Tsuchida Noriko, Satou Harumi, Yamabe Shinichi
Department of Chemistry, Nara University of Education; Takabakake-cho, Nara 630-8528, Japan.
J Phys Chem A. 2007 Jul 19;111(28):6296-303. doi: 10.1021/jp068051r. Epub 2007 Jun 20.
Density functional theory calculations were conducted on the title reactions with explicit inclusion of a variety of water molecules, H-CO-NMe2+MeOH+(H2O)n-->H-CO-OMe+HNMe2+(H2O)n. Geometries of transition states, reactant-like complexes and product-like ones were determined by the use of RB3LYP/6-31G(d) SCRF=dipole. Concerted paths were examined with n=0-3. Their Gibbs activation energies are larger than the experimental value. Stepwise paths were also investigated with n=2-4. The n=4 model has the energy close to the experimental value. However, when the catalytic water molecules were added to the n=4 one, the stepwise path was switched to the concerted one. A systematic comparison of the concerted path with n=2+1, 2+2, 2+3, 2+4, 2+5, 2+4+4, and 2+5+5 models was made, and the water-dimer based reaction path was found to be most favorable. The contrast between the concerted path of the amide solvolysis (and hydrolysis) and the stepwise one of the ester hydrolysis was discussed in terms of the frontier-orbital theory.
对标题反应进行了密度泛函理论计算，明确包含了各种水分子，即H-CO-NMe2+MeOH+(H2O)n→H-CO-OMe+HNMe2+(H2O)n。通过使用RB3LYP/6-31G(d) SCRF=偶极来确定过渡态、反应物类似络合物和产物类似络合物的几何结构。对n = 0 - 3的协同路径进行了研究。它们的吉布斯活化能大于实验值。还对n = 2 - 4的分步路径进行了研究。n = 4模型的能量接近实验值。然而，当将催化水分子添加到n = 4模型中时，分步路径转变为协同路径。对n = 2+1、2+2、2+3、2+4、2+5、2+4+4和2+5+5模型的协同路径进行了系统比较，发现基于水二聚体的反应路径最有利。根据前沿轨道理论讨论了酰胺溶剂解（和水解）的协同路径与酯水解的分步路径之间的对比。
