Reduction kinetics of 2,3-dimethoxy-5-methyl-1,4-benzoquinone by ascorbic acid in acid solution

Abstract

The mechanism of the oxidation of ascorbic acid by 2, 3-dimethoxy-5-methyl-1, 4-benzoquinone was studied as a function of pH, ionic strength and temperature in aqueous buffer solutions, using dc polarography and UV–VIS spectrophotometry. The study was performed at pH values 3.0–6.2 at which the quinone is stable. From the experimental results, a mechanism for oxidation of the ascorbic acid which involves several steps with the participation of AH˙ and QH˙ radicals as intermediate species, has been proposed.