Diphenyl disulfide
Diphenyl disulfide is the chemical compound with the formula (C6H5S)2. This colorless crystalline material is often abbreviated Ph2S2. It is one of the more commonly encountered organic disulfides in organic synthesis. Minor contamination by thiophenol is responsible for the disagreeable odour associated with this compound. Preparation and structure Diphenyl disulfide is usually prepared by the oxidation of thiophenol: 2 PhSH + I2 → Ph2S2 + 2 HI Hydrogen peroxide can also be used as the oxidant. Ph2S2 is rarely prepared in the laboratory because it is inexpensive, and the precursor has a disagreeable odour. Like most organic disulfides, the C–S–S–C core of Ph2S2 is non-planar with a dihedral angle approaching 85°. Reactions Ph2S2 is mainly used in organic synthesis as a source of the PhS substituent.<ref>{{cite book|author=Byers, J. H.|chapter=Diphenyl Disulfide|title=Encyclopedia of Reagents for Organic Synthesis (Ed: L. Paquette)|year=2004|editor=J. Wiley & Sons|location=New York|doi=10.1002/047084289X|hdl=10261/236866 |isbn=9780471936237 }}.</ref> A typical reaction entails the formation of PhS-substituted carbonyl compounds via the enolate: RC(O)CHLiR' + Ph2S2 → RC(O)CH(SPh)R' + LiSPh Reduction Ph2S2 undergoes reduction, a reaction characteristic of disulfides: Ph2S2 + 2 M → 2 MSPh (M = Li, Na, K) Hydride reagents such as sodium borohydride and super hydride can also be used as reductants.