Hydride Transfer and Rates of Transport Across Synthetic Membranes

这项由Maurice Kreevoy博士在有机动力学计划内进行的项目旨在更好地了解一种重要的有机反应，即氢化物转移。这个问题将通过计算详细的反应路径从理论上解决，也可以通过测量反应速率从实验上解决。这项工作意义重大，因为所研究的反应是酶催化的氧化还原反应的原型。借助于Truhlar PolyRate程序，将生成氢化物转移反应的多维势能面。利用具有最小作用隧穿的变分过渡态理论，模拟了实验观察到的速率与平衡常数之间的关系、氢同位素效应的大小以及氢同位素效应与平衡常数之间的关系。在本项目的第二部分中，我们将研究1-苄基-3-氰基喹啉离子与10-甲基-9，10-二氢吖啶的氢化物转移反应的速率常数、一级动力学同位素效应和平衡常数与溶剂的关系。本研究的目的如下：建立和测试反应模型，以便于确定动态溶剂对反应活性的影响；确定与这种影响成比例的参数；并将其与当前的动态溶剂效应的理论和其他实验方法进行比较。动态溶剂效应是那些在传统的准平衡过渡态理论中无法解释的效应。

This project by Dr. Maurice Kreevoy within the Organic Dynamics Program is aimed at a better understanding of an important organic reaction known as hydride transfer. The problem will be approached theoretically by calculation of the detailed reaction pathway, and also experimentally by the measurement of reaction rates. This work is quite significant in that the reaction to be studied is a prototype for enzyme catalyzed oxidation-reduction reactions. With the aid of the Truhlar POLYRATE program, a multi-dimensional potential surface will be generated for the hydride transfer reaction. Using variational transition state theory with least-action tunneling, it will be used to mimic the experimentally observed relationship between rate and equilibrium constants, the magnitude of primary and secondary hydrogen isotope effects, and the relation between primary isotope effects and equilibrium constants. In the second part of this project, the solvent dependence of the rate constant, primary kinetic isotope effect, and equilibrium constant of the model hydride transfer reaction between 1-benzyl-3-cyano- quinolinium ion and 10-methyl-9,10-dihydroacridine will be studied. The object of this investigation is as follows: to establish and test a model for the reaction that will facilitate the identification of dynamic solvent effects on reactivity; to determine a parameter proportional to such effects; and to compare it with current theory and other experimental measures of dynamic solvent effects. Dynamic solvent effects are those that are not accounted for in conventional, quasi-equilibrium, transition state theory.