The kinetics of the oxidation of 2,3-dimethylbutane-2,3-diol (pinacol) by aquomanganese(III) ions in aqueous perchlorate media

Abstract

The oxidation of pinacol (2,3-dimethylbutane-2,3-diol) by Mn^III in perchlorate media is of the first order in both [Mn^III] and [pinacol] at high [pinacol]/[Mn^III]. Stopped-flow oscilloscope traces show the presence of intermediate Mn^III–pinacol complexes, and the variation of the rate of oxidation with acidity shows that these complexes are Mn³⁺Me₂COH·Me₂COH_aq and Mn³⁺Me₂COH·Me₂CO_aq^–. Overall energies and entropies of activation are determined. This is compared with other cation–pinacol redox reactions.