20-3 Chemistry of Carboxylic Anhydrides The leavinggroucabylte nsted of a halide. Aeee ash dde 0 0H,+o yyndesndergsmhiceadtong 20-4 Chemistry of Esters Esters are alkyl alkanoates 0 ca eae0gogfieeoocntgpaiotwhou bea9emaoesmr8eaenuceophlesarem enbr8oecaae 5tesMpemetenrhpandpbyboogcalrolesnthe 89 roethane as a cleaning aheromoheestesaeusedassotenesoastcaesjo 4 4 20-3 Chemistry of Carboxylic Anhydrides Carboxylic anhydrides are named by adding the term “anhydride” to the acid name (or names, if a mixed anhydride). This method also applies to cyclic derivatives. The reactions of anhydrides with nucleophiles are the same as for alkanoyl halide, only less vigorous. The leaving group is a carboxylate instead of a halide. Cyclic anhydrides undergo similar reactions which lead to ring opening. Alkanoyl halides are difficult to store for extended periods without undergoing hydrolysis from atmospheric moisture. Anhydrides, although less reactive towards nucleophiles, are more stable and many are commercially available. For these reasons, anhydrides are often preferred for the preparation of many carboxylic acid derivatives. 20-4 Chemistry of Esters Esters are alkyl alkanoates. Esters are named alkyl alkanoates, and the ester grouping as a substituent is called “alkoxycarbonyl.” Cyclical esters are named oxa-2-cycloalkanone (common name, lactone). The common name is preceded by α,β,γ,etc., depending upon ring size. Esters are prevalent in plants and play biological roles in the animal kingdom, often as pheromones. (Z)-7-dodecenyl acetate is a component in the pheromone mixture of several species of moths, as well as the mating pheromone of the elephant. In industry, lower esters such as ethyl acetate and butyl acetate are used as solvents. Butyl butanoate has replaced trichloroethane as a cleaning solvent in the electronics industry. Higher nonvolatile esters are used as softeners (plasticizers) for brittle polymers