This study investigates the solvation effect on the decarboxylation of -phthalic acid using quantum calculations with a continuum solvation model with varying dielectric constants. Two mechanisms were considered: with and without a catalytic water molecule. The latter had a lower reaction barrier. Increasing the dielectric constant facilitates the hydrogen transfer but impedes C–C bond breaking in both mechanisms. The change in the free energies due to solvation of the transition state is generally greater than the reactant. The reaction barrier predominantly increased with the dielectric constant in both mechanisms. The Kirkwood slope estimated by plotting estimated rate constants against the Kirkwood polarity parameter, (, was close to the experimental value (only for the assisted mechanism). The simulations indicate that the solvation effect on the decarboxylation rate can be elucidated by considering the effect of dielectric constant of supercritical water.

中文翻译：

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改变溶剂介电常数超临界水对邻苯二甲酸脱羧作用的计算研究

本研究使用具有不同介电常数的连续溶剂化模型的量子计算研究了溶剂化对邻苯二甲酸脱羧的影响。考虑了两种机制：有和没有催化水分子。后者的反应势垒较低。增加介电常数有利于氢转移，但会阻碍两种机制中的 C-C 键断裂。由于过渡态溶剂化而导致的自由能变化通常大于反应物。在两种机制中，反应势垒主要随着介电常数的增加而增加。通过绘制估计速率常数与柯克伍德极性参数 (，接近实验值（仅适用于辅助机制）来估计柯克伍德斜率。模拟表明，可以通过考虑溶剂化对脱羧速率的影响来阐明溶剂化对脱羧速率的影响）超临界水的介电常数。