Department of Organic Chemistry, Research Building Jeroni Muñoz, University of Valencia, Dr. Moliner 50, ESP-46100 Burjassot, Valencia, Spain.
Universidad Andres Bello, Facultad de Ciencias Exactas, Departamento de Ciencias Químicas, Computational and Theoretical Chemistry Group, Av. República 498, 8370146 Santiago, Chile.
Org Biomol Chem. 2019 Sep 21;17(35):8185-8193. doi: 10.1039/c9ob01589b. Epub 2019 Aug 27.
Aromatic nucleophilic substitution (SAr) reactions of non-electrophilically activated benzenes have been studied within the Molecular Electron Density Theory (MEDT) at the B3LYP/6-311+G(d) computational level. These reactions, taking place through a one-step mechanism, present a high activation Gibbs free energy, ΔG = 31.0 kcal mol, which decreases to 22.1 kcal mol in the intramolecular process. A topological analysis of the electron localisation function along the reaction paths permits establishing the non-concerted nature of these SAr reactions. A series of unstable structures, with similar electronic structures to those of Meisenheimer intermediates, are characterised. The present MEDT study makes it possible to establish that even these one-step SAr reactions involving only two single bonds are non-concerted processes.
非亲电活化苯的芳环亲核取代（SAr）反应已在分子电子密度理论（MEDT）中，在 B3LYP/6-311+G(d)计算水平上进行了研究。这些反应通过一步机制发生，具有较高的活化吉布斯自由能ΔG=31.0 kcal mol，而在分子内过程中降低至 22.1 kcal mol。沿反应路径的电子定域函数的拓扑分析允许确定这些 SAr 反应的非协同性质。一系列具有类似于 Meisenheimer 中间体的电子结构的不稳定结构被表征。本 MEDT 研究使得有可能确定，即使是这些仅涉及两个单键的一步 SAr 反应也是非协同过程。
