Kinetic investigation of the oxidation of bromide ions by cobalt(III). Part 1.—The influence of pyridine in acetic acid solvent

Abstract

A kinetic investigation of the reduction of cobalt(III) acetate by bromide ions in acetic acid and in the presence of pyridine at 60–93 °C has shown that the initial rate obeys the rate law –(d[Co^III]//_dt)₀=–(d[Br^–]//_dt)₀=k_obs[Co^III]²[HBr]²//_{[Co^II][Py]²}. A mechanism is proposed involving the formation of bromine anion radicals as intermediates. Pyridine or other amines influence mainly (i) the actual concentration of bromide ions, (ii) the dissociation of active dimeric Co^III species and (iii) the exchange of bromide ligands.