The addition of dithiocarbamic acids to p-benzoquinone

Abstract

Dithiocarbamic acids readily add to p-benzoquinone under carefully controlled conditions to give 2,5-dihydroxyphenyl dithiocarbamates (5a-f) in good yield. Oxidation of these esters with bromine in chloroform gives 1,3-benzodithioliminium salts (6), whereas oxidation with bromine in methanol gives 5-hydroxy-1,3-benzoxathioliminium salts (7). N,N-Disubstituted 1,3-benzodithioliminium salts (6a,b) give stable coloured free bases formulated as zwitterions (8a,b). Further transformations of these products are described.