Definition of Benzoyl chloride

Benzoyl chloride, also known as benzenecarbonyl chloride, is a colourless, fuming liquid, C₆H₅COCl, with an irritating odour. In the laboratory it may be prepared by distilling benzoic acid (C₆H₅COOH) with phosphorus pentachloride in anhydrous conditions. This replaces the hydroxy group of benzoic acid with a chlorine atom. This chlorination can also be accomplished using thionyl chloride. On a larger scale it is prepared by chlorinating benzaldehyde.