Kinetics and mechanism of oxidation of L-ascorbic acid by platinum(IV) in aqueous acid medium

The oxidation of l-ascorbic acid (H2A) by platinum(IV) in aqueous acid medium exhibits overall second-order kinetics, being first order with respect to each reactant. Increasing both hydrogen and chloride ion concentrations inhibits the rate. The stoichiometry involves reaction of one platinum(IV) ion with H2A to give dehydroascorbic acid. A reaction mechanism consistent with all the experimental observations is proposed.