Phenylacetic acid (

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

phenylacetate), also known by various synonyms, is an

organic compound Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-co ...

containing a

phenyl In organic chemistry, the phenyl group, or phenyl ring, is a cyclic group of atoms with the formula , and is often represented by the symbol Ph (archaically φ) or Ø. The phenyl group is closely related to benzene and can be viewed as a benzene ...

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

and a

carboxylic acid In organic chemistry, a carboxylic acid is an organic acid that contains a carboxyl group () attached to an Substituent, R-group. The general formula of a carboxylic acid is often written as or , sometimes as with R referring to an organyl ...

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 a smell or a scent caused by one or more volatilized chemical compounds generally found in low concentrations that humans and many animals can perceive ...

. Endogenously, it is a catabolite of

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

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

phenylacetone Phenylacetone, also known as phenyl-2-propanone, is an organic compound with the chemical formula C6H5CH2COCH3. It is a colorless oil that is soluble in organic solvents. It is a mono- substituted benzene derivative, consisting of an acetone att ...

(used in the manufacture of

substituted amphetamine Substituted amphetamines, or simply amphetamines, are a chemical class, class of compounds based upon the amphetamine structure; it includes all derivative (chemistry), derivative compounds which are formed by replacing, or substitution reacti ...

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

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

and

China China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...

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 essent ...

(a type of

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

), found predominantly in

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

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 ami ...

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 fi ...

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 ...

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 reaction, substitution, elimination reaction, elimination, and solvation reactions in which water ...

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. It is also an important pheromone in certain s ...

: :

Synthesis of phenylacetic acid from benzyl cyanide

Reactions

Phenylacetic acid undergoes

ketonic decarboxylation Ketonic decarboxylation (also known as decarboxylative ketonization) is a type of organic reaction involving decarboxylation, converting two equivalents of a carboxylic acid () to a symmetric ketone (). The reaction typically requires heat and a ...

to form

ketone In organic chemistry, a ketone is an organic compound with the structure , where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group (a carbon-oxygen double bond C=O). The simplest ketone is acetone ( ...

s. It can be condensed with itself to form

dibenzyl ketone Dibenzyl ketone, or 1,3-diphenylacetone, is an organic compound composed of two benzyl groups attached to a central carbonyl group. This results in the central carbonyl carbon atom being electrophilic and the two adjacent carbon atoms slightly nucl ...

, or with a large excess of another carboxylic acid (in the form of an

acid anhydride An acid anhydride is a type of chemical compound derived by the removal of water molecules from an acid. In organic chemistry, organic acid anhydrides contain the functional group . Organic acid anhydrides often form when one equivalent of wa ...

), such as with

acetic anhydride Acetic anhydride, or ethanoic anhydride, is the chemical compound with the chemical formula, formula . Commonly abbreviated , it is one the simplest organic acid anhydride, anhydrides of a carboxylic acid and is widely used in the production of c ...

to form

Applications

Phenylacetic acid is used in some

perfume Perfume (, ) is a mixture of fragrance, fragrant essential oils or aroma compounds (fragrances), Fixative (perfumery), fixatives and solvents, usually in liquid form, used to give the human body, animals, food, objects, and living-spaces an agre ...

s, as it possesses a

honey Honey is a sweet and viscous substance made by several species of 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 pl ...

-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, is an antibiotic used to treat a number of bacterial infections. This includes pneumonia, strep throat, syphilis, necrotizing enterocolitis, diphtheria, gas gangrene, leptospiros ...

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 can be taken orally (swallowed by mouth), inserted rectally as a ...

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

, 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 use, recreational or Performance-enhancing substance, performance-enhancing drug and less commonly as a secon ...

. The sodium

salt In common usage, salt is a mineral composed primarily of sodium chloride (NaCl). When used in food, especially in granulated form, it is more formally called table salt. In the form of a natural crystalline mineral, salt is also known as r ...

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

urea cycle disorder The urea cycle (also known as the ornithine cycle) is a cycle of biochemical reactions that produces urea (NH2)2CO from ammonia (NH3). Animals that use this cycle, mainly amphibians and mammals, are called ureotelic. The urea cycle converts highly ...

s, including as the

combination drug A combination drug is a combination of two or more pharmaceutical drugs as active ingredients combined into a single dosage form, typically as a ''fixed-dose combination'', with each constituent standardized to specifications of a fixed dose. Fix ...

sodium phenylacetate/sodium benzoate (Ammonul). Phenylacetic acid is used in the preparation of and derived from several pharmaceutical drugs, including

camylofin Camylofin is an antimuscarinic drug. Camylofin is a smooth muscle relaxant with both anticholinergic action and direct smooth muscle action. Anticholinergic action is produced by inhibiting the binding of acetylcholine to muscarinic receptors, b ...

, bendazol, triafungin,

phenacemide Phenacemide (International Nonproprietary Name, INN, British Approved Name, BAN) (brand name Phenurone), also known as phenylacetylurea, is an anticonvulsant of the ureide (acetylurea) class. It is a congener (chemistry), congener and ring-opene ...

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 sy ...

phenindione Phenindione is an anticoagulant which functions as a Vitamin K antagonist. Phenindione was introduced in the early 1950s. It acts similar to warfarin Warfarin, sold under the brand name Coumadin among others. It is used as an anticoagul ...

phenelzine Phenelzine, sold under the brand name Nardil among others, is a non-selective and irreversible monoamine oxidase inhibitor (MAOI) of the hydrazine family which is primarily used as an antidepressant and anxiolytic to treat depression and a ...

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/Accommodation (eye), accommodating (cycloplegia, cycloplegic). Cyclop ...

In popular culture

In the crime drama ''

Breaking Bad ''Breaking Bad'' is an American crime drama television series created and produced by Vince Gilligan for AMC (TV channel), AMC. Set and filmed in Albuquerque, New Mexico, the series follows Walter White (Breaking Bad), Walter White (Bryan Cran ...

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

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

References