Benzyl mercaptan
Names | |
---|---|
Preferred IUPAC name
Phenylmethanethiol | |
Other names
alpha-Toluenethiol Benzylthiol Thiobenzyl alcohol Benzyl mercaptan alpha-Toluolthiol Benzylhydrosulfide Benzyl hydrosulfide | |
Identifiers | |
3D model (JSmol) |
|
ChEBI | |
ChEMBL | |
ChemSpider | |
ECHA InfoCard | 100.002.602 |
PubChem CID |
|
UNII | |
| |
| |
Properties | |
C7H8S | |
Molar mass | 124.20 g/mol |
Appearance | colourless liquid |
Odor | leek or garlic-like |
Density | 1.058 g/mL |
Melting point | −30 °C (−22 °F; 243 K) |
Boiling point | 195 °C (383 °F; 468 K) |
low | |
Solubility | very soluble in ethanol, ether soluble in CS2 slightly soluble in CCl4 |
Refractive index (nD) |
1.5751 (20 °C) |
Hazards | |
NFPA 704 | |
Flash point | 70 °C (158 °F; 343 K) |
Lethal dose or concentration (LD, LC): | |
LD50 (median dose) |
493 mg/kg (rat, oral) |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
Infobox references | |
Benzyl mercaptan is an organosulfur compound with the formula C6H5CH2SH. It is a common laboratory alkylthiol that occurs in trace amounts naturally. It is a colorless, malodorous liquid.
Preparation and occurrence
It can be prepared by the reaction of benzyl chloride and thiourea.
Benzyl mercaptan has been identified in boxwood (Buxus sempervirens L.) and is known to contribute to the smoky aroma of certain wines.[1] It also occurs naturally in coffee.
Use in organic synthesis
The compound has been used as a source of the thiol functional group in organic synthesis. It is introduced by S-alkylation to give alkyl benzylthioethers. Debenzylation is effected by dissolving metal reduction, which attacks the weakened S-benzyl bond:[2]
- RSCH2C6H5 + 2 "H" → RSH + CH3C6H5
Condensed tannins undergo acid-catalyzed cleavage in the presence of benzyl mercaptan.
Related derivatives
Methoxy-substituted benzyl mercaptans have been developed that cleave easily, are recyclable, and are odourless.[3]
References
- ↑ Takatoshi Tominaga, Guy Guimbertau and Denis Dubourdieu, "Contribution of Benzenemethanethiol to Smoky Aroma of Certain Vitis vinifera L. Wines", J Ag Food Chem, 51, 1373-1376(2003) doi:10.1021/jf020756c
- ↑ Norman Kharasch; Robert B. Langford (1973). "2,4-dinitro-Benzenesulfenyl chloride". Organic Syntheses. ; Collective Volume, 5, p. 474
- ↑ M. Matoba, T. Kajimoto, M. Node "Development of a Novel Benzyl Mercaptan as a Recyclable Odorless Substitute of Hydrogen Sulfide" Synlett 2007, pp. 1930–4. doi:10.1055/s-2007-984524