Oxidative transformation of methionine by pyridinium chlorochromate in aqueous DMF medium: A kinetic study

The Kinetics of Oxidative transformation of Methionine by pyridinium chlorochromate in aqueous DMF medium, containing perchloric acid has been studied. The rate of reaction was found to be of first order dependence on PCC, Methionine, and H+ ion Concentration. Michaelis–Menten type kinetics is observed respect to substrate. The increase in the rate of reaction with increase in acidity indicates the involvement of a protonated chromium(VI) species in the rate-determining step. The product of oxidation has been identified as methionine sulfoxide. The rate of reaction increased with increase in dielectric constant of the reaction medium. The plots of logkobs versus (D-1) / (2D+1) are non linear Indicating that there is an involvement of positive ion-dipole in the rate determining step. The activation parameters have been evaluated. On the basis of the experimental findings, a suitable mechanism and rate law has been proposed.