Kinetics of oxidation of nitrogen compounds by cerium(IV)

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 > N-3(-) > NO2-. An intermediate in the hydrazine/nitrous acid reaction, NH2N=NOH, 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-N=O, formed by combination of azide and nitrogen dioxide radicals.