Nomenclature
CAS number: 74-93-1
Methyl mercaptan; mercaptomethane; thiomethyl alcohol; methyl sulfhydrate.
CH
4S; mol wt 48.11.
C 24.97%, H 8.38%, S 66.65%.
CH
3SH.
Description and 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; (liquid 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.Derivative
Sodium salt heminonahydrate.
CH
3SNa.4H
2O; mol wt 151.16.
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
Copper salt.
CH
3SCu; mol wt 110.65.
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.