Carboxylic anhydride

A compound with the grouping $\mathrm{R}-\mathrm{C}(=\mathrm{O})-\mathrm{O}-\mathrm{C}(=\mathrm{O})-R\prime$. A carboxylate-derived leaving group can be expelled during nucleophilic acyl substitution.

$(\mathrm{C}{\mathrm{H}}_3\mathrm{CO}{)}_2\mathrm{O}$. It can give a persistent low-temperature tetrahedral addition complex with a grignard reagent, allowing methyl-ketone isolation after aqueous work-up under controlled conditions.