|CAS number||, (R), (S)|
|Jmol-3D images||Image 1|
|Molar mass||152.15 g mol−1|
|Appearance||White crystalline powder|
119 °C, 392 K, 246 °F (optically pure: 132 – 135 °C)
321.8 °C, 595 K, 611 °F
|Solubility in water||15.87 g/100 mL|
|Solubility||soluble in diethyl ether, ethanol, isopropanol|
|Refractive index (nD)||1.5204|
|Std enthalpy of
|Flash point||162.6 °C (324.7 °F)|
|Related compounds||mandelonitrile, phenylacetic acid, vanillylmandelic acid|
| (what is: / ?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
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. Since the molecule is chiral, it exists in either of two enantiomers as well as the racemic mixture, known as paramandelic acid.
Isolation and synthesis
Mandelic acid was discovered while heating amygdalin, an extract of bitter almonds, with diluted hydrochloric acid. 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, 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:
Mandelic acid has a long history of use in the medical community as an antibacterial, particularly in the treatment of urinary tract infections. It has also been used as an oral antibiotic, and as a component of 'chemical face peels', along with other alpha-hydroxy acids (AHAs).
- Merck Index, 11th Edition, 5599.
- Bjerrum, J., et al. Stability Constants, Chemical Society, London, 1958.
- 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
- Corson, B. B.; Dodge, R. A.; Harris, S. A.; Yeaw, J. S. (1941), "Mandelic Acid", Org. Synth.; Coll. Vol. 1: 336
- J. G. Aston, J. D. Newkirk, D. M. Jenkins, and Julian Dorsky (1952), "Mandelic Acid", Org. Synth.; Coll. Vol. 3: 538
- Putten, P. L. (1979). "Mandelic acid and urinary tract infections". Antonie van Leeuwenhoek 45 (4): 622. doi:10.1007/BF00403669.
- This article incorporates text from a publication now in the public domain: Chisholm, Hugh, ed. (1911). Encyclopædia Britannica (11th ed.). Cambridge University Press