H2N2O2

H2N2O2, also known as hyponitrous acid, is a chemical compound with the molecular formula H2N2O2. It is a weak acid and exists primarily in aqueous solution. In its pure form, hyponitrous acid is unstable and can decompose explosively. It is a diprotic acid, meaning it can donate two protons. The salts derived from hyponitrous acid are called hyponitriles.

Hyponitrous acid is formed by the reaction of nitrous oxide (N2O) with water under specific conditions, though this is not a common or easy synthesis. More typically, it is encountered as an intermediate in the decomposition of other nitrogen-containing compounds. For instance, the reduction of nitric acid or nitrites can lead to the formation of hyponitrous acid or its derivatives.

The compound exhibits tautomerism, existing in equilibrium with its isomer, the nitrosohydroxylamine, which has the formula HONHNO. The anion of hyponitrous acid is the hyponitrite ion (N2O2^2-).

Hyponitrous acid and its salts have found limited practical applications. Historically, some hyponitrite salts have been investigated for their potential pharmacological effects, but their instability and toxicity have largely precluded their widespread use. Research continues into understanding the chemical properties and potential reactivity of hyponitrous acid and its related species.