多胺基烷基酰胺生成机理的量子化学研究

用量子化学方法研究了丙酸与多乙烯多胺缩合反应机理。采用AM1方法全优化计算了丙酸多胺盐及其质子化盐的几何构型、电子结构以及酸催化下的亲核加成和消除反应的机能曲线，求得该两步反应的活化能分别为6.258kJ/mol和206.15kJ/mol。消除反应是速度控制步骤。发现质子化后丙酸羰基碳原子上的净电荷增大，前线分子轨道能级差减小，前线分子轨道间相互作用增强，表明酸催化大大增强反应活性。

Quantum chemistry applied to condensation mechanism of formation of alkyl polyethyleneamide

Quantum chemistry is applied to the study of condensation mechanism of the reaction between propionate acid and polyethylene polyamine. It is found that the activation energy is increased remarkably by acid catalyst. Nucle-ophilic addition and elimination are considered as the key steps of this reaction, and the rate of reaction is determined by the latter. By using AM1 method, equilibrium geometries, net charges and the potential curves of the reaction are obtained . The activation energies calculated for the nucleophilic addition and elimination are 6.258 kJ/mol and 206. 15 kJ/mol respectively. The results indicate that protonation of O(3) atom lead to an increase of charge on C(2), N( 12) and smaller gap between the HOMO and LUMO. This suggests the interaction between the frontier orbitals is enhnced by protonation. In this case, acid catalyst plays an important role in the reaction.