Nitrite
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[[Image:Nitrite-ion-resonance-hybrid.png|thumb|200px|right|A [[Resonance (chemistry)#Resonance as a diagrammatic tool|resonance hybrid]], showing the N-O bonds in the nitrite ion have a [[bond order]] of about 1.5, leaving most of the single negative charge shared between the terminal oxygen atoms]]
[[Image:Nitrite-3D-vdW.png|thumb|200px|right|[[Space-filling model]] of NO<sub>2</sub><sup>−</sup>]]
The '''nitrite''' [[ion]] is NO<sub>2</sub><sup>−</sup>. The anion is bent, being [[isoelectronic]] with [[ozone|O<sub>3</sub>]].
A '''nitrite''' is either a [[Salt (chemistry)|salt]] or an [[ester]] of [[nitrous acid]].
==Examples==
* [[nitrous acid]], HNO<sub>2</sub>
* [[sodium nitrite]], NaNO<sub>2</sub>
* [[alkyl nitrites]], some of which are known as [[poppers]].
See [[:Category:Nitrites|category]] for a bigger list.
In [[inorganic chemistry]], nitrites are [[salt]]s of [[nitrous acid]] (HNO<sub>2</sub>). They contain the nitrite [[ion]] (NO<sub>2</sub><sup>−</sup>). Nitrites of the [[alkali metal|alkali]] and [[alkaline earth metal]]s can be synthesized by reacting a mixture of [[nitrogen monoxide]] (NO) and [[nitrogen dioxide]] (NO<sub>2</sub>) with a corresponding metal [[hydroxide]] solution, as well as through the thermal decomposition of the corresponding [[nitrate]]. Other nitrites are available through the [[Redox|reduction]] of the corresponding [[nitrate]]s.
[[Image:Nitrite-ion-canonical-structures.png|thumb|300px|right|The two [[Resonance (chemistry)#Resonance as a diagrammatic tool|canonical structures]] of NO<sub>2</sub><sup>−</sup> which contribute to the resonance hybrid shown at the top of the article]]
[[Sodium nitrite]] is used for the [[Curing (food preservation)|curing]] of [[meat]] because it prevents bacterial growth and, in a reaction with the meat's [[myoglobin]], gives the product a desirable dark red color. Because of the toxicity of nitrite (the lethal dose of nitrite for humans is about 22 mg per kg body weight), the maximum allowed nitrite concentration in meat products is 200 [[Parts per million|ppm]]. Under certain conditions, especially during cooking, nitrites in meat can react with degradation products of [[amino acids]], forming [[nitrosamine]]s, which are known [[carcinogen]]s.
Nitrite is detected and analyzed by the [[Griess test|Griess Reaction]], involving the formation of a deep red-colored [[azo dye]] upon treatment of a NO<sub>2</sub><sup>−</sup>-containing sample with [[sulfanilic acid]] and naphthyl-1-amine in the presence of acid.<ref>{{cite journal | author = V. M. Ivanov | year = 2004 | title = The 125th Anniversary of the Griess Reagent | journal = Journal of Analytical Chemistry | volume = 59 | issue = 10 | pages = 1002 – 1005 | doi = 10.1023/B:JANC.0000043920.77446.d7}} Translated from {{cite journal | author = V. M. Ivanov | year = 2004 | journal = Zhurnal Analiticheskoi Khimii | volume = 59 | issue = 10 | pages = 1109 – 1112
| title = }}</ref>
Nitrite can be reduced to [[nitric oxide]] or [[ammonia]] by many species of [[bacteria]].
Under hypoxic conditions, nitrite may release nitric oxide, which causes potent vasodilation. Several mechanisms for nitrite conversion to NO have been described including enzymatic
reduction by xanthine oxidoreductase, the mitochondria, and NO synthase (NOS), as well as nonenzymatic acidic disproportionation.
==Organic nitrites==
[[Image:Nitrite-ester-2D.png|thumb|right|150px|Structure of the nitrosooxy functional group]]
In [[organic chemistry]], nitrites are [[ester]]s of nitrous acid and contain the nitrosooxy functional group. They possess the general formula RONO, where R is an [[aryl]] or [[alkyl]] group. [[Amyl nitrite]] is used in medicine for the treatment of heart diseases.
Nitrites should not be confused with [[nitrate]]s, the salts of [[nitric acid]], or with [[nitro compound]]s, though they share the formula RNO<sub>2</sub>. The nitrite [[anion]] NO<sub>2</sub><sup>−</sup> should not be confused with the [[nitronium]] [[cation]] NO<sub>2</sub><sup>+</sup>.
A classic [[named reaction]] for the synthesis of alkyl nitrites is the '''Meyer synthesis'''<ref>{{cite journal
| title = Ueber die Nitroverbindungen der Fettreihe
| author = [[Victor Meyer]]
| journal = [[Justus Liebig's Annalen der Chemie]]
| volume = 171
| issue = 1
| pages = 1–56
| year = 1872
| url =
| doi = 10.1002/jlac.18741710102 }}</ref><!--<ref>{{cite journal
| title = Ueber die Nitroverbindungen der Fettreihe
| author = V. Meyer, Stuber, Rilliet and Chojnacki
| journal = [[Justus Liebig's Annalen der Chemie]]
| volume = 171
| issue = 1
| pages = 1–56
| year = 1874
| url =
| doi = 10.1002/jlac.18741710102 }}</ref>--><ref>{{cite journal
| title = Ueber die Pseudonitrole, die Isomeren der Nitrolsäuren
| author = Victor Meyer, J. Locher
| journal = [[Justus Liebig's Annalen der Chemie]]
| volume = 180
| issue = 1-2
| pages = 133–155
| year = 1876
| url =
| doi = 10.1002/jlac.18761800113}}</ref><ref>{{cite journal
| title = Vorläufige Mittheilung
| author = V. Meyer and Stüber
| journal = [[Chemische Berichte ]]
| volume = 5
| issue =
| pages = 203–205
| year = 1872
| url =
| doi = 10.1002/cber.18720050165}}</ref><ref>{{cite journal
| title = Ueber die Nitroverbindungen der Fettreihe
| author = Victor Meyer, O. Stüber
| journal = [[Chemische Berichte ]]
| volume = 5
| issue =
| pages = 399
| year = 1872
| url =
| doi = 10.1002/cber.187200501121}}</ref><ref>{{cite journal
| title = Ueber die Nitroverbindungen der Fettreiche. Dritte Mittheilung
| author = Victor Meyer, A. Rilliet
| journal = [[Chemische Berichte ]]
| volume = 5
| issue =
| pages = 1029–1034
| year = 1872
| url =
| doi = 10.1002/cber.187200502133}}</ref><ref>{{cite journal
| title = Ueber die Nitroverbindungen der Fettreihe. Vierte Mittheilung
| author = Victor Meyer, C. Chojnacki
| journal = [[Chemische Berichte ]]
| volume = 5
| issue =
| pages = 1034–1038
| year = 1872
| url =
| doi = 10.1002/cber.187200502134}}</ref><ref>{{cite journal
| title = The Relationship of the Constitution of Certain Alky Halides to the Formation of Nitroparaffins and Alkyl Nitrites
| author = Robert B. Reynolds, Homer Adkins
| journal = [[Journal of the American Chemical Society]]
| volume = 51
| issue = 1
| pages = 279–287
| year = 1929
| url =
| doi = 10.1021/ja01376a037}}</ref> in which [[alkyl halide]]s react with metallic [[nitrite]]s to a mixture to nitroalkanes and nitrites.
==External links==
* [http://www.atsdr.cdc.gov/csem/nitrate/ ATSDR - Case Studies in Environmental Medicine - Nitrate/Nitrite Toxicity] U.S. [[Department of Health and Human Services]] (public domain)
==References==
{{Reflist}}
[[Category:Curing agents]]
[[Category:Garde manger]]
[[Category:Nitrogen metabolism]]
[[Category:Oxoanions]]
[[Category:functional groups]]
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