The Electrochemical Study of Vanillin in Acetonitrile
By Jazreen H.Q. Lee and Sherman J.L. Lauw and Richard D. Webster
Published in Electrochimica Acta
2016
Abstract
A detailed electrochemical study of vanillin was performed in acetonitrile using a platinum electrode. At low scan rates ? 1 V s?1, vanillin displayed an anodic peak at ca. 1.12 vs. (Fc/Fc+)/V, and a cathodic peak at ca. 0.09 vs. (Fc/Fc+)/V (on the reverse cyclic voltammetry (CV) scan after the initial oxidation) due to the reduction of a secondary reaction product. Both redox processes were found to involve a transfer of two electrons via controlled-potential electrolysis experiments, and it is surmised that vanillin first undergoes a ?2e?/-H+ oxidation, followed by a hydrolysis reaction and the loss of its methoxy substituent to generate a corresponding 1,2-benzoquinone that can subsequently be reduced via +2e?/ + 2H+. When higher scan rates ?2 V s?1 were employed, however, the aforementioned homogeneous reactions were partially outrun; leading to the detection of an additional cathodic peak at ca. ?0.28 vs. (Fc/Fc+)/V which is ascribed to the reduction of the transient hemiketal intermediate that is formed immediately after the reaction of the phenoxonium cation with trace water. A similar trend to the fast scan rate \CVs\ was likewise recorded at lowered temperatures (??10