Anomalous Influence of Adsorbed Higher Aliphatic Alcohols on Electroreduction of Nitromethane and 1-Nitrohexane on Mercury Electrodes

Abstract

The electroreduction of nitromethane and 1-nitrohexane in both the absence and in the presence of n-octanol and n-decanol was studied. It was found that, under comparable conditions at smaller concentrations of inhibitors, nitromethane is inhibited more strongly than 1-nitrohexane by the n-alcohol adsorbed monolayer on the mercury electrodes. This was explained by the larger affinity of nitrohexane to the alcohol-rich surface phase and of nitromethane to the aqueous solution phase. Through the increased affinity of both reactants to the electrode surface phase at the inhibitor concentration, c/cs, exceeding 0.6, the independence of the electroreduction rate constant of both reactants was explained. When the bulk concentration of inhibitors approached saturation even the increase of the rate constant was observed. The change of the solvent composition, from pure water to 10 vol. % ethanol, increases the inhibition by increasing the affinity of the reactant to the solution phase.