Nitrous acid

Nitrous acid (HNO₂) is an unstable, weak nitrogen oxoacid. Its salts and esters are called nitrites.

Nitrous acid disproportionation: A redox reaction in which nitrous acid forms nitric acid and nitric oxide. This reaction illustrates why nitrous acid is chemically unstable.
Diazotization: The conversion of a primary aromatic amine into a diazonium salt using nitrous acid under acidic conditions. Nitrous acid generates the nitrosating species that initiate this reaction.
Oxoacid: An acid containing oxygen, hydrogen, and another element, with acidic hydrogen often bonded through oxygen. Nitrous acid belongs to this structural family.
Nitrite: The anion NO₂⁻ and salts containing it, formed when nitrous acid loses a proton. Nitrous acid is commonly generated in solution by acidifying a nitrite salt.
Nitric oxide: A colorless nitrogen oxide gas with formula NO and an odd number of electrons. It is one product of nitrous acid disproportionation.
Arenediazonium salt: An organic salt containing an aryl group bonded to a diazonium group, Ar–N₂⁺. These salts are the principal products of aromatic amine diazotization.
Conjugate acid–base pair: Two species related by the gain or loss of a proton. HNO₂ and NO₂⁻ form such a pair.
Sodium nitrite: The ionic compound NaNO₂, a widely used source of nitrite ions. Acidification of sodium nitrite provides a practical route to nitrous acid in situ.
Nitric acid: A strong mineral acid with formula HNO₃ and nitrogen in oxidation state +5. It is the oxidized product when nitrous acid disproportionates.
Nitrosation: The introduction of a nitroso group, –N=O, into a molecule. Nitrous acid and its derivatives act as nitrosating agents.

Linked from 9 pages