Behaviour of disubstituted dithiocarbamates at the mercury electrode

The electrochemical behaviour at the mercury electrode of a series of sodium dithiocarbamates in aqueous solution has been investigated. Although the overall electrode reaction mechanism is the same as that for sodium diethyldithiocarbamate in each case, the current flowing in the main anodic wave is determined by the nature of the film of the particular insoluble mercury(II) dithiocarbamate deposited on the electrode and varies with the alkyl substituent group in the dithiocarbamate. A porous, loosely bound film which periodically bursts, causing localized stirring and large irregular currents, was indicated for large bulky alkyl groups (e.g. butyl) while for small or planar alkyl groups (e.g. methyl, tetramethylene) current inhibition was observed, suggesting a compact surface film. The influence of the surfactant Triton X-100 on the product film has also been examined. Linear sweep chronoamperometry is recommended as a general method of analysis for dithiocarbamates as the electrolysis time (and therefore the film thickness) can be selected to avoid the above interferences.