Transition States in Polar Solvents. A Kinetic Isotope Effect Study

这个项目由华盛顿大学的J. Kurz支持 由有机动力学计划，旨在更好地 了解溶剂分子在某些 取代反应。 这个问题将由 观察到的同位素反应速率的变化 替代。 调查将继续调查最近发生的 观察到的异常同位素对化学反应速率的影响 反应. 这些反常的同位素效应是对甲基 极性溶剂中的转移反应;它们似乎暗示， 在甲基转移到不带电荷的氧亲核试剂的过程中， 成键和溶剂化的变化是高度异步的。 在 为了适应这些数据，将进行一些修订， 要求：无论是当前的物理有机理论，或 动力学同位素解释的当前方法 方面的影响. 这些异常效应的起源将是 通过（a）整套同位素的测量来阐明 对已知存在的反应速率的影响 异常，以及模型反应的速率和平衡， (b)对可观察后果的理论估计 隐含的键合/溶剂化过程，以及（c） 过渡态力场的计算机建模， 对这些数据集进行定量解释所需的 同位素效应

This project by J. Kurz of Washington University is supported by the Organic Dynamics Program, and is aimed at a better understanding of the role of solvent molecules in certain substitution reactions. This problem will be investigated by the observed changes in the rate of the reactions upon isotopic substitution. Investigations will continue into the origins of the recently observed anomalous isotope effects on the rates of chemical reactions. These anomalous isotope effects are for methyl transfer reactions in polar solvents; they seem to imply that during methyl transfer to an uncharged oxygen nucleophile, changes in bonding and solvation are highly asynchronous. In order to accommodate these data, some revision will be required: either of current physical organic theory, or of current approaches to the interpretation of kinetic isotope effects. The origin of these anomalous effects will be elucidated by (a) measurements of complete sets of isotope effects on the rates of reactions that are known to present anomalies, and on the rates and equilibria of model reactions, (b) the theoretical estimations of observable consequences of the implied bonding/solvation asynchronies, and (c) the computer modeling of transition state force fields that is required for the quantitative interpretation of those sets of isotope effects.