THE ROLE OF INTERMEDIATE OXIDATION-STATES OF TECHNETIUM IN CATALYSIS OF THE OXIDATION OF HYDRAZINE BY OXO-ANIONS .1. NITRATE IONS

The catalysis by technetium of the oxidation of hydrazine by nitric ac id has been studied over a wide range of concentrations of hydrazine a nd nitric acid and also in media where HNO3 is replaced by HBF4. The r eaction is confirmed as a chain process, exhibiting a higher turnover number of hydrazine molecules per atom of Tc and a kinetic profile con sisting of an initial slow stage, a very fast stage and a termination stage characterised by a high residual concentration of unreacted hydr azine and the existence of all Tc in the form of the initial pertechne tate ion. A model of the reaction which is an elaboration of that devi sed earlier by Garraway and Wilson, reproduces the main characteristic s of reaction over a much wider range of reactants than before. The st rong effects of increasing the acid concentration are in the opposite direction for HNO3 and HBF4.