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

Benzyl mercaptan can be prepared by the reaction of benzyl chloride and

thiourea Thiourea () is an organosulfur compound with the formula and the structure . It is structurally similar to urea (), except that the oxygen atom is replaced by a sulfur atom (as implied by the ''thio-'' prefix); however, the properties of urea a ...

. The initially formed isothiouronium salt must be subjected to alkaline

hydrolysis Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution, elimination, and solvation reactions in which water is the nucleophile. Biological hydrolys ...

to obtain the thiol. It has been identified in

boxwood ''Buxus'' is a genus of about seventy species in the family Buxaceae. Common names include box or boxwood. The boxes are native to western and southern Europe, southwest, southern and eastern Asia, Africa, Madagascar, northernmost South ...

(''Buxus sempervirens'' L.) and is known to contribute to the smoky aroma of certain

wine Wine is an alcoholic drink typically made from fermented grapes. Yeast consumes the sugar in the grapes and converts it to ethanol and carbon dioxide, releasing heat in the process. Different varieties of grapes and strains of yeasts are m ...

s. It also occurs naturally in

coffee Coffee is a drink prepared from roasted coffee beans. Darkly colored, bitter, and slightly acidic, coffee has a stimulating effect on humans, primarily due to its caffeine content. It is the most popular hot drink in the world. Seeds of ...

Use in organic synthesis

Benzyl mercaptan is used for S-alkylation to give benzyl

thioether In organic chemistry, an organic sulfide (British English sulphide) or thioether is an organosulfur functional group with the connectivity as shown on right. Like many other sulfur-containing compounds, volatile sulfides have foul odors. A su ...

s. It has been used as a source of the

thiol In organic chemistry, a thiol (; ), or thiol derivative, is any organosulfur compound of the form , where R represents an alkyl or other organic substituent. The functional group itself is referred to as either a thiol group or a sulfhydryl gro ...

functional group In organic chemistry, a functional group is a substituent or moiety in a molecule that causes the molecule's characteristic chemical reactions. The same functional group will undergo the same or similar chemical reactions regardless of the re ...

in organic synthesis. Debenzylation can be effected by dissolving metal reduction: :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.

References

{{reflist Thiols Benzyl compounds Foul-smelling chemicals