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Amines are a class of organic compounds derived from ammonia by replacement of one or more hydrogen atoms with alkyl or aryl groups. They feature a nitrogen atom with a lone pair and typical basicity comparable to ammonia. Depending on the number of carbon substituents on nitrogen, amines are classified as primary (one carbon substituent), secondary (two), or tertiary (three). Quaternary ammonium salts form when nitrogen bears four carbon substituents and carries a positive charge.

Amines vary in solubility and lipophilicity. Simple low‑molecular‑weight amines are often water-soluble, while increasing alkyl substitution raises hydrophobicity. Aromatic amines, such as anilines, are less basic due to conjugation with the aryl ring.

Common preparation methods include reduction of nitro compounds, reductive amination of aldehydes or ketones with ammonia or primary/secondary amines, and the Gabriel synthesis for primary amines. Other routes include hydrolysis of nitriles and alkylation of amines. Reactions of amines encompass alkylation and acylation to give substituted amines and amides, formation of ammonium salts upon protonation, and condensation with carbonyls to yield imines or enamines; tertiary amines can be quaternized to form ammonium salts.

Amines have broad occurrence in biology and industry. They are constituents of amino acids, alkaloids, dyes, surfactants, and many pharmaceuticals, as well as catalysts and monomers for polymers.

Safety and environmental considerations include potential irritation and toxicity of certain amines, and the risk of nitrosamine formation under certain conditions. Proper handling, ventilation, and waste treatment are recommended.