Acylklorider

Acylklorider are a class of organic compounds with the general formula R-CO-Cl, where R represents an alkyl or aryl group. They are derived from carboxylic acids by replacing the hydroxyl group with chlorine, producing acyl chlorides. Most acyl chlorides are colorless liquids or low-melting solids and are highly reactive toward nucleophiles such as water, alcohols, and amines, releasing hydrogen chloride upon hydrolysis.

Preparation is typically by chlorination of carboxylic acids using reagents like thionyl chloride (SOCl2), oxalyl chloride (COCl)2, phosphorus pentachloride (PCl5), or phosphorus oxychloride (POCl3).

Reactivity: Acyl chlorides react readily with water to form the corresponding carboxylic acids and HCl. They react with alcohols to give esters and with amines to give amides. They can also form anhydrides when two acyl groups are involved or when an acyl chloride reacts with carboxylates. The carbonyl carbon is highly electrophilic, and the chloride is a good leaving group, making these reagents among the most reactive carboxyl derivatives.

Uses: They are widely used as acylating agents in organic synthesis. They introduce acyl groups into alcohols, amines, and other substrates, enabling formation of esters, amides, and anhydrides. Common examples include acetyl chloride and benzoyl chloride, which are employed to prepare acetylated derivatives, benzamides, and benzoates in pharmaceutical, polymer, and fragrance chemistry.

Safety: Acyl chlorides are corrosive and moisture-sensitive. They release corrosive hydrogen chloride upon contact with water and air. They should be handled in fume hoods with appropriate PPE, under dry conditions, and stored in tightly closed containers.