Title: Ethanethiol
CAS Registry Number: 75-08-1
Additional Names: Ethyl mercaptan; mercaptoethane; ethyl sulfhydrate; thioethyl alcohol
Molecular Formula: C2H6S
Molecular Weight: 62.13
Percent Composition: C 38.66%, H 9.73%, S 51.61%
Line Formula: CH3CH2SH
Literature References: Found in urine of rabbits after ingestion of cabbage. Is formed in vinous fermentation. Occurs in illuminating gas, in "sour" natural gas of W. Texas; in petroleum distillates from which it may be separated by chemical or physical methods: Thompson et al., Anal. Chem. 27, 175 (1955). Prepn from sodium ethylsulfate and KSH: Klason, Ber. 20, 3407 (1887); catalytically from ethanol and hydrogen sulfide: Kramer, Reid, J. Am. Chem. Soc. 43, 880 (1921). Review on occurrence, prepn, properties and reactions: E. Emmet Reid, Organic Chemistry of Bivalent Sulfur vol. I, 15-261 (Chemical Publishing Co., New York, 1958).
Properties: Liquid; penetrating leek-like odor: minimum detectable concn = 1 part in 50 billion parts of air. d40 0.8617; d425 0.83147. bp 34.7-35.04°; bp400 17.7°; bp200 1.5°; bp100 -13.0°; bp10 -50.2°; bp1 -76.1°. mp -147.97 to -144.4°. nD20 1.431; nD25 1.420. Crit temp 225.5°. Crit pressure 54.2 atm. Explosive limits 2.8 and 18.2% by vol of vapor. Min ignition temp in air 299°, in oxygen 261°. Entropy at 25°: 70.77 cal/deg/mole. Heat capacity at 25°: 17.37 cal/deg/mole. Surface tension at 2°: 23.63 dynes/cm; at 16.7°: 21.62 dynes/cm. Viscosity at 20°: 0.003155 g/cm sec. Azeotrope with n-pentane (51% ethanethiol) bp 30.46°; with ether (40% ethanethiol) bp 31.50°. Soly in water at 20°: 6.76 g/l or 0.112 moles/l. Sol in alcohol, ether. Keep tightly closed and in a cool place.
Melting point: mp -147.97 to -144.4°
Boiling point: bp 34.7-35.04°; bp400 17.7°; bp200 1.5°; bp100 -13.0°; bp10 -50.2°; bp1 -76.1°; bp 30.46°; bp 31.50°
Index of refraction: nD20 1.431; nD25 1.420
Density: d40 0.8617; d425 0.83147
Derivative Type: Octadecahydrate
Properties: Needles. Practically insol in water, ethanethiol.
Derivative Type: Sodium salt
Molecular Formula: C2H5NaS
Molecular Weight: 84.12
Percent Composition: C 28.56%, H 5.99%, Na 27.33%, S 38.12%
Properties: Hydrolyzes instantly in water.
CAUTION: Potential symptoms of overexposure to ethanethiol are headache, nausea and irritation of mucous membranes. See NIOSH Pocket Guide to Chemical Hazards (DHHS/NIOSH 97-140, 1997) p 140.
Use: Odorant for natural gas; intermediate and starting material in manuf of plastics, insecticides, antioxidants.
Ethanolamine Ethaverine Ethebenecid Ethenzamide Ethephon

Skeletal structure of ethanethiol
Ball-and-stick model of the ethanethiol molecule
CAS number 75-08-1 YesY
PubChem 6343
ChemSpider 6103 YesY
UNII M439R54A1D YesY
RTECS number KI9625000
Jmol-3D images Image 1
Molecular formula C2H6S
Molar mass 62.13404 g·mol−1
Density 0.8617 g·cm−3
Melting point −148 °C; −234 °F; 125 K
Boiling point 35 °C; 95 °F; 308 K
Acidity (pKa) 10.6
EU classification Flammable F Harmful Xn Dangerous for the Environment (Nature) N
R-phrases R11, R20, R50/53
S-phrases S16, S25, S60, S61
Main hazards Nauseating
NFPA 704
NFPA 704.svg
Related compounds
Related compounds Methanethiol
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Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references

Ethanethiol, commonly known as ethyl mercaptan, is a colorless gas or clear liquid with a distinct odor. It is an organosulfur compound with the formula CH3CH2SH. Abbreviated EtSH, it consists of an ethyl group (Et), CH3CH2, attached to a thiol group, SH. Its structure parallels that of ethanol, but with S instead of O. 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. 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.