DFT Study On The Mechanisms Of N-alkylation Reactions Of Aniline

In present paper, respectively, N-Phenylpyrrolidine formation mechanism based on the reaction of phenylamine with 1,4-butanediol and mechanism of N-ethylaniline formation from aniline and ethanol are studied by means of the density functional method (DFT).The mechanisms of these N-alkylation reactions are discussed in detail.Theoretical Studies on the N-Phenylpyrrolidine Formation Mechanism Based on the Reaction of Phenylamine with 1,4-ButanediolThe reaction mechanism of phenylamine reacting with 1,4-butanediol to give N-phenylpyrrolidine was investigated with traditional transition state theory. Based on the experimental results, two reaction channels were discussed. The geometries of their reactants, products, intermediates and transition states were optimized. The possible transition state and activation energy were determined by vibrational analysis and IRC verification. And finally, the main reaction channel was given.DFT Theoretical Study on Mechanism of N-ethylaniline Formation from Aniline and EthanolThe mechanism and related reaction channels in the N-alkylation of aniline were studied by DFT calculations at the B3LYP/6-31G** level. Some possible transition states were theoretically predicted and verified by the vibration frequency analysis as well as the calculations of intrinsic reaction coordinates (IRC).Furthermore, the related reaction barriers were evaluated by the calculation of single point energy at the MP2/6-31G** level and zero-point energy(ZPE) corrections at the B3LYP/6-31G** level. Thus, it is concluded that the reaction might go through three channels and the main channel is channel III: ethanol is dehydrogenated to ethanal by the catalyst, then the formed ethanal reacts with aniline to form N=C intermediate via dehydration. Finally, N=C intermediate is hydrogenated to the product.