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.

Diphenyl disulfide
Names
Preferred IUPAC name
1,1'-Disulfanediyldibenzene
Other names
Disulfanyldibenzene
Diphenyl disulfide
Phenyl disulfide
1,2-Diphenyldisulfane (not recommended)
Identifiers
3D model (JSmol)
ChEMBL
ChemSpider
ECHA InfoCard 100.011.752
RTECS number
  • SS6825000
UNII
Properties
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)
Insoluble
Solubility in other solvents Soluble in diethyl ether, benzene, carbon disulfide, and THF
Structure
0 D
Hazards
Main hazards Flammable
R-phrases (outdated) R36/37/38
S-phrases (outdated) S26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

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.[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°.[2]

Reactions

Ph2S2 is mainly used in organic synthesis as a source of the PhS substituent.[3] 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.[4]

Oxidation

Oxidation of Ph2S2 with lead(IV) acetate (Pb(OAc)4) in methanol affords the sulfinite ester PhS(O)OMe.[5]

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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". Organic Syntheses. 80: 184.CS1 maint: multiple names: authors list (link)
  2. T.Shimizu; H.Isono; M.Yasui; F. Iwasaki; N. Kamigata (2001). "Solid State Optical Activity of Dichalcogenides:  Isolation by Chiral Crystallization and Determination of Absolute Configuration". Org. Lett. 3: 3639. doi:10.1021/ol010172g.
  3. 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.
  4. Thalmann, A. Oertle, K.; Gerlach, H. (1990). "Ricinelaidic Acid Lactone". Organic Syntheses.CS1 maint: multiple names: authors list (link); Collective Volume, 7, p. 470
  5. Field, L.; Locke, J. M. (1973). "Methyl Benzenesulfinate". Organic Syntheses.CS1 maint: multiple names: authors list (link); Collective Volume, 5, p. 723
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