Thiophenol
[CAS# 108-98-5]

Identification

• Classification: Organic raw materials >> Alcohols, phenols, phenolic compounds and derivatives >> Phenol and its halogenated, sulfonated, nitrated or nitrosated derivatives
• Name: Thiophenol
• Synonyms: Benzenethiol; Phenyl mercaptan
• Molecular Formula: C₆H₆S
• Molecular Weight: 110.18
• CAS Registry Number: 108-98-5
• EC Number: 203-635-3
• FEMA: 3616
• SMILES: C1=CC=C(C=C1)S

Properties

• Density: 1.078
• Melting point: -15 °C
• Boiling point: 167-169 °C
• Refractive index: 1.588-1.59
• Flash point: 50 °C
• Water solubility: insoluble

Safety Data

• Hazard Symbols: GHS02;GHS05;GHS06;GHS07;GHS09 Danger
• Risk Statements: H226-H300-H301-H310-H311-H314-H315-H318-H330-H400-H410
• Safety Statements: P210-P233-P240-P241-P242-P243-P260-P262-P264-P264+P265-P270-P271-P273-P280-P284-P301+P316-P301+P330+P331-P302+P352-P302+P361+P354-P303+P361+P353-P304+P340-P305+P354+P338-P316-P317-P320-P321-P330-P332+P317-P361+P364-P362+P364-P363-P370+P378-P391-P403+P233-P403+P235-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Flammable liquids	Flam. Liq.	3	H226
Acute toxicity	Acute Tox.	1	H330
Acute toxicity	Acute Tox.	2	H300
Skin irritation	Skin Irrit.	2	H315
Serious eye damage	Eye Dam.	1	H318
Acute hazardous to the aquatic environment	Aquatic Acute	1	H400
Chronic hazardous to the aquatic environment	Aquatic Chronic	1	H410
Acute toxicity	Acute Tox.	3	H311
Acute toxicity	Acute Tox.	2	H310
Acute toxicity	Acute Tox.	3	H301
Skin corrosion	Skin Corr.	1C	H314
Eye irritation	Eye Irrit.	2	H319
Specific target organ toxicity - single exposure	STOT SE	2	H371
Specific target organ toxicity - single exposure	STOT SE	3	H335
Specific target organ toxicity - repeated exposure	STOT RE	1	H372
Reproductive toxicity	Repr.	2	H361
Acute toxicity	Acute Tox.	2	H330
Flammable solids	Flam. Sol.	1	H228
Flammable liquids	Flam. Liq.	4	H227
Eye irritation	Eye Irrit.	2A	H319
Specific target organ toxicity - single exposure	STOT SE	3	H371
Skin corrosion	Skin Corr.	1B	H314

• Transport Information: UN 2337

Discovery and Applications

Thiophenol, also known as mercaptobenzene or benzenethiol, is a chemical compound with the chemical formula C₆H₅SH. It is characterized by a benzene ring bonded to a sulfur atom and a thiol (-SH) functional group. Thiophenol was first synthesized in the 19th century, when chemists were exploring the properties and reactions of thiols and aromatic compounds. Its discovery marked an important development in organic chemistry, especially in the understanding of sulfur-containing organic molecules. Thiophenol consists of a benzene ring (C₆H₅-) to which is attached a sulfur atom (-S-) and a hydrogen atom (-H). It is a colorless to pale yellow liquid with a strong malodor reminiscent of rotting cabbage, which is typical of thiol compounds.

Thiophenol is widely used as a building block in organic synthesis, especially in the production of pharmaceuticals, agrochemicals, and dyes. Its sulfur-containing functional group promotes a variety of chemical reactions, including nucleophilic substitution and metal complex formation.

It is a key intermediate in the synthesis of other sulfur-containing compounds such as thiophenolates and disulfides. These intermediates can be used to make rubber additives, pesticides, and antioxidants.

The reactivity and stability of thiophenols make them valuable in industrial processes, including the production of specialty chemicals and polymer additives. It helps modify polymer surfaces and synthesize materials with specific chemical and physical properties.

Thiophenols are toxic if inhaled, ingested, or absorbed through the skin. Proper handling and ventilation are essential to prevent exposure to its vapor or liquid form. The strong odor of thiophenols is easily detectable even at low concentrations and serves as a warning of potential exposure.

Thiophenols and their derivatives are biodegradable in soil and water and have reduced environmental persistence compared to some other aromatic compounds. Due to their toxicity and environmental impact, the use and disposal of thiophenols are regulated in different jurisdictions to minimize potential hazards.

References

2018. XPS Analysis of 2- and 3-Aminothiophenol Grafted on Silicon (111) Hydride Surfaces. Molecules.
DOI: 10.3390/molecules23102712

2013. Peptide Release, Side-Chain Deprotection, Work-Up, and Isolation. Methods in Molecular Biology.
DOI: 10.1007/978-1-62703-544-6_3

2003. Mechanistic Studies of the Tellurium(II)/Tellurium(IV) Redox Cycle in Thiol Peroxidase-like Reactions of Diorganotellurides in Methanol. Journal of the American Chemical Society.
DOI: 10.1021/ja029590m