Kinetics and Mechanism of Oxidative Conversion of Methionine to Sulfone by Chloramine-B in Acid Medium

Background: Methionine, Met, is one of the sulfur containing amino acids required in the human body by certain biochemical reactions. Since Met is not biosynthesized in humans, it needs to be supplied externally in diet. Met is highly susceptible to oxidation. Objective: The oxidation of Met to its sulfone by CAB in aqueous perchloric acid medium at 323 K has been kinetically studied. Method: Effect of varying ionic strength, solvent composition, dielectric constant has been determined. Effect of reduction product of Chloramine-B (CAB), benzenesulfonamide, on the reaction rate has also been investigated. Conclusion: The experimental rate law obtained is: rate = k#128; [CAB] [H2O]. Activation parameters have been evaluated using Arrhenius and Eyring plots. A mechanism consistent with the observed kinetic data has been discussed. A rate law has been derived based on the mechanism.