Benzyl mercaptan

Chemical compound From Wikipedia, the free encyclopedia

Benzyl mercaptan is an organosulfur compound with the formula C7H8S or C6H5CH2SH. It is a common laboratory alkylthiol that occurs in trace amounts naturally. It is a colorless, malodorous liquid.

Quick facts Names, Identifiers ...
Benzyl mercaptan
Skeletal formula benzyl mercaptan
Ball-and-stick model of the benzyl mercaptan molecule
Names
Preferred IUPAC name
Phenylmethanethiol
Other names
alpha-Toluenethiol
Benzylthiol
Thiobenzyl alcohol
Benzyl mercaptan
alpha-Toluolthiol
Benzylhydrosulfide
Benzyl hydrosulfide
Identifiers
3D model (JSmol)
Abbreviations BnSH
PhCH2SH
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.002.602 Edit this at Wikidata
UNII
  • InChI=1S/C7H8S/c8-6-7-4-2-1-3-5-7/h1-5,8H,6H2 checkY
    Key: UENWRTRMUIOCKN-UHFFFAOYSA-N checkY
  • InChI=1/C7H8S/c8-6-7-4-2-1-3-5-7/h1-5,8H,6H2
    Key: UENWRTRMUIOCKN-UHFFFAOYAC
  • SCc1ccccc1
Properties
C7H8S
Molar mass 124.20 g·mol−1
Appearance colourless liquid
Odor Unpleasant 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
Acidity (pKa) 9.43 (H2O)[1]
1.5751 (20 °C)
Hazards
GHS labelling:
GHS07: Exclamation mark
Warning
H302, H319
P264, P264+P265, P270, P280, P301+P317, P305+P351+P338, P330, P337+P317, P501
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformFlammability 2: Must be moderately heated or exposed to relatively high ambient temperature before ignition can occur. Flash point between 38 and 93 °C (100 and 200 °F). E.g. diesel fuelInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
2
2
0
Flash point 70 °C (158 °F; 343 K)
Lethal dose or concentration (LD, LC):
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).
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Preparation and occurrence

Benzyl mercaptan can be prepared by the reaction of benzyl chloride and thiourea. The initially formed isothiouronium salt must be subjected to alkaline hydrolysis to obtain the thiol.

It has been identified in boxwood (Buxus sempervirens L.) and is known to contribute to the smoky aroma of certain wines.[2] It also occurs naturally in coffee.

Use in organic synthesis

Benzyl mercaptan is used for S-alkylation to give benzylthioethers.[3]

It has been used as a source of the thiol functional group in organic synthesis. Debenzylation can be effected by dissolving metal reduction:[4]

RSCH2C6H5 + 2 H+ + 2 e− → 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 odorless.[5]

References

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