Mandelic acid

From Wikipedia, the free encyclopedia
Jump to navigation Jump to search
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
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).
☑Y verify (what is ☑Y☒N ?)
Infobox references

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.[3] The name is derived from the German "Mandel" for "almond". Derivatives of mandelic acid are formed as a result of metabolism of adrenaline and noradrenaline by monoamine oxidase and catechol-O-methyl transferase.

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]

Preparation of mandelic acid.png

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

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.[9]

It also arises from the biodegradation of styrene, as detected in urine.[10]


Mandelic acid has a long history of use in the medical community as an antibacterial, particularly in the treatment of urinary tract infections.[11] It has also been used as an oral antibiotic, and as a component of chemical face peels analogous to other alpha hydroxy acids.[12]

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. ^ Edwin Ritzer and Rudolf Sundermann "Hydroxycarboxylic Acids, Aromatic" in Ullmann's Encyclopedia of Industrial Chemistry 2002, Wiley-VCH, Weinheim. doi: 10.1002/14356007.a13_519
  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.CS1 maint: multiple names: authors list (link)
  6. ^ J. G. Aston, J. D. Newkirk, D. M. Jenkins, and Julian Dorsky (1952). "Mandelic Acid". Organic Syntheses.CS1 maint: multiple names: authors list (link); Collective Volume, 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. ^ 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.
  10. ^ 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.
  11. ^ Putten, P. L. (1979). "Mandelic acid and urinary tract infections". Antonie van Leeuwenhoek. 45 (4): 622–623. doi:10.1007/BF00403669.
  12. ^ Taylor, MB. (1999). "Summary of mandelic acid for the improvement of skin conditions". Cosmetic Dermatology. 21: 26–28.