Kinetics and Mechanism of Selenium(IV) Oxidation of Ascorbic Acid in Aqueous Perchlorate Solutions

The kinetics of oxidation of L-ascorbic acid by selenium(IV) in aqueous solutions of perchloric acid at a constant ionic strength of 1.0 mol dm-3 has been investigated spectrophotometrically. A first order reaction in ascorbic acid and a fractional order with respect of selenium(IV) were observed. The rate of reaction was found to be acid catalyzed. The results obtained at various hydrogen ion concentrations indicate that the ascorbate anion plays a role in the reaction kinetics through formation of a complex ion intermediate. The activation parameters have been evaluated and a tentative reaction mechanism was suggested