Theoretical study of a reaction path via a hydrogen-bonded intermediate for the alkaline hydrolysis of esters in the gas phase
Theoretical study of a reaction path via a hydrogen-bonded intermediate for the alkaline hydrolysis of esters in the gas phase
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酯气相碱解氢键中间体反应路径的理论研究
DOI：
10.1039/p29920001629
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发表时间：
1992
期刊：
影响因子：
--
通讯作者：
K. Hori
中科院分区：
文献类型：
--
作者：
K. Hori
乙酸甲酯在气相中的碱水解反应分为两步进行。第一步是四面体中间体的形成，第二步是其分解。本文通过从头算分子轨道计算讨论了第二步反应的机理。释放乙酸和甲醇根阴离子的路径是能量上不利的路径，正如它们的pKa值所容易预测的那样。最终产物乙酸根离子和甲醇比四面体中间体更稳定。我们发现一个氢键乙酸酯-甲醇分子作为中间体，这是更稳定的四面体中间体和最终产品。寻找并找到了连接四面体中间体和氢键中间体的过渡态。通过过渡态的路径的活化能计算为8.7 kcal mol-1（MP2/6-31 + G**//RHF/6- 31 G：5.8）。这一机理很好地解释了酯在气相中的碱性水解。
Two steps are considered for the alkaline hydrolysis of methyl acetate in the gas phase. The first step is the formation of a tetrahedral intermediate and the second is its decomposition. In the present paper, the mechanism for the second step is discussed by using ab initio molecular orbital calculations. The path releasing acetic acid and methoxide anion is an energetically unfavourable path, as easily expected by their pKa values. The final products, acetate ion and methanol, are more stable than the tetrahedral intermediate. We found a hydrogen-bonded acetate–methanol molecule as the intermediate that was more stable than both the tetrahedral intermediates and the final products. We searched and found the transition state which connected the tetrahedral intermediate with the hydrogen-bonded intermediate. The activation energy of the path through the transition state was calculated to be 8.7 kcal mol–1(MP2/6–31 + G**//RHF/6–31G: 5.8). This mechanism explains well the alkaline hydrolysis of esters in the gas phase.