Ammonolysis of morpholine-2,5-diones: participation of the primary amide group. Part 2

The ammonolysis of three morpholine-2,5-dione derivatives was investigated and the mechanism ascertained by kinetic studies and theoretical calculations. The kinetics, followed by high-performance liquid chromatography analysis, evidenced the presence of two intermediates, which were isolated and characterized. The ammonolysis occurs with a complex mechanism involving two consecutive reactions followed by two parallel ones. The second step of the whole reaction involves an anchimeric assistance of the primary amide group. The pseudo-first-order rate constants were calculated by appropriate equations, which describe the single steps of the process. Computational density functional theory investigations of vicinal primary amide group participation were performed using a model compound, and the transition states were generated. The theoretical calculations evidenced the essential role exerted by ammonia, which acts as a proton transfer. Copyright © 2011 John Wiley & Sons, Ltd.