Mechanism of L-ascorbic acid oxidation on a mercury electrode. II. Basic medium

Abstract

A polarographic study of the oxidation mechanism of L-ascorbic acid is carried out in a basic medium and two oxidation waves are observed.An analysis of these waves shows that the limiting current is governed by diffusion and that in each reaction a two electron transfer takes place. On the rising portion of the waves, the oxidation process consists of two consecutive one electron transfers. In the first wave, the second transfer is the rate determining step, whilst in the second wave, a chemical stage subsequent to the second electron transfer is the rate determining step. The reaction orders, together with the Tafel slopes, are calculated.The oxidation mechanism of this acid in basic media is different from that in acid media.