Micellar Effect on the Catalytic Co-Oxidation of Dimethyl Sulfoxide and Oxalic Acid by Chromium(VI) in Aqueous Acid Media: A Kinetic Study

The CrVI oxidation of a mixture of dimethyl sulfoxide (DMSO) and oxalic acid (OXH2) in aqueous acid media occurs much faster than that of either of the two substrates alone (DMSO reacts extremely slowly under the experimental conditions). In the mixture, both substrates undergo oxidation simultaneously in a ternary complex of CrVI through a three electron transfer step (i.e. CrVI → CrIII), two electrons from DMSO and one electron from oxalic acid. Hitherto there has been a debate regarding the existence of a 3e transfer in a single step. The micellar effect may be considered as a probe for 3e transfer in a single step.