THE ROLE OF INTERMEDIATE OXIDATION-STATES OF TECHNETIUM IN CATALYSIS OF THE OXIDATION OF HYDRAZINE BY OXO-ANIONS .2. PERCHLORATE IONS

The oxidation of hydrazine by an aqueous acid perchlorate medium is ca talysed very efficiently by TcO4- ions in a manner recalling the nitra te ion system. The reaction shows an induction period followed by a fa st stage of evolution of N2, and a high turnover number (>60) but no r esidue of unreacted hydrazine is left in contrast to the nitrate syste m, especially under strongly acid conditions. The concentration of Tc( IV) in the system goes through two maxima as reaction proceeds, the fi rst being extremely sharp, the second much broader. This complex kinet ic behaviour has been computer-modelled reasonably successfully. The c olour changes depend on the acidity of the system, but some coloured p roducts have been characterised by UV/VIS and/or ESR spectroscopy.