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{{short description|Methoxyphenol compound, constituent of plant lignins and essential oils}}
{{chembox {{chembox
| Watchedfields = changed
| verifiedrevid = 415511788
| verifiedrevid = 443849411
|Reference=<ref>'']'', 13th Edition, '''4568'''.</ref>
| Reference =<ref>{{cite book|title=Merck Index|edition=13th|page=4568|title-link=Merck Index}}</ref>
|ImageFileL1=Guaiacol.png
| ImageFileL1 =Guaiacol.png
|ImageSizeL1=130px
|ImageFileR1=Guaiacol 3D.png | ImageFileR1 =Guaiacol 3D spacefill.png
| PIN =2-Methoxyphenol
|ImageSizeR1 = 120px
| OtherNames =''o''-Methoxyphenol<br>''O''-Methylcatechol<ref>{{cite web|url=http://www.chemindustry.com/chemicals/464173.html|website=Chemindustry|title=List of synonyms for guaiacol|access-date=2009-03-20|archive-date=2016-08-10|archive-url=https://web.archive.org/web/20160810082353/http://www.chemindustry.com/chemicals/464173.html|url-status=dead}}</ref><br> 2-Hydroxyanisole<br> Pyroguaiac acid<br> Pyrocatechol monomethyl ether<br> 1-hydroxy-2-methoxybenzene<br>
|IUPACName=2-methoxyphenol
|Section1={{Chembox Identifiers
|OtherNames=''o''-Methoxyphenol; Methylcatechol<ref></ref>
| UNII_Ref = {{fdacite|correct|FDA}}
|Section1= {{Chembox Identifiers
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = 6JKA7MAH9C | UNII = 6JKA7MAH9C
| KEGG_Ref = {{keggcite|correct|kegg}} | KEGG_Ref = {{keggcite|correct|kegg}}
Line 22: Line 22:
| StdInChIKey = LHGVFZTZFXWLCP-UHFFFAOYSA-N | StdInChIKey = LHGVFZTZFXWLCP-UHFFFAOYSA-N
| CASNo_Ref = {{cascite|correct|CAS}} | CASNo_Ref = {{cascite|correct|CAS}}
| CASNo=90-05-1 | CASNo = 90-05-1
| PubChem=460 | PubChem = 460
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} | ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 447 | ChemSpiderID = 447
| ChEBI_Ref = {{ebicite|correct|EBI}}
| SMILES = COc1ccccc1O
| ChEBI = 28591
}}
| SMILES = COc1ccccc1O
|Section2= {{Chembox Properties
}}
| Formula=C<sub>7</sub>H<sub>8</sub>O<sub>2</sub>
|Section2={{Chembox Properties
| MolarMass=124.14 g/mol
| C=7|H=8|O=2
| Appearance=
| MolarMass =
| Density=1.112 g/cm<sup>3</sup>, liquid<br />1.129 g/cm<sup>3</sup>, crystals
| Appearance = colorless oil or crystalline solid
| MeltingPtC=28
| Density = 1.112 g/cm<sup>3</sup>, liquid<br />1.129 g/cm<sup>3</sup>, crystals
| BoilingPt=204-206 °C
| MeltingPtC = 26-29
| Solubility=
| BoilingPtC = 204–206
}}
| BoilingPt_notes =
|Section3= {{Chembox Hazards
| Solubility = 23.3 g/L at 25&nbsp;°C
| MainHazards=
}}
| FlashPt=
|Section3={{Chembox Hazards
| Autoignition=
| MainHazards =
| FlashPt =
| AutoignitionPt =
}}
|Section4={{Chembox Related
| OtherFunction_label = ]s
| OtherFunction = ]<br /> ]
}} }}
}} }}


'''Guaiacol''' ({{IPAc-en|ˈ|ɡ|w|aɪ|ə|k|ɒ|l}}) is an ] with the ] C<sub>6</sub>H<sub>4</sub>(OH)(OCH<sub>3</sub>). It is a phenolic compound containing a ] functional group. Guaiacol appears as a viscous colorless oil, although aged or impure samples are often yellowish. It occurs widely in nature and is a common product of the ] of wood.<ref name=Ullmann/>
'''Guaiacol''' is a naturally occurring ] with the ] C<sub>6</sub>H<sub>4</sub>(OH)(OCH<sub>3</sub>). Although it is biosynthesized by a variety of organisms,<ref>See for example, {{cite journal | doi = 10.1016/0305-0491(77)90029-3 | author = Duffey, S. S.; Aldrich, J. R.; Blum, M. S. | title = Biosynthesis of phenol and guaiacol by the hemipteran Leptoglossus phyllopus | journal = Comparative Biochemistry and Physiology, Part B: Biochemistry & Molecular Biology | year = 1977 | volume = 56 | issue = 2B | pages = 101–102}}</ref> this colorless aromatic oil is usually derived from ] or wood ]. Samples darken upon exposure to air and light. Guaiacol is present in wood ], resulting from the ] of ]. The compound contributes to the flavor of many compounds, e.g. roasted coffee.<ref>{{cite journal | doi = 10.1021/jf0341767 | year = 2003 | month = Sep | author = Dorfner, R; Ferge, T; Kettrup, A; Zimmermann, R; Yeretzian, C | title = Real-time monitoring of 4-vinylguaiacol, guaiacol, and phenol during coffee roasting by resonant laser ionization time-of-flight mass spectrometry | volume = 51 | issue = 19 | pages = 5768–5773 | issn = 0021-8561 | pmid = 12952431 | journal = Journal of agricultural and food chemistry}}</ref>

==Occurrence==
Guaiacol is usually derived from ] or wood ].

It is produced by a variety of plants.<ref>{{cite journal | doi = 10.1016/0305-0491(77)90029-3 |pmid=830476 |last1=Duffey |first1=S. S. |last2=Aldrich |first2=J. R. |last3=Blum |first3=M. S. | title = Biosynthesis of phenol and guaiacol by the hemipteran ''Leptoglossus phyllopus'' | journal = Comparative Biochemistry and Physiology B | year = 1977 | volume = 56 | issue = 2B | pages = 101–102}}</ref> It is also found in essential oils from ] seeds, ] leaves, ] leaves, and ] peels.<ref>{{cite book |last=Burdock|first=G. A.|date=1995|title=Encyclopedia of Food and Color Additives|location=Boca Raton, FL|publisher=CRC Press|pages=1244–1245|isbn=978-0849394126}}</ref> The pure substance is colorless, but samples become yellow upon exposure to air and light. The compound is present in wood ], resulting from the ] of ]. The compound contributes to the flavor of many substances such as ]<ref>{{cite news |last=Gallegos |first=Jenna |date=August 17, 2017 |title=The best way to drink whiskey, according to science |newspaper=The Washington Post |url=https://www.washingtonpost.com/news/speaking-of-science/wp/2017/08/17/the-best-way-to-drink-whiskey-according-to-science/ |quote=Guaiacol is what gives whiskey that smoky, spicy, peaty flavor.}}</ref> and ].<ref>{{cite journal |last1=Dorfner |first1=R. |last2=Ferge |first2=T. |last3=Kettrup |first3=A. |last4=Zimmermann |first4=R. |last5=Yeretzian |first5=C. |date=Sep 2003 |title=Real-time monitoring of 4-vinylguaiacol, guaiacol, and phenol during coffee roasting by resonant laser ionization time-of-flight mass spectrometry |journal=Journal of Agricultural and Food Chemistry |issn=0021-8561 |doi=10.1021/jf0341767 |pmid=12952431 |volume=51 |issue=19 |pages=5768–5773}}</ref>


==Preparation== ==Preparation==
Guaiacol is produced industrially by ] of ], e.g. using potash and ]:<ref name=Ullmann>Helmut Fiege, Heinz-Werner Voges, Toshikazu Hamamoto, Sumio Umemura, Tadao Iwata, Hisaya Miki, Yasuhiro Fujita, Hans-Josef Buysch, Dorothea Garbe, Wilfried Paulus "Phenol Derivatives" Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2002. {{doi|10.1002/14356007.a19_313}}</ref> The compound was first isolated by ] in 1826.<ref>{{cite journal|last1=Stevens |first1=M. E. |last2=Ronan |first2=A. K. |last3=Sourkes |first3=T. S. |first4=Boyd |last4=E. M. | title=On the Expectorant Action of Creosote and the Guaiacols | journal=Canadian Medical Association Journal | year= 1943 | volume= 48 | issue= 2 | pages= 124–127 | pmid=20322688 | pmc=1827660}}</ref> Guaiacol is produced by ] of ''o''-], for example using ] and ]:<ref name=Ullmann>{{Ullmann|first1=Helmut |last1=Fiege |first2=Heinz-Werner |last2=Voges |first3=Toshikazu |last3=Hamamoto |first4=Sumio |last4=Umemura |first5=Tadao |last5=Iwata |first6=Hisaya |last6=Miki |first7=Yasuhiro |last7=Fujita |first8=Hans-Josef |last8=Buysch |first9=Dorothea |last9=Garbe |first10=Wilfried |last10=Paulus |title=Phenol Derivatives|doi=10.1002/14356007.a19_313}}</ref>
:C<sub>6</sub>H<sub>4</sub>(OH)<sub>2</sub> + ] → C<sub>6</sub>H<sub>4</sub>(OH)(OCH<sub>3</sub>) + HO(CH<sub>3</sub>O)SO<sub>2</sub> :C<sub>6</sub>H<sub>4</sub>(OH)<sub>2</sub> + ] → C<sub>6</sub>H<sub>4</sub>(OH)(OCH<sub>3</sub>) + HO(CH<sub>3</sub>O)SO<sub>2</sub>


===Laboratory methods=== ===Laboratory methods===
Guaiacol can be prepared by diverse routes in the laboratory. 2-Aminoanisole, derived in two steps from ], can be hydrolyzed via its diazonium derivative. Guaiacol can be synthesized by the di] of ] followed by selective mono-].<ref>{{OrgSynth | author = R. N. Mirrington and G. I. Feutrill | | year = 1988 | title = Orcinol Monomethyl Ether | collvol = 6 | collvolpages = 859 | prep = cv6p0859}}</ref> Guaiacol can be prepared by diverse routes in the laboratory. ], derived in two steps from ], can be hydrolyzed via its ] derivative. Guaiacol can be synthesized by the ] of ] followed by selective mono-].<ref>{{OrgSynth | first1= R. N. |last1=Mirrington |first2= G. I. |last2=Feutrill | year = 1988 | title = Orcinol Monomethyl Ether | collvol = 6 | collvolpages = 859 | prep = cv6p0859}}</ref>
:C<sub>6</sub>H<sub>4</sub>(OCH<sub>3</sub>)<sub>2</sub> + ] → C<sub>6</sub>H<sub>4</sub>(OCH<sub>3</sub>)(ONa) + C<sub>2</sub>H<sub>5</sub>SCH<sub>3</sub> :C<sub>6</sub>H<sub>4</sub>(OCH<sub>3</sub>)<sub>2</sub> + C<sub>2</sub>H<sub>5</sub>SNa → C<sub>6</sub>H<sub>4</sub>(OCH<sub>3</sub>)(ONa) + C<sub>2</sub>H<sub>5</sub>SCH<sub>3</sub>


==Uses== ==Uses and chemical reactions==
===Syringyl/guaiacyl ratio===
Guaiacol is a precursor to various ]s such as ]<ref>{{OrgSynth | author = C. F. H. Allen and J. W. Gates, Jr. | title = ''o''-Eugenol | collvol = 3 | collvolpages = 418 | year = 1955 | prep = cv30418}}</ref> and ].<ref>{{cite encyclopedia
], comprising a major fraction of biomass, is sometimes classified according to the '''guaiacyl''' component. Pyrolysis of lignin from ]s gives more guaiacol, resulting from removal of the ] group of ]. These lignins are said to have a high guaiacyl (or G) content. In contrast, lignins derived from ] affords ]. A high syringyl (or S) content is indicative of lignin from ]s.<ref name=TPC>{{cite journal |doi=10.1105/tpc.010111|title=The Last Step of Syringyl Monolignol Biosynthesis in Angiosperms is Regulated by a Novel Gene Encoding Sinapyl Alcohol Dehydrogenase |year=2001 |last1=Li |first1=Laigeng |last2=Cheng |first2=Xiao Fei |last3=Leshkevich |first3=Jacqueline |last4=Umezawa |first4=Toshiaki |last5=Harding |first5=Scott A. |last6=Chiang |first6=Vincent L. |journal=The Plant Cell |volume=13 |issue=7 |pages=1567–1586 |pmid=11449052 |pmc=139549 }}</ref> Sugarcane ] is one useful source of guaiacol; pyrolysis of the bagasse lignins yields compounds including guaiacol, 4-methylguaiacol and 4-vinylguaiacol.<ref>{{Cite journal |last1=del Río |first1=José C. |last2=Lino |first2=Alessandro G. |last3=Colodette |first3=Jorge L. |last4=Lima |first4=Claudio F. |last5=Gutiérrez |first5=Ana |last6=Martínez |first6=Ángel T. |last7=Lu |first7=Fachuang |last8=Ralph |first8=John |last9=Rencoret |first9=Jorge |date=2015-10-01 |title=Differences in the chemical structure of the lignins from sugarcane bagasse and straw |journal=Biomass and Bioenergy |language=en |volume=81 |pages=322–338 |doi=10.1016/j.biombioe.2015.07.006 |issn=0961-9534|doi-access=free }}</ref>
| last = Esposito

| first = Lawrence J.
===Chemical intermediate===
| coauthors = K. Formanek, G. Kientz, F. Mauger, V. Maureaux, G. Robert, and F. Truchet
Guaiacol is a useful precursor for the synthesis of other compounds.<ref>{{cite journal|doi=10.1351/pac200577071221|title=Masked ''o''-benzoquinone strategy in organic synthesis: Short and efficient construction of ''cis''-decalins and linear triquinanes from 2-methoxyphenols|journal=Pure and Applied Chemistry|volume=77|issue=7|pages=1221–1234|year=2005|last1=Liao|first1=Chun-Chen|doi-access=free}}</ref> Being derived from biomass, it is a potential component or precursor to "green fuels".<ref>{{cite journal|doi=10.1039/C3EE43081B|title=Upgrading of lignin-derived bio-oils by catalytic hydrodeoxygenation|journal=Energy Environ. Sci.|volume=7|pages=103–129|year=2014|last1=Saidi|first1=Majid|last2=Samimi|first2=Fereshteh|last3=Karimipourfard|first3=Dornaz|last4=Nimmanwudipong|first4=Tarit|last5=Gates|first5=Bruce C.|last6=Rahimpour|first6=Mohammad Reza}}</ref>

Guaiacol is also a useful reagent for the quantification of ]s, as in the presence of ] these enzymes will catalyse with it the formation of tetraguaiacol,<ref>{{cite journal | vauthors = Koduri RS, Tien M | journal = Journal of Biological Chemistry | volume = 270 | issue = 38 | pages = 22254–8 | date = 1995 | pmid = 7673205 | doi = 10.1074/jbc.270.38.22254 | title = Oxidation of Guaiacol by Lignin Peroxidase. Role of veratryl alcohol | doi-access = free }}</ref> a coloured compound that can be quantified by its absorbance at 420–470&nbsp;nm, following the equation:

:4 {{chem|guaiacol (colorless)}} + 2 {{chem|H|2|O|2}} → {{chem|tetraguaiacol (colored)}} + 8 {{chem|H|2|O}}.

===Medicinal and food===
Guaiacol is a precursor to various ]s, such as ].<ref>{{OrgSynth | first1= C. F. H. |last1=Allen |first2=J. W. Jr |last2=Gates | title = ''o''-Eugenol | collvol = 3 | collvolpages = 418 | year = 1955 | prep = cv3P0418}}</ref> An estimated 85% of the world's supply of ] comes from guaiacol. Because consumers tend to prefer natural vanillin to synthetic vanillin, methods such as microbial fermentation have been adopted. The route entails the ] of ] with guaiacol to give mandelic acid, which is oxidized to produce ]. This acid undergoes a decarboxylation to afford vanillin.<ref>{{cite encyclopedia
| last1 = Esposito
| first1 = Lawrence J.
| first2=K. |last2=Formanek |first3=G. |last3=Kientz |first4=F. |last4=Mauger |first5=V. |last5=Maureaux |first6=G. |last6=Robert |first7=F. |last7=Truchet
| title = Vanillin | title = Vanillin
| encyclopedia = Kirk-Othmer Encyclopedia of Chemical Technology, 4th edition | encyclopedia = Kirk–Othmer Encyclopedia of Chemical Technology |edition=4th
| volume = 24 | volume = 24
| pages = 812–825 | pages = 812–825
| publisher = John Wiley & Sons | publisher = John Wiley & Sons
| location = New York | location = New York, NY
| year = 1997}}</ref> Its derivatives are used medicinally as an ], ], and local ]. | year = 1997}}</ref> The crude vanillin product can then be purified with vacuum distillation and recrystallization.
It also can be used as a dye in chemical reactions as oxygen will turn guaiacol from colorless to brown.


Guaiacol is also used medicinally as an ], ], and local ].<ref>{{cite web |url=https://www.drugbank.ca/drugs/DB11359|title=Guaiacol|author=<!--Not stated--> |date=2019-11-02|website=DrugBank|access-date=2019-11-18}}</ref>
==Related compounds==
Guaiacol carbonate is known as duotal, the phosphate as phosphatol, the phosphite as guaiaco-phosphal (phosphotal is a mixture of the phosphites of creosote phenols).{{Citation needed|date=October 2007}} The valerianic ester of guaiacol is known as geosote, the benzoic as benzosol, the salicylic as guaiacolsalol, while the glycerin ether is the drug ]. The related derivative, dimethoxybenzene or ], is also useful. In preparation of food by smoking, guaiacol is the main chemical responsible for the smoky taste, whereas syringol is responsible for the smoky aroma.


Guaiacol is produced in the gut of ]s, ''Schistocerca gregaria'', by the breakdown of plant material. This process is undertaken by the gut bacterium '']'' (''Enterobacter''). It is one of the main components of the pheromones that cause ] ].<ref>{{cite journal|doi=10.1038/35002669|pmid=10706273|title=Pheromones: Exploitation of gut bacteria in the locust|first1=Rod J.|last1=Dillon|first2=Chris T.|last2=Vennard|first3=A. Keith|last3=Charnley|journal=Nature|volume=403|issue=6772|page=851|date=2000-02-24|bibcode=2000Natur.403..851D|s2cid=5207502|doi-access=free}}</ref>
Guaiacol is used as an inducer in Biochemical transformation, it has powerful effect on the fungi culture to incite them for producing the enzyme in their liquid or agar culture.<ref></ref><ref></ref>


==Safety== ==Safety==
Methoxyphenols are potential biomarkers of biomass smoke exposure, e.g. from inhalation of woodsmoke. Dietary sources of methoxyphenols overwhelm the contribution from inhalational exposures to woodsmoke.<ref></ref> ]s are potential biomarkers of biomass smoke exposure, such as from inhalation of woodsmoke. Dietary sources of methoxyphenols overwhelm the contribution from inhalational exposures to woodsmoke.<ref>{{cite web|last=Smith|first=K. R.|date=2005|url=http://ehs.sph.berkeley.edu/krsmith/publications/2005%20pubs/HC%20woodsmoke%20report%20Mar%2031%2005%20%28rev%29.pdf |title=Critical review of the health effects of woodsmoke|publisher=School of Public Health, University of Berkeley|url-status=dead|archive-url=https://web.archive.org/web/20090710235756/http://ehs.sph.berkeley.edu/krsmith/publications/2005%20pubs/HC%20woodsmoke%20report%20Mar%2031%2005%20%28rev%29.pdf|archive-date=2009-07-10}}</ref>


==Locust pheromone== == See also ==
* ]
Guaiacol is produced in the gut of ], ''Schistocerca gregaria'', by the breakdown of plant material. This process is undertaken by the gut bacterium ] (= Enterobacter) agglomerans. Guaiacol is one of the main components of the pheromones that cause locust swarming.<ref></ref>
* ]


==References== == References ==
{{reflist}} {{reflist|30em}}


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Latest revision as of 02:10, 24 December 2024

Methoxyphenol compound, constituent of plant lignins and essential oils
Guaiacol
Names
Preferred IUPAC name 2-Methoxyphenol
Other names o-Methoxyphenol
O-Methylcatechol
2-Hydroxyanisole
Pyroguaiac acid
Pyrocatechol monomethyl ether
1-hydroxy-2-methoxybenzene
Identifiers
CAS Number
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.001.786 Edit this at Wikidata
KEGG
PubChem CID
UNII
CompTox Dashboard (EPA)
InChI
  • InChI=1S/C7H8O2/c1-9-7-5-3-2-4-6(7)8/h2-5,8H,1H3Key: LHGVFZTZFXWLCP-UHFFFAOYSA-N
  • InChI=1/C7H8O2/c1-9-7-5-3-2-4-6(7)8/h2-5,8H,1H3Key: LHGVFZTZFXWLCP-UHFFFAOYAI
SMILES
  • COc1ccccc1O
Properties
Chemical formula C7H8O2
Molar mass 124.139 g·mol
Appearance colorless oil or crystalline solid
Density 1.112 g/cm, liquid
1.129 g/cm, crystals
Melting point 26–29 °C (79–84 °F; 299–302 K)
Boiling point 204–206 °C (399–403 °F; 477–479 K)
Solubility in water 23.3 g/L at 25 °C
Related compounds
Related methoxyphenols Mequinol
3-Methoxyphenol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa). checkY verify (what is  ?) Infobox references
Chemical compound

Guaiacol (/ˈɡwaɪəkɒl/) is an organic compound with the formula C6H4(OH)(OCH3). It is a phenolic compound containing a methoxy functional group. Guaiacol appears as a viscous colorless oil, although aged or impure samples are often yellowish. It occurs widely in nature and is a common product of the pyrolysis of wood.

Occurrence

Guaiacol is usually derived from guaiacum or wood creosote.

It is produced by a variety of plants. It is also found in essential oils from celery seeds, tobacco leaves, orange leaves, and lemon peels. The pure substance is colorless, but samples become yellow upon exposure to air and light. The compound is present in wood smoke, resulting from the pyrolysis of lignin. The compound contributes to the flavor of many substances such as whiskey and roasted coffee.

Preparation

The compound was first isolated by Otto Unverdorben in 1826. Guaiacol is produced by methylation of o-catechol, for example using potash and dimethyl sulfate:

C6H4(OH)2 + (CH3O)2SO2 → C6H4(OH)(OCH3) + HO(CH3O)SO2

Laboratory methods

Guaiacol can be prepared by diverse routes in the laboratory. o-Anisidine, derived in two steps from anisole, can be hydrolyzed via its diazonium derivative. Guaiacol can be synthesized by the dimethylation of catechol followed by selective mono-demethylation.

C6H4(OCH3)2 + C2H5SNa → C6H4(OCH3)(ONa) + C2H5SCH3

Uses and chemical reactions

Syringyl/guaiacyl ratio

Lignin, comprising a major fraction of biomass, is sometimes classified according to the guaiacyl component. Pyrolysis of lignin from gymnosperms gives more guaiacol, resulting from removal of the propenyl group of coniferyl alcohol. These lignins are said to have a high guaiacyl (or G) content. In contrast, lignins derived from sinapyl alcohol affords syringol. A high syringyl (or S) content is indicative of lignin from angiosperms. Sugarcane bagasse is one useful source of guaiacol; pyrolysis of the bagasse lignins yields compounds including guaiacol, 4-methylguaiacol and 4-vinylguaiacol.

Chemical intermediate

Guaiacol is a useful precursor for the synthesis of other compounds. Being derived from biomass, it is a potential component or precursor to "green fuels".

Guaiacol is also a useful reagent for the quantification of peroxidases, as in the presence of hydrogen peroxide these enzymes will catalyse with it the formation of tetraguaiacol, a coloured compound that can be quantified by its absorbance at 420–470 nm, following the equation:

4 guaiacol (colorless) + 2 H
2O
2 → tetraguaiacol (colored) + 8 H
2O.

Medicinal and food

Guaiacol is a precursor to various flavorants, such as eugenol. An estimated 85% of the world's supply of vanillin comes from guaiacol. Because consumers tend to prefer natural vanillin to synthetic vanillin, methods such as microbial fermentation have been adopted. The route entails the condensation reaction of glyoxylic acid with guaiacol to give mandelic acid, which is oxidized to produce phenylglyoxylic acid. This acid undergoes a decarboxylation to afford vanillin. The crude vanillin product can then be purified with vacuum distillation and recrystallization.

Guaiacol is also used medicinally as an expectorant, antiseptic, and local anesthetic.

Guaiacol is produced in the gut of desert locusts, Schistocerca gregaria, by the breakdown of plant material. This process is undertaken by the gut bacterium Pantoea agglomerans (Enterobacter). It is one of the main components of the pheromones that cause locust swarming.

Safety

Methoxyphenols are potential biomarkers of biomass smoke exposure, such as from inhalation of woodsmoke. Dietary sources of methoxyphenols overwhelm the contribution from inhalational exposures to woodsmoke.

See also

References

  1. Merck Index (13th ed.). p. 4568.
  2. "List of synonyms for guaiacol". Chemindustry. Archived from the original on 2016-08-10. Retrieved 2009-03-20.
  3. ^ Fiege, Helmut; Voges, Heinz-Werner; Hamamoto, Toshikazu; Umemura, Sumio; Iwata, Tadao; Miki, Hisaya; Fujita, Yasuhiro; Buysch, Hans-Josef; Garbe, Dorothea; Paulus, Wilfried. "Phenol Derivatives". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a19_313. ISBN 978-3527306732.
  4. Duffey, S. S.; Aldrich, J. R.; Blum, M. S. (1977). "Biosynthesis of phenol and guaiacol by the hemipteran Leptoglossus phyllopus". Comparative Biochemistry and Physiology B. 56 (2B): 101–102. doi:10.1016/0305-0491(77)90029-3. PMID 830476.
  5. Burdock, G. A. (1995). Encyclopedia of Food and Color Additives. Boca Raton, FL: CRC Press. pp. 1244–1245. ISBN 978-0849394126.
  6. Gallegos, Jenna (August 17, 2017). "The best way to drink whiskey, according to science". The Washington Post. Guaiacol is what gives whiskey that smoky, spicy, peaty flavor.
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