SCHEDULED MAINTENANCE
New aspects of the oxidation–reduction mechanism of the ascorbic–dehydroascorbic acid system on the dropping mercury electrode
Abstract
Recent studies of the oxidation of enediol compounds and the reduction of di- and tri-carbonyl compounds on a mercury electrode have made it advisable to review the oxidation–reduction mechanism of the ascorbic–dehydroascorbic acid system on the dropping mercury electrode. On the basis of the variation of E½ with log t, the Tomes and Tafel slopes and the reaction orders with respect to both the reactant and the H+ ion we propose reaction mechanisms for both processes. In both, a chemical step prior to transfer is the rate-determining step at potentials corresponding to the foot of the wave. The reversibility of the oxidation–reduction process is also discussed. Capacity vs. potential curves have been obtained showing that under our experimental conditions ascorbic acid is not adsorbed on the mercury surface.
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