Abstract

Trends in the influence of a proton-donor solvent on the reaction of aminolysis of ethylene carbonate, which proceeds through concerted and stepwise mechanisms, are studied. The study is based on kinetic data of model reactions in alcohol solutions and results of DFT quantum chemical calculations of reaction paths that involve hydrogen-bonded transition states and intermediates containing different numbers of solvent molecules in the proton-transfer and stabilization cycles. The calculated data on the activation energies of the reaction, which includes cycles of different sizes, indicate that the stepwise mechanism is preferable compared to the concerted one when the reaction proceeds in methanol. The activation barrier of the stepwise path of the reaction is lower by 2.9 kcal/mol than that for the concerted path. Only the proton-transfer cycle is essential for the progress of the reaction, and the presence of a stabilization cycle does not lead to a decrease in the activation barrier.

中文翻译：

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试剂在液相反应动力学和催化中的分子组织：XIII。涉及溶剂分子的环转移态在醇介质中环碳酸酯的氨解机理中

摘要

研究了质子供体溶剂对碳酸亚乙酯氨基分解反应的影响的趋势，该反应通过协同和逐步的机理进行。该研究基于醇溶液中模型反应的动力学数据以及反应路径的DFT量子化学计算结果，该反应路径涉及氢键合的过渡态以及质子转移和稳定循环中包含不同数量溶剂分子的中间体。关于反应的活化能的计算数据，包括不同大小的循环，表明当反应在甲醇中进行时，与一致的机理相比，逐步机理是优选的。反应的逐步路径的活化势垒比一致路径的活化势垒低2.9 kcal / mol。