Diphenyl disulfide

Diphenyl disulfide
IUPAC name Diphenyl disulfide
Preferred IUPAC name Disulfanyldibenzene
Other names Phenyl disulfide
Identifiers
CAS number	882-33-7 Y
PubChem	13436
ChemSpider	12861 Y
ChEMBL	CHEMBL462861 Y
RTECS number	SS6825000
Jmol-3D images	Image 1
SMILES c1ccc(cc1)SSc2ccccc2
InChI InChI=1S/C12H10S2/c1-3-7-11(8-4-1)13-14-12-9-5-2-6-10-12/h1-10H Y Key: GUUVPOWQJOLRAS-UHFFFAOYSA-N Y InChI=1/C12H10S2/c1-3-7-11(8-4-1)13-14-12-9-5-2-6-10-12/h1-10H Key: GUUVPOWQJOLRAS-UHFFFAOYAY
Properties
Molecular formula	C12H10S2
Molar mass	218.36 g/mol
Appearance	Colourless crystals
Density	? g/cm3
Melting point	61–62 °C
Solubility in water	Insoluble
Solubility in other solvents	Diethyl ether, Benzene, Carbon disulfide, THF
Structure
Dipole moment	0 D
Hazards
R-phrases	36/37/38
S-phrases	26
Main hazards	Flammable
Related compounds
Related compounds	C6H5SH, (CH3)2S2, Diphenyl diselenide
Y (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
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 photoisomerisation of alkenes

Ph₂S₂catalyzes 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, http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=v80p0184 
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., http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv7p0470 ; Coll. Vol. 7: 470 
4. ^ Field, L.; Locke, J. M. (1973), "Methyl Benzenesulfinate", Org. Synth., http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv5p0723 ; Coll. Vol. 5: 723