Oxidation of hydroxylamine by nitrous and nitric acids

Article abstract of DOI:10.1021/ic00136a066

The kinetics of the reaction of hydroxylamine with nitrous acid and with nitric acid were studied in an acidic nitrate medium. The mechanism of the reaction with nitrous acid in an acidic perchlorate medium, proposed by previous workers, is O-nitrosation of the hydroxylammonium ion; our data are consistent with this mechanism at an ionic strength of 2 M. The data at higher ionic strength (3 and 4 M), when compared to an extended treatment of the proposed mechanism, indicate either a deviation from this mechanism at high acid concentration or a change in one of the principal species in solution. Raman and UV spectroscopies were unable to verify a change in the species. In the reaction of hydroxylamine with nitric acid, we identified HNO₂, N₂O, and N₂ as products. This reaction is autocatalytic in HNO₂, and the distribution of products is dependent on the initial concentrations of HNO₂, NH₃OH⁺, and HNO₃. The product N₂O derives from the nitrosation of NH₃OH⁺. The reaction of the intermediate N₂O₄ with NH₂OH produces HNO₂, and N₂ is postulated to arise from the reaction of HNO₂ with hyponitrous acid, which is an intermediate in the nitrosation of NH₃OH⁺. A kinetic model is partially successful in rationalizing the distribution of products.