Oxidation of methionine by tetraethylammonium chlorochromate in non-aqueous media – A kinetic and mechanistic study

The kinetics of oxidation of methionine (Met) by tetraethylammonium chlorochromate (TEACC) in dimethyl sulfoxide (DMSO) leads to the formation of the corresponding sulfoxide. The reaction is first order each in Met and TEACC. The reaction is catalyzed by hydrogen ions. The hydrogen ion dependence has the form : kobs = a + b [H+]. The reaction rate has been determined at different temperatures and activation parameters are calculated. The solvent effect has been analyzed using Kamlet’s multi parametric equation. A correlation of data with Kamlet–Taft solvatochromic parameters (α, β, π∗) suggests that the specific solute–solvent interactions play a major role in governing the reactivity. The reaction does not induce polymerization of acrylonitrile. A suitable mechanism has been proposed.