Bromide oxidation and bromine reduction in propylene carbonate

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.