acylhalidit

An acyl halide, or acid halide, is an organic compound with the structure R-CO-X, where R is an alkyl or aryl group and X is a halogen (typically chlorine, bromine, or iodine; fluorides are less common). The carbonyl carbon is highly electrophilic, and the attached halogen is a good leaving group, making acyl halides highly reactive toward nucleophiles.

They are typically prepared from carboxylic acids by converting the carboxyl group to the acid chloride using reagents such as thionyl chloride (SOCl2), oxalyl chloride ((COCl)2), phosphorus trichloride (PCl3) or phosphorus pentachloride (PCl5), or by reaction with phosgene. They are usually moisture-sensitive and hydrolyze in water to give the parent carboxylic acid and hydrogen halide.

Reactions and applications: due to their high reactivity, acyl halides serve as versatile acylating agents. They react with amines to form amides, with alcohols to form esters, and with other nucleophiles to form various acyl derivatives. They are also used to activate carboxylic acids and in the synthesis of anhydrides and cyclic structures. Common examples include acetyl chloride (CH3COCl) and benzoyl chloride (C6H5COCl).

Safety and handling: these compounds are corrosive and often emit fumes. They react violently with water and air moisture, releasing hydrogen halide gases. They are typically handled under inert atmosphere and stored in moisture-free conditions with appropriate personal protective equipment.

Notes: The term acylhalidit appears to be a variant spelling of acyl halide; the standard English term is acyl halide or acid halide.