Kinetics and mechanism of the reaction between nitrous acid and hydroxylamine. Part II. The alkyl hydroxylamines

Abstract

O-Alkylhydroxylamines react with nitrous acid with a rate law v=k₂[R¹NH₂⁺OR²][HNO₂]; the mechanism involves electrophilic nitrosation at the nitrogen atom of the free base. At acid concentrations below 2M-per-chloric acid, hydroxylamine and N-methylhydroxylamine react with nitrous acid by an acid-catalysed mechanism with a rate law v=k₃[RNH₂⁺OH][HNO₂]h₀; this involves initial nitrosation at the oxygen atom of the conjugate acid, followed by migration of the nitrosonium ion to the nitrogen. At higher acidities the O-nitrosation can be reversed, and the migration of the nitrosonium ion becomes the rate-determining stage.