Acid halides (chlorides)
Acid halides or acyl halides are reactive derivatives of carboxylic acids. Most important halides are chlorides which are made from appropriate carboxylic acid by reaction with chlorinating agent such as thionyl chloride, oxalyl chloride, phosgene, phosphorus chlorides. They are reactive and versatile reagents suitable for preparation of various esters, amides, and anhydrides. The reactions of acyl halides with certain organocadmium and Gilman reagent stop at the ketone stage while reactions with Grignard reagents lead to tertiary alcohols. Chlorides can be reduced to primary alcohols or aldehydes. They participate in Friedel-Crafts alkylations, to give aryl ketones.