Diphenyl disulfide

Diphenyl disulfide

Names
IUPAC name Diphenyl disulfide
Preferred IUPAC name Disulfanyldibenzene
Other names Phenyl disulfide
Identifiers
CAS Number	882-33-7
ChEMBL	ChEMBL462861
ChemSpider	12861
Jmol interactive 3D	Image
PubChem	13436
RTECS number	SS6825000
InChI InChI=1S/C12H10S2/c1-3-7-11(8-4-1)13-14-12-9-5-2-6-10-12/h1-10H Key: GUUVPOWQJOLRAS-UHFFFAOYSA-N InChI=1/C12H10S2/c1-3-7-11(8-4-1)13-14-12-9-5-2-6-10-12/h1-10H Key: GUUVPOWQJOLRAS-UHFFFAOYAY
SMILES c1ccc(cc1)SSc2ccccc2
Properties
Chemical formula	C12H10S2
Molar mass	218.33 g·mol^−1
Appearance	Colorless crystals
Melting point	61 to 62 °C (142 to 144 °F; 334 to 335 K)
Solubility in water	Insoluble
Solubility in other solvents	Soluble in diethyl ether, benzene, carbon disulfide, and THF
Structure
Dipole moment	0 D
Hazards
Main hazards	Flammable
R-phrases	R36/37/38
S-phrases	S26
Related compounds
Related compounds	Thiophenol, Dimethyl disulfide, Diphenyl diselenide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

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

Ph₂S₂ is usually prepared by the oxidation of thiophenol:

2 PhSH + I₂ → Ph₂S₂ + 2 HI

Hydrogen peroxide can also be used as the oxidant.^[1] Ph₂S₂ 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°.

Reactions

Ph₂S₂ is mainly used in organic synthesis as a source of the PhS substituent.^[2] 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. The salts PhSM are sources of the potent nucleophile PhS⁻. 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

Chlorination

Ph₂S₂ reacts with chlorine to give phenylsulfenyl chloride PhSCl (Zincke disulfide cleavage). This species is somewhat difficult to isolate, so it is usually generated in situ.

Catalyst for photoisomerization of alkenes

Ph₂S₂ catalyzes the cis-trans isomerization of alkenes under UV-irradiation.^[3]

Oxidation

Oxidation of Ph₂S₂ with lead(IV) acetate (Pb(OAc)₄) in methanol affords the sulfinite ester PhS(O)OMe.^[4]

References

1. Ravikumar,K. S.; Kesavan, V.; Crousse, B.; Bonnet-Delpon, D.; Bégué, J.-P. (2003). "Mild and Selective Oxidation of Sulfur Compounds in Trifluoroethanol: Diphenyl Disulfide and Methyl Phenyl Sulfoxide". Org. Synth. 80: 184.
2. Byers, J. H. "Diphenyl Disulfide" in Encyclopedia of Reagents for Organic Synthesis (Ed: L. Paquette) 2004, J. Wiley & Sons, New York. doi:10.1002/047084289.
3. Thalmann, A. Oertle, K.; Gerlach, H. (1990). "Ricinelaidic Acid Lactone". Org. Synth.; Coll. Vol. 7, p. 470
4. Field, L.; Locke, J. M. (1973). "Methyl Benzenesulfinate". Org. Synth.; Coll. Vol. 5, p. 723