Glycolic acid

Structural formula
General
Surname	Glycolic acid
other names	Hydroxyacetic acid ( IUPAC ) Hydroxyethanoic acid ( system. IUPAC )
Molecular formula	C 2 H 4 O 3
Brief description	colorless, odorless, hygroscopic solid
External identifiers / databases
CAS number 79-14-1 EC number 201-180-5 ECHA InfoCard 100.001.073 PubChem 757 ChemSpider 737 DrugBank DB03085 Wikidata Q409373
properties
Molar mass	76.05 g mol −1
Physical state	firmly
density	1.49 g cm −3
Melting point	76-80 ° C
boiling point	100 ° C (decomposition)
Vapor pressure	10.8 h Pa (80 ° C)
pK s value	3.83
solubility	very good in water (1000 g l −1 at 25 ° C), acetone , ethanol and diethyl ether
safety instructions
GHS labeling of hazardous substances danger H and P phrases H: 314-332 P: 260-280-301 + 330 + 331-303 + 361 + 353-304 + 340 + 310-305 + 351 + 338
Toxicological data	1000 mg kg −1 ( LD 50 ,  cat ,  iv ) 7.1 mg m −3 / 4 h ( LC 50 ,  rat ,  inh. ) 1920 mg · kg -1 ( LD 50 ,  guinea pigs ,  oral ) 1950 mg kg −1 ( LD 50 ,  rat ,  oral )
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Glycolic acid ( hydroxyacetic acid ) is the simplest α - hydroxycarboxylic acid with the formula HOCH ₂ –COOH. The hydroxymethyl group can be, as in other primary alcohols via the aldehyde ( glyoxylic acid ) to the carboxy group ( oxalic acid ) oxidize.

Occurrence

Rosemary sprigs

Glycolic acid is found in unripe grapes , sugar cane juice , sugar beets , the leaves of wild wine and rosemary . As an oxidation product , it is also contained in glacial acetic acid . Due to its natural occurrence, glycolic acid is counted among the fruit acids .

Manufacturing

On a large scale, glycolic acid is synthesized by alkaline hydrolysis of chloroacetic acid:

${\displaystyle \mathrm {ClCH_{2}COO^{-}\ +\ OH^{-}\longrightarrow \ HOCH_{2}COO^{-}\ +\ Cl^{-}} }$

The synthesis from carbon monoxide , water and formaldehyde is also possible:

${\displaystyle \mathrm {H_{2}CO\ +\ H_{2}O\ +\ CO\longrightarrow \ HOCH_{2}COOH} }$

Glycolic acid is produced from formaldehyde, water and carbon monoxide

use

Glycolic acid as a 20% aqueous solution for removal of rust from piping by chelation of calcium - and iron employed ions. In the textile industry, the acid is used for preservation ("finishing") and as a catalyst , in the leather industry for decalcifying animal hides, for chrome tanning and for dyeing. Glycolic acid is also used in synthesis (as a mild organic acid ) and as a starting product for various esters .

In addition, the fruit acid glycolic acid is used for skin care. Here it fulfills a peeling function and thus improves the appearance of the skin.

safety instructions

In its pure form, the combustible glycolic acid has a corrosive effect on the eyes, skin, mucous membranes and respiratory tract. In animal experiments with rats, guinea pigs and cats, it was found to be only slightly toxic. It showed effects on the ability to smell, breathing disorders, drowsiness and changes in stomach and kidney tissue.

Individual evidence

1. ↑ ^{a b c d e f g h} Entry on glycolic acid in the GESTIS substance database of the IFA , accessed on January 17, 2020(JavaScript required) .
2. ↑ ^{a b} Entry on glycolic acid in the ChemIDplus database of the United States National Library of Medicine (NLM)
3. ↑ ^{a b} Entry on glycolic acid. In: Römpp Online . Georg Thieme Verlag, accessed on June 13, 2014.
4. ↑ Prehled Prumyslove Toxicology; Organicke Latky. Marhold, J., Prague, Czechoslovakia, Avicenum, 1986, p. 656, 1986.
5. ↑ Inhalation Toxicology . Vol. 9, p. 435, 1997.
6. ↑ ^{a b c} Journal of Industrial Hygiene and Toxicology. Vol. 23, p. 259, 1941.

Web links

Wiktionary: Glycolic acid  - explanations of meanings, word origins, synonyms, translations