Kinetics and mechanism of oxidation of <Emphasis Type="SmallCaps">l</Emphasis>-cystine by manganese(III) in sulfuric acid medium

The kinetics of oxidation of l-cystine by Mn^III have been studied in sulfuric acid medium at 30 °C. The reaction was followed spectrophotometrically at λmax = 500 nm. The reaction shows first order dependence on both Mn^III] and cystine]. It was found that the rate of the reaction decreases with increase of H⁺] up to a certain point and then remains unchanged. The oxidation product of the reaction was found to be cysteic acid. A plausible mechanism has been proposed to account for the experimental results.