Diphenyl disulfide

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Diphenyl disulfide
Skeletal formula of diphenyl disulfide
Ball-and-stick model of diphenyl disulfide
Identifiers
CAS number 882-33-7 YesY
PubChem 13436
ChemSpider 12861 YesY
ChEMBL CHEMBL462861 YesY
RTECS number SS6825000
Jmol-3D images Image 1
Properties
Molecular formula C12H10S2
Molar mass 218.34 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
R-phrases R36/37/38
S-phrases S26
Main hazards Flammable
Related compounds
Related compounds Thiophenol,
Dimethyl disulfide,
Diphenyl diselenide
Except where noted otherwise, 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[edit]

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[edit]

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[edit]

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[edit]

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[edit]

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

Oxidation[edit]

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

References[edit]

  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: 470 
  4. ^ Field, L.; Locke, J. M. (1973), "Methyl Benzenesulfinate", Org. Synth. ; Coll. Vol. 5: 723