HYDROGEN-SULFIDE REACTIVITY WITH THIOLS IN THE PRESENCE OF COPPER(II)IN HYDROALCOHOLIC SOLUTIONS COGNAC BRANDIES - FORMATION OF SYMMETRICAL AND UNSYMMETRICAL DIALKYL TRISULFIDES

In the presence of copper(II), hydrogen sulfide reacts with thiols (me thanethiol and ethanethiol) to yield symmetrical or unsymmetrical tris ulfides (dimethyl trisulfide, diethyl trisulfide, and ethyl methyl tri sulfide). In alcoholic beverages, these compounds are known for their nauseous character reminiscent of onion smell, and for their low detec tion levels (dimethyl trisulfide: 0.1 mu g/L). A mechanism for trisulf ide formation is proposed that involves a two-step redox reaction.