Diphenyl disulfide is the chemical compound with the formula [C6H5S]2. This colorless crystalline material is often abbreviated Ph2S2. It is one of the most popular organic disulfides used in organic synthesis. Minor contamination by thiophenol is responsible for the disagreeable odour associated with this compound.
Preparation and structure
is usually prepared by the oxidation of thiophenol:
- 2 PhSH + I2 → Ph2S2 + 2 HI
can also be used as the oxidant. Ph2
is rarely prepared in the laboratory because it is inexpensive, and the precursor has a disagreeable odour.
Like most organic disulfides, the C2S2 core of Ph2S2 is non-planar with a dihedral angle approaching 85°.
is mainly used in organic synthesis as a source of the PhS substituent. A typical reaction entails the formation of PhS-substituted carbonyl compounds via the enolate
- RC(O)CHLiR’ + Ph2S2 → RC(O)CH(SPh)R’ + LiSPh
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.
The salts PhSM are sources of the potent nucleophile
. Most alkyl halides
, RX (X = halide) convert it to the thioethers
with the general formula RSPh. Analogously, protonation of MSPh gives thiophenol:
- PhSM + HCl → HSPh + MCl
reacts with chlorine
to give phenylsulfenyl chloride
PhSCl (Zincke disulfide cleavage
). This species is difficult to isolate, so it is usually generated in situ.
Catalyst for photoisomerisation of alkenes
catalyzes the cis-trans isomerization of alkenes under UV-irradiation.
Oxidation of Ph2
with lead(IV) acetate
) in methanol
affords the sulfinite ester PhS(O)OMe.