20.1 () Carboxylic aci id anhydrides bear two acyl groups on oxygen, as in RCOCR. They are named as derivatives of carboxylic acids. Q CH:CH2CHCOH CH,CH,CHCOCCHCH_CH3 C6H C. C. 2-Phenylbutanoic acid 2-Phenylbutanoic anhydride (c) Butyl 2-phenylbutanoate is the butyl ester of 2-phenylbutanoic acid. CH,CH,CHCOCH,CH,CH2CH