2-hydroxybutyric acid

Structural formula
Structure without considering stereochemistry
General
Surname	2-hydroxybutyric acid
other names	2-hydroxybutanoic acid α-hydroxybutyric acid
Molecular formula	C 4 H 8 O 3
Brief description	white crystals
External identifiers / databases
CAS number 600-15-7 [(±) -2-hydroxybutyric acid] 565-70-8 (unspecified mixture of enantiomers) 20016-85-7 [( R ) -2-hydroxybutyric acid] 3347-90-8 [( S ) -2-hydroxybutyric acid] EC number 209-985-3 ECHA InfoCard 100.009.079 PubChem 11266 ChemSpider 10792 Wikidata Q3288610
properties
Molar mass	104.10 g mol −1
Physical state	firmly
density	1.125 g cm −3 (20 ° C, racemate)
Melting point	50–54 ° C (enantiomers) 44 ° C (racemate)
boiling point	260 ° C (racemate)
solubility	soluble in water, ether and ethanol
safety instructions
GHS labeling of hazardous substances danger H and P phrases H: 315-318-335 P: 261-280-305 + 351 + 338
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

2-Hydroxybutyric acid , systematically 2-hydroxybutanoic acid , is a chemical compound from the group of hydroxycarboxylic acids . Their salts are called 2-hydroxybutyrates.

Isomers

2-Hydroxybutyric acid contains a stereocenter , is therefore chiral and occurs in two enantiomeric forms , ( R ) -2-hydroxybutyric acid and ( S ) -2-hydroxybutyric acid. Racemic 2-hydroxybutyric acid [synonym: ( RS ) -2-hydroxybutyric acid] is a 1: 1 mixture of the ( R ) - and the ( S ) -enantiomer.

Isomers of 2-hydroxybutyric acid
Surname	( S ) -2-hydroxybutyric acid	( R ) -2-hydroxybutyric acid
other names	(+) - 2-hydroxybutyric acid L -2-hydroxybutyric acid	(-) - 2-Hydroxybutyric acid D -2-hydroxybutyric acid
Structural formula
CAS number	3347-90-8	20016-85-7
	600-15-7 (racemate)
EC number	628-477-6	627-239-9
	209-985-3 (racemate)
ECHA info card	100.156.743	100.155.619
	100.009.079 (racemate)
PubChem	440864	449265
	11266 (racemate)
Wikidata	Q27887417	Q27122144
	Q3288610 (racemate)

presentation

2-Hydroxybutyric acid can be made from 2-bromobutanoic acid and silver oxide .

Another synthesis starts from propanal , which is converted into the corresponding cyanohydrin with hydrogen cyanide . The hydrolysis of the nitrile group leads to 2-hydroxybenzoic acid with elimination of ammonia .

Heating ethyltartronic acid to 180 ° C also gives 2-hydroxybutanoic acid with decarboxylation .

See also

• 2-hydroxyisobutyric acid

Individual evidence

1. ↑ ^{a b c d} data sheet (R) -2-Hydroxybutyric acid from Sigma-Aldrich , accessed on January 7, 2013 ( PDF ).
2. ^ ^{A b} D. R. Lide: CRC Handbook of Chemistry and Physics . CRC Press, 2012, ISBN 1-4398-8049-2 ( limited preview in Google Book Search).
3. ↑ ^{a b} Entry on (S) -2-HYDROXYBUTYRIC ACID at ChemicalBook , accessed September 14, 2012.
4. ^ ^{A b c} F. Beilstein: Handbook of organic chemistry , 3rd edition, 1st volume, Verlag Leopold Voss, 1893. P. 561 ( full text ).
5. ↑ C. Friedel, V. Machuca: About bromobutyric acid and a new acid derived from it . In: Justus Liebigs Annalen der Chemie , 1861, 120 (3), pp. 279-285 ( doi : 10.1002 / jlac.18611200305 ).