Thiophenol

Thiophenol

Names
IUPAC name Thiophenol
Other names Benzenethiol
Identifiers
CAS Number	108-98-5 N
3D model (JSmol)	Interactive image
ECHA InfoCard	100.003.306
RTECS number	DC0525000
CompTox Dashboard (EPA)	DTXSID7026811
SMILES c1ccccc1S
Properties
Chemical formula	C6H6S
Molar mass	110.19 g/mol
Appearance	colorless liquid
Density	1.0766 g/mL
Melting point	-15 °C
Boiling point	169 °C
Hazards
Occupational safety and health (OHS/OSH):
Main hazards	Toxic
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

Thiophenol is an organosulfur compound with the formula C₆H₅SH, and sometimes abbreviated as PhSH. Thisfoul-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 (-OH) bonded to the aromatic ring is replaced by a sulfur atom. The prefix thio- implies a sulfur-containing compound and when used before a root word name for a compound which would normally contain an oxygen atom, thio- commonly means that the oxygen atom is replaced by a sulfur atom.

Thiophenols also describes a class of compounds formally derived from thiophenol itself. All have a sulfhydryl group (-SH) covalently bonded to an aromatic ring. The organosulfur ligand in the medicine merthiolate is a thiophenol.

Synthesis

Many ways exist to generate thiophenol and related compounds, although thiophenol is usually purchased for laboratory operations.

• Reduction of benzenesulfonyl chloride with zinc.
• Action of elemental sulfur on phenyl magnesium halide or phenyllithium followed by acificiation.

Phenols can be converted to the thiophenols via rearrangement of their O-aryl dialkylthiocarbamates.

Properties

Acidity

Thiophenol has appreciably greater acidity than does phenol. Thiophenol has a pK_a's of 6 vs 10 for phenol. A similar pattern is seen for H₂S vs. H₂O and all thiols vs. the corresponding alcohols. Treatment of PhSH with strong base such as sodium hydroxide (NaOH) or sodium metal affords the salt sodium thiophenolate (PhSNa).

Alkylation

The thiophenolate is highly nucleophilic, which translates to an high rate of alkylation. Thus, treatment of C₆H₅SH with methyl iodide in the presence of a base gives methyl phenyl sulfide, C₆H₅SCH₃, a thioether. Such reactions are fairly irreversible. C₆H₅SH also adds to α,β-unsaturated carbonyls via Michael addition.

Oxidation

Thiophenols, expecially in the presence of base is easily oxidized to diphenyl disulfide:

2 C₆H₅SH + 1/2 O₂ → C₆H₅S-SC₆H₅ + H₂O

The disulfide can be reduced back the thiol using sodium borohydride followed by acidification. This redox reaction is also exploited in the use of C₆H₅SH as a source of H atoms.

Chlorination

Phenylsulfenyl chloride, a blood-red liquid (b.p. 41–42 °C), can be prepared by the reaction of thiophenol with chlorine (Cl₂).

Coordination to metals

Metal cations form thiophenolates, some of which are polymeric. One example is "C₆H₅SCu," obtained by treating copper(I) chloride with thiophenol.

Safety

Thiophenol is highly toxic.