Transition States for Surface Reactions

该研究项目由卡内基梅隆大学Andrew Gellman教授的实验室进行，得到了分析和表面化学项目的支持。重点是对表面催化反应过渡态的理解和热力学表征。利用取代基对有机反应物的影响，对一系列测试反应的表面反应过渡态的性质和热力学稳定性进行了探讨。不同程度的氟取代影响探针反应的活化能和过渡态的稳定性，包括氯氟化碳的脱氯、羧酸的去质子化和醇中O-H键的裂解。实验测量的能量与高能级电子结构计算的结果进行了比较，以解释表面反应过渡态的性质。对表面催化化学反应过渡态的详细了解有助于催化剂设计和工艺优化。通过使用取代基对反应速率的影响等物理有机概念，Gellman教授和他的同事们正在探索一系列探针反应的表面过渡态的本质。将这些测量结果与计算结果进行比较，以便对表面反应过渡态的性质有一个大致的了解。

This research project, carried out at Carnegie Mellon University in the laboratory of Professor Andrew Gellman, is supported in the Analytical and Surface Chemistry Program. It is focussed on the understanding and thermodynamic characterization of the transition state for surface catalyzed reactions. Using substituent effects on organic reactants, the nature and thermodynamic stability of the surface reaction transition state is probed for a series of test reactions. Varying degrees of fluorine substitution affects the activation energy and stability of the transition state for probe reactions including dechlorination of chlorofluorocarbons, deprotonation of carboxylic acids, and O-H bond cleavage in alcohols. Experimentally measured energetics are compared with the results of high level electronic structure calculations to interpret the nature of the surface reaction transition state. A detailed understanding of the transition state in surface catalyzed chemical reactions is useful in catalyst design and process optimization. By using physical organic concepts such as substituent effects on reaction rates, Professor Gellman and his coworkers are probing the nature of the surface transition state for a series of probe reactions. Results from these measurements are compared with calculations, in order to develop a general understanding of the nature of the surface reaction transition state.