Phenylacetic acid

Phenylacetic acid (PAA), also known as alpha-toluic acid, is an organic compound with the formula C₆H₅CH₂COOH. It is a white, solid substance with a characteristic honey-like odor. Phenylacetic acid is classified as an aromatic carboxylic acid and is used in various chemical syntheses, including the production of pharmaceuticals, perfumes, and polymers.

Properties

Phenylacetic acid is slightly soluble in water but highly soluble in organic solvents such as ethanol, diethyl ether, and benzene. It has a melting point of 76.5-77.5 °C and a boiling point of 265.5 °C. The compound exhibits a strong absorption in the ultraviolet-visible spectrum, which is characteristic of aromatic compounds.

Synthesis

Phenylacetic acid can be synthesized through several methods. One common approach is the oxidation of ethylbenzene or benzyl chloride. Another method involves the hydrolysis of benzyl cyanide, which is a nitrile hydrolysis reaction.

Applications

Pharmaceuticals

Phenylacetic acid is a precursor in the synthesis of a variety of pharmaceuticals. It is used in the production of penicillin G, a widely used antibiotic, and phenylacetone, which is an intermediate in the synthesis of amphetamines. Its derivatives, such as phenylacetylglutamine, are excreted by humans after ingestion of phenylalanine, making it relevant in medical research and diagnostics.

Perfumery

In the perfumery industry, phenylacetic acid is valued for its honey-like odor. It is used as a fixative or an additive in the formulation of fragrances and flavorings.

Chemical Synthesis

Beyond its applications in pharmaceuticals and perfumery, phenylacetic acid serves as a starting material in the synthesis of various organic compounds. It is involved in the production of dyes, synthetic resins, and other polymers.

Safety and Regulation

Phenylacetic acid must be handled with care due to its potential health hazards. It can cause skin irritation and severe eye damage upon contact. Inhalation of its vapors can lead to respiratory irritation. Safety measures, including the use of personal protective equipment, are recommended when handling this chemical.

In some jurisdictions, phenylacetic acid is regulated due to its use as a precursor in the illicit synthesis of phenylacetone, which can be further processed into amphetamines. Regulations may include monitoring of its sale, distribution, and use.

See Also

• Carboxylic acid
• Aromatic compound
• Penicillin
• Amphetamine