The chemistry of peroxonitrites. Part II. Copper(II)-catalysed reaction between hydroxylamine and peroxonitrite in alkali

Abstract

Hydroxylamine and peroxonitrite react in alkaline solution in the absence of oxygen, in a metal-ion catalysed reaction, giving nitrite and nitrous oxide. It is suggested that the nitrous oxide is formed by the decomposition of cis-hyponitrite, which, in turn, is produced by the dimerisation of nitroxyl, NO^–, one of the initial products of the reaction. Evidence is presented to show the presence of NO^– as an intermediate and the instability of cis-hyponitrite under the conditions of the reaction. A little trans-hyponitrite is probably formed in this reaction, presumably also by NO^– dimerisation. In the presence of oxygen, the stoicheiometry is changed, hydroxylamine being oxidised to nitrite with apparently no loss of peroxonitrite. It is suggested that this is due to the reformation of peroxonitrite by the addition of oxygen to NO^–. The stability of Angeli's salt has been re-investigated while we have been unable to prepare sodium β-oxohyponitrite by the N₂O₄ oxidation of hyponitrite. Both these were considered as intermediates.