Electroreduction of alkaline-earth metal cations at mercury in aprotic media

Abstract

The kinetics of the electroreduction of the alkaline-earth metal cations have been determined at mercury in dimethylformamide and acetonitrile containing various tetra-alkylammonium perchlorates as supporting electrolytes. Kinetic data were also obtained for the electro-oxidation of the corresponding amalgams. The kinetic parameters were observed to depend markedly on solution composition, the standard rate constant increasing with decrease in cation solvating ability of the solvent, and with increase in crystallographic radius of the tetra-alkylammonium cation. On the basis of a detailed analysis of double-layer effects it is concluded that the kinetics of the reduction process are controlled by adsorption of the cation at the electrode, and its subsequent transfer to the metal phase. The present data are compared with those obtained earlier for the alkali-metal cations.