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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Convergent Results from Experimental and Theoretical DFT Studies of the Intramolecular Rearrangement of Z-Hydrazones of 3-Acyl-1,2,4-Oxadiazoles
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Convergent Results from Experimental and Theoretical DFT Studies of the Intramolecular Rearrangement of Z-Hydrazones of 3-Acyl-1,2,4-Oxadiazoles

机译：实验和理论DFT研究的3-酰基-1,2,4-氧杂二唑Z-H的分子内重排的收敛结果

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摘要

A combined kinetic and theoretical study of the monocyclic rearrangements of heterocycles (MRH) has been carried out. The interconversion of the Z-hydrazone of 3-benzoyl-5-phenyl-1,2,4-oxadiazole into the corresponding triazole has been experimentally investigated in dioxane/water in the p~S+ range 5.5_5-13.9. The uncatalyzed region has been examined at the DFT level using a model system formed by the Z-hydrazone of 3-formyl-1,2,4-oxadiazole and one or two water molecules. The environmental effect of the solvent has been emulated using a continuum model (COSMO) approach. The kinetic data suggest a concerted process where the magnitude of the activation barrier is determined by the interplay of two opposite factors, that is, the nucleophilicity of the nitrogen atom and the acidity of the nitrogen-bonded protons. The computations indicate the existence of two multistep reaction pathways. When the solvent environment is taken into account, the preferred path, which involves two water molecules acting as a base, becomes a concerted highly asynchronous path, where the nucleophilic attack and the proton transfer occur not simultaneously but in the same kinetic step.
机译：进行了单环杂环重排（MRH）的动力学和理论的组合研究。在二恶烷/水中，在p〜S +范围为5.5_5-13.9的范围内，实验研究了3-苯甲酰基-5-苯基-1,2,4-恶二唑的Z into相互转化为相应的三唑。使用由3-甲酰基-1，2，4-恶二唑的Z- and和一个或两个水分子形成的模型系统，在DFT级别上检查了未催化区域。使用连续模型（COSMO）方法模拟了溶剂对环境的影响。动力学数据表明了一个协调的过程，其中激活势垒的大小取决于两个相反因素的相互作用，即氮原子的亲核性和与氮键合的质子的酸度。计算表明存在两个多步反应路径。当考虑到溶剂环境时，涉及两个水分子作为碱的优选途径成为协调一致的高度异步途径，亲核攻击和质子转移不是同时发生，而是在同一动力学步骤中发生。

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