The electrochemical characterization of CS₂₊reduction products and intermediates, and related sulfur containing compounds

The electrochemical reduction of carbon disulfide in DMF was studied using HPLC and mass spectral techniques. Trithiocarbonate was shown not to be formed initially in the electrode processes. Instead, the dimer of carbon disulfide, tetrathiooxalate, forms initially as an intermediate, but slowly decomposes to form trithiocarbonate, and other species. The principal product of interest from this reduction, 4,5-dimercapto-1,3-dithiole-2-thione, was not formed directly from the intermediate decomposition. Mass spectra of carbon disulfide reduction solutions display a complex pattern of fragment ions representative of the variety of products derived from this reduction. Formation of some high molecular weight carbon-sulfur compounds is indicated by the pattern.

The electrochemical behavior of 4,5-bis(methylthio)-1,3-dithiole- 2-one was also studied. Oxidation of this compound gave the radical cation which disproportionated to the dication and the starting compound. Further reaction with residual water led to sulfoxide formation.

The principal product from the photolysis of the 1,3-dithiole-2-one was dimethyltetrathiooxalate. Electrochemical reduction of this product to the dianion gave tetramethylthioethylene after methylation. The crude photolysis product was shown by mass spectroscopy to contain minor amounts of high molecular weight species similar to those observed earlier in the carbon disulfide reduction solutions. Several unsuccessful experiments in which the isolation of these species was attempted using standard chromatography methods and electrocrystallization are also described.