Heterogeneous epoxidation of alkenes containing allylic hydrogen on Cu-based catalysts

烯丙基烯的非均相环氧化是一项要求很高的任务，因为不稳定的烯丙基氢的容易提取会引发烯烃的完全燃烧，并防止选择性氧化。最近，研究表明，在一般的烯烃环氧化反应中，尤其是在烯丙基烯的困难情况下，铜比广泛使用的银具有更高的选择性。本项目旨在了解烯丙基烯在铜单晶表面上环氧化的微观机理，以及这些机理与铜基负载型催化剂在实际条件下的反应活性和选择性之间的关系。本研究的重点是考察烯烃吸附几何形状、烯烃双键和烯丙基氢与表面的距离、催化剂表面的微观结构等结构参数对环氧化反应活性和选择性的影响。此外，还将研究可能的替代环氧化途径，其中不包括用原子氧氧化烯烃的常见步骤。这些实验将在兰伯特教授(英国剑桥大学)的团队中进行。

Heterogeneous epoxidation of allylic alkenes represents a demanding task, since the easy abstraction of labile allylic hydrogen triggers total combustion of the alkene and prevents selective oxidation. Recently, it was shown that copper is intrinsically much more selective than widely used silver for both alkene epoxidation in general and for the difficult case of allylic alkenes in particular. The present project aims at an understanding of the microscopic mechanisms of allylic alkenes epoxidation on well-defined Cu single crystal surfaces and a connection of these mechanisms with the reactivity and selectivity of Cu-based supported catalysts operated under practical conditions. The main focus of this study will lie on investigation of the role of structural parameters such as alkene adsorption geometry, vicinity of the olefinic double bond and of the allylic hydrogen to the surface, the microscopic structure of the catalyst surface etc. in the activity and selectivity towards epoxidation. Additionally, possible alternative epoxidation pathways will be investigated, which do not include a common step of alkene oxidation with atomic oxygen. The experiments will be carried out in the group of Prof. Lambert (University of Cambridge, England).