Acylhalider

Acyl halides are a class of organic compounds characterized by the presence of a functional group with the formula RCOX, where R is an organic group, and X is a halogen atom (typically chlorine, bromine, or iodine). They are derivatives of carboxylic acids, where the hydroxyl group (-OH) has been replaced by a halogen atom. Acyl halides are highly reactive compounds due to the electronegativity of the halogen atom and the electron-withdrawing effect of the carbonyl group, which makes the carbonyl carbon electrophilic.

The most common acyl halide is acetyl chloride (CH3COCl). Acyl halides readily undergo nucleophilic acyl substitution reactions. This means they react with nucleophiles such as alcohols, amines, and water to form esters, amides, and carboxylic acids, respectively. These reactions are generally vigorous and often release the hydrogen halide (HX) as a byproduct. Due to their reactivity, acyl halides are important intermediates in organic synthesis, allowing for the introduction of acyl groups into other molecules. They are typically prepared by treating carboxylic acids with halogenating agents like thionyl chloride (SOCl2), phosphorus pentachloride (PCl5), or phosphorus tribromide (PBr3). Their high reactivity also means they are sensitive to moisture and must be handled with care.