Kinetics of oxidation of hydrazine and of t-butylhydrazine using tris(dimethylglyoximato)nickelate(IV) in the presence of added Cu2+(aq)

Abstract

The kinetics of the oxidation of hydrazine and t-butylhydrazine using tris(dimethylglyoximato)-nickelate(IV), [Ni(dmg)₃]^2–, in the presence of added Cu²⁺(aq), and in the pH range 5.0–7.0 at 35 °C and I= 0.25 mol dm^–3in aqueous medium, follow pseudo-first-order and pseudo-zero-order disappearance of the Ni^IVcomplex, respectively. Results of the Cu²⁺(aq)-promoted oxidation of hydrazine by [Ni(dmg)₃]^2–, are consistent with a probable scheme involving pH-dependent equilibrium formation of intermediate adducts between the Ni^IV and Cu^II–hydrazine complex species present in the solution and subsequent rate-determining electron transfer(s) to the adduct(s) from the hydrazine species in the presence of H⁺. Results of the Cu²⁺(aq)-catalyzed oxidation of t-butylhydrazine are interpreted in terms of a probable mechanism involving a rate-determining decomposition of the 1 : 1 intermediate complex between the Cu^II and t-butylhydrazine species in the solution, with a concomitant electron transfer. While the oxidation of hydrazine leads to nitrogen, the main products of the t-butylhydrazine oxidation are nitrogen and t-butyl alcohol.