Jump to content

Mandelic acid

From Wikipedia, the free encyclopedia
Mandelic acid[1]
Structural formula of mandelic acid
Ball-and-stick model of the mandelic acid molecule
Preferred IUPAC name
Hydroxy(phenyl)acetic acid
Other names
2-Hydroxy-2-phenylacetic acid
Mandelic acid
Phenylglycolic acid
α-Hydroxyphenylacetic acid
3D model (JSmol)
ECHA InfoCard 100.001.825 Edit this at Wikidata
EC Number
  • 202-007-6
RTECS number
  • OO6300000
  • InChI=1S/C8H8O3/c9-7(8(10)11)6-4-2-1-3-5-6/h1-5,7,9H,(H,10,11) checkY
  • InChI=1/C8H8O3/c9-7(8(10)11)6-4-2-1-3-5-6/h1-5,7,9H,(H,10,11)
  • O=C(O)C(O)c1ccccc1
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)
15.87 g/100 mL
Solubility soluble in diethyl ether, ethanol, isopropanol
Acidity (pKa) 3.41[2]
0.1761 kJ/g
B05CA06 (WHO) J01XX06 (WHO)
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).
checkY verify (what is checkY☒N ?)

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.

Isolation, synthesis, occurrence[edit]

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 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]


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.


Mandelic acid has a long history of use in the medical community as an antibacterial, particularly in the treatment of urinary tract infections.[13] It has also been used as an oral antibiotic, and as a component of chemical face peels analogous to other alpha hydroxy acids.[14]

The drugs cyclandelate and homatropine are esters of mandelic acid.


  1. ^ Merck Index, 11th Edition, 5599.
  2. ^ Bjerrum, J., et al. Stability Constants, Chemical Society, London, 1958.
  3. ^ See:
  4. ^ Ritzer, Edwin; Sundermann, Rudolf (2000). "Hydroxycarboxylic Acids, Aromatic". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a13_519. ISBN 3527306730.
  5. ^ Corson, B. B.; Dodge, R. A.; Harris, S. A.; Yeaw, J. S. (1926). "Mandelic Acid". Org. Synth. 6: 58. doi:10.15227/orgsyn.006.0058.
  6. ^ J. G. Aston; J. D. Newkirk; D. M. Jenkins & Julian Dorsky (1952). "Mandelic Acid". Organic Syntheses; Collected Volumes, vol. 3, p. 538.
  7. ^ Pechmann, H. von (1887). "Zur Spaltung der Isonitrosoverbindungen". Berichte der Deutschen Chemischen Gesellschaft. 20 (2): 2904–2906. doi:10.1002/cber.188702002156.
  8. ^ Pechmann, H. von; Muller, Hermann (1889). "Ueber α-Ketoaldehyde". Berichte der Deutschen Chemischen Gesellschaft. 22 (2): 2556–2561. doi:10.1002/cber.188902202145.
  9. ^ Kenyon, George L.; Gerlt, John A.; Petsko, Gregory A.; Kozarich, John W. (1995). "Mandelate Racemase: Structure-Function Studies of a Pseudosymmetric Enzyme". Accounts of Chemical Research. 28 (4): 178–186. doi:10.1021/ar00052a003.
  10. ^ Lapadatescu, Carmen; Giniès, Christian; Le QuéRé, Jean-Luc; Bonnarme, Pascal (2000). "Novel Scheme for Biosynthesis of Aryl Metabolites from l-Phenylalanine in the Fungus Bjerkandera adusta". Applied and Environmental Microbiology. 66 (4): 1517–1522. Bibcode:2000ApEnM..66.1517L. doi:10.1128/AEM.66.4.1517-1522.2000. PMC 92016. PMID 10742235.
  11. ^ Mara Reifenrath, Eckhard Boles: Engineering of hydroxymandelate synthases and the aromatic amino acid pathway enables de novo biosynthesis of mandelic and 4-hydroxymandelic acid with Saccharomyces cerevisiae. Metabolic Engineering 45, Januar 2018; S. 246-254. doi:10.1016/j.ymben.2018.01.001.
  12. ^ Engström K, Härkönen H, Kalliokoski P, Rantanen J. "Urinary mandelic acid concentration after occupational exposure to styrene and its use as a biological exposure test" Scand. J. Work Environ. Health. 1976, volume 2, pp. 21-6.
  13. ^ Putten, P. L. (1979). "Mandelic acid and urinary tract infections". Antonie van Leeuwenhoek. 45 (4): 622–623. doi:10.1007/BF00403669. S2CID 28467515.
  14. ^ Taylor, MB. (1999). "Summary of mandelic acid for the improvement of skin conditions". Cosmetic Dermatology. 21: 26–28.