Phenylacetic acid (PAA;

conjugate base A conjugate acid, within the Brønsted–Lowry acid–base theory, is a chemical compound formed when an acid donates a proton () to a base—in other words, it is a base with a hydrogen ion added to it, as in the reverse reaction it loses a ...

phenylacetate), also known by various synonyms, is an

organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. Th ...

containing a phenyl

functional group In organic chemistry, a functional group is a substituent or moiety in a molecule that causes the molecule's characteristic chemical reactions. The same functional group will undergo the same or similar chemical reactions regardless of the r ...

and a

carboxylic acid In organic chemistry, a carboxylic acid is an organic acid that contains a carboxyl group () attached to an R-group. The general formula of a carboxylic acid is or , with R referring to the alkyl, alkenyl, aryl, or other group. Carboxyli ...

functional group. It is a white solid with a strong honey-like

odor An odor (American English) or odour (Commonwealth English; see spelling differences) is caused by one or more volatilized chemical compounds that are generally found in low concentrations that humans and animals can perceive via their sense ...

. Endogenously, it is a catabolite of

phenylalanine Phenylalanine (symbol Phe or F) is an essential α-amino acid with the formula . It can be viewed as a benzyl group substituted for the methyl group of alanine, or a phenyl group in place of a terminal hydrogen of alanine. This essential amin ...

. As a commercial chemical, because it can be used in the illicit production of phenylacetone (used in the manufacture of

substituted amphetamine Substituted amphetamines are a class of compounds based upon the amphetamine structure; it includes all derivative compounds which are formed by replacing, or substituting, one or more hydrogen atoms in the amphetamine core structure with s ...

s), it is subject to controls in countries including the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...

and

China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's List of countries and dependencies by population, most populous country, with a Population of China, population exceeding 1.4 billion, slig ...

Occurrence

Phenylacetic acid has been found to be an active

auxin Auxins (plural of auxin ) are a class of plant hormones (or plant-growth regulators) with some morphogen-like characteristics. Auxins play a cardinal role in coordination of many growth and behavioral processes in plant life cycles and are essenti ...

(a type of

plant hormone Plant hormone (or phytohormones) are signal molecules, produced within plants, that occur in extremely low concentrations. Plant hormones control all aspects of plant growth and development, from embryogenesis, the regulation of organ size, pat ...

), found predominantly in

fruit In botany, a fruit is the seed-bearing structure in flowering plants that is formed from the ovary after flowering. Fruits are the means by which flowering plants (also known as angiosperms) disseminate their seeds. Edible fruits in partic ...

s. However, its effect is much weaker than the effect of the basic auxin molecule

indole-3-acetic acid Indole-3-acetic acid (IAA, 3-IAA) is the most common naturally occurring plant hormone of the auxin class. It is the best known of the auxins, and has been the subject of extensive studies by plant physiologists. IAA is a derivative of indole, con ...

. 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 Phenethylamine (PEA) is an organic compound, natural monoamine alkaloid, and trace amine, which acts as a central nervous system stimulant in humans. In the brain, phenethylamine regulates monoamine neurotransmission by binding to trace am ...

in humans following metabolism by

monoamine oxidase Monoamine oxidases (MAO) () are a family of enzymes that catalyze the oxidation of monoamines, employing oxygen to clip off their amine group. They are found bound to the outer membrane of mitochondria in most cell types of the body. The firs ...

and subsequent metabolism of the intermediate product,

phenylacetaldehyde Phenylacetaldehyde is an organic compound used in the synthesis of fragrances and polymers. Phenylacetaldehyde is an aldehyde that consists of acetaldehyde bearing a phenyl substituent; the parent member of the phenylacetaldehyde class of compound ...

, by the

aldehyde dehydrogenase Aldehyde dehydrogenases () are a group of enzymes that catalyse the oxidation of aldehydes. They convert aldehydes (R–C(=O)) to carboxylic acids (R–C(=O)). The oxygen comes from a water molecule. To date, nineteen ALDH genes have b ...

enzyme; these enzymes are also found in many other organisms.

Preparation

This compound may be prepared by the

hydrolysis Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution, elimination, and solvation reactions in which water is the nucleophile. Biological hydrolysi ...

benzyl cyanide Benzyl cyanide (abbreviated BnCN) is an organic compound with the chemical formula C6H5CH2CN. This colorless oily aromatic liquid is an important precursor to numerous compounds in organic chemistry. Preparation Benzyl cyanide can be produced via ...

: :

Synthesis of phenylacetic acid from benzyl cyanide

Applications

Phenylacetic acid is used in some

perfume Perfume (, ; french: parfum) is a mixture of fragrant essential oils or aroma compounds (fragrances), fixatives and solvents, usually in liquid form, used to give the human body, animals, food, objects, and living-spaces an agreeable scent ...

s, as it possesses a

honey Honey is a sweet and viscous substance made by several bees, the best-known of which are honey bees. Honey is made and stored to nourish bee colonies. Bees produce honey by gathering and then refining the sugary secretions of plants (primar ...

-like

even in low

concentration In chemistry, concentration is the abundance of a constituent divided by the total volume of a mixture. Several types of mathematical description can be distinguished: '' mass concentration'', '' molar concentration'', ''number concentration'', ...

s. It is also used in

penicillin G Benzylpenicillin, also known as penicillin G (PenG) or BENPEN, and in military slang "Peanut Butter Shot" is an antibiotic used to treat a number of bacterial infections. This includes pneumonia, strep throat, syphilis, necrotizing enterocol ...

production and

diclofenac Diclofenac, sold under the brand name Voltaren, among others, is a nonsteroidal anti-inflammatory drug (NSAID) used to treat pain and inflammatory diseases such as gout. It is taken by mouth or rectally in a suppository, used by injection, or ...

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 Methamphetamine (contracted from ) is a potent central nervous system (CNS) stimulant that is mainly used as a recreational drug and less commonly as a second-line treatment for attention deficit hyperactivity disorder and obesity. Methamp ...

. The sodium

salt Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of salts; salt in the form of a natural crystalline mineral is known as rock salt or halite. Salt is present in vast quant ...

of phenylacetic acid, sodium phenylacetate, is used as a pharmaceutical drug for the treatment of

urea cycle disorder Urea, also known as carbamide, is an organic compound with chemical formula . This amide has two amino groups (–) joined by a carbonyl functional group (–C(=O)–). It is thus the simplest amide of carbamic acid. Urea serves an importan ...

s, including as the

combination drug A combination drug or a fixed-dose combination (FDC) is a medicine that includes two or more active ingredients combined in a single dosage form. Terms like "combination drug" or "combination drug product" can be common shorthand for a FDC prod ...

sodium phenylacetate/sodium benzoate (Ammonul). Phenylacetic acid is used in the preparation of several pharmaceutical drugs, including camylofin, bendazol, triafungin,

phenacemide Phenacemide (INN, BAN) (brand name Phenurone), also known as phenylacetylurea, is an anticonvulsant of the ureide (acetylurea) class. It is a congener and ring-opened analogue of phenytoin (a hydantoin), and is structurally related to the barb ...

lorcainide Lorcainide (Lorcainide hydrochloride) is a Class 1c antiarrhythmic agent that is used to help restore normal heart rhythm and conduction in patients with premature ventricular contractions, ventricular tachycardiac and Wolff–Parkinson–White ...

, phenindione, and

cyclopentolate Cyclopentolate is a muscarinic antagonist. It is commonly used as an eye drop during pediatric eye examinations to dilate the eye (mydriatic) and prevent the eye from focusing/ accommodating (cycloplegic). Cyclopentolate or atropine can also be ...

In popular culture

In the crime drama ''

Breaking Bad ''Breaking Bad'' is an American crime drama television series created and produced by Vince Gilligan. Set and filmed in Albuquerque, New Mexico, the series follows Walter White (Bryan Cranston), an underpaid, overqualified, and dispirited h ...

'', phenylacetic acid is featured twice as a precursor to

, first in the episode titled " A No-Rough-Stuff-Type Deal", then in " Salud".

References

{{Authority control Flavors Drug control law in the United States Auxins Acetic acids Phenyl alkanoic acids

Occurrence

Preparation

Applications

In popular culture

See also

References