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首页> 外文期刊>Computational & theoretical chemistry >Theoretical study of the mechanism and regioselectivity of the alkylation reaction of the phenoxide ion in polar protic and aprotic solvents
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Theoretical study of the mechanism and regioselectivity of the alkylation reaction of the phenoxide ion in polar protic and aprotic solvents

机译：酚类离子烷基化反应在极性质子和非质子溶剂中的烷基化反应机理和区域选择性的理论研究

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Alkylation of the phenoxide ion in the solution phase can take place on the oxygen atom (O-alkylation) and the carbon atoms of the aromatic ring in the ortho- and para-positions (C-alkylation). The reaction outcome depends on the alkylating molecule and the solvent. This work presents a density functional theory calculation (X3LYP and M08-SO functionals) of the possible reaction pathways for alkylation of phenoxide ions with ethyl chloride in the following solvents: water, methanol, and dimethyl sulfoxide. The solvent effect was included through the SMD and PCM models. Our results pointed out that O-alkylation was much more favorable than C-alkylation in the gas phase. Solvent effect favors C-alkylation, although it was unable to change the reactivity preference of O-alkylation, even in aqueous solution. Alkylation on the meta-carbon atom corresponded to a second-order saddle point and was the most unfavorable pathway. The calculations indicated that only O-alkylation would be observed, with an activation free energy of 23.6 kcal mol(-1) in dimethyl sulfoxide solution, in good agreement with the experimental barrier of 20.8 kcal mol(-1).
机译：在溶液相中的苯氧化离子的烷基化可以在氧原子（O-烷基化）和芳环中的芳环（C-烷基化）中进行芳环的碳原子。反应结果取决于烷基化分子和溶剂。该工作呈现了可能的反应途径的密度函数理论计算（X3LyP和M08-所以功能），其在下列溶剂中用乙酰氯烷基化离子烷基化：水，甲醇和二甲基亚甲醚。通过SMD和PCM模型包括溶剂效应。我们的结果指出，O-烷基化比气相中的C-烷基化更有利。溶剂效应优化C-烷基化，尽管即使在水溶液中也无法改变O-烷基化的反应性偏好。在荟萃碳原子上的烷基化对应于二阶鞍点，是最不利的途径。该计算表明，仅观察到O-烷基化，在二甲基亚砜溶液中具有23.6kcal摩尔（-1）的活化能量，与20.8kcal摩尔（-1）的实验屏障很好。

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