RUI: Computational Studies on Hydrocarbon Rearrangements: From Reactions of Polycyclic Aromatic Hydrocarbons to Tunneling in Annulenes

化学结构、动力学和机理-NSF化学部的一个项目支持旧金山大学化学系的克莱尔·卡斯特罗教授和威廉·卡尼教授的研究。卡斯特罗教授和卡尼教授以及他们的学生正在通过计算探索碳氢化合物在广泛温度范围内发生的反应：从燃烧过程中发生的反应到在环境温度下发生的反应。这项研究的目标之一是阐明解释实验结果的可行的机制路径。高温反应与碳纳米管等材料的合成有关；较低温度的反应与理解重原子隧穿的量子化学概念有关，重原子隧穿是化学反应的基本方面。该项目位于有机、物理和材料化学的交界处。本研究非常适合于本科生的体育教育。卡斯特罗/卡尼团队也处于有利地位，可以为科学领域代表性不足的群体的学生提供教育和培训。芳香烃在高温和低温下都会发生剧烈的重排。在800-1200°C的温度下，感兴趣的反应类型包括氢转移、斯通-威尔士重排和亚乙烯插入。计算研究试图将各种反应置于共同的理论基础上，以比较相对速率，并生成多环芳烃的统一反应性图。这项工作还旨在澄清结构-反应性关系，例如，通过评估曲率程度如何影响Stone-Wales重排的不同机制。在较低的温度下，环烯中的pi键移动是很容易的，这项研究探索了量子力学隧道效应的贡献。通过比较经典和量子隧穿速率，探索了大量碳原子同时隧穿的可能性。这项工作解决了有机反应中隧道效应的范围。该教育计划包括对物理本科生进行计算方法以及物理化学和有机化学原理方面的培训。

The Chemical Structure, Dynamics and Mechanism-A Program of the NSF Chemistry Division supports the research of Professors Claire Castro and William Karney in the Department of Chemistry at the University of San Francisco. Professors Castro and Karney and their students are computationally probing reactions of hydrocarbons that occur over a wide range of temperature: from those that occur during combustion to those that occur at ambient temperature. One goal of this research is to elucidate feasible mechanistic pathways that explain experimental results. The high temperature reactions are relevant to the synthesis of materials such as carbon nanotubes; the lower temperature reactions are relevant to understanding the quantum chemical concept of heavy-atom tunneling, a fundamental aspect of chemical reactions. The project lies at the interface of organic, physical, and materials chemistry. This research is well suited for the education of undergraduate physical science students. The Castro/Karney team is also well positioned to provide education and training for students from groups that are underrepresented in science. Aromatic hydrocarbons undergo dramatic rearrangements at both high and low temperatures. At temperatures of 800-1200 °C, reaction types of interest include hydrogen transfers, Stone-Wales rearrangements, and vinylidene insertions. The computational study attempts to place the various reactions on a common theoretical footing to compare relative rates and generate a unified picture of reactivity for polycyclic aromatic hydrocarbons. The work also aims to clarify structure-reactivity relationships, for example, by evaluating how the degree of curvature influences the different mechanisms for Stone-Wales rearrangement. At lower temperatures, pi-bond shifting in annulenes is known to be facile, and the research explores the contribution of quantum mechanical tunneling. The possibility that large numbers of carbon atoms are tunneling simultaneously are explored by comparing classical and quantum tunneling rates. The work addresses the scope of tunneling in organic reactions. The educational plan includes training physical science undergraduates in computational methods and both physical and organic chemistry principles.