Effect of 4-[2-(dimethylamino)ethyl]morpholine, and N, N-dimethylbenzylamine on urethane formation - A theoretical study

The formation of urethane through the reaction between phenyl isocyanate (PhNCO)-butan-1-ol (BuOH) was investigated. The reactions, without and in the presence of 4-[2-(dimethylamino)ethyl]morpholine (DMAEM), and N,N-dimethylbenzylamine (DMBA) catalysts have been examined using the BHandHLYP/6-31G(d) and G3MP2BHandHLYP levels of theory. The SMD implicit solvent model has been applied to simulate the solvent effect. As the reaction mechanism contains protonation steps, therefore the proton affinity for the selected catalysts has also been determined. Furthermore, the two selected catalysts have been compared. DMAEM contains different cyclic and aliphatic nitrogen functional groups, while the DMBA contains only aliphatic catalytic site. All in all, the presence of the catalysts significantly changes the reaction mechanism and the energetics of the reaction compared to the catalyst-free case. It was found that the cyclic amine has a slightly greater effect on the energetics of the catalytic reaction compared to the aliphatic one.