Diphenyl disulfide is the chemical compound

Chemical compound

A chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions. Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together...

 with the formula [C₆H₅S]₂. This colorless crystalline material is often abbreviated Ph₂S₂. It is one of the most popular organic disulfide

Disulfide

In chemistry, a disulfide usually refers to the structural unit composed of a linked pair of sulfur atoms. Disulfide usually refer to a chemical compound that contains a disulfide bond, such as diphenyl disulfide, C6H5S-SC6H5....

s used in organic synthesis

Organic synthesis

Organic synthesis is a special branch of chemical synthesis and is concerned with the construction of organic compounds via organic reactions. Organic molecules can often contain a higher level of complexity compared to purely inorganic compounds, so the synthesis of organic compounds has...

. Minor contamination by thiophenol

Thiophenol

Thiophenol is an organosulfur compound with the formula C6H6S, and sometimes abbreviated as PhSH. This foul-smelling colourless liquid is the simplest aromatic thiol. The chemical structures of thiophenols are analogous to phenols except the oxygen atom in the hydroxyl group bonded to the...

 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

Iodine

Iodine is a chemical element with the symbol I and atomic number 53. The name is pronounced , , or . The name is from the , meaning violet or purple, due to the color of elemental iodine vapor....

  → Ph₂S₂ + 2 HI

Hydrogen peroxide

Hydrogen peroxide

Hydrogen peroxide is the simplest peroxide and an oxidizer. Hydrogen peroxide is a clear liquid, slightly more viscous than water. In dilute solution, it appears colorless. With its oxidizing properties, hydrogen peroxide is often used as a bleach or cleaning agent...

 can also be used as the oxidant. 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. 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

Sodium borohydride

Sodium borohydride, also known as sodium tetrahydridoborate, is an inorganic compound with the formula NaBH4. This white solid, usually encountered as a powder, is a versatile reducing agent that finds wide application in chemistry, both in the laboratory and on a technical scale. Large amounts are...

 and super hydride

Lithium triethylborohydride

Lithium triethylborohydride , commonly abbreviated to LiTEBH or Superhydride, is a powerful and selective reducing agent used in inorganic and organic chemistry. LiTEBH is far more powerful than lithium borohydride and more powerful than lithium aluminium hydride in many cases...

 can also be used as reductants.
The salts PhSM are sources of the potent nucleophile

Nucleophile

A nucleophile is a species that donates an electron-pair to an electrophile to form a chemical bond in a reaction. All molecules or ions with a free pair of electrons can act as nucleophiles. Because nucleophiles donate electrons, they are by definition Lewis bases.Nucleophilic describes the...

 PhS^-. Most alkyl halides, RX (X = halide) convert it to the thioether

Thioether

A thioether is a functional group in organosulfur chemistry with the connectivity C-S-C as shown on right. Like many other sulfur-containing compounds, volatile thioethers have foul odors. A thioether is similar to an ether except that it contains a sulfur atom in place of the oxygen...

s with the general formula RSPh. Analogously, protonation of MSPh gives thiophenol:

PhSM + HCl → HSPh + MCl

Chlorination

Ph₂S₂ reacts with chlorine

Chlorine

Chlorine is the chemical element with atomic number 17 and symbol Cl. It is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine...

 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 alkene

Alkene

In organic chemistry, an alkene, olefin, or olefine is an unsaturated chemical compound containing at least one carbon-to-carbon double bond...

s under UV-irradiation.

Oxidation

Oxidation of Ph₂S₂ with lead(IV) acetate

Lead(IV) acetate

Lead acetate or lead tetraacetate is a chemical compound with chemical formula Pb4 and is a lead salt of acetic acid. It is commercially available often stabilized with acetic acid....

 (Pb(OAc)₄) in methanol

Methanol

Methanol, also known as methyl alcohol, wood alcohol, wood naphtha or wood spirits, is a chemical with the formula CH3OH . It is the simplest alcohol, and is a light, volatile, colorless, flammable liquid with a distinctive odor very similar to, but slightly sweeter than, ethanol...

affords the sulfinite ester PhS(O)OMe.