Reactive Intermediates and Reaction Mechanisms

本课程将探讨涉及不稳定化学物种(如多自由基和两性离子)的形成和随后的反应活性的反应的基本动力学。同时使用ESR、核磁共振和光学瞬变光谱将提供基本的机理信息，这些信息将有助于从理性的角度设计涉及高活性中间体的化学反应。将研究的内容包括：(1)二甲基富烯及其相关试剂对羟基烯丙基的捕获；(2)脱节双自由基的生成；(3)四亚甲基苯的自旋多重性和反应性的确认；(4)基于脱位的四亚甲基乙烷的双自由基多重态间隙的调节；(5)基于两个二甲基杂环通过苯环偶联的多自由基的合成；以及(6)稳定双自由基的合成和表征。这些化学体系将作为具有实际重要性的光学、导电和磁性材料的模型。来自有机动力学项目的这笔资金支持耶鲁大学杰罗姆·A·伯森教授的继续工作。伯森教授和他的研究小组将探索非常活跃的物种，称为双自由基，它是在化学过程的中间阶段形成的，通常只有几十亿分之一秒的寿命。有关这些中间体的信息可能使设计具有重要化学和技术性质的全新分子成为可能。从这项工作中得出的概念对于理解分子如何导电和与光相互作用至关重要，也将有助于设计可用于使光纤以光脉冲的形式在长距离更快、更有效地传输信息的化学系统。

The basic kinetics of reactions which involve the formation and subsequent reactivity of unstable chemical species such as multiradicals and zwitterions will be probed. The concurrent use of ESR, NMR, and optical transient spectroscopy will provide basic mechanistic information which will aid in designing chemical reactions involving highly reactive intermediates from a rational viewpoint. The research topics to be investigated include: (1) the trapping of oxyallyls via dimethylfulvene and related agents; (2) production of disjointed biradicals; (3) confirmation of the spin multiplicity and reactivity of tetramethylene benzene; (4) adjustment of the multiplet gap of biradicals based upon disjointed tetramethyleneethanes; (5) synthesis of polyradicals based upon coupling of two dimethyleneheterocycles via a benzene ring; and (6) synthesis and characterization of stable biradicals. These chemical systems will serve as models for materials with optical, conducting, and magnetic properties of practical importance. %%% This grant from the Organic Dynamics Program supports the continuing work of Professor Jerome A. Berson at Yale University. Professor Berson and his research group will probe very reactive species, called diradicals, which are formed in the intermediate stages of chemical processes and often live for only a few billionths of a second. Information about these intermediates may make it possible design totally new molecules with important chemical and technical properties. The concepts to be derived from this work are critical to the understanding of how molecules conduct electricity and interact with light, and will also aid in the design of chemical systems which can be used to make optical fibers to transmit information in the form of light pulses faster and more efficiently over long distances.