Chemistry of Carbanions

有机和高分子化学项目的资助 支持安德鲁教授的实验和理论研究 加州大学伯克利分校的Streitwieser， 分析碳负离子的化学结构和反应活性。 碳负离子是带负电荷的有机碎片 分子，如碳氢化合物，并作为瞬态发生 在各种各样的化学反应过程中， 实验室、人体和工业化学品 流程. 因此，碳负离子的化学反应性可能是 据说它决定了许多化学变化的路径。 Streitwieser博士的研究将包括测量 用氢研究弱碳酸的动力学酸度 同位素交换率，包括苯的钠水溶液 含锂和铯氢氧化物和环烃 环己基酰胺在环己胺中的溶液。 平衡酸度 研究将继续进行，特别是对二价阴离子和 碳负离子在THF中不稳定。 后者的实例包括 五氟苯和其它卤代烃。 在观察到芳基乙酸的第二pKa较低之后， 酸，浓度效应的测量将进行， 分析单盐和二盐的聚集效应。 理论工作将集中在从头计算的 碳负离子的电子结构和几何形状及其 锂和钠盐。 计算还将用于 估计碳负离子反应的过渡结构， 特别强调前面提到的系统，以及 金属化的腙、肟和亚胺， 立体化学性质还没有被很好地理解。

This grant in the Organic and Macromolecular Chemistry Program supports experimental and theoretical research by Prof. Andrew Streitwieser, University of California at Berkeley, aimed at analyzing the chemical structure and reactivity of carbanions. Carbanions are negatively charged fragments of organic molecules such as hydrocarbons and occur as transient intermediates during a wide variety of chemical reactions in the laboratory, in the body, and in industrial chemical processes. Thus, the chemical reactivity of carbanions may be said to determine the path of many chemical changes. Dr. Streitwieser's research will include measurements of kinetic acidities of weak carbon acids by the study of hydrogen isotope exchange rates, including benzene in aqueous sodium hydroxide and cyclic hydrocarbons with lithium and cesium cyclohexylamide in cyclohexylamine. Equilibrium acidity studies will be continued, particularly for dianions and for carbanions not stable in THF. Examples of the latter include pentafluorobenzene and other halogenated hydrocarbons. Following observations of low second pKa's for arylacetic acids, measurements of concentration effects will be made to analyze effects of aggregation of both mono- and di-salts. Theoretical work will focus on ab initio computations of electronic structures and geometries of carbanions and their lithium and sodium salts. Calculations will also be used to estimate the transition structures of carbanion reactions, with particular emphasis on the previously noted systems, and on metallated hydrazones, oximes, and imines whose important stereochemical properties are not yet well understood.