Oxidation of thiols by superoxide ion

Abstract

Superoxide ion oxidizes aromatic thiols to disulfides or sulfonic acids. Benzene-1,2-dithiol and its 4-methyl analogue formed the cyclic disulfides dibenzo[c,g]tetrathiocins. Aliphatic thiols gave disulfides, and ethane-1,2-dithiol and propane-1,3-dithiol formed the cyclic disulfides 1,2,5,6- tetrathiocan and 1,2,6,7-tetrathiecan respectively. Butane-1,4-dithiol underwent an intramolecular cyclization to 1,2-dithian. Cysteine was oxidized by O₂^-· to cysteic acid.