Description
Diphenyl disulfide is a colorless crystalline material with the formula (C6H5S)2 and often abbreviated Ph2S2. It is most commonly utilized as a reagent for integration of a phenylthio functionality into molecules. The phenylthio group in the compound has a useful function due to the numerous of reaction that it can facilitate in organic chemistry. Phenysulfides, for instance, undergo oxidative elimination, producing alkenes under relatively mild, normal conditions. Also phenyl sulfides can serve as a source of carbon-centered radicals in radical reactions.
Diphenyl disulfide is usually synthesized by the oxidation of thiophenol:
2 PhSH + I2 → Ph2S2 + 2 HI
Reactions and Uses
With Alkenes
Ph2S2 adds cleanly to many dienes and alkenes upon catalysis by BF3.OMe2. The trifluoroacetoxysulfenylation of unsaturated esters, nitriles, amides, and carboxylic acids is possible with Ph2S2.
As a Source of Thiiyl Radicals
In the presence of radical initiators, upon thermolysis or photolysis, thiiyl radicals can be generated from PhSSPh. Therefore, the radicals generated add reversibly to alkynes and alkenes generating vinyl and alkyl radicals respectively (1).
Reduction
Ph2S2 undergoes reduction, which is a characteristic of disulfides. Hydride reagents such as super hydride and sodium borohydride can be used as reductants.
Ph2S2 + 2 M → 2 MSPh (M = Li, Na, K)
Chemical Properties
White to light yellow crystal.
Occurrence
Naturally occurring phytoalexin-like substan
Uses
Diphenyl disulfide is one of the most popular organic disulfides used in organic synthesis. It is used as a reagent for the α-phenylsulfenylation of carbonyl compounds. It participates in hydrothiolation of alkynes via amine-mediated single electron transfer mechanism. It is the hydrolysis product of dyfonate.
Preparation
By heating and passing a stream of air over an ammoniacal solution of thiophenol.
Definition
ChEBI: Diphenyl disulfide is a member of benzenes.
Purification Methods
Crystallise the disulfide from MeOH. [Alberti et al. J Am Chem Soc 108 3024 1986]. Also crystallise it repeatedly from hot Et2O, then dry it in a vacuum at 30o over P2O5, fuse it under N2 and re-dry it; the whole procedure being repeated, with a final drying under a vacuum for 24hours. Alternatively, recrystallise it from hexane/EtOH solution. [Burkey & Griller J Am Chem Soc 107 246 1985, Beilstein 6 H 323, 6 IV 1560.]
