Direct Oxidation of Dimethylsulphoxide and Reduction of Maleic Acid in Methanesulphonic Acid Medium

Abstract

The direct electro oxidation of dimethylsulphoxide (DMSO) to dimethylsulphone (DMSO2) at a Pb/PbO2 anode and electro reduction of maleic acid (MA) to succinic acid (SA) at stainless steel cathode have been has been carried out in methane sulphonic acid (MSA) medium in a batch divided cell. It is to be noted that, as methane sulphonic acid medium (MAS) is biodegradable, it is a preferred medium for the electrochemical reactions.The process parameters such as concentration of MSA, DMSO and current density have been critically examined and the comparative performances of Pb/PbO2 with TSIA electrode as well as the reusing of electrolyte under optimum conditions have been investigated. The reaction parameters such as acid concentration, current density, the use of divided and undivided cells, etc. have been studied on electrochemical reduction of MA to SA.In the case of direct electro oxidation of dimethylsulphoxide to dimethylsulphone, the current efficiency on TSIA anode has been around 60- 65% while that with Pb/PbO2 has been more than 90%. The electro reduction of MA to SA has given current efficiency around 65 – 70%. Based on the result obtained on trials, the optimum parameters of the reaction found to be 1.0 M acid concentration and 5.0 A dm-2 current density. Divided cell has given good results when compared to undivided cell.