Bromide oxidation and bromine reduction in propylene carbonate

Abstract

Bromide oxidation and bromine reduction in propylene carbonate (PC) +1 M LiClO4 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-→Br2+2e- was found to proceed through two steps, which are caused by the formation of a stable intermediate Br3- ion. The stability constant of tri-bromine ion was estimated to be 105.5 M. The diffusion coefficient of Br- ion in this solution was determined to be 3.41 × 10-6 cm2 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. © 2003 Elsevier Science B.V. All rights reserved.