KINETICS ASPECTS OF THE ELECTROOXIDATION OF VERATROLE IN WET ACETONITRILE

Abstract

The electrooxidation of veratrole (1,2-dimethoxybenzene) at a platinum surface, was evaluated in dry and wet acetonitrile in tetrabutylammonium tetrafluoroborate, using in situ UV-Visible spectroelectrochemistry. As the content of water was increased, a competition between growth of polyveratrole and formation of soluble species (mainly 2,3- dimethoxybenzoacetamide) was observed. It was found that the decay rate of the cation radical formed during the electrooxidation in dry acetonitrile obeys a second order kinetics (kf1 = 258 M-1s-1), involving a chemical step coupled to the first electron transference with growth of polyveratrole on the electrode surface. Under wet conditions, the decay rate constant of the cation radical follows a pseudo first order kinetics (kf2 = 2.40 s-1 when measured by differential reflectance spectroscopy, DRS, and kf2 = 3.25 s-1 when measured by absorbance determinations, AD), leading to formation of soluble species diffusing to the bulk.