Physical Chemistry Division, National Chemical Laboratory, Pune 411 008, India.
J Phys Chem A. 2011 Sep 15;115(36):10211-7. doi: 10.1021/jp205181e. Epub 2011 Aug 22.
The rate constants of a bimolecular Diels-Alder reaction in binary mixtures of ionic liquids prepared in molecular solvents were analyzed to investigate the effect of viscosity of the medium and solvent effect. In this connection, we have carried out the Diels-Alder reaction of anthracene 9-carbinol with N-ethyl maleimide in binary mixtures of pyridinium-based ionic liquids, 1-butyl-pyridinium tetrafluoroborate, 1-butyl-3-pyridinium tetrafluoroborate, and 1-butyl-4-methyl pyridinium tetrafluoroborate in water, methanol, and chloroform at 298.15 K. The rates of reaction decreased, caused by gradually increasing the volume fraction of ionic liquids in solvents for all three ionic liquids. The kinetic results demonstrate a successful application of the pairwise interaction model built upon the concept of enforced hydrophobic hydration. A temperature-dependent study of kinetics of the Diels-Alder reaction was carried out in the binary mixtures of ionic liquids in water and was explained by the entropy-enthalpy compensation effect based upon activation parameters. Kinetics of the Diels-Alder reaction in highly aqueous medium was noted to be entropically driven.
在分子溶剂中制备的离子液体二元混合物中双分子 Diels-Alder 反应的速率常数进行了分析，以研究介质粘度和溶剂效应的影响。为此，我们在吡啶基离子液体二元混合物中进行了蒽 9-醇与 N-乙基马来酰亚胺的 Diels-Alder 反应，1-丁基-吡啶四氟硼酸盐、1-丁基-3-吡啶四氟硼酸盐和 1-丁基-4-甲基吡啶四氟硼酸盐在水、甲醇和氯仿中于 298.15 K 下进行。反应速率随着溶剂中离子液体体积分数的逐渐增加而降低，对于所有三种离子液体都是如此。动力学结果成功地应用了基于强制疏水水合概念构建的成对相互作用模型。在水和离子液体的二元混合物中进行了 Diels-Alder 反应动力学的温度依赖性研究，并根据基于活化参数的熵焓补偿效应进行了解释。在高水介质中，Diels-Alder 反应的动力学被证明是熵驱动的。
