Benzonitrile

Benzonitrile, also known as benzenecarbonitrile, is an aromatic nitrile with the chemical formula C7H5N. It consists of a benzene ring bearing a single cyano substituent (-CN). It is typically a colorless liquid with a boiling point around 191 °C and limited water solubility, though it dissolves in many organic solvents.

Industrial production of benzonitrile is mainly by ammoxidation of toluene in the presence of ammonia and air over a heterogeneous catalyst, yielding benzonitrile and water. In the laboratory, benzonitrile can also be prepared via routes that convert benzoic acid derivatives to nitriles, such as dehydration of amide intermediates or related transformations.

The nitrile group in benzonitrile makes it a versatile building block in organic synthesis. Hydrolysis converts it to benzoic acid under acidic or basic conditions, while reduction yields benzylamine. Through various transformations, benzonitrile serves as a precursor in the preparation of pharmaceuticals, dyes, and agrochemicals, and it is used as an intermediate for other benzenoid nitriles and related compounds.

Safety and handling considerations are important: benzonitrile is a toxic and flammable liquid. Exposure can irritate skin, eyes, and the respiratory tract. Like many nitriles, it can release hydrogen cyanide under strong acid hydrolysis or certain catalytic conditions, so appropriate engineering controls, protective equipment, and containment are required.