indicates that the true distillation of alcohol began during the ] (1115–1234) or ] (1127–1279) dynasties.<ref name=haw>{{cite book | last= Haw | first= Stephen G. | name-list-style = vanc | author-link= Stephen G. Haw | title= Marco Polo in China | publisher= Routledge | year= 2006 | isbn= 978-1-134-27542-7 | chapter= Wine, women and poison | pages= 147–148 | chapter-url= {{google books |plainurl=y |id=DSfvfr8VQSEC|page=148}} | access-date= 10 July 2016 | quote= The earliest possible period seems to be the Eastern Han dynasty... the most likely period for the beginning of true distillation of spirits for drinking in China is during the Jin and Southern Song dynasties}}</ref> A still has been found at an archaeological site in Qinglong, ], dating to the 12th century.<ref name="haw" /> In India, the true distillation of alcohol was introduced from the Middle East, and was in wide use in the ] by the 14th century.<ref name="habib">{{cite book|last=Habib|first=Irfan|author-link=Irfan Habib|title=Economic History of Medieval India, 1200–1500|url={{google books |plainurl=y |id=K8kO4J3mXUAC|page=55}}|year=2011|publisher=Pearson Education India|isbn=978-81-317-2791-1|pages=55–}}</ref>
==Further reading==
*The ] maintains a database of alcohol-related health effects. Alcohol and Alcohol Problems Science Database.
*Boyce, John M., and Pittet Didier. (2003). ], ], ], United States.
*
*Smith, M.G., and M. Snyder. (2005). "Ethanol-induced virulence of ''Acinetobacter baumannii''". ''American Society for Microbiology meeting''. June 5 – June 9. Atlanta.


In 1796, German-Russian chemist ] obtained pure ethanol by mixing partially purified ethanol (the alcohol-water azeotrope) with an excess of anhydrous alkali and then distilling the mixture over low heat.<ref>{{cite journal|last=Lowitz |first=T. | name-list-style = vanc |journal=Chemische Annalen für die Freunde der Naturlehre, Aerznengelartheit, Haushaltungskunde und Manufakturen|url={{google books |plainurl=y |id=Zws_AAAAcAAJ}}|year=1796|title=Anzeige eines, zur volkommen Entwasserung des Weingeistes nothwendig zu beobachtenden, Handgriffs | language = de | trans-title = Report of a task that must be done for the complete dehydration of wine spirits ) |volume= 1 |pages= 195–204 | quote = See pp. 197–198: Lowitz dehydrated the azeotrope by mixing it with a 2:1 excess of anhydrous alkali and then distilling the mixture over low heat.}}</ref> French chemist ] described ethanol as a compound of carbon, hydrogen, and oxygen, and in 1807 ] determined ethanol's chemical formula.<ref>{{cite EB1911|wstitle = Alcohol|volume=1|pages=525–527}}</ref><ref>{{cite journal|last=de Saussure |first=Théodore | name-list-style = vanc |journal=Journal de Physique, de Chimie, d'Histoire Naturelle et des Arts | url = {{google books |plainurl=y |id=G-UPAAAAQAAJ|page=316}} |year=1807|title=Mémoire sur la composition de l'alcohol et de l'éther sulfurique |volume= 64 |pages= 316–354}} In his 1807 paper, Saussure determined ethanol's composition only roughly; a more accurate analysis of ethanol appears on page 300 of his 1814 paper: {{cite journal|last=de Saussure |first=Théodore|journal=Annales de Chimie et de Physique|url={{google books |plainurl=y |id=ch8zAQAAMAAJ|page=273}}|year=1814|pages=273–305|title=Nouvelles observations sur la composition de l'alcool et de l'éther sulfurique|volume=89}}</ref> Fifty years later, ] published the structural formula of ethanol, one of the first structural formulas determined.<ref name="Couper">{{cite journal | vauthors = Couper AS | year = 1858 | title = On a new chemical theory|journal=Philosophical Magazine|format=online reprint|volume=16|issue=104–116|url=http://web.lemoyne.edu/~giunta/couper/couper.html|access-date=3 September 2007}}</ref>
==Appendix==


Ethanol was first prepared synthetically in 1825 by ]. He found that sulfuric acid could absorb large volumes of ].<ref>{{cite journal | vauthors = Faraday M | year = 1825 | url = http://gallica.bnf.fr/ark:/12148/bpt6k559209/f473.image | title = On new compounds of carbon and hydrogen, and on certain other products obtained during the decomposition of oil by heat | journal = Philosophical Transactions of the Royal Society of London | volume = 115 | pages = 440–466 | doi=10.1098/rstl.1825.0022| doi-access = free}} In a footnote on page 448, Faraday notes the action of sulfuric acid on coal gas and coal-gas distillate; specifically, "The acid combines directly with carbon and hydrogen; and I find when united with bases forms a peculiar class of salts, somewhat resembling the sulphovinates , but still different from them."</ref> He gave the resulting solution to ], a British chemist, who found in 1826 that it contained "sulphovinic acid" (ethyl hydrogen sulfate).<ref>{{cite journal | vauthors = Hennell H |journal=Philosophical Transactions of the Royal Society of London|url={{google books |plainurl=y |id=f05FAAAAcAAJ|page=}}|year=1826|title=On the mutual action of sulphuric acid and alcohol, with observations on the composition and properties of the resulting compound|volume= 116 | pages = 240–249 |doi=10.1098/rstl.1826.0021|s2cid=98278290}} On page 248, Hennell mentions that Faraday gave him some sulfuric acid in which coal gas had dissolved and that he (Hennell) found that it contained "sulphovinic acid" (ethyl hydrogen sulfate).</ref> In 1828, Hennell and the French chemist ] independently discovered that sulphovinic acid could be decomposed into ethanol.<ref name="Hennell">{{cite journal | vauthors = Hennell H | year = 1828 | title = On the mutual action of sulfuric acid and alcohol, and on the nature of the process by which ether is formed|journal=Philosophical Transactions of the Royal Society of London|volume=118|url={{google books |plainurl=y |id=X-9FAAAAMAAJ|page=365}}|doi=10.1098/rstl.1828.0021|pages=365–371| s2cid = 98483646 }} On page 368, Hennell produces ethanol from "sulfovinic acid" (]).</ref><ref>{{cite journal|last=Sérullas |first=Georges-Simon|editor-first1=Louis-Bernard |editor-last1=Guyton de Morveau|editor-first2=Joseph Louis |editor-last2=Gay-Lussac|editor-first3=François |editor-last3=Arago|editor4=Michel Eugène Chevreul|editor5= Marcellin Berthelot|editor6= Éleuthère Élie Nicolas Mascart|editor7= Albin Haller| name-list-style = vanc |journal=Annales de Chimie et de Physique|url={{google books |plainurl=y |id=ZxUAAAAAMAAJ|page=152}}|year=1828|title=De l'action de l'acide sulfurique sur l'alcool, et des produits qui en résultent|volume=39 |pages=152–186}} On page 158, Sérullas mentions the production of alcohol from "sulfate acid d'hydrogène carboné" (hydrocarbon acid sulfate).</ref> Thus, in 1825 Faraday had unwittingly discovered that ethanol could be produced from ethylene (a component of coal gas) by ] hydration, a process similar to current industrial ethanol synthesis.<ref>In 1855, the French chemist ] confirmed Faraday's discovery by preparing ethanol from pure ethylene. {{cite journal|first=Marcellin |last=Berthelot|editor-first1=François |editor-last1=Arago|editor-first2=Joseph Louis |editor-last2=Gay-Lussac| name-list-style = vanc |journal=Annales de Chimie et de Physique|url={{google books |plainurl=y |id=1ClCAAAAcAAJ|page=385}}|year=1855|title=Sur la formation de l'alcool au moyen du bicarbure d'hydrogène (On the formation of alcohol by means of ethylene) |volume= 43 |pages=385–405}} (Note: The chemical formulas in Berthelot's paper are wrong because chemists at that time used the wrong atomic masses for the elements; e.g., carbon (6 instead of 12), oxygen (8 instead of 16), etc.)</ref>
{| class="wikitable" style="text-align:center"
|+Thermophysical properties of mixtures of ethanol with water and dodecane
| style="width:33%;"|]
| style="width:33%;"|]
| style="width:33%;"|]
|-
|Excess volume of the mixture of ethanol and water (volume contraction)
|Heat of mixing of the mixture of ethanol and water
|Vapor-liquid equilibrium of the mixture of ethanol and water (including ])
|-
| style="width:33%;"|]
| style="width:33%;"|]
|
|-
|Solid-liquid equilibrium of the mixture of ethanol and water (including ])
|Miscibility gap in the mixture of dodecane and ethanol
|}


Ethanol was used as lamp fuel in the U.S. as early as 1840, but a tax levied on industrial alcohol during the ] made this use uneconomical. The tax was repealed in 1906.<ref name="siegel">{{cite news|url=https://www.npr.org/templates/story/story.php?storyId=7426827|title=Ethanol, Once Bypassed, Now Surging Ahead | last = Siegel | first = Robert | name-list-style = vanc |publisher=NPR|date=15 February 2007|access-date=22 September 2007}}</ref> Use as an automotive fuel dates back to 1908, with the ] able to run on ] (gasoline) or ethanol.<ref name="dipardo">{{cite web|url=http://www.eia.gov/oiaf/analysispaper/pdf/biomass.pdf|title=Outlook for Biomass Ethanol Production and Demand|publisher=United States Department of Energy| last = DiPardo | first = Joseph | name-list-style = vanc | access-date=22 September 2007|url-status=dead|archive-url=https://web.archive.org/web/20150924050511/http://www.eia.gov/oiaf/analysispaper/pdf/biomass.pdf|archive-date=24 September 2015|df=dmy-all}}</ref> It fuels some ].
==External links==

Ethanol intended for industrial use is often produced from ethylene.<ref name="myers">{{Cite book | last1 = Myers | first1 = Richard L. | last2 = Myers | first2 = Rusty L. | name-list-style = vanc |title=The 100 most important chemical compounds: a reference guide|year=2007|publisher=Greenwood Press|location=Westport, CN|isbn=978-0-313-33758-1|page=122|url={{google books |plainurl=y |id=0AnJU-hralEC|page=122}}}}</ref> Ethanol has widespread use as a solvent of substances intended for human contact or consumption, including scents, flavorings, colorings, and medicines. In chemistry, it is both a solvent and a feedstock for the synthesis of other products. It has a long history as a fuel for heat and light, and more recently as a fuel for internal combustion engines.

== See also ==
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== References ==
{{Reflist|30em}}

== Further reading ==
* {{cite web | last1 = Boyce | first1 = John M | last2 = Pittet | first2 = Didier | name-list-style = vanc | year = 2003 | url = http://cdc.gov/handhygiene/ | title = Hand Hygiene in Healthcare Settings | publisher = ] | location = Atlanta, GA |ref=none}}
* {{cite conference |url=http://lib.dr.iastate.edu/abe_eng_conf/68/ |title=Ethanol production, purification, and analysis techniques: a review |first1=Shinnosuke |last1=Onuki |first2=Jacek A. |last2=Koziel |first3=Johannes |last3=van Leeuwen |first4=William S. |last4=Jenks |first5=David |last5=Grewell |first6=Lingshuang |last6=Cai | name-list-style = vanc |date=June 2008 |conference=2008 ASABE Annual International Meeting |location=Providence, RI |access-date=16 February 2013 |ref=none}}
* {{cite web | url = http://sci-toys.com/ingredients/alcohol.html | website = Sci-toys | title = Explanation of US denatured alcohol designations |ref=none}}
* {{cite book|last=Lange|first=Norbert Adolph|editor=John Aurie Dean|title=Lange's Handbook of Chemistry|url=https://books.google.com/books?id=4YlqAAAAMAAJ|edition=10th|year=1967|publisher=McGraw-Hill |ref=none}}
*{{Cite encyclopedia |title=Alcohols |encyclopedia=Encyclopedia of Liquid Fuels |publisher=De Gruyter |last=Schmidt |first=Eckart W. |date=2022 |pages=12–32 |doi=10.1515/9783110750287-001 |isbn=978-3-11-075028-7 |chapter=Ethanol}}

== External links ==
{{Wiktionary|alcohol|ethanol}}
{{Commons}} {{Commons}}
* at '']'' (University of Nottingham)
* ethanol safety information
* ethanol safety information
*
*
* chemical data on ethanol
*
*
* news and market data on ethanol futures * chemical data on ethanol
* news and market data on ethanol futures
*Calculation of , , , of ethanol
* Calculation of , , , of ethanol
*
* A look into the history of ethanol * A look into the history of ethanol
*
*


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Latest revision as of 20:43, 4 January 2025

Organic compound (CH₃CH₂OH) For ethanol as a drug or medicine, see Alcohol (drug) and Alcohols (medicine). Not to be confused with Ethenol or Ethynol.

Ethanol
Full structural formula of ethanol
Full structural formula of ethanol
Skeletal formula of ethanol
Skeletal formula of ethanol
Ball-and-stick model of ethanol
Ball-and-stick model of ethanol
Space-filling model of ethanol
Space-filling model of ethanol

Absolute ethanol
Names
Pronunciation /ˈɛθənɒl/
Preferred IUPAC name Ethanol
Other names
  • Absolute alcohol
  • Alcohol
  • Cologne spirit
  • Drinking alcohol
  • Ethylic alcohol
  • EtOH
  • Ethyl alcohol
  • Ethyl hydroxide
  • Ethylene hydrate
  • Ethylol
  • Grain alcohol
  • Hydroxyethane
  • Methylcarbinol
Identifiers
CAS Number
3D model (JSmol)
Beilstein Reference 1718733
ChEBI
ChEMBL
ChemSpider
DrugBank
ECHA InfoCard 100.000.526 Edit this at Wikidata
Gmelin Reference 787
IUPHAR/BPS
KEGG
PubChem CID
UNII
UN number UN 1170
CompTox Dashboard (EPA)
InChI
  • InChI=1S/C2H6O/c1-2-3/h3H,2H2,1H3Key: LFQSCWFLJHTTHZ-UHFFFAOYSA-N
  • InChI=1/C2H6O/c1-2-3/h3H,2H2,1H3Key: LFQSCWFLJHTTHZ-UHFFFAOYAB
SMILES
  • OCC
Properties
Chemical formula C2H6O
Molar mass 46.069 g·mol
Appearance Colourless liquid
Odor wine-like, pungent
Density 0.78945 g/cm (at 20 °C)
Melting point −114.14 ± 0.03 °C (−173.45 ± 0.05 °F; 159.01 ± 0.03 K)
Boiling point 78.23 ± 0.09 °C (172.81 ± 0.16 °F; 351.38 ± 0.09 K)
Solubility in water Miscible
log P −0.18
Vapor pressure 5.95 kPa (at 20 °C)
Acidity (pKa) 15.9 (H2O), 29.8 (DMSO)
Magnetic susceptibility (χ) −33.60·10 cm/mol
Refractive index (nD) 1.3611
Viscosity 1.2 mPa·s (at 20 °C), 1.074 mPa·s (at 25 °C)
Dipole moment 1.69 D
Hazards
GHS labelling:
Pictograms GHS02: Flammable GHS07: Exclamation mark
Signal word Danger
Hazard statements H225, H319, H360D
Precautionary statements P210, P233, P240, P241, P242, P305+P351+P338
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformFlammability 3: Liquids and solids that can be ignited under almost all ambient temperature conditions. Flash point between 23 and 38 °C (73 and 100 °F). E.g. gasolineInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
2 3 0
Flash point 14 °C (Absolute)
Lethal dose or concentration (LD, LC):
LD50 (median dose)
  • 7060 mg/kg (oral, rat)
  • 3450 mg/kg (mouse)
NIOSH (US health exposure limits):
PEL (Permissible) TWA 1000 ppm (1900 mg/m)
REL (Recommended) TWA 1000 ppm (1900 mg/m)
IDLH (Immediate danger) 3300 ppm
Safety data sheet (SDS)
Related compounds
Related compounds
Supplementary data page
Ethanol (data page)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa). ☒verify (what is  ?) Infobox references
Chemical compound

Ethanol (also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound with the chemical formula CH3CH2OH. It is an alcohol, with its formula also written as C2H5OH, C2H6O or EtOH, where Et stands for ethyl. Ethanol is a volatile, flammable, colorless liquid with a characteristic wine-like odor and pungent taste. In nature, grape-sugar breaks up by the action of fermentation into alcohol or carbonic acid, without anything being added. As a psychoactive depressant, it is the active ingredient in alcoholic beverages, and the second most consumed drug globally behind caffeine.

Ethanol is naturally produced by the fermentation process of sugars by yeasts or via petrochemical processes such as ethylene hydration. Historically it was used as a general anesthetic, and has modern medical applications as an antiseptic, disinfectant, solvent for some medications, and antidote for methanol poisoning and ethylene glycol poisoning. It is used as a chemical solvent and in the synthesis of organic compounds, and as a fuel source for lamps, stoves, and internal combustion engines. Ethanol also can be dehydrated to make ethylene, an important chemical feedstock. As of 2023, world production of ethanol fuel was 29,590,000,000 US gallons (112.0 gigalitres), coming mostly from the U.S. (51%) and Brazil (26%).

Name

Ethanol is the systematic name defined by the International Union of Pure and Applied Chemistry for a compound consisting of an alkyl group with two carbon atoms (prefix "eth-"), having a single bond between them (infix "-an-") and an attached −OH functional group (suffix "-ol").

The "eth-" prefix and the qualifier "ethyl" in "ethyl alcohol" originally came from the name "ethyl" assigned in 1834 to the group C
2H
5− by Justus Liebig. He coined the word from the German name Aether of the compound C
2H
5−O−C
2H
5 (commonly called "ether" in English, more specifically called "diethyl ether"). According to the Oxford English Dictionary, Ethyl is a contraction of the Ancient Greek αἰθήρ (aithḗr, "upper air") and the Greek word ὕλη (hýlē, "wood, raw material", hence "matter, substance"). Ethanol was coined as a result of a resolution on naming alcohols and phenols that was adopted at the International Conference on Chemical Nomenclature that was held in April 1892 in Geneva, Switzerland.

The term alcohol now refers to a wider class of substances in chemistry nomenclature, but in common parlance it remains the name of ethanol. It is a medieval loan from Arabic al-kuḥl, a powdered ore of antimony used since antiquity as a cosmetic, and retained that meaning in Middle Latin. The use of 'alcohol' for ethanol (in full, "alcohol of wine") was first recorded in 1753. Before the late 18th century the term alcohol generally referred to any sublimated substance.

Uses

Recreational drug

Main article: Alcohol (drug)

As a central nervous system depressant, ethanol is one of the most commonly consumed psychoactive drugs. Despite alcohol's psychoactive, addictive, and carcinogenic properties, it is readily available and legal for sale in many countries. There are laws regulating the sale, exportation/importation, taxation, manufacturing, consumption, and possession of alcoholic beverages. The most common regulation is prohibition for minors.

In mammals, ethanol is primarily metabolized in the liver and stomach by ADH enzymes. These enzymes catalyze the oxidation of ethanol into acetaldehyde (ethanal):

CH3CH2OH + NAD → CH3CHO + NADH + H

When present in significant concentrations, this metabolism of ethanol is additionally aided by the cytochrome P450 enzyme CYP2E1 in humans, while trace amounts are also metabolized by catalase. The resulting intermediate, acetaldehyde, is a known carcinogen, and poses significantly greater toxicity in humans than ethanol itself. Many of the symptoms typically associated with alcohol intoxication—as well as many of the health hazards typically associated with the long-term consumption of ethanol—can be attributed to acetaldehyde toxicity in humans.

The subsequent oxidation of acetaldehyde into acetate is performed by aldehyde dehydrogenase (ALDH) enzymes. A mutation in the ALDH2 gene that encodes for an inactive or dysfunctional form of this enzyme affects roughly 50 % of east Asian populations, contributing to the characteristic alcohol flush reaction that can cause temporary reddening of the skin as well as a number of related, and often unpleasant, symptoms of acetaldehyde toxicity. This mutation is typically accompanied by another mutation in the ADH enzyme ADH1B in roughly 80 % of east Asians, which improves the catalytic efficiency of converting ethanol into acetaldehyde.

Medical

Main article: Alcohol (medicine)

Ethanol is the oldest known sedative, used as an oral general anesthetic during surgery in ancient Mesopotamia and in medieval times. Mild intoxication starts at a blood alcohol concentration of 0.03-0.05 % and induces anesthetic coma at 0.4%. This use carries the high risk of deadly alcohol intoxication, pulmonary aspiration and vomiting, which led to use of alternatives in antiquity, such as opium and cannabis, and later diethyl ether, starting in the 1840s.

Ethanol is used as an antiseptic in medical wipes and hand sanitizer gels for its bactericidal and anti-fungal effects. Ethanol kills microorganisms by dissolving their membrane lipid bilayer and denaturing their proteins, and is effective against most bacteria, fungi and viruses. It is ineffective against bacterial spores, which can be treated with hydrogen peroxide.

A solution of 70% ethanol is more effective than pure ethanol because ethanol relies on water molecules for optimal antimicrobial activity. Absolute ethanol may inactivate microbes without destroying them because the alcohol is unable to fully permeate the microbe's membrane. Ethanol can also be used as a disinfectant and antiseptic by inducing cell dehydration through disruption of the osmotic balance across the cell membrane, causing water to leave the cell, leading to cell death.

Ethanol may be administered as an antidote to ethylene glycol poisoning and methanol poisoning. It does so by acting as a competitive inhibitor against methanol and ethylene glycol for alcohol dehydrogenase (ADH). Though it has more side effects, ethanol is less expensive and more readily available than fomepizole in the role.

Ethanol is used to dissolve many water-insoluble medications and related compounds. Liquid preparations of pain medications, cough and cold medicines, and mouth washes, for example, may contain up to 25% ethanol and may need to be avoided in individuals with adverse reactions to ethanol such as alcohol-induced respiratory reactions. Ethanol is present mainly as an antimicrobial preservative in over 700 liquid preparations of medicine including acetaminophen, iron supplements, ranitidine, furosemide, mannitol, phenobarbital, trimethoprim/sulfamethoxazole and over-the-counter cough medicine.

Some medicinal solutions of ethanol are also known as tinctures.

Energy source

See also: Food vs. fuel Main article: Ethanol fuel
Corn vs ethanol production in the United States   Total corn production (bushels) (left)   Corn used for Ethanol fuel (bushels) (left)   Percent of corn used for Ethanol (right)
Energy content (lower heating value) of some fuels compared with ethanol.
Fuel type MJ/L MJ/kg Research
octane
number
Dry wood (20% moisture) ~19.5
Methanol 17.9 19.9 108.7
Ethanol 21.2 26.8 108.6
E85
(85% ethanol, 15% gasoline)
25.2 33.2 105
Liquefied natural gas 25.3 ~55
Autogas (LPG)
(60% propane + 40% butane)
26.8 50
Aviation gasoline
(high-octane gasoline, not jet fuel)
33.5 46.8 100/130 (lean/rich)
Gasohol
(90% gasoline + 10% ethanol)
33.7 47.1 93/94
Regular gasoline/petrol 34.8 44.4 min. 91
Premium gasoline/petrol max. 104
Diesel 38.6 45.4 25
Charcoal, extruded 50 23

The largest single use of ethanol is as an engine fuel and fuel additive. Brazil in particular relies heavily upon the use of ethanol as an engine fuel, due in part to its role as one of the world's leading producers of ethanol. Gasoline sold in Brazil contains at least 25% anhydrous ethanol. Hydrous ethanol (about 95% ethanol and 5% water) can be used as fuel in more than 90% of new gasoline-fueled cars sold in the country.

The US and many other countries primarily use E10 (10% ethanol, sometimes known as gasohol) and E85 (85% ethanol) ethanol/gasoline mixtures. Over time, it is believed that a material portion of the ≈150-billion-US-gallon (570,000,000 m) per year market for gasoline will begin to be replaced with fuel ethanol.

USP grade ethanol for laboratory use

Australian law limits the use of pure ethanol from sugarcane waste to 10 % in automobiles. Older cars (and vintage cars designed to use a slower burning fuel) should have the engine valves upgraded or replaced.

According to an industry advocacy group, ethanol as a fuel reduces harmful tailpipe emissions of carbon monoxide, particulate matter, oxides of nitrogen, and other ozone-forming pollutants. Argonne National Laboratory analyzed greenhouse gas emissions of many different engine and fuel combinations, and found that biodiesel/petrodiesel blend (B20) showed a reduction of 8%, conventional E85 ethanol blend a reduction of 17% and cellulosic ethanol 64%, compared with pure gasoline. Ethanol has a much greater research octane number (RON) than gasoline, meaning it is less prone to pre-ignition, allowing for better ignition advance which means more torque, and efficiency in addition to the lower carbon emissions.

Ethanol combustion in an internal combustion engine yields many of the products of incomplete combustion produced by gasoline and significantly larger amounts of formaldehyde and related species such as acetaldehyde. This leads to a significantly larger photochemical reactivity and more ground level ozone. This data has been assembled into The Clean Fuels Report comparison of fuel emissions and show that ethanol exhaust generates 2.14 times as much ozone as gasoline exhaust. When this is added into the custom Localized Pollution Index of The Clean Fuels Report, the local pollution of ethanol (pollution that contributes to smog) is rated 1.7, where gasoline is 1.0 and higher numbers signify greater pollution. The California Air Resources Board formalized this issue in 2008 by recognizing control standards for formaldehydes as an emissions control group, much like the conventional NOx and reactive organic gases (ROGs).

More than 20% of Brazilian cars are able to use 100% ethanol as fuel, which includes ethanol-only engines and flex-fuel engines. Flex-fuel engines in Brazil are able to work with all ethanol, all gasoline or any mixture of both. In the United States, flex-fuel vehicles can run on 0% to 85% ethanol (15% gasoline) since higher ethanol blends are not yet allowed or efficient. Brazil supports this fleet of ethanol-burning automobiles with large national infrastructure that produces ethanol from domestically grown sugarcane.

Ethanol's high miscibility with water makes it unsuitable for shipping through modern pipelines like liquid hydrocarbons. Mechanics have seen increased cases of damage to small engines (in particular, the carburetor) and attribute the damage to the increased water retention by ethanol in fuel.

Ethanol was commonly used as fuel in early bipropellant rocket (liquid-propelled) vehicles, in conjunction with an oxidizer such as liquid oxygen. The German A-4 ballistic rocket of World War II (better known by its propaganda name V-2), which is credited as having begun the space age, used ethanol as the main constituent of B-Stoff. Under such nomenclature, the ethanol was mixed with 25% water to reduce the combustion chamber temperature. The V-2's design team helped develop U.S. rockets following World War II, including the ethanol-fueled Redstone rocket, which launched the first U.S. astronaut on suborbital spaceflight. Alcohols fell into general disuse as more energy-dense rocket fuels were developed, although ethanol was used in recent experimental lightweight rocket-powered racing aircraft.

Commercial fuel cells operate on reformed natural gas, hydrogen or methanol. Ethanol is an attractive alternative due to its wide availability, low cost, high purity and low toxicity. There is a wide range of fuel cell concepts that have entered trials including direct-ethanol fuel cells, auto-thermal reforming systems and thermally integrated systems. The majority of work is being conducted at a research level although there are a number of organizations at the beginning of the commercialization of ethanol fuel cells.

Ethanol fireplaces can be used for home heating or for decoration. Ethanol can also be used as stove fuel for cooking.

Other uses

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Ethanol is an important industrial ingredient. It has widespread use as a precursor for other organic compounds such as ethyl halides, ethyl esters, diethyl ether, acetic acid, and ethyl amines. It is considered a universal solvent, as its molecular structure allows for the dissolving of both polar, hydrophilic and nonpolar, hydrophobic compounds. As ethanol also has a low boiling point, it is easy to remove from a solution that has been used to dissolve other compounds, making it a popular extracting agent for botanical oils. Cannabis oil extraction methods often use ethanol as an extraction solvent, and also as a post-processing solvent to remove oils, waxes, and chlorophyll from solution in a process known as winterization.

Ethanol is found in paints, tinctures, markers, and personal care products such as mouthwashes, perfumes and deodorants. Polysaccharides precipitate from aqueous solution in the presence of alcohol, and ethanol precipitation is used for this reason in the purification of DNA and RNA. Because of its low freezing point of −114 °C (−173 °F) and low toxicity, ethanol is sometimes used in laboratories (with dry ice or other coolants) as a cooling bath to keep vessels at temperatures below the freezing point of water. For the same reason, it is also used as the active fluid in alcohol thermometers.

Chemistry

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Further information: Ethanol (data page)

Ethanol is a 2-carbon alcohol. Its molecular formula is CH3CH2OH. The structure of the molecule of ethanol is CH3−CH2−OH (an ethyl group linked to a hydroxyl group), which indicates that the carbon of a methyl group (CH3−) is attached to the carbon of a methylene group (−CH2–), which is attached to the oxygen of a hydroxyl group (−OH). It is a constitutional isomer of dimethyl ether. Ethanol is sometimes abbreviated as EtOH, using the common organic chemistry notation of representing the ethyl group (C2H5−) with Et.

Physical properties

Ethanol burning with its spectrum depicted

Ethanol is a volatile, colorless liquid that has a slight odor. It burns with a smokeless blue flame that is not always visible in normal light. The physical properties of ethanol stem primarily from the presence of its hydroxyl group and the shortness of its carbon chain. Ethanol's hydroxyl group is able to participate in hydrogen bonding, rendering it more viscous and less volatile than less polar organic compounds of similar molecular weight, such as propane. Ethanol's adiabatic flame temperature for combustion in air is 2082 °C or 3779 °F.

Ethanol is slightly more refractive than water, having a refractive index of 1.36242 (at λ=589.3 nm and 18.35 °C or 65.03 °F). The triple point for ethanol is 150 ± 20 K.

Solvent properties

Ethanol is a versatile solvent, miscible with water and with many organic solvents, including acetic acid, acetone, benzene, carbon tetrachloride, chloroform, diethyl ether, ethylene glycol, glycerol, nitromethane, pyridine, and toluene. Its main use as a solvent is in making tincture of iodine, cough syrups, etc. It is also miscible with light aliphatic hydrocarbons, such as pentane and hexane, and with aliphatic chlorides such as trichloroethane and tetrachloroethylene.

Ethanol's miscibility with water contrasts with the immiscibility of longer-chain alcohols (five or more carbon atoms), whose water miscibility decreases sharply as the number of carbons increases. The miscibility of ethanol with alkanes is limited to alkanes up to undecane: mixtures with dodecane and higher alkanes show a miscibility gap below a certain temperature (about 13 °C for dodecane). The miscibility gap tends to get wider with higher alkanes, and the temperature for complete miscibility increases.

Ethanol-water mixtures have less volume than the sum of their individual components at the given fractions. Mixing equal volumes of ethanol and water results in only 1.92 volumes of mixture. Mixing ethanol and water is exothermic, with up to 777 J/mol being released at 298 K.

Hydrogen bonding in solid ethanol at −186 °C

Hydrogen bonding causes pure ethanol to be hygroscopic to the extent that it readily absorbs water from the air. The polar nature of the hydroxyl group causes ethanol to dissolve many ionic compounds, notably sodium and potassium hydroxides, magnesium chloride, calcium chloride, ammonium chloride, ammonium bromide, and sodium bromide. Sodium and potassium chlorides are slightly soluble in ethanol. Because the ethanol molecule also has a nonpolar end, it will also dissolve nonpolar substances, including most essential oils and numerous flavoring, coloring, and medicinal agents.

The addition of even a few percent of ethanol to water sharply reduces the surface tension of water. This property partially explains the "tears of wine" phenomenon. When wine is swirled in a glass, ethanol evaporates quickly from the thin film of wine on the wall of the glass. As the wine's ethanol content decreases, its surface tension increases and the thin film "beads up" and runs down the glass in channels rather than as a smooth sheet.

Azeotrope with water

At atmospheric pressure, mixtures of ethanol and water form an azeotrope at about 89.4 mol% ethanol (95.6% ethanol by mass, 97% alcohol by volume), with a boiling point of 351.3 K (78.1 °C). At lower pressure, the composition of the ethanol-water azeotrope shifts to more ethanol-rich mixtures. The minimum-pressure azeotrope has an ethanol fraction of 100% and a boiling point of 306 K (33 °C), corresponding to a pressure of roughly 70 torr (9.333 kPa). Below this pressure, there is no azeotrope, and it is possible to distill absolute ethanol from an ethanol-water mixture.

Flammability

An ethanol–water solution will catch fire if heated above a temperature called its flash point and an ignition source is then applied to it. For 20% alcohol by mass (about 25% by volume), this will occur at about 25 °C (77 °F). The flash point of pure ethanol is 13 °C (55 °F), but may be influenced very slightly by atmospheric composition such as pressure and humidity. Ethanol mixtures can ignite below average room temperature. Ethanol is considered a flammable liquid (Class 3 Hazardous Material) in concentrations above 2.35% by mass (3.0% by volume; 6 proof). Dishes using burning alcohol for culinary effects are called flambé.

Flash points of ethanol–water mixtures
Ethanol
mole fraction, %
Temperature
°C °F
1 84.5 184.1
2 64 147
2.35 60 140
3 51.5 124.7
5 43 109
6 39.5 103.1
10 31 88
20 25 77
30 24 75
50 20 68
70 16 61
80 15.8 60.4
90 14 57
100 12.5 54.5

Natural occurrence

Ethanol is a byproduct of the metabolic process of yeast. As such, ethanol will be present in any yeast habitat. Ethanol can commonly be found in overripe fruit. Ethanol produced by symbiotic yeast can be found in bertam palm blossoms. Although some animal species, such as the pentailed treeshrew, exhibit ethanol-seeking behaviors, most show no interest or avoidance of food sources containing ethanol. Ethanol is also produced during the germination of many plants as a result of natural anaerobiosis.

Ethanol has been detected in outer space, forming an icy coating around dust grains in interstellar clouds. Minute quantity amounts (average 196 ppb) of endogenous ethanol and acetaldehyde were found in the exhaled breath of healthy volunteers. Auto-brewery syndrome, also known as gut fermentation syndrome, is a rare medical condition in which intoxicating quantities of ethanol are produced through endogenous fermentation within the digestive system.

Production

94% denatured ethanol sold in a bottle for household use

Ethanol is produced both as a petrochemical, through the hydration of ethylene and, via biological processes, by fermenting sugars with yeast. Which process is more economical depends on prevailing prices of petroleum and grain feed stocks.

Sources

World production of ethanol in 2006 was 51 gigalitres (1.3×10 US gal), with 69% of the world supply coming from Brazil and the U.S. Brazilian ethanol is produced from sugarcane, which has relatively high yields (830% more fuel than the fossil fuels used to produce it) compared to some other energy crops. Sugarcane not only has a greater concentration of sucrose than corn (by about 30%), but is also much easier to extract. The bagasse generated by the process is not discarded, but burned by power plants to produce electricity. Bagasse burning accounts for around 9% of the electricity produced in Brazil.

In the 1970s most industrial ethanol in the U.S. was made as a petrochemical, but in the 1980s the U.S. introduced subsidies for corn-based ethanol. According to the Renewable Fuels Association, as of 30 October 2007, 131 grain ethanol bio-refineries in the U.S. have the capacity to produce 7×10^ US gal (26,000,000 m) of ethanol per year. An additional 72 construction projects underway (in the U.S.) can add 6.4 billion US gallons (24,000,000 m) of new capacity in the next 18 months.

In India ethanol is made from sugarcane. Sweet sorghum is another potential source of ethanol, and is suitable for growing in dryland conditions. The International Crops Research Institute for the Semi-Arid Tropics is investigating the possibility of growing sorghum as a source of fuel, food, and animal feed in arid parts of Asia and Africa. Sweet sorghum has one-third the water requirement of sugarcane over the same time period. It also requires about 22% less water than corn. The world's first sweet sorghum ethanol distillery began commercial production in 2007 in Andhra Pradesh, India.

Ethanol has been produced in the laboratory by converting carbon dioxide via biological and electrochemical reactions.

CO2 + H
2O → CH
3CH
2OH + side products

Hydration

Ethanol can be produced from petrochemical feed stocks, primarily by the acid-catalyzed hydration of ethylene. It is often referred to as synthetic ethanol.

C2H4 + H2O → C2H5OH

The catalyst is most commonly phosphoric acid, adsorbed onto a porous support such as silica gel or diatomaceous earth. This catalyst was first used for large-scale ethanol production by the Shell Oil Company in 1947. The reaction is carried out in the presence of high pressure steam at 300 °C (572 °F) where a 5:3 ethylene to steam ratio is maintained. This process was used on an industrial scale by Union Carbide Corporation and others. It is no longer practiced in the US as fermentation ethanol produced from corn is more economical.

In an older process, first practiced on the industrial scale in 1930 by Union Carbide but now almost entirely obsolete, ethylene was hydrated indirectly by reacting it with concentrated sulfuric acid to produce ethyl sulfate, which was hydrolyzed to yield ethanol and regenerate the sulfuric acid:

C2H4 + H2SO4 → C2H5HSO4
C2H5HSO4 + H2O → H2SO4 + C2H5OH

Fermentation

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Main articles: Ethanol fermentation and Cellulosic ethanol See also: Yeast in winemaking

Ethanol in alcoholic beverages and fuel is produced by fermentation. Certain species of yeast (e.g., Saccharomyces cerevisiae) metabolize sugar (namely polysaccharides), producing ethanol and carbon dioxide. The chemical equations below summarize the conversion:

C
6H
12O
6
→ 2 CH
3CH
2OH + 2 CO2 C
12H
22O
11
+ H
2O → 4 CH
3CH
2OH + 4 CO2

Fermentation is the process of culturing yeast under favorable thermal conditions to produce alcohol. This process is carried out at around 35–40 °C (95–104 °F). Toxicity of ethanol to yeast limits the ethanol concentration obtainable by brewing; higher concentrations, therefore, are obtained by fortification or distillation. The most ethanol-tolerant yeast strains can survive up to approximately 18% ethanol by volume.

To produce ethanol from starchy materials such as cereals, the starch must first be converted into sugars. In brewing beer, this has traditionally been accomplished by allowing the grain to germinate, or malt, which produces the enzyme amylase. When the malted grain is mashed, the amylase converts the remaining starches into sugars.

Sugars for ethanol fermentation can be obtained from cellulose. Deployment of this technology could turn a number of cellulose-containing agricultural by-products, such as corncobs, straw, and sawdust, into renewable energy resources. Other agricultural residues such as sugarcane bagasse and energy crops such as switchgrass may also be fermentable sugar sources.

Testing

Infrared reflection spectra of liquid ethanol, showing the −OH band centered near 3300 cm and C−H bands near 2950 cm
Near-infrared spectrum of liquid ethanol

Breweries and biofuel plants employ two methods for measuring ethanol concentration. Infrared ethanol sensors measure the vibrational frequency of dissolved ethanol using the C−H band at 2900 cm. This method uses a relatively inexpensive solid-state sensor that compares the C−H band with a reference band to calculate the ethanol content. The calculation makes use of the Beer–Lambert law. Alternatively, by measuring the density of the starting material and the density of the product, using a hydrometer, the change in specific gravity during fermentation indicates the alcohol content. This inexpensive and indirect method has a long history in the beer brewing industry.

Purification

Ethylene hydration or brewing produces an ethanol–water mixture. For most industrial and fuel uses, the ethanol must be purified. Fractional distillation at atmospheric pressure can concentrate ethanol to 95.6% by weight (89.5 mole%). This mixture is an azeotrope with a boiling point of 78.1 °C (172.6 °F), and cannot be further purified by distillation. Addition of an entraining agent, such as benzene, cyclohexane, or heptane, allows a new ternary azeotrope comprising the ethanol, water, and the entraining agent to be formed. This lower-boiling ternary azeotrope is removed preferentially, leading to water-free ethanol.

Apart from distillation, ethanol may be dried by addition of a desiccant, such as molecular sieves, cellulose, or cornmeal. The desiccants can be dried and reused. Molecular sieves can be used to selectively absorb the water from the 95.6% ethanol solution. Molecular sieves of pore-size 3 Ångstrom, a type of zeolite, effectively sequester water molecules while excluding ethanol molecules. Heating the wet sieves drives out the water, allowing regeneration of their desiccant capability.

Membranes can also be used to separate ethanol and water. Membrane-based separations are not subject to the limitations of the water-ethanol azeotrope because the separations are not based on vapor-liquid equilibria. Membranes are often used in the so-called hybrid membrane distillation process. This process uses a pre-concentration distillation column as the first separating step. The further separation is then accomplished with a membrane operated either in vapor permeation or pervaporation mode. Vapor permeation uses a vapor membrane feed and pervaporation uses a liquid membrane feed.

A variety of other techniques have been discussed, including the following:

Grades of ethanol

Further information: Denatured alcohol

Pure ethanol and alcoholic beverages are heavily taxed as psychoactive drugs, but ethanol has many uses that do not involve its consumption. To relieve the tax burden on these uses, most jurisdictions waive the tax when an agent has been added to the ethanol to render it unfit to drink. These include bittering agents such as denatonium benzoate and toxins such as methanol, naphtha, and pyridine. Products of this kind are called denatured alcohol.

Absolute or anhydrous alcohol refers to ethanol with a low water content. There are various grades with maximum water contents ranging from 1% to a few parts per million (ppm). If azeotropic distillation is used to remove water, it will contain trace amounts of the material separation agent (e.g. benzene). Absolute alcohol is not intended for human consumption. Absolute ethanol is used as a solvent for laboratory and industrial applications, where water will react with other chemicals, and as fuel alcohol. Spectroscopic ethanol is an absolute ethanol with a low absorbance in ultraviolet and visible light, fit for use as a solvent in ultraviolet-visible spectroscopy. Pure ethanol is classed as 200 proof in the US, equivalent to 175 degrees proof in the UK system. Rectified spirit, an azeotropic composition of 96% ethanol containing 4% water, is used instead of anhydrous ethanol for various purposes. Spirits of wine are about 94% ethanol (188 proof). The impurities are different from those in 95% (190 proof) laboratory ethanol.

Reactions

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Further information: Alcohol (chemistry)

Ethanol is classified as a primary alcohol, meaning that the carbon that its hydroxyl group attaches to has at least two hydrogen atoms attached to it as well. Many ethanol reactions occur at its hydroxyl group.

Ester formation

In the presence of acid catalysts, ethanol reacts with carboxylic acids to produce ethyl esters and water:

RCOOH + HOCH2CH3RCOOCH2CH3 + H2O

This reaction, which is conducted on large scale industrially, requires the removal of the water from the reaction mixture as it is formed. Esters react in the presence of an acid or base to give back the alcohol and a salt. This reaction is known as saponification because it is used in the preparation of soap. Ethanol can also form esters with inorganic acids. Diethyl sulfate and triethyl phosphate are prepared by treating ethanol with sulfur trioxide and phosphorus pentoxide respectively. Diethyl sulfate is a useful ethylating agent in organic synthesis. Ethyl nitrite, prepared from the reaction of ethanol with sodium nitrite and sulfuric acid, was formerly used as a diuretic.

Dehydration

In the presence of acid catalysts, alcohols can be converted to alkenes such as ethanol to ethylene. Typically solid acids such as alumina are used.

CH3CH2OH → H2C=CH2 + H2O

Since water is removed from the same molecule, the reaction is known as intramolecular dehydration. Intramolecular dehydration of an alcohol requires a high temperature and the presence of an acid catalyst such as sulfuric acid. Ethylene produced from sugar-derived ethanol (primarily in Brazil) competes with ethylene produced from petrochemical feedstocks such as naphtha and ethane. At a lower temperature than that of intramolecular dehydration, intermolecular alcohol dehydration may occur producing a symmetrical ether. This is a condensation reaction. In the following example, diethyl ether is produced from ethanol:

2 CH3CH2OH → CH3CH2OCH2CH3 + H2O

Combustion

Complete combustion of ethanol forms carbon dioxide and water:

C2H5OH (l) + 3 O2 (g) → 2 CO2 (g) + 3 H2O (l); −ΔcH = 1371 kJ/mol = 29.8 kJ/g = 327 kcal/mol = 7.1 kcal/g
C2H5OH (l) + 3 O2 (g) → 2 CO2 (g) + 3 H2O (g); −ΔcH = 1236 kJ/mol = 26.8 kJ/g = 295.4 kcal/mol = 6.41 kcal/g

Specific heat = 2.44 kJ/(kg·K)

Acid-base chemistry

Ethanol is a neutral molecule and the pH of a solution of ethanol in water is nearly 7.00. Ethanol can be quantitatively converted to its conjugate base, the ethoxide ion (CH3CH2O), by reaction with an alkali metal such as sodium:

2 CH3CH2OH + 2 Na → 2 CH3CH2ONa + H2

or a very strong base such as sodium hydride:

CH3CH2OH + NaH → CH3CH2ONa + H2

The acidities of water and ethanol are nearly the same, as indicated by their pKa of 15.7 and 16 respectively. Thus, sodium ethoxide and sodium hydroxide exist in an equilibrium that is closely balanced:

CH3CH2OH + NaOH ⇌ CH3CH2ONa + H2O

Halogenation

Ethanol is not used industrially as a precursor to ethyl halides, but the reactions are illustrative. Ethanol reacts with hydrogen halides to produce ethyl halides such as ethyl chloride and ethyl bromide via an SN2 reaction:

CH3CH2OH + HCl → CH3CH2Cl + H2O

HCl requires a catalyst such as zinc chloride. HBr requires refluxing with a sulfuric acid catalyst. Ethyl halides can, in principle, also be produced by treating ethanol with more specialized halogenating agents, such as thionyl chloride or phosphorus tribromide.

CH3CH2OH + SOCl2 → CH3CH2Cl + SO2 + HCl

Upon treatment with halogens in the presence of base, ethanol gives the corresponding haloform (CHX3, where X = Cl, Br, I). This conversion is called the haloform reaction. An intermediate in the reaction with chlorine is the aldehyde called chloral, which forms chloral hydrate upon reaction with water:

4 Cl2 + CH3CH2OH → CCl3CHO + 5 HCl
CCl3CHO + H2O → CCl3C(OH)2H

Oxidation

Ethanol can be oxidized to acetaldehyde and further oxidized to acetic acid, depending on the reagents and conditions. This oxidation is of no importance industrially, but in the human body, these oxidation reactions are catalyzed by the enzyme liver ADH. The oxidation product of ethanol, acetic acid, is a nutrient for humans, being a precursor to acetyl CoA, where the acetyl group can be spent as energy or used for biosynthesis.

Metabolism

Ethanol is similar to macronutrients such as proteins, fats, and carbohydrates in that it provides calories. When consumed and metabolized, it contributes 7 kilocalories per gram via ethanol metabolism.

Safety

See also: Alcohol (chemistry) § Toxicity

Ethanol is very flammable and should not be used around an open flame.

Pure ethanol will irritate the skin and eyes. Nausea, vomiting, and intoxication are symptoms of ingestion. Long-term use by ingestion can result in serious liver damage. Atmospheric concentrations above one part per thousand are above the European Union occupational exposure limits.

History

Further information: Liquor

The fermentation of sugar into ethanol is one of the earliest biotechnologies employed by humans. Ethanol has historically been identified variously as spirit of wine or ardent spirits, and as aqua vitae or aqua vita. The intoxicating effects of its consumption have been known since ancient times. Ethanol has been used by humans since prehistory as the intoxicating ingredient of alcoholic beverages. Dried residue on 9,000-year-old pottery found in China suggests that Neolithic people consumed alcoholic beverages.

The inflammable nature of the exhalations of wine was already known to ancient natural philosophers such as Aristotle (384–322 BCE), Theophrastus (c. 371–287 BCE), and Pliny the Elder (23/24–79 CE). However, this did not immediately lead to the isolation of ethanol, despite the development of more advanced distillation techniques in second- and third-century Roman Egypt. An important recognition, first found in one of the writings attributed to Jābir ibn Ḥayyān (ninth century CE), was that by adding salt to boiling wine, which increases the wine's relative volatility, the flammability of the resulting vapors may be enhanced. The distillation of wine is attested in Arabic works attributed to al-Kindī (c. 801–873 CE) and to al-Fārābī (c. 872–950), and in the 28th book of al-Zahrāwī's (Latin: Abulcasis, 936–1013) Kitāb al-Taṣrīf (later translated into Latin as Liber servatoris). In the twelfth century, recipes for the production of aqua ardens ("burning water", i.e., ethanol) by distilling wine with salt started to appear in a number of Latin works, and by the end of the thirteenth century it had become a widely known substance among Western European chemists.

The works of Taddeo Alderotti (1223–1296) describe a method for concentrating ethanol involving repeated fractional distillation through a water-cooled still, by which an ethanol purity of 90% could be obtained. The medicinal properties of ethanol were studied by Arnald of Villanova (1240–1311 CE) and John of Rupescissa (c. 1310–1366), the latter of whom regarded it as a life-preserving substance able to prevent all diseases (the aqua vitae or "water of life", also called by John the quintessence of wine). In China, archaeological evidence indicates that the true distillation of alcohol began during the Jin (1115–1234) or Southern Song (1127–1279) dynasties. A still has been found at an archaeological site in Qinglong, Hebei, dating to the 12th century. In India, the true distillation of alcohol was introduced from the Middle East, and was in wide use in the Delhi Sultanate by the 14th century.

In 1796, German-Russian chemist Johann Tobias Lowitz obtained pure ethanol by mixing partially purified ethanol (the alcohol-water azeotrope) with an excess of anhydrous alkali and then distilling the mixture over low heat. French chemist Antoine Lavoisier described ethanol as a compound of carbon, hydrogen, and oxygen, and in 1807 Nicolas-Théodore de Saussure determined ethanol's chemical formula. Fifty years later, Archibald Scott Couper published the structural formula of ethanol, one of the first structural formulas determined.

Ethanol was first prepared synthetically in 1825 by Michael Faraday. He found that sulfuric acid could absorb large volumes of coal gas. He gave the resulting solution to Henry Hennell, a British chemist, who found in 1826 that it contained "sulphovinic acid" (ethyl hydrogen sulfate). In 1828, Hennell and the French chemist Georges-Simon Serullas independently discovered that sulphovinic acid could be decomposed into ethanol. Thus, in 1825 Faraday had unwittingly discovered that ethanol could be produced from ethylene (a component of coal gas) by acid-catalyzed hydration, a process similar to current industrial ethanol synthesis.

Ethanol was used as lamp fuel in the U.S. as early as 1840, but a tax levied on industrial alcohol during the Civil War made this use uneconomical. The tax was repealed in 1906. Use as an automotive fuel dates back to 1908, with the Ford Model T able to run on petrol (gasoline) or ethanol. It fuels some spirit lamps.

Ethanol intended for industrial use is often produced from ethylene. Ethanol has widespread use as a solvent of substances intended for human contact or consumption, including scents, flavorings, colorings, and medicines. In chemistry, it is both a solvent and a feedstock for the synthesis of other products. It has a long history as a fuel for heat and light, and more recently as a fuel for internal combustion engines.

See also

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