Mandelic acid

Mandelic acid is an aromatic alpha hydroxy acid with the molecular formula C₆H₅CH(OH)CO₂H. It is a white crystalline solid that is soluble in water and polar organic solvents. It is a useful precursor to various drugs. The molecule is chiral. The racemic mixture is known as paramandelic acid.

Mandelic acid^[1]

Names
Preferred IUPAC name Hydroxy(phenyl)acetic acid
Other names 2-Hydroxy-2-phenylacetic acid Mandelic acid Phenylglycolic acid α-Hydroxyphenylacetic acid
Identifiers
CAS Number	90-64-2 Y (R): 611-71-2 Y (S): 17199-29-0 Y
3D model (JSmol)	Interactive image
Beilstein Reference	510011
ChEBI	CHEBI:35825 Y
ChEMBL	ChEMBL1609 Y
ChemSpider	1253 Y
DrugBank	DB13218 (R): DB02280 (S): DB03357
ECHA InfoCard	100.001.825
EC Number	202-007-6
Gmelin Reference	218213
KEGG	(R): C01983 (S): C01984
PubChem CID	1292
RTECS number	OO6300000
UNII	NH496X0UJX Y (R): PPL7YW1M9W Y (S): L0UMW58G3T Y
CompTox Dashboard (EPA)	DTXSID6023234
InChI InChI=1S/C8H8O3/c9-7(8(10)11)6-4-2-1-3-5-6/h1-5,7,9H,(H,10,11) Y Key: IWYDHOAUDWTVEP-UHFFFAOYSA-N Y InChI=1/C8H8O3/c9-7(8(10)11)6-4-2-1-3-5-6/h1-5,7,9H,(H,10,11) Key: IWYDHOAUDWTVEP-UHFFFAOYAD
SMILES O=C(O)C(O)c1ccccc1
Properties
Chemical formula	C8H8O3
Molar mass	152.149 g·mol−1
Appearance	White crystalline powder
Density	1.30 g/cm3
Melting point	119 °C (246 °F; 392 K) optically pure: 132 to 135 °C (270 to 275 °F; 405 to 408 K)
Boiling point	321.8 °C (611.2 °F; 595.0 K)
Solubility in water	15.87 g/100 mL
Solubility	soluble in diethyl ether, ethanol, isopropanol
Acidity (pKa)	3.41[2]
Refractive index (nD)	1.5204
Thermochemistry
Std enthalpy of formation (ΔfH⦵298)	0.1761 kJ/g
Pharmacology
ATC code	B05CA06 (WHO) J01XX06 (WHO)
Hazards
Flash point	162.6 °C (324.7 °F; 435.8 K)
Related compounds
Related compounds	mandelonitrile, phenylacetic acid, vanillylmandelic acid
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

Isolation, synthesis, occurrence

Mandelic acid was discovered in 1831 by the German pharmacist Ferdinand Ludwig Winckler (1801–1868) while heating amygdalin, an extract of bitter almonds, with diluted hydrochloric acid. The name is derived from the German "Mandel" for "almond".^[3]

Mandelic acid is usually prepared by the acid-catalysed hydrolysis of mandelonitrile,^[4] which is the cyanohydrin of benzaldehyde. Mandelonitrile can also be prepared by reacting benzaldehyde with sodium bisulfite to give the corresponding adduct, forming mandelonitrile with sodium cyanide, which is then hydrolyzed:^[5]

Alternatively, it can be prepared by base hydrolysis of phenylchloroacetic acid as well as dibromacetophenone.^[6] It also arises by heating phenylglyoxal with alkalis.^[7][8]

Biosynthesis

Mandelic acid is a substrate or product of several biochemical processes called the mandelate pathway. Mandelate racemase interconverts the two enantiomers via a pathway that involves cleavage of the alpha-CH bond. Mandelate dehydrogenase is yet another enzyme on this pathway.^[9] Mandelate also arises from trans-cinnamate via phenylacetic acid, which is hydroxylated.^[10] Phenylpyruvic acid is another precursor to mandelic acid.

Derivatives of mandelic acid are formed as a result of metabolism of adrenaline and noradrenaline by monoamine oxidase and catechol-O-methyl transferase. The biotechnological production of 4-hydroxy-mandelic acid and mandelic acid on the basis of glucose was demonstrated with a genetically modified yeast Saccharomyces cerevisiae, in which the hydroxymandelate synthase naturally occurring in the bacterium Amycolatopsis was incorporated into a wild-type strain of yeast, partially altered by the exchange of a gene sequence and expressed.^[11]

It also arises from the biodegradation of styrene^[12] and ethylbenzene, as detected in urine.

Uses

Mandelic acid has a long history of use in the medical community as an antibacterial, particularly in the treatment of urinary tract infections.^[13]

Mandelic acid has been used as an oral antibiotic, and as a component of chemical face peels analogous to other alpha hydroxy acids.^[14]

Lumē brand whole body deodorant contains mandelic acid, which serves as an antimicrobial on the skin as well as a deodorizer in areas of the body with odors from sweat.

The drugs cyclandelate and homatropine are esters of mandelic acid.

See also

• Salicylic Acid
• Lactic Acid