Kinetics and Mechanism of the Oxidation of DL-Methionine by Tetrakis(Pyridine)silver Dichromate

摘要

The oxidation of methionine by tetrakis(pyridine)silver dichromate in dimethyl sulphoxide leads to the formation of cortesponding sulphoxide. The reaction is of first order with respect to tetrakis(pyridine)silver dichromate. Michaelis-Menten type kinetics was observed with respect to methionine. The reaction is catalyzed by hydrogen ions. The hydrogen-ion dependence has the form: k_(obs) = a + b [H~+]. The oxidation of methionine was studied in 19 different organic solvents. The solvent effect was analyzed by Kamlet's and Swain's multiparametric equations. Solvent effect indicated the importance of the cation-solvating power of the solvent. A suitable mechanism has also been postulated.