Benzyl mercaptan

Last updated
Benzyl mercaptan
Benzenemethanethiol.svg
Benzyl-mercaptan-from-xtal-3D-bs-17.png
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 OOjs UI icon edit-ltr-progressive.svg
PubChem CID
UNII
  • InChI=1S/C7H8S/c8-6-7-4-2-1-3-5-7/h1-5,8H,6H2 Yes check.svgY
    Key: UENWRTRMUIOCKN-UHFFFAOYSA-N Yes check.svgY
  • 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
Appearancecolourless 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
NFPA 704 (fire diamond)
NFPA 704.svgHealth 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).
X mark.svgN  verify  (what is  Yes check.svgYX mark.svgN ?)

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.

Contents

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.

Methoxy-substituted benzyl mercaptans have been developed that cleave easily, are recyclable, and are odorless. [5]

Related Research Articles

<span class="mw-page-title-main">Benzoic acid</span> Organic compound (C6H5COOH)

Benzoic acid is a white solid organic compound with the formula C6H5COOH, whose structure consists of a benzene ring with a carboxyl substituent. The benzoyl group is often abbreviated "Bz", thus benzoic acid is also denoted as BzOH, since the benzoyl group has the formula –C6H5CO. It is the simplest aromatic carboxylic acid. The name is derived from gum benzoin, which was for a long time its only source.

<span class="mw-page-title-main">Haloalkane</span> Group of chemical compounds derived from alkanes containing one or more halogens

The haloalkanes are alkanes containing one or more halogen substituents. They are a subset of the general class of halocarbons, although the distinction is not often made. Haloalkanes are widely used commercially. They are used as flame retardants, fire extinguishants, refrigerants, propellants, solvents, and pharmaceuticals. Subsequent to the widespread use in commerce, many halocarbons have also been shown to be serious pollutants and toxins. For example, the chlorofluorocarbons have been shown to lead to ozone depletion. Methyl bromide is a controversial fumigant. Only haloalkanes that contain chlorine, bromine, and iodine are a threat to the ozone layer, but fluorinated volatile haloalkanes in theory may have activity as greenhouse gases. Methyl iodide, a naturally occurring substance, however, does not have ozone-depleting properties and the United States Environmental Protection Agency has designated the compound a non-ozone layer depleter. For more information, see Halomethane. Haloalkane or alkyl halides are the compounds which have the general formula "RX" where R is an alkyl or substituted alkyl group and X is a halogen.

<span class="mw-page-title-main">Thiol</span> Any organic compound having a sulfanyl group (–SH)

In organic chemistry, a thiol, or thiol derivative, is any organosulfur compound of the form R−SH, where R represents an alkyl or other organic substituent. The −SH functional group itself is referred to as either a thiol group or a sulfhydryl group, or a sulfanyl group. Thiols are the sulfur analogue of alcohols, and the word is a blend of "thio-" with "alcohol".

<span class="mw-page-title-main">Methanethiol</span> Chemical compound

Methanethiol is an organosulfur compound with the chemical formula CH
3
SH
. It is a colorless gas with a distinctive putrid smell. It is a natural substance found in the blood, brain and feces of animals, as well as in plant tissues. It also occurs naturally in certain foods, such as some nuts and cheese. It is one of the chemical compounds responsible for bad breath and the smell of flatus. Methanethiol is the simplest thiol and is sometimes abbreviated as MeSH. It is very flammable.

<span class="mw-page-title-main">Ethanethiol</span> Chemical compound

Ethanethiol, commonly known as ethyl mercaptan, is an organosulfur compound with the formula CH3CH2SH. is a colorless liquid with a distinct odor. Abbreviated EtSH, it consists of an ethyl group (Et), CH3CH2, attached to a thiol group, SH. Its structure parallels that of ethanol, but with sulfur in place of oxygen. The odor of EtSH is infamous. Ethanethiol is more volatile than ethanol due to a diminished ability to engage in hydrogen bonding. Ethanethiol is toxic in high concentrations. It occurs naturally as a minor component of petroleum, and may be added to otherwise odorless gaseous products such as liquefied petroleum gas (LPG) to help warn of gas leaks. At these concentrations, ethanethiol is not harmful.

<span class="mw-page-title-main">Cinnamic acid</span> Chemical compound

Cinnamic acid is an organic compound with the formula C6H5-CH=CH-COOH. It is a white crystalline compound that is slightly soluble in water, and freely soluble in many organic solvents. Classified as an unsaturated carboxylic acid, it occurs naturally in a number of plants. It exists as both a cis and a trans isomer, although the latter is more common.

<span class="mw-page-title-main">Aroma compound</span> Chemical compound that has a smell or odor

An aroma compound, also known as an odorant, aroma, fragrance or flavoring, is a chemical compound that has a smell or odor. For an individual chemical or class of chemical compounds to impart a smell or fragrance, it must be sufficiently volatile for transmission via the air to the olfactory system in the upper part of the nose. As examples, various fragrant fruits have diverse aroma compounds, particularly strawberries which are commercially cultivated to have appealing aromas, and contain several hundred aroma compounds.

<span class="mw-page-title-main">Sodium borohydride</span> Chemical compound

Sodium borohydride, also known as sodium tetrahydridoborate and sodium tetrahydroborate, is an inorganic compound with the formula NaBH4. It is a white crystalline solid, usually encountered as an aqueous basic solution. Sodium borohydride is a reducing agent that finds application in papermaking and dye industries. It is also used as a reagent in organic synthesis.

<span class="mw-page-title-main">Benzyl group</span> Chemical group (–CH₂–C₆H₅)

In organic chemistry, benzyl is the substituent or molecular fragment possessing the structure R−CH2−C6H5. Benzyl features a benzene ring attached to a methylene group group.

<span class="mw-page-title-main">Benzyl chloroformate</span> Chemical compound

Benzyl chloroformate, also known as benzyl chlorocarbonate or Z-chloride, is the benzyl ester of chloroformic acid. It can be also described as the chloride of the benzyloxycarbonyl group. In its pure form it is a water-sensitive oily colorless liquid, although impure samples usually appear yellow. It possesses a characteristic pungent odor and degrades in contact with water.

Organosulfur chemistry is the study of the properties and synthesis of organosulfur compounds, which are organic compounds that contain sulfur. They are often associated with foul odors, but many of the sweetest compounds known are organosulfur derivatives, e.g., saccharin. Nature is abound with organosulfur compounds—sulfur is vital for life. Of the 20 common amino acids, two are organosulfur compounds, and the antibiotics penicillin and sulfa drugs both contain sulfur. While sulfur-containing antibiotics save many lives, sulfur mustard is a deadly chemical warfare agent. Fossil fuels, coal, petroleum, and natural gas, which are derived from ancient organisms, necessarily contain organosulfur compounds, the removal of which is a major focus of oil refineries.

<span class="mw-page-title-main">Knorr pyrrole synthesis</span> Chemical reaction

The Knorr pyrrole synthesis is a widely used chemical reaction that synthesizes substituted pyrroles (3). The method involves the reaction of an α-amino-ketone (1) and a compound containing an electron-withdrawing group α to a carbonyl group (2).

<span class="mw-page-title-main">Thiophenol</span> Chemical compound

Thiophenol is an organosulfur compound with the formula C6H5SH, sometimes abbreviated as PhSH. This foul-smelling colorless liquid is the simplest aromatic thiol. The chemical structures of thiophenol and its derivatives are analogous to phenols. An exception is 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, in the case of 'thiol' that the alcohol oxygen atom is replaced by a sulfur atom.

Benzyl bromide is an organic compound with the formula C6H5CH2Br. The molecule consists of a benzene ring substituted with a bromomethyl group. It is a colorless liquid with lachrymatory properties. The compound is a reagent for introducing benzyl groups.

Grapefruit mercaptan is the common name for a natural organic compound found in grapefruit. It is a monoterpenoid that contains a thiol functional group. Structurally a hydroxy group of terpineol is replaced by the thiol in grapefruit mercaptan, so it also called thioterpineol. Volatile thiols typically have very strong, often unpleasant odors that can be detected by humans in very low concentrations. Grapefruit mercaptan has a very potent, but not unpleasant, odor, and it is the chemical constituent primarily responsible for the aroma of grapefruit. This characteristic aroma is a property of only the R enantiomer.

<span class="mw-page-title-main">Benzylamine</span> Chemical compound

Benzylamine is an organic chemical compound with the condensed structural formula C6H5CH2NH2 (sometimes abbreviated as PhCH2NH2 or BnNH2). It consists of a benzyl group, C6H5CH2, attached to an amine functional group, NH2. This colorless water-soluble liquid is a common precursor in organic chemistry and used in the industrial production of many pharmaceuticals. The hydrochloride salt was used to treat motion sickness on the Mercury-Atlas 6 mission in which NASA astronaut John Glenn became the first American to orbit the Earth.

<span class="mw-page-title-main">3-Mercapto-3-methylbutan-1-ol</span> Chemical compound

3-Mercapto-3-methylbutan-1-ol, also known as MMB, is a common odorant found in food and cat urine. The aromas ascribed to MMB include catty, roasty, broth-like, meaty, and savory, or similar to cooked leeks.

<i>tert</i>-Butylthiol Chemical compound

tert-Butylthiol, also known as 2-methylpropane-2-thiol, 2-methyl-2-propanethiol, tert-butyl mercaptan (TBM), and t-BuSH, is an organosulfur compound with the formula (CH3)3CSH. This thiol is used as an odorant for natural gas, which is otherwise odorless. It may also have been used as a flavoring agent.

<span class="mw-page-title-main">Trichloroacetonitrile</span> Chemical compound

Trichloroacetonitrile is an organic compound with the formula CCl3CN. It is a colourless liquid, although commercial samples often are brownish. It is used commercially as a precursor to the fungicide etridiazole. It is prepared by dehydration of trichloroacetamide. As a bifunctional compound, trichloroacetonitrile can react at both the trichloromethyl and the nitrile group. The electron-withdrawing effect of the trichloromethyl group activates the nitrile group for nucleophilic additions. The high reactivity makes trichloroacetonitrile a versatile reagent, but also causes its susceptibility towards hydrolysis.

<span class="mw-page-title-main">Benzyl iodide</span> Chemical compound

Benzyl iodide is an organic compound with the chemical formula C
7
H
7
I
. The compound consists of a benzene ring with an attached iodidemethyl group. The substance is an alkyl halide and is a constitutional isomer of the iodotoluenes.

References

  1. Haynes, William M., ed. (2016). CRC Handbook of Chemistry and Physics (97th ed.). CRC Press. pp. 5–89. ISBN   978-1-4987-5428-6.
  2. Tominaga, Takatoshi; Guimbertau, Guy; Dubourdieu, Denis (2003). "Contribution of Benzenemethanethiol to Smoky Aroma of Certain Vitis vinifera L. Wines". Journal of Agricultural and Food Chemistry. 51 (5): 1373–1376. doi:10.1021/jf020756c. PMID   12590483.
  3. Norman Kharasch; Robert B. Langford (1964). "2,4-Dinitrobenzenesulfenyl Chloride". Org. Synth. 44: 47. doi:10.15227/orgsyn.044.0047.
  4. Wuts, Peter G. M. (2014). Greene's Protective Groups in Organic Synthesis (5th ed.). Hoboken, NJ: Wiley. p. 842. ISBN   978-1-118-05748-3.
  5. Matoba, Manabu; Kajimoto, Tetsuya; Node, Manabu (2007). "Development of a Novel Benzyl Mercaptan as a Recyclable Odorless Substitute of Hydrogen Sulfide". Synlett. 2007 (12): 1930–1934. doi:10.1055/s-2007-984524.