THE ELECTROCHEMISTRY OF DIBUTYLTIN AT MERCURY-ELECTRODES IN AQUEOUS-MEDIA

The electrochemical reduction of dibutyltin (Bu(2)Sn(2+)) at mercury electrodes has been investigated in aqueous media containing nitrate and chloride electrolytes using the techniques of direct. current (DC) polarography, differential pulse (DP) polarography, DP voltammetry, and cyclic voltammetry. In 0.10 M nitrate media, the initial charge transfer process occurs at approximately -0.7 V (vs. Ag/AgCl) and is described by the equation [GRAPHICS] in which a reversible charge transfer occurs with completely surface-confined dibutyltin. However, when longer time domains at a hanging mercury drop electrode (HMDE) are used, the complexity of the electrochemistry increases, which is attributed to the occurrence of butyl exchange processes with the electrode mercury and consequent disruption of the film of adsorbed dibutyltin. In 0.50 M chloride media, the extent of adsorption is considerably less, and the processes, but not necessarily the postulated mechanism, correspond more closely to that described by previous workers for the reduction of dibutyltin compounds in ethanol-water mixtures.