Neutral Products from Ionic Reactions in the Gas Phase

在化学系有机动力学项目的支持下，托马斯H.加州大学滨江分校的莫顿研究了正离子与中性分子在气相中反应形成的中性产物。气相离子化学已经被许多研究小组使用质谱技术进行了广泛的探索，但是关于正离子的结构和反应性的许多关键问题只能通过观察它们与亲核试剂或布朗斯台德碱反应的不带电产物来解决。本文介绍了三种从气态阳离子反应中分离中性产物的技术：（1）含两个氚原子的有机分子的核衰变。b-粒子从其中一个原子核中射出，产生一个仍然保留单个氚的离子;因此，其离子-分子反应的中性产物可以通过其剩余的放射性来检测。（2）电子轰击流（EBFlow）反应堆中作为靶的C1和C2卤烃。除了其电离产物的潜在环境相关性之外，由于卤素原子的损失而产生的偶电子离子可以与各种分子反应以产生中性物，其异构体分布将回答关于在没有溶剂的情况下立体化学的动力学控制的因素的问题，以及（3）将单原子和双原子离子注入反应气体中。物理学家在加速器中广泛使用高强度离子源，首先产生负离子，然后从它们中剥离电子以产生正离子。这种来源的适应化学实验增加了双分子反应的范围，可以由有机化学家研究。在化学系的有机和高分子化学计划支持教授托马斯H。他提出了几个关于有机反应性的假设，这些假设可以通过观察气相中离子反应的中性产物来检验。这些包括各种关于刘易斯酸碱化学的基本问题。理解立体选择性的起源和提高化学反应的产率代表了有机化学研究的两个主要方面。莫顿教授的工作将描述如何利用离子-分子反应来提供以前没有制备过的有用数量的分子，或者提供可以更有效地从气体反应混合物中形成和回收的产物。例子包括用于核医学的放射性标记化合物和尚未以任何其他方式合成的含氟分子。这项工作将为研究生和本科生提供几个重要的化学领域的培训：有机反应机制，实验物理化学，计算和质谱。

With the support of the Organic Dynamics Program in the Chemistry Division, Professors Thomas H. Morton at University of California- Riverside explores the neutral products formed by reactions of positive ions with neutral molecules in the vapor phase. Gas phase ion chemistry has been extensively explored by many research groups using mass spectrometric techniques, but a number of crucial questions about the structures and reactivities of positive ions can be addressed only by looking at the electrically uncharged products of their reactions with nucleophiles or Bronsted bases. Three techniques are described for producing isolable yields of neutral products from gaseous cationic reactions: (1) Nuclear decay of organic molecules containing 2 tritium atoms. b-Particle ejection from one of those nuclei yields an ion that still retains a single tritium; hence, neutral products of its ion-molecule reactions can be detected by virtue of their remaining radioactivity, (2) Electron impact on C1 and C2 halocarbons as targets in an Electron Bombardment Flow (EBFlow) reactor. Apart from the potential environmental relevance of the products of their ionization, the even-electron ions resulting from loss of a halogen atom can react with a variety molecules to give neutrals, whose isomeric distributions will answer questions regarding the factors that underlie kinetic control of stereochemistry in the absence of solvent, and (3) Injection of monatomic and diatomic ions into reactive gases. High intensity ion sources are extensively used by physicists in accelerators that first produce negative ions and then strip electrons from them to make positive ions. Adaptation of such a source to chemical experiments increases the scope of bimolecular reactions that can be studied by organic chemists.The Organic and Macromolecular Chemistry Program in the Chemistry Division supports Professor Thomas H. Morton at University of California- Riverside who proposes several hypotheses regarding organic reactivity that can be tested by looking at neutral products from ionic reactions in the gas phase. These include a variety of fundamental questions about Lewis acid-base chemistry. Understanding the origin of stereoselectivity and increasing the yield of chemical reactions represent two major aspects of organic chemical research. Professor Morton's work will describe ways in which ion-molecule reactions might be harnessed to provide useful quantities of molecules that have not been previously prepared or give products that can be more efficiently formed and recovered from gaseous reaction mixtures. Examples include radio labelled compounds used for nuclear medicine and fluorine-containing molecules that have not been synthesized in any other way. This work will provide training for graduate and undergraduate students in several important areas of chemistry: organic reactions mechanisms, experimental physical chemistry, computations, and mass spectrometry.