Acyl chlorides, also known as acid chlorides, are organic compounds derived from carboxylic acids by replacing the hydroxyl group (-OH) with a chlorine atom. They have the general formula RCOCl, where R represents an alkyl or aryl group. Acyl chlorides are typically colorless liquids with a pungent odor and are highly reactive, making them useful intermediates in organic synthesis. These compounds are commonly used to produce esters, amides, and anilines through reactions with alcohols, amines, and other nucleophiles. Due to their reactivity, acyl chlorides can also be employed in the preparation of various pharmaceuticals and agrochemicals.