Title: Thioglycolic Acid
CAS Registry Number: 68-11-1
CAS Name: Mercaptoacetic acid
Additional Names: thioglycollic acid
Molecular Formula: C2H4O2S
Molecular Weight: 92.12
Percent Composition: C 26.08%, H 4.38%, O 34.74%, S 34.81%
Line Formula: HSCH2COOH
Literature References: Prepd by the action of sodium sulfhydrate on sodium chloroacetate; by electrolysis of dithioglycollic acid (from sodium sulfide and sodium chloroacetate). Toxicity study: Deichmann, Mergard, J. Ind. Hyg. Toxicol. 30, 373 (1948).
Properties: Liquid, strong, unpleasant odor. Readily oxidized by air. d 1.325. mp -16.5°. bp29 123°. bp15 108°. bp5 96°. K1 at 25° = 2.1 ´ 10-4; K2 = 2.1 ´ 10-11. Miscible with water, alcohol, ether, chloroform, benzene, and many other organic solvents. LD50 orally in rats: 0.15 ml/kg (Deichmann, Mergard).
Melting point: mp -16.5°
Boiling point: bp29 123°; bp15 108°; bp5 96°
Density: d 1.325
Toxicity data: LD50 orally in rats: 0.15 ml/kg (Deichmann, Mergard)
CAUTION: Potential symptoms of overexposure are irritation of eyes, skin, nose, throat; lacrimation, corneal damage; skin burns, blisters. See NIOSH Pocket Guide to Chemical Hazards (DHHS/NIOSH 97-140, 1997) p 306.
Use: Sensitive reagent for iron, molybdenum, silver, tin. With ferric iron a blue color appears, and when an alkali hydroxide is added to a soln contg ferrous salts and thioglycolic acid, a yellow precipitate forms. Used in the manuf of thioglycolates. The ammonium and sodium salts are commonly used for cold waving and the calcium salt is a depilatory. The sodium salt also is used in bacteriology in the prepn of thioglycolate media. |