Acid chlorides, also known as acyl chlorides, are organic compounds derived from carboxylic acids by replacing the hydroxyl group (-OH) with a chlorine atom (-Cl). They are typically represented by the general formula RCOCl, where R is a hydrocarbon group. Acid chlorides are highly reactive and are commonly used in organic synthesis to produce esters, amides, and other derivatives. These compounds are usually colorless liquids or solids with a pungent odor. Acid chlorides can be produced through the reaction of carboxylic acids with thionyl chloride or oxalyl chloride. Due to their reactivity, they must be handled with care, as they can react violently with water and alcohols.