Disulfiram, Metals, and Melanoma

A two-session general chemistry laboratory experiment is described concerning redox transformations of disulfiram, the disulfide of diethyldithiocarbamate (deDTC), related to its use in clinical trials for treatment of melanoma. In this laboratory, the students follow three different procedures to synthesize the complex Cu(deDTC)2 using sodium diethyldithiocarbamate, Na(deDTC)·3H2O; disulfiram, DSF; and an oxidized analogue, bis(dialkyliminium) tetrathiolane dication, (bitt-4)2+, as starting materials. The first method is essentially quantitative and has been used as an analytic method for trace metal detection as characterized by colorimetric analysis. The Zn, Ni, and Fe complexes are also synthesized and spectrally characterized. The latter two pathways involve redox disproportionation reactions of the sulfur compounds in which the stoichiometric ratios are obtained by balancing equations. Precipitation analysis is also used to qualitatively identify byproducts of the disproportionation reactions.