Benzoyl chloride

Benzoyl chloride, also known as benzenecarbonyl chloride, is an organochlorine compound with the formula C₆H₅COCl. It is a colourless, fuming liquid with an irritating odour. It is mainly useful for the production of peroxides but is generally useful in other areas such as in the preparation of dyes, perfumes, pharmaceuticals, and resins.

It reacts with water to produce hydrochloric acid and benzoic acid:

C₆H₅COCl + H₂O → C₆H₅CO₂H + HCl

Benzoyl chloride is a typical acyl chloride. It reacts with alcohols to give the corresponding esters. Similarly, it reacts with amines to give the amide.

It undergoes the Friedel-Crafts acylation with aromatic compounds to give the corresponding benzophenones and related derivatives. With carbanions, it serves again as a source of "PhCO⁺".

Benzoyl peroxide, a common reagent in polymer chemistry, is produced industrially by treating benzoyl chloride with hydrogen peroxide and sodium hydroxide:

2 C₆H₅COCl + H₂O₂ + 2 NaOH → (C₆H₅CO)₂O₂ + 2 NaCl + 2 H₂O