Oxidation processes for tetraethyllead and tetramethyllead in dichloromethane at mercury electrodes

Electrochemical studies on tetraethyllead and tetramethyllead at mercury electrodes in dichloromethane are characterised by a one electron oxidation process in contrast to the two electron step reported for the tetraphenyllead compound. Short time pulse techniques and coulometric techniques with tetraethyllead are consistent with the mechanism: {A figure is presented}{A figure is presented}. The initial reaction pathway with the methyl analogue is the same. However, long time scale experiments with tetramethyllead are modified by further reactions of the kind {A figure is presented}. New studies on tetraphenyllead employing variable time domain pseudo derivative normal pulse polarography show that the oxidation of this compound is also consistent with a one electron process at very short times. However the Φ₃Pb^{{radical dot}} radical is slower to dimerise than the alkyllead radicals and so direct reaction with ΦHg⁺ is observed to generate Φ₃Pb⁺ and Φ₂Hg. A subsequent electrochemical process involving Φ₃Pb⁺ at the mercury electrode is responsible for the overall two electron transfer reaction observed.