Efficient synthesis of symmetrical and unsymmetrical acyclic imides catalyzed by reusable 12-tungstophosphoric acid under thermal conditions and microwave irradiation

An efficient and environmentally friendly procedure has been developed for the synthesis of symmetrical and unsymmetrical acyclic imides by the reaction of nitriles with acyclic anhydrides in the presence of catalytic amounts of 12-tungstophosphoric acid (H3PW12O40) under thermal conditions and microwave irradiation. It was found that microwave improves the yields and significantly reduces the reaction times. Furthermore, the catalyst could be recovered and reused several times without decrease in its activity.