anilinas

Anilines are a family of aromatic amines based on the core structure of aniline (C6H5NH2). They are typically colorless to pale yellow liquids at room temperature with a strong, characteristic odor. The amino group makes them basic and capable of forming salts with acids; substituted anilines are common, with various groups attached to the benzene ring.

Industrial production of anilines mainly involves the catalytic hydrogenation of nitrobenzene, which is derived from benzene. Historically, nitrobenzene was reduced with iron or tin in acid. Substituted anilines are prepared through methods such as diazotization of anilines followed by coupling or by direct amination of substituted benzenes. Aniline serves as the parent compound for many derivatives.

Uses and applications of anilines are broad. The most important is as a precursor to dyes, particularly azo dyes, produced by diazotization of aniline and subsequent coupling reactions. Anilines are also used in the manufacture of polyurethanes and other polymers, rubber processing chemicals, agrochemicals, and pharmaceutical intermediates. Some derivatives are employed in pigment, optical, and specialty chemical sectors.

Safety and handling are essential due to toxicity and potential health hazards. Anilines can be absorbed through the skin and may cause methemoglobinemia and other adverse effects; they are also flammable and can form hazardous nitrosamine compounds under certain conditions. Environmental release can be toxic to aquatic life. Handling requires appropriate engineering controls, protective equipment, and adherence to regulatory guidelines and waste disposal practices.

History notes that aniline was isolated in the 19th century from coal tar and quickly became a cornerstone of the synthetic dye industry, spurring widespread development of related aromatic amines and industrial chemistry.