Conversion to anhydrides [RCO2(–)]

Conversion to anhydrides [RCO2‾] Definition:

 

Addition of a carboxylic acid to an acid chloride results in the anhydride.

 

 

Conversion to anhydrides [RCO2‾] Explained:

 

Treatment of an acid chloride and a carboxylate ion is the method for preparation of an anhydride. This reaction proceeds via an addition-elimination reaction, which mechanism is similar to the conversion of acyl chloride to carboxylic acid, ester, amide. Actually, the first two steps are analogous but the third one does not exist. This reaction is a useful method for preparation symmetrical or unsymmetrical anhydrides.