Nitrite

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Image:Nitrite-ion-resonance-hybrid.png Image:Nitrite-ion-canonical-structures.png

Contents 1 Definition 2 Examples 3 Discussion 4 External links 5 References

Definition

The nitrite ion is NO₂⁻. The anion is bent, being isoelectronic with O₃.

A nitrite is a compound that contains this group, being either an ionic or a covalent compound, i.e. a salt or an ester of nitrous acid.

Examples

• nitrous acid, HNO₂
• sodium nitrite, NaNO₂
• methyl nitrite, CH₃NO₂
• alkyl nitrites, commonly known as poppers

See category for a bigger list.

Discussion

In inorganic chemistry, nitrites are salts of nitrous acid HNO₂. They contain the nitrite ion NO₂⁻. Nitrites of the alkali and alkaline earth metals can be synthesized by reacting a mixture of nitrogen monoxide NO and nitrogen dioxide NO₂ with the corresponding metal hydroxide solution. Other nitrites are available through the reduction of the corresponding nitrates.

Sodium nitrite is used for the 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 (lethal dose of nitrite for humans is about 22 mg per kg body weight), the maximum allowed nitrite concentration in meat products is 200 ppm. Under certain conditions, especially during cooking, nitrites in meat can react with degradation products of amino acids, forming nitrosamines, which are known carcinogens.

In organic chemistry, nitrites mean the esters of nitrous acid. They possess the general formula R-O-N=O, R being an aryl or alkyl group. Amyl nitrite is used in medicine for the treatment of heart diseases.

Nitrites should not be confused with nitrates, the salts of nitric acid, or with nitro compounds, though they share the formula NO₂. The nitrite ion NO₂⁻ should not be confused with the nitronium ion NO₂⁺.

Nitrite is detected and analyzed by the Griess Reaction, involving the formation of a deeply red-color azo dye upon treatment of a NO₂⁻-containing sample with sulfanilic acid and naphthyl-1-amine in the presence of acid.¹

External links

• Case Studies in Environmental Medicine - Nitrate/Nitrite Toxicity

References

(1) "The 125th Anniversary of the Griess Reagent" by V. M. Ivanov in Journal of Analytical Chemistry, Vol. 59, No. 10, 2004, pp. 1002–1005. Translated from Zhurnal Analiticheskoi Khimii, Vol. 59, No. 10, 2004, pp. 1109–1112.

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