Bromide oxidation and bromine reduction in propylene carbonate

Abstract

Bromide oxidation and bromine reduction in propylene carbonate (PC) +1 M LiClO 4 was investigated voltammetrically using polycrystalline platinum rotating disc electrode. The corresponding voltammograms were compared to those of iodide oxidation and HCl decomposition. The oxidation 2Br −→Br 2+2e − was found to proceed through two steps, which are caused by the formation of a stable intermediate Br 3 − ion. The stability constant of tri-bromine ion was estimated to be 10 5.5 M. The diffusion coefficient of Br − ion in this solution was determined to be 3.41×10 −6 cm 2 s −1. In the case of bromine reduction, a time dependence of the shape of the voltammogram was observed, which showed that one is dealing with a direct bromination of PC.