| Revision as of 14:10, 24 November 2011 editBeetstra (talk | contribs)Edit filter managers, Administrators172,031 edits Saving copy of the {{chembox}} taken from revid 443445462 of page Nitrous_acid for the Chem/Drugbox validation project (updated: 'KEGG'). |
Latest revision as of 23:12, 16 December 2024 edit Arthurfragoso (talk | contribs)Extended confirmed users2,101 edits Fixes infobox image on dark mode |
| Line 1: |
Line 1: |
|
|
{{Distinguish|nitric acid}} |
|
{{ambox | text = This page contains a copy of the infobox ({{tl|chembox}}) taken from revid of page ] with values updated to verified values.}} |
|
|
|
{{Redirect|Hono|the place in Sweden|Hönö}} |
|
{{Chembox |
|
{{Chembox |
|
| Verifiedfields = changed |
|
| Verifiedfields = changed |
|
|
| verifiedrevid = 462262187 |
|
| Watchedfields = changed |
|
|
|
| ImageFile = Nitrous acid acsv.svg |
|
| verifiedrevid = 396509456 |
|
|
|
| ImageClass = skin-invert |
|
| ImageFile = Nitrous acid acsv.svg |
|
|
|
| ImageName = Nitrous acid |
|
| ImageSize = 200px |
|
|
|
| IUPACName = Nitrous acid<ref>{{Cite web |title=Nitrous Acid |url=https://pubchem.ncbi.nlm.nih.gov/compound/24529#section=IUPAC-Name&fullscreen=true}}</ref> |
|
| ImageName = Nitrous acid |
|
|
|
|Section1={{Chembox Identifiers |
|
| PIN = Nitrous acid |
|
|
|
| CASNo = 7782-77-6 |
|
| SystematicName = Hydroxidooxidonitrogen |
|
|
|
| CASNo_Ref = {{cascite|correct|CAS}} |
|
| Section1 = {{Chembox Identifiers |
|
|
|
| UNII_Ref = {{fdacite|correct|FDA}} |
|
| CASNo = 7782-77-6 |
|
|
|
| UNII = T2I5UM75DN |
|
| CASNo_Ref = {{cascite|correct|CAS}} |
|
|
| PubChem = 24529 |
|
| PubChem = 24529 |
|
|
| ChemSpiderID = 22936 |
|
| PubChem_Ref = {{Pubchemcite}} |
|
|
|
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} |
|
| ChemSpiderID = 22936 |
|
|
|
| EINECS = 231-963-7 |
|
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} |
|
|
|
| KEGG_Ref = {{keggcite|changed|kegg}} |
|
| EINECS = 231-963-7 |
|
|
|
| KEGG = C00088 |
|
| KEGG_Ref = {{keggcite|correct|kegg}} |
|
|
|
| MeSHName = Nitrous+acid |
|
| KEGG = <!-- blanked - oldvalue: C00088 --> |
|
|
|
| ChEBI_Ref = {{ebicite|correct|EBI}} |
|
| MeSHName = Nitrous+acid |
|
|
| ChEBI_Ref = {{ebicite|correct|EBI}} |
|
|
| ChEBI = 25567 |
|
| ChEBI = 25567 |
|
| SMILES = O=NO |
|
| SMILES = O=NO |
|
| ChEMBL_Ref = {{ebicite|changed|EBI}} |
|
| ChEMBL_Ref = {{ebicite|correct|EBI}} |
|
| ChEMBL = 1161681 |
|
| ChEMBL = 1161681 |
|
| StdInChI_Ref = {{stdinchicite|correct|chemspider}} |
|
| StdInChI_Ref = {{stdinchicite|correct|chemspider}} |
|
| StdInChI = 1S/HNO2/c2-1-3/h(H,2,3) |
|
| StdInChI = 1S/HNO2/c2-1-3/h(H,2,3) |
|
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}} |
|
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}} |
|
| StdInChIKey = IOVCWXUNBOPUCH-UHFFFAOYSA-N |
|
| StdInChIKey = IOVCWXUNBOPUCH-UHFFFAOYSA-N |
|
| Gmelin = 983 |
|
| Gmelin = 983 |
|
| 3DMet = B00022}} |
|
| 3DMet = B00022}} |
|
| Section2 = {{Chembox Properties |
|
|Section2={{Chembox Properties |
|
| Formula = HNO<sub>2</sub> |
|
| Formula = HNO<sub>2</sub> |
|
| Appearance = Pale blue solution |
|
| Appearance = Pale blue solution |
|
| MolarMass = 47.013 g/mol |
|
| MolarMass = 47.013 g/mol |
|
| Density = Approx. 1 g/ml |
|
| Density = Approx. 1 g/ml |
|
| Solubility = |
|
| Solubility = |
|
| MeltingPt = Only known in solution |
|
| MeltingPt = Only known in solution or as gas |
|
|
| ConjugateBase = ] |
|
| pKa = 3.398 |
|
|
|
| pKa = 3.15<ref name=P82db>{{cite book|title=Ionisation Constants of Inorganic Acids and Bases in Aqueous Solution|editor-first=D. D.|editor-last=Perrin|edition=2nd|series=] Chemical Data|issue=29|publisher=Pergamon|location=Oxford|year=1982|publication-date=1984|orig-date=1969|lccn=82-16524|isbn=0-08-029214-3|at=Entry 156}}</ref> |
|
}} |
|
}} |
|
| Section7 = {{Chembox Hazards |
|
|Section7={{Chembox Hazards |
|
| ExternalMSDS = |
|
| ExternalSDS = |
|
|
| MainHazards = |
|
| EUIndex = Not listed |
|
|
|
| NFPA-H = 4 |
|
| EUClass = |
|
|
|
| NFPA-F = 0 |
|
| RPhrases = |
|
|
|
| NFPA-R = 2 |
|
| SPhrases = |
|
|
|
| NFPA-S = OX |
|
| MainHazards = |
|
|
|
| FlashPt = Non-flammable |
|
| NFPA-H = |
|
|
| NFPA-F = |
|
|
| NFPA-R = |
|
|
| NFPA-O = |
|
|
| FlashPt = Non-flammable |
|
|
}} |
|
}} |
|
| Section8 = {{Chembox Related |
|
|Section8={{Chembox Related |
|
| OtherAnions = ] |
|
| OtherAnions = ] |
|
| OtherCations = ]<br/>]<br/>] |
|
| OtherCations = ]<br/>]<br/>] |
|
| OtherCpds = ] |
|
| OtherCompounds = ] |
|
}} |
|
}} |
|
}} |
|
}} |
|
|
|
|
|
'''Nitrous acid''' (molecular formula {{chem|]|]|]|2}}) is a weak and ] known only in ], in the gas phase, and in the form of ] ({{chem|NO|-|2}}) salts.<ref name=G&E/> It was discovered by ], who called it "] acid of niter". Nitrous acid is used to make ]s from amines. The resulting diazonium salts are reagents in ] reactions to give ]s. |
|
|
|
|
|
==Structure== |
|
|
In the gas phase, the planar nitrous acid molecule can adopt both a ''syn'' and an ''anti'' form. The ''anti'' form predominates at room temperature, and ] indicate it is ] by around 2.3 kJ/mol.<ref name="G&E">{{Greenwood&Earnshaw}} p. 462.</ref> |
|
|
|
|
|
<gallery widths="180px" heights="120px"> |
|
|
Image:Trans-nitrous-acid-2D-dimensions.png | Dimensions of the ''anti'' form<br />(from the ]) |
|
|
Image:Trans-nitrous-acid-3D-balls.png | ] of the ''anti'' form |
|
|
Image:Cis-nitrous-acid-3D-balls.png | ''syn'' form |
|
|
</gallery> |
|
|
|
|
|
==Preparation and decomposition== |
|
|
{{See also|Dinitrogen trioxide}} |
|
|
|
|
|
Free, gaseous nitrous acid is unstable, rapidly ] to ]: |
|
|
:2 HNO<sub>2</sub> → NO<sub>2</sub> + NO + H<sub>2</sub>O |
|
|
In aqueous solution, the nitrogen dioxide also disproportionates, for a net reaction producing ] and ]:<ref name="Nitros">{{cite book|title=Nitrosation|first=D. L. H.|last=Williams|publisher=]|location=Cambridge, UK|year=1988|isbn=0-521-26796-X|url=https://archive.org/details/nitrosation0000will|url-access=registration}}</ref>{{rp|1}}<ref>{{Cite journal |last1=Kameoka |first1=Yohji |last2=Pigford |first2=Robert |date=February 1977 |title=Absorption of Nitrogen Dioxide into Water, Sulfuric Acid, Sodium Hydroxide, and Alkaline Sodium Sulfite Aqueous |journal=Ind. Eng. Chem. Fundamen. |volume=16 |issue=1 |pages=163–169 |doi=10.1021/i160061a031}}</ref> |
|
|
:3 HNO<sub>2</sub> → 2 NO + HNO<sub>3</sub> + {{H2O-nl}} |
|
|
|
|
|
Consequently applications of nitrous acid usually begin with ] acidification of ]. The acidification is usually conducted at ice temperatures, and the HNO<sub>2</sub> consumed ''in situ''.<ref>{{Cite journal |last1=Petit |first1=Y. |last2=Larchevêque |first2=M. |year=1998 |title=Ethyl Glycidate from (S)-Serine: Ethyl (R)-(+)-2,3-Epoxypropanoate |journal=Org. Synth. |volume=75 |page=37 |doi=10.15227/orgsyn.075.0037 |doi-access=free}}</ref><ref>{{Cite journal |last1=Smith |first1=Adam P. |last2=Savage |first2=Scott A. |last3=Love |first3=J. Christopher |last4=Fraser |first4=Cassandra L. |year=2002 |title=Synthesis of 4-, 5-, and 6-methyl-2,2'-bipyridine by a Negishi Cross-coupling Strategy: 5-methyl-2,2'-bipyridine |journal=Org. Synth. |volume=78 |page=51 |doi=10.15227/orgsyn.078.0051 |doi-access=free}}</ref> |
|
|
|
|
|
Nitrous acid equilibrates with ] in water, so that concentrated solutions are visibly blue:<ref name="Nitros" />{{rp|2}} |
|
|
: N<sub>2</sub>O<sub>3</sub> + H<sub>2</sub>O {{eqm}} 2 HNO<sub>2</sub> |
|
|
Addition of dinitrogen trioxide to water is thus another preparatory technique. |
|
|
|
|
|
==Chemical applications== |
|
|
Nitrous acid is the main chemophore in the ], used to ] for alkaloids. |
|
|
|
|
|
At high acidities ({{Math|] ≪ 2}}), nitrous acid is protonated to give water and ] cations.<ref name="Nitros" />{{Rp|page=2}} |
|
|
|
|
|
===Reduction=== |
|
|
With I<sup>−</sup> and Fe<sup>2+</sup> ions, NO is formed:<ref name="InorgChem">{{Cite book |last1=Housecroft |first1=Catherine E. |title=Inorganic Chemistry, 3rd Edition |last2=Sharpe |first2=Alan G. |publisher=Pearson |year=2008 |isbn=978-0-13-175553-6 |page=449 |chapter=Chapter 15: The group 15 elements}}</ref> |
|
|
|
|
|
: 2 HNO<sub>2</sub> + 2 KI + 2 H<sub>2</sub>SO<sub>4</sub> → I<sub>2</sub> + 2 NO + 2 H<sub>2</sub>O + 2 K<sub>2</sub>SO<sub>4</sub> |
|
|
: 2 HNO<sub>2</sub> + 2 FeSO<sub>4</sub> + 2 H<sub>2</sub>SO<sub>4</sub> → Fe<sub>2</sub>(SO<sub>4</sub>)<sub>3</sub> + 2 NO + 2 H<sub>2</sub>O + K<sub>2</sub>SO<sub>4</sub> |
|
|
|
|
|
With Sn<sup>2+</sup> ions, N<sub>2</sub>O is formed: |
|
|
|
|
|
: 2 HNO<sub>2</sub> + 6 HCl + 2 SnCl<sub>2</sub> → 2 SnCl<sub>4</sub> + N<sub>2</sub>O + 3 H<sub>2</sub>O + 2 KCl |
|
|
|
|
|
With SO<sub>2</sub> gas, NH<sub>2</sub>OH is formed: |
|
|
|
|
|
: 2 HNO<sub>2</sub> + 6 H<sub>2</sub>O + 4 SO<sub>2</sub> → 3 H<sub>2</sub>SO<sub>4</sub> + K<sub>2</sub>SO<sub>4</sub> + 2 NH<sub>2</sub>OH |
|
|
|
|
|
With Zn in alkali solution, NH<sub>3</sub> is formed: |
|
|
|
|
|
: 5 H<sub>2</sub>O + KNO<sub>2</sub> + 3 Zn → NH<sub>3</sub> + KOH + 3 Zn(OH)<sub>2</sub> |
|
|
|
|
|
With {{chem|N|2|H|5|+}}, both HN<sub>3</sub> and (subsequently) N<sub>2</sub> gas are formed: |
|
|
|
|
|
: HNO<sub>2</sub> + <sup>+</sup> → HN<sub>3</sub> + H<sub>2</sub>O + H<sub>3</sub>O<sup>+</sup> |
|
|
|
|
|
: HNO<sub>2</sub> + HN<sub>3</sub> → N<sub>2</sub>O + N<sub>2</sub> + H<sub>2</sub>O |
|
|
|
|
|
Oxidation by nitrous acid has a ] over ], this is best illustrated that dilute nitrous acid is able to oxidize I<sup>−</sup> to I<sub>2</sub>, but dilute nitric acid cannot. |
|
|
|
|
|
: I<sub>2</sub> + 2 e<sup>−</sup> ⇌ 2 I<sup>−</sup> {{pad|3em}} ''E''<sup>o</sup> = +0.54 V |
|
|
|
|
|
: {{chem|NO|3|−}} + 3 H<sup>+</sup> + 2 e<sup>−</sup> ⇌ HNO<sub>2</sub> + H<sub>2</sub>O {{pad|3em}} ''E''<sup>o</sup> = +0.93 V |
|
|
|
|
|
: HNO<sub>2</sub> + H<sup>+</sup> + e<sup>−</sup> ⇌ NO + H<sub>2</sub>O {{pad|3em}} ''E''<sup>o</sup> = +0.98 V |
|
|
|
|
|
It can be seen that the values of ''E''{{su|b=cell|p=o}} for these reactions are similar, but nitric acid is a more powerful oxidizing agent. Base on the fact that dilute nitrous acid can oxidize iodide into ], it can be deduced that nitrous is a faster, rather than a more powerful, oxidizing agent than dilute nitric acid.<ref name="InorgChem" /> |
|
|
|
|
|
===Organic chemistry=== |
|
|
Nitrous acid is used to prepare ]s: |
|
|
:HNO<sub>2</sub> + ArNH<sub>2</sub> + H<sup>+</sup> → {{chem|ArN|2|+}} + 2 H<sub>2</sub>O |
|
|
where Ar is an ] group. |
|
|
|
|
|
Such salts are widely used in ], e.g., for the ] and in the preparation ]s, brightly colored compounds that are the basis of a qualitative test for ]s.<ref>{{Cite journal |last1=Clarke |first1=H. T. |last2=Kirner |first2=W. R. |date=1922 |title=Methyl Red |url=http://orgsyn.org/demo.aspx?prep=CV1P0374 |journal=Organic Syntheses |volume=2 |pages=47 |doi=10.15227/orgsyn.002.0047 |doi-access=free}}</ref> Nitrous acid is used to destroy toxic and potentially explosive ]. For most purposes, nitrous acid is usually formed ''in situ'' by the action of mineral acid on ]:<ref>{{Cite book |url=http://books.nap.edu/openbook.php?record_id=4911&page=165 |title=Prudent practices in the laboratory: handling and disposal of chemicals |publisher=] |year=1995 |isbn=978-0-309-05229-0 |location=Washington, D.C. |doi=10.17226/4911}}</ref> |
|
|
It is mainly blue in colour |
|
|
|
|
|
: NaNO<sub>2</sub> + HCl → HNO<sub>2</sub> + NaCl |
|
|
: 2 NaN<sub>3</sub> + 2 HNO<sub>2</sub> → 3 N<sub>2</sub> + 2 NO + 2 NaOH |
|
|
|
|
|
Reaction with two ] atoms in ]s creates ]s, which may be further oxidized to a carboxylic acid, or reduced to form amines. This process is used in the commercial production of ]. |
|
|
|
|
|
Nitrous acid reacts rapidly with ] to produce ], which are potent ]: |
|
|
|
|
|
:(CH<sub>3</sub>)<sub>2</sub>CHCH<sub>2</sub>CH<sub>2</sub>OH + HNO<sub>2</sub> → (CH<sub>3</sub>)<sub>2</sub>CHCH<sub>2</sub>CH<sub>2</sub>ONO + H<sub>2</sub>O |
|
|
|
|
|
The carcinogens called ]s are produced, usually not intentionally, by the reaction of nitrous acid with ]s: |
|
|
:HNO<sub>2</sub> + R<sub>2</sub>NH → R<sub>2</sub>N-NO + H<sub>2</sub>O |
|
|
|
|
|
==Atmosphere of the Earth== |
|
|
Nitrous acid is involved in the ] budget of the lower ], the ]. The ] reaction of ] (NO) and water produces nitrous acid. When this reaction takes place on the surface of atmospheric ]s, the product readily ] to ] ]s.<ref>{{Cite journal |last1=Spataro |first1=F |last2=Ianniello |first2=A |date=November 2014 |title=Sources of atmospheric nitrous acid: state of the science, current research needs, and future prospects |journal=Journal of the Air & Waste Management Association |volume=64 |issue=11 |pages=1232–1250 |doi=10.1080/10962247.2014.952846 |pmid=25509545 |doi-access=free|bibcode=2014JAWMA..64.1232S }}</ref><ref>{{Cite journal |last1=Anglada |first1=Josef M. |last2=Solé |first2=Albert |date=November 2017 |title=The Atmospheric Oxidation of HONO by OH, Cl, and ClO Radicals |journal=The Journal of Physical Chemistry A |volume=121 |issue=51 |pages=9698–9707 |bibcode=2017JPCA..121.9698A |doi=10.1021/acs.jpca.7b10715 |pmid=29182863}}</ref> |
|
|
|
|
|
==DNA damage and mutation== |
|
|
|
|
|
Treatment of '']'' cells with nitrous acid causes ] including ] of ] to ], and these damages are subject to repair by specific enzymes.<ref>{{Cite journal |last1=Da Roza |first1=R. |last2=Friedberg |first2=E. C. |last3=Duncan |first3=B. K. |last4=Warner |first4=H. R. |date=1977-11-01 |title=Repair of nitrous acid damage to DNA in Escherichia coli |journal=Biochemistry |volume=16 |issue=22 |pages=4934–4939 |doi=10.1021/bi00641a030 |issn=0006-2960 |pmid=334252}}</ref> Also, nitrous acid causes base substitution ]s in organisms with double-stranded DNA.<ref>{{Cite journal |last1=Hartman |first1=Z. |last2=Henrikson |first2=E. N. |last3=Hartman |first3=P. E. |last4=Cebula |first4=T. A. |date=1994 |title=Molecular models that may account for nitrous acid mutagenesis in organisms containing double-stranded DNA |journal=Environmental and Molecular Mutagenesis |volume=24 |issue=3 |pages=168–175 |doi=10.1002/em.2850240305 |issn=0893-6692 |pmid=7957120|bibcode=1994EnvMM..24..168H }}</ref> |
|
|
|
|
|
==See also== |
|
|
{{Commons category|Nitrous acid|lcfirst=yes}} |
|
|
* ] |
|
|
* ] (]]]<sub>3</sub>) |
|
|
* ] |
|
|
* ] |
|
|
|
|
|
==References== |
|
|
{{reflist}} |
|
|
|
|
|
{{Nitrogen compounds}} |
|
|
{{Nitrites}} |
|
|
{{Authority control}} |
|
|
|
|
|
] |
|
|
] |
|
|
] |
|
|
] |
|
|
] |