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Anhydrides may be symmetrical, mixed, or cyclic; common preparation routes include combining an acyl chloride with a carboxylate, dehydrating carboxylic acids, and closing a dicarboxylic acid into a ring. Their carbonyls are electrophilic, and carboxylate is the leaving group. In the central substitution mechanism, nucleophilic attack forms a tetrahedral intermediate, which then collapses to restore the carbonyl. Reaction partners determine the outcome: hydrolysis gives carboxylic acids, alcoholysis gives an ester and a carboxylic acid, and aminolysis gives an amide. Organometallic reagents, hydride reagents, and Friedel–Crafts conditions provide additional pathways. The lesson also addresses identification, naming, applications, and safe handling.