substitution reaction, but also a cleavage reaction because it splits an anhydride in two. In this
reaction, ammonia acts as the nucleophile, one of the carbonyl carbons acts as the electrophile, and
a carboxylic acid is the leaving group.
Figure 9.13. Nucleophilic Acyl Substitution: Anhydride to Amide and Carboxylic AcidAlcohols can also act as nucleophiles toward anhydrides; this nucleophilic substitution reaction will
result in the formation of esters and carboxylic acids, as shown in Figure 9.14.
Figure 9.14. Nucleophilic Acyl Substitution: Anhydride to Ester and Carboxylic AcidAnhydrides can also be reverted to carboxylic acids by exposing them to water, as shown in Figure
9.15. For these reactions to be useful, the anhydride should be symmetric; otherwise, one forms a
mixture of products.