SELECTIVE OXIDATION OF D-GLUCONIC ACID ON PLATINUM AND LEAD ADATOMS MODIFIED PLATINUM-ELECTRODES IN ALKALINE-MEDIUM

Long term electrolyses of aqueous solutions of D-gluconic acid, in alk aline medium, were carried out on smooth and upd Pb modified Pt electr odes. The reaction products in solution were analysed by ionic chromat ography. It was found that the kinetics of oxidation and the orientati on of the reaction depend strongly on the catalytic properties of the surface. On a smooth Pt electrode, the main products of D-gluconic aci d oxidation are oxalic, tartaric, 5-keto-D-gluconic and D-glucuronic a cids, while on Pt-Pb electrodes, D-gluconic acid is oxidized selective ly to 2-keto-D-gluconic acid. This product and other by-products were identified by GC-MS coupling techniques.