Phenylacetic acid (PAA) (conjugate base phenylacetate), also known by various synonyms, is an organic compound containing a phenyl functional group and a carboxylic acid functional group. It is a white solid with a strong honey-like odor. Endogeneously, it is a catabolite of phenylalanine. As a commercial chemical, because it can be used in the illicit production of phenylacetone (used in the manufacture of substituted amphetamines), it is subject to controls in countries including the United States and China.
|Preferred IUPAC name
|Systematic IUPAC name
3D model (JSmol)
CompTox Dashboard (EPA)
|Molar mass||136.15 g/mol|
|Melting point||76 to 77 °C (169 to 171 °F; 349 to 350 K)|
|Boiling point||265.5 °C (509.9 °F; 538.6 K)|
|Acidity (pKa)||4.31 (H2O)|
|Safety data sheet||External MSDS|
|Benzoic acid, Phenylpropanoic acid, Cinnamic acid|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|what is ?)(|
Synonyms include α-toluic acid, benzeneacetic acid, alpha tolylic acid, 2-phenylacetic acid, and β-phenylacetic acid.
Phenylacetic acid has been found to be an active auxin (a type of plant hormone), found predominantly in fruits. However, its effect is much weaker than the effect of the basic auxin molecule indole-3-acetic acid. In addition the molecule is naturally produced by the metapleural gland of most ant species and used as an antimicrobial. It is also the oxidation product of phenethylamine in humans following metabolism by monoamine oxidase and subsequent metabolism of the intermediate product, phenylacetaldehyde, by the aldehyde dehydrogenase enzyme; these enzymes are also found in many other organisms.
Phenylacetic acid is used in some perfumes, as it possesses a honey-like odor even in low concentrations. It is also used in penicillin G production and diclofenac production. It is also employed to treat type II hyperammonemia to help reduce the amounts of ammonia in a patient's bloodstream by forming phenylacetyl-CoA, which then reacts with nitrogen-rich glutamine to form phenylacetylglutamine. This compound is then excreted from the patient's body. It's also used in the illicit production of phenylacetone, which is used in the manufacture of methamphetamine.
- Haynes, William M., ed. (2016). CRC Handbook of Chemistry and Physics (97th ed.). CRC Press. p. 5–89. ISBN 978-1498754286.
- "List of Regulated Drug Precursor Chemicals in China". Archived from the original on 17 August 2015. Retrieved 27 April 2015.
- Wightman, F.; Lighty, D. L. (1982). "Identification of phenylacetic acid as a natural auxin in the shoots of higher plants". Physiologia Plantarum. 55 (1): 17–24. doi:10.1111/j.1399-3054.1982.tb00278.x.
- Adams R.; Thal, A. F. (1922). "Phenylacetic acid". Organic Syntheses. 2: 59.CS1 maint: Multiple names: authors list (link); Collective Volume, 1, p. 436
- Wenner, W. (1952). "Phenylacetamide". Organic Syntheses. 32: 92.; Collective Volume, 4, p. 760