Electro-oxidation of meso-erythritol on platinum in acid medium: analysis of the reaction products

The electrocatalytic oxidation of 1,2,3,3-butanetetrol (meso-erythritol) ha s been studied on polycrystalline platinum in 0.1 M HClO4. A preliminary in vestigation by cyclic voltammetry, used to determine the optimized conditio ns of electrolysis, showed that the electro-oxidation of mesa-erythritol is a slow reaction on a bare platinum electrode. When the electrode surface i s modified by underpotential deposition of lead or thallium adatoms, the cu rrent densities increase significantly. Otherwise, long-time electrolyses w ere carried out using a three potential plateau program with different valu es of the oxidation potentials. Chromatographic analyses showed that the ox idation of erythritol led mainly to 2,3,4-trihydroxybutanal (erythrose), 1, 3,4-trihydroxy-2-butanone (erythrulose) and to the lactone of 2,3,4-trihydr oxybutanoic acid (i.e. erythrono-gamma-lactone); this lactone is hydrolyzed in solution into erythronic acid. When increasing the oxidation potential, the degradation of the initial molecule skeleton becomes more and more imp ortant and the selectivity decreases. In situ FTIR reflectance spectroscopi c investigations showed that the adsorption of erythritol is dissociative w hich is proved by the presence of CO species absorption bands. The identifi cation of other kinds of adsorbed species and reaction products is also dis cussed. Finally, a reaction mechanism for the oxidation of erythritol is pr oposed. (C) 1999 Elsevier Science S.A. All rights reserved.