KINETICS AND MECHANISM OF OXIDATION OF DIMETHYL SULPHOXIDE BY ALKALINE PERIODATE

The kinetics of oxidation of imethyl sulphoxide (DMSO) by periodate, (H3IO62-) was studied in alkaline medium at constant ionic strength of 0.5 mol dm(-3). The reaction shows first order kinetics in [periodate] and a fractional order dependence both on [DMSO] and [OH-]. The ionic strength and dielectric constant of the medium did not affect the rate significantly. Addition of products has no significant effect on the reaction rate. The oxidation process in alkaline medium has been shown to proceed via the formation of a complex between the active species of the oxidant and the substrate followed by the decomposition of the complex in a slow rate-determining step to yield the product. The reaction constants involved in the mechanism were determined; calculated and observed rate constants agree excellently. The activation parameters were computed with respect to the slow step of the reaction.