Reaction Trajectories at Nonstereogenic Atoms

有机和高分子化学项目的资助 支持伊利诺伊大学Peter Beak教授的研究， 旨在确定原子运动的轨迹， 化学反应。 可以考虑反应轨迹 在最基本的信息中， 关于化学反应性的知识， 原子在分子中的排列为 了解分子结构及其与 化学反应性 然而，这项工作是针对 以确定过渡结构的几何形状 涉及非立体原子，迄今为止， 不可用. Beak博士及其同事将研究 在非立体异构杂原子上的反应， 内环限制试验。 在这种方法中， 原子Z的转移将通过以下研究来评估： 成键原子X和离去原子Y 是由一条链子连接起来的。 戒指所需的尺寸 协同内环分子内反应在转移 Z从Y到X限制了可用的反应几何形状。 如果 转移具有不能满足的几何要求 分子内的反应变成了分子间的反应。 这些 可能性将通过双标记、同位素 影响和动力学实验。 替代机制 涉及关联和分离步骤， 评估。 反应几何学的研究. 将产生氧、氮、卤素、氢和硫。 其他机制探针，包括取代基效应和 结构重组将用于提供机械 这些信息和相关反应。

This grant in the Organic and Macromolecular Chemistry Program supports research by Prof. Peter Beak, University of Illinois, aimed at determining the trajectories of atomic motion during chemical reactions. Reaction trajectories may be considered among the most fundamental sorts of information to be derived about chemical reactivity, and knowledge of the geometrical arrangements of atoms in molecules has provided the basis for understanding molecular structure and its relationship to chemical reactivity. However, this work is directed towards determining geometries of transition structures involving nonstereogenic atoms, which heretofore have been unavailable. Dr. Beak and co-workers will investigate the trajectories for reactions at nonstereogenic heteroatoms by use of the endocyclic restriction test. In this approach, the geometry of the transfer of atom Z will be evaluated by investigations of systems in which the bond-forming atom X and the leaving atom Y are joined by a chain. The size of the ring required for a concerted endocyclic intramolecular reaction in the transfer of Z from Y to X limits the available reaction geometry. If the transfer has geometrical requirements which cannot be met intramolecularly, the reaction becomes intermolecular. These possibilities will be distinguished by double labeling, isotope effect, and kinetic experiments. Alternative mechanisms involving associative and dissociative steps will also be evaluated. Investigations of the geometries of reactions at oxygen, nitrogen, halogen, hydrogen and sulfur will be made. Other mechanistic probes, including substituent effects and structural rearrangements will be used to provide mechanistic information about these and related reactions.