Kinetics of oxidation of nitrogen compounds by cerium(IV)

The kinetics of oxidation by Ce-IV in sulfuric acid of hydrazine, hydroxyla mine, nitrous acid, hydrazoic acid and of an intermediate involved in the n itrite/hydrazine reaction has been examined under a uniform set of conditio ns. Reaction proceeds through the free base form of the nitrogen substrate, probably by an inner-sphere mechanism, with a reactivity sequence N2H4 > N H2OH > N-3(-) > NO2-. An intermediate in the hydrazine/nitrous acid reactio n, NH2N=NOH, is also oxidised by Ce-IV in a Ce-IV/HNO2/N2H5+ system. For th e Ce-IV/HNO/HN3 system there is a much larger consumption of oxidant than c an be accounted for by the separate oxidations of nitrite and azide. An add itional pathway is proposed, probably involving NNN-O-N=O, formed by combin ation of azide and nitrogen dioxide radicals.