Kinetics of oxidation of nitrogen compounds by cerium (IV)

摘要

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 examine 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 N_2H_4 > NH_2OH > N_3~ -> NO_2~-. An intermediate in the hydrazineitrous acid reaction, NH_2N=NOH, is also oxidised by Ce~(IV) in a Ce~(IV)/HNO_2/N_2H_5~+ system. For the Ce~(II)/HNO/HN_3 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.