14.17 : 酸酐的反应

The reactions of acid anhydrides are similar to those of acid chlorides and follow the general mechanism of nucleophilic acyl substitutions.

The only difference is that the carboxylate ion is the leaving group with acid anhydrides, whereas the chloride ion is the leaving group with acyl chloride.

Accordingly, hydrolysis of anhydrides gives two equivalents of carboxylic acids. On the other hand, alcoholysis of anhydrides produces esters and carboxylates.

Similarly, anhydrides undergo aminolysis, where they react with ammonia, forming primary amides. Primary amines give secondary amides, and secondary amines give tertiary amides.

Reduction of anhydrides with lithium aluminum hydride gives primary alcohols. Similarly, the Grignard reagent reduces anhydrides to tertiary alcohols.

Additionally, anhydrides can react with aluminum trichloride in benzene to acylate the benzene ring.

Notably, most of these reactions involve losing half of the anhydride molecule as a leaving group, representing a poor atom economy.