g Carboxylic acids are just one member of a class of acyl derivatives, RCOY where the acyl group is bonded to an electronegatives substituent .Y that can act as a leaving group in substitution reactions. Numerous acyl derivatives are possible, but we'll be concerned only with four of the more common ones in addition to carboxylic acids themselves acid halides, acid anhydrides, esters, and amidesOrganic Chemistry Organic Chemistry Xiamen Xiamen University University „ Carboxylic acids are just one member of a class of acyl derivatives, RCOY, where the acyl group is bonded to an electronegatives substituent -Y that can act as a leaving group in substitution reactions. Numerous acyl derivatives are possible, but we’ll be concerned only with four of the more common ones, in addition to carboxylic acids themselves: acid halides, acid anhydrides, esters, and amides