CAS Registry Number: 74-93-1
Additional Names: Methyl mercaptan; mercaptomethane; thiomethyl alcohol; methyl sulfhydrate
Molecular Formula: CH4S
Molecular Weight: 48.11
Percent Composition: C 24.97%, H 8.38%, S 66.65%
Line Formula: CH3SH
Literature References: Occurs in "sour" gas of W. Texas, in coal tar, and in petroleum distillates. Isolated from roots of Raphanus sativus. Produced in the intestinal tract by the action of anaerobic bacteria on albumin. Evolved from Penicillium brevicaule bread cultures containing disulfides. Prepn from sodium methyl sulfate and KHS: Klason, Ber. 20, 3409 (1887); Arndt, ibid. 54, 2236 (1921); catalytically from methanol and hydrogen sulfide: Kramer, Reid, J. Am. Chem. Soc. 43, 880 (1921); from methyl chloride and sodium hydrosulfide: Scott et al., Ind. Eng. Chem. 47, 876 (1955). Review of occurrence, preparation, properties and reactions: E. E. Reid, Organic Chemistry of Bivalent Sulfur vol. I (Chemical Publishing Co., New York, 1958) pp 15-261; of toxicology and human exposure: Toxicological Profile for Methyl Mercaptan (PB93-110799, 1992) 92 pp.
Properties: Flammable gas; odor of rotten cabbage. mp -123°. bp760 5.95°; d420 0.8665; d425 0.9600. Critical temp 196.8°. Critical pressure 71.4 atm. Heat capacity (solid at 14.97-146.57 K): 0.773-17.47 cal/deg/mole; (liq at 154.16-271.06 K): 21.27-21.13 cal/deg/mole, Russell et al., J. Am. Chem. Soc. 64, 165 (1942). Azeotrope with isobutane (14.9% methanethiol) bp -13.00°. Soly in water at 20°: 23.30 g/l. Forms a cryst hydrate.
Melting point: mp -123°
Boiling point: bp760 5.95°; bp -13.00°
Density: d420 0.8665; d425 0.9600
Derivative Type: Sodium salt heminonahydrate
Molecular Formula: CH3SNa.4½H2O
Molecular Weight: 151.16
Percent Composition: C 7.95%, H 8.00%, S 21.21%, Na 15.21%, O 47.63%
Properties: Needles. Freely sol in water, methanol. Practically insol in ether.
Derivative Type: Copper salt
Molecular Formula: CH3SCu
Molecular Weight: 110.65
Percent Composition: C 10.85%, H 2.73%, S 28.98%, Cu 57.43%
Properties: Pale yellow crystals. Practically insol in water, ethanol, ether, benzene.
CAUTION: Potential symptoms of overexposure to methanethiol are irritation of eyes, skin and respiratory system; narcosis; cyanosis; convulsions; direct contact with liquid may cause frostbite. See NIOSH Pocket Guide to Chemical Hazards (DHHS/NIOSH 97-140, 1997) p 214.
Use: Intermediate in manuf of jet fuels, pesticides, fungicides, plastics; synthesis of methionine.