Rational Reaction Promoter and Ligand Design in Synthesis

非技术性：在这个由化学系化学催化计划资助的项目中，路易斯维尔大学的杰拉尔德·B·哈蒙德教授正在提高化学合成中离子反应的效率。离子反应，根据定义，包括带电物种，是化学合成中最常见的反应。这类合成在医药、材料、农用化学品等许多相关领域发挥着至关重要的作用。该项目的更广泛影响包括培训博士后研究员以及研究生和本科生，并通过由知名拉美裔美国化学家参加的研讨会以及与拉丁美洲教师的科学合作来增加拉美裔美国学生的招聘机会。这项拟议的工作对制造业产生了广泛的影响，因为它使人们能够容易地获得能够简化化学合成的催化剂和促进剂。技术：离子是否分离或相互关联取决于溶剂的极性。在低介电常数的溶剂中，离子通常以离子对的形式存在。成对工作离子的反应性被认为低于相应的自由离子，尽管还没有系统的方法来从定量或数学的角度理解离子配对在离子反应中的影响。在大多数离子反应的理论和实验研究中，反离子被简单地忽略了。这个项目支持的假设是，离子反应中的过渡态结构比起始离子对的尺寸更大，并被反离子扭曲。将开展的工作应导致反应促进剂和配体的设计，以减少离子配对的阻碍效应，这反过来可能导致离子反应中更高的反应活性。本研究提供了广泛适用的反应促进剂、聚合物键合反应促进剂、手性反应促进剂以及手性超强Bronsted酸。此外，体积较大的配体将用于阳离子金催化和其他阳离子金属催化--无论有没有反应促进剂--最终目标是引入新一代阳离子金属催化剂，在温和的反应条件下，具有前所未有的ppm水平的反应活性。英国牛津大学的合作者罗伯特·佩顿教授利用计算化学技术对典型反应体系中的离子配对进行了实验研究，并开发了测量离子对中离子之间的距离以及离子大小的计算方法。

Nontechnical: In this project, funded by the Chemical Catalysis program of the Chemistry Division, Professor Gerald B. Hammond, of the University of Louisville, is improving the efficiency of ionic reactions in chemical synthesis. Ionic reactions, involving by definition charged species, are the most common reactions used in chemical synthesis. Such synthesis plays a vital role in pharmaceuticals, materials, agrochemicals and many other related fields. The broader impacts of this project involve training postdoctoral fellows and graduate and undergraduate students, and enhancing the recruitment opportunities of Hispanic American students through symposia featuring high-profile Hispanic-American chemists, and scientific collaborations with Latin American faculty. The proposed work impacts the manufacturing industry broadly defined because it gives ready access to catalysts and promoters capable of streamlining chemical syntheses.Technical: Whether ions are separated or associated with each other depends on the polarity of the solvent. In low dielectric constant solvents, ions usually exist as ion pairs. The reactivity of a paired working ion is considered lower than the corresponding 'free' ion although there has been no systematic approach to understand, in quantitative or mathematical terms, the effect of ion pairing in ionic reactions. In most theoretical and experimental studies of ionic reactions, counterions are simply ignored. The hypothesis espoused in this project is that the transition state structure in an ionic reaction is bigger in size than the starting ion pair and is distorted by the counterion. The work to be carried out should lead to the design of reaction promoters and ligands that will reduce the hindrance effect of ion pairing, which, in turn, may lead to higher reactivity in ionic reactions. This research makes available broadly applicable reaction promoters, polymer-bound reaction promoters, and chiral reaction promoters, as well as chiral super strong Bronsted acids. In addition, bulky ligands are to be utilized in cationic gold catalysis and other cationic metal catalysis--with or without a reaction promoter--with the ultimate goal of ushering in a new generation of cationic metal catalyst with unprecedented reactivity at ppm level loadings under mild reaction conditions. Experimental investigations of ion pairing in typical reaction systems, and developing calculation methods to measure the distance between ions in an ion pair, as well as the size of ions, are performed using computational chemistry techniques by a collaborator, Professor Robert Paton, from Oxford University, England.