Acylchloriden

Acylchloriden, commonly known as acid chlorides, are a class of organic compounds with the general formula R-CO-Cl. The carbonyl carbon is highly electrophilic and the C–Cl bond is a good leaving group, making acyl chlorides among the most reactive carboxylic derivatives. They are typically colorless liquids or low-melting solids and are moisture sensitive, hydrolyzing rapidly in water to a carboxylic acid and hydrogen chloride. Common examples include acetyl chloride (ethanoyl chloride) and benzoyl chloride (benzoyl chloride).

Preparation: They are usually prepared by chlorinating carboxylic acids with reagents such as thionyl chloride (SOCl2), oxalyl chloride ((COCl)2), or phosphorus chlorides (PCl3, PCl5). The general equation: RCO2H + SOCl2 → RCOCl + SO2 + HCl.

Reactions: Acyl chlorides undergo nucleophilic acyl substitution. They react with water to give carboxylic acids, with alcohols to give esters, and with amines to give amides; with carboxylic acids they form mixed anhydrides. They may also react with Grignard reagents to yield tertiary alcohols after workup.

Uses: As versatile acylating agents in organic synthesis, they introduce acyl groups into alcohols and amines, enabling formation of esters and amides. They are used in the manufacture of pharmaceuticals, dyes, fragrances, and as intermediates in polymer and organic synthesis.

Safety: Handling requires a fume hood; they are corrosive and release HCl upon hydrolysis. They are reactive with moisture and may cause severe irritation to skin, eyes, and the respiratory tract. Proper storage under dry, inert conditions is recommended.