Electrochemical behavior of decyl mercuric halides at mercury cathodes in dimethylformamide

Polarograms for decyl mercuric halides in dimethylformamide containing tetraalkylammonium perchlorates exhibit two waves. When large-scale electrolyses of decyl mercuric halides are performed at potentials corresponding to the first polarographic wave, the couldometric n value is unity and didecylmercury is obtained in quantitative yield; electrolyses carried out at potentials on the plateau of the second polarographic wave afford only decane and the n value is essentially 2. Double-potential-step chronocoulometry and staircase voltammetry indicate that, at potentials corresponding to the first polarographic wave, the decyl mercuric halide (which is itself adsorbed onto mercury to the extent of less than a monolayer) undergoes reversible one-electron reduction to adsorbed decyl mercury radicals and to adsorbed decyl mercury radical “polymer”; the adsorbed radicals have a lifetime of approximately 10^?3s and disproportionate into didecylmercury and elemental mercury. In the presence of electrolytically released halide ion, the adsorbed radicals are reoxidized to the decyl mercuric halide; alternately, the adsorbed species are reoxidized to decyl mercury cations at a potential approximately 600 mV more positive than that required for reoxidation to the decyl mercuric halide. At potentials corresponding to the second polarographic wave, reduction of decyl mercuric halides is an irreversible process producing decyl carbanions which are protonated by traces of water in the solvent to give decane.