2-mercaptopropionic acid

Structural formula
( R ) shape (left) and ( S ) shape (right)
General
Surname	2-mercaptopropionic acid
other names	Thiolactic acid ( RS ) -thiolactic acid (±) -thiolactic acid rac -thiolactic acid TMS
Molecular formula	C 3 H 6 O 2 S
Brief description	colorless liquid with a rancid odor
External identifiers / databases
CAS number 79-42-5 EC number 201-206-5 ECHA InfoCard 100.001.097 PubChem 62326 ChemSpider 56121 Wikidata Q27120833
properties
Molar mass	106.15 g mol −1
Physical state	liquid
density	1.196 g cm −3  (25 ° C)
Melting point	10-14 ° C
boiling point	203-208 ° C
Vapor pressure	1.7 hPa (20 ° C)
solubility	soluble in water
Refractive index	1.4809 (20 ° C)
safety instructions
GHS labeling of hazardous substances danger H and P phrases H: 290-302-314 P: 280-301 + 330 + 331-303 + 361 + 353-305 + 351 + 338-310
Toxicological data	730 mg kg −1 ( LD 50 ,  rat ,  oral )
Thermodynamic properties
ΔH f 0	−468.4 kJ / mol
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . Refractive index: Na-D line , 20 ° C

2-mercaptopropionic acid , also called thiolactic acid, is an organic chemical compound that is required for the synthesis of herbicides and is also used in depilatory creams . The ammonium salt of thiolactic acid, ammonium thiolactate, is used similarly to ammonium thioglycolate for the permanent wave in the hairdressing salon.

Isomerism

2-mercaptopropionic acid is chiral , so there are two enantiomers , ( R ) -thiolactic acid and ( S ) -thiolactic acid. Whenever “thiolactic acid” is spoken of without any additional designation, a 1: 1 mixture ( racemate ) of ( R ) -thiolactic acid and ( S ) -thiolactic acid is always meant. This mixture is called precisely ( RS ) -thiolactic acid [synonym: ( RS ) -2-mercaptopropionic acid].

Individual evidence

1. ↑ ^{a b c d e f g h} Entry on 2-mercaptopropionic acid in the GESTIS substance database of the IFA , accessed on January 8, 2020(JavaScript required) .
2. ↑ ^{a b} Data sheet 2-mercaptopropionic acid (PDF) from Merck , accessed on April 29, 2014.
3. ↑ David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Standard Thermodynamic Properties of Chemical Substances, pp. 5-24.
4. ↑ External identifiers of or database links to (RS) ammonium thiolactate : CAS number: 13419-67-5, EC number: 236-526-4, ECHA -InfoCard: 100.033.192 , PubChem : 114517 , ChemSpider : 102571 , Wikidata : Q2823310 .