ELECTROCHEMICAL OXIDATION OF DIMETHYL SULFONE IN ALKALINE MEDIUM

Abstract

In this paper the electrochemical oxidation of dimethyl sulfone (DMSO2) on a platinum electrode in an alkaline medium has been studied by cyclic voltammetry. It is shown that during the electrochemical oxidation of dimethylsulfone in an alkaline medium on a smooth platinum electrode, a significant suppression of the oxygen evolution (O2) occurs in the potential range of E = 1.3-2.0 V. By scanning electron microscopy methods, Raman scattering and infrared spectrometry it is shown that the main substance is the dimethyl disulfone (DMDSO2) during the anodic oxidation of DMSO2 on a platinum electrode. By the preparative electrolysis of aqueous solutions of various concentrations of DMSO2 in 0.1 M NaOH solution at controlled potentials E = 1.6 and 1.8 V it is established that the current yield of the base material is not more than 84%. Based on the data of the physicochemical analysis of the final products of preparative electrolysis, a mechanism is proposed for the formation of dimethyl disulfone in an alkaline medium. It has been shown that the oxidation of dimethyl sulfone proceeds in the oxygen region by breaking C-S bonds in the DMSO2 molecule to form methyl (CH3•) and methylsulfonic (CH3S•(O)2) radicals. It is assumed that the methylsulfone radicals readily dimerize with the formation of stable DMDSO2 molecules and are desorbed in the bulk of the solution, and the methyl radicals bind to the HO radicals to form methanol molecules. The latter is well chemisorbed on the surface of platinum with the formation of adsorbed COH particles that are oxidized on a platinum electrode with the formation and evolution of carbon dioxide (CO2) from the volume of the anolyte solution. The formation of molecules of methanol was identified by the method of chromato-mass -spectrometry, and the emission of carbon dioxide by the gravimetry.