The action of 70y0 perchloric acid on 8-keto 9-methyltrithiocarbonates and 8-keto 0- ethyldithiocarbonates is described. Dithiolium derivatives have been obtained from the trithiocarbonate intermediates. The synthesis of some 4-hydroxyl-1, 3-dithiolium perchlorates from appropriate carboxymethyl, carbethoxymethyl, and carbamidomethyl esters is also described, and the ultraviolet and nuclear magnetic resonance spectral ...