Kinetics of oxidation of nitrogen compounds by cerium(IV)

Abstract

The kinetics of oxidation by Ce^IV in sulfuric acid of hydrazine, hydroxylamine, nitrous acid, hydrazoic acid and of an intermediate involved in the nitrite/hydrazine reaction has been examined under a uniform set of conditions. Reaction proceeds through the free base form of the nitrogen substrate, probably by an inner-sphere mechanism, with a reactivity sequence N₂H₄ > NH₂OH > N₃^– > NO₂^–. An intermediate in the hydrazine/nitrous acid reaction, NH₂NNOH, is also oxidised by Ce^IV in a Ce^IV/HNO₂/N₂H₅⁺ system. For the Ce^IV/HNO/HN₃ system there is a much larger consumption of oxidant than can be accounted for by the separate oxidations of nitrite and azide. An additional pathway is proposed, probably involving NNN–O–NO, formed by combination of azide and nitrogen dioxide radicals.