0 PhOCH,C- NH CH CH COOH Acid Derivatives acylated. mnactive enzyme All can be converted to the carboxylic acid by acidic or basic hydrolysis. Esters and amides common in nature. -0-R C一NH R一C=N acid halide anhydride ester amide nitrile Condensed structure:RCOX (RCO).O RCO,R' RCONH, RCN Copyright2005 Pearson Prentice Hall,Inc. Chapter 21 2Chapter 21 2 Acid Derivatives • All can be converted to the carboxylic acid by acidic or basic hydrolysis. • Esters and amides common in nature. =>