KINETICS AND MECHANISM OF THE OXIDATION OF L-ASCORBIC-ACID BY HEXACYANOIRON(III) IN ACIDIC AQUEOUS-SOLUTION - APPLICATION OF HIGH-PRESSURE TECHNIQUES

The kinetics of the oxidation of L-ascorbic acid by Fe(CN)6(3-) in aqueous solution was investigated as a function of pH, temperature and pressure. Rate and activation parameters (DELTA-H], DELTA-S] and DELTA-V]) are reported for the two main reactions at pH < 7, i.e. the oxidation of L-ascorbic acid and of the ascorbate anion. The activation parameters support the operation of an outer-sphere electron-transfer mechanism, and the values of DELTA-V] are in good agreement with those calculated theoretically using the Stranks-Marcus-Hush relationships. The results are compared with available data reported in the literature.