A Colour Reaction for Thiosulphinates

INVESTIGATIONS of the chemistry of the thiolsulphinates, both synthetic and of natural provenance, would be aided if a rapid colorimetric test for these compounds were available. Aliphatic thiolsulphinates can be characterized, in part at least, by reaction with thiamine 1 or with cysteine 2 to yield crystalline derivatives; but these methods do not generally distinguish thiolsulphinates from thiolsulphonates, since the latter compounds will also react with these reagents. The addition of sodium nitroprusside 3 solution followed by base will yield orange to red colours in the presence of aliphatic thiolsulphinates or thiolsulphonates. This procedure has found application in paper chromatography 3 in investigations of the formation of thiolsulphinates in plants of the genus Allium . In our experience, the colour, however, is very fugitive and is apparently not produced by some aromatic thiolsulphinates.