C7H5ClO

C7H5ClO is a molecular formula that may refer to more than one chemical compound. The formula corresponds to two main classes: chlorobenzaldehyde isomers (ortho-, meta-, and para-chlorobenzaldehyde) and benzoyl chloride (benzenecarbonyl chloride). Both share the same elemental composition C7H5ClO but differ in connectivity: chlorobenzaldehydes contain a formyl group (-CHO) attached to a chlorinated benzene ring, whereas benzoyl chloride contains a carbonyl chloride group (-COCl) attached to the benzene ring.

Chlorobenzaldehyde isomers are used as intermediates in the synthesis of fragrances, dyes, and pharmaceuticals. The three isomers differ in physical properties and reactivity, but all feature an aldehyde functional group on a chlorinated aromatic ring. Benzoyl chloride is a versatile acylating agent used to form benzamide and benzoyl esters; it reacts readily with amines, alcohols, and other nucleophiles. It is typically handled as a corrosive, lachrymatory liquid.

Because C7H5ClO can denote more than one compound, identification requires structural information (substitution pattern or functional group) rather than the formula alone. The context—such as an experimental procedure or a catalog entry—usually specifies whether chlorobenzaldehyde isomers or benzoyl chloride is intended. Safety considerations include the hazardous nature of both classes: chlorobenzaldehydes and benzoyl chloride can pose irritant and corrosive risks and should be handled with appropriate protective equipment in a fume hood.

See also: chlorobenzaldehyde, benzoyl chloride, isomers, acylation, aromatic aldehydes.