纳米金属/离子液体系催化芳香酮选择性加氢研究

The quest for economic and green methods to prepare aromatic alcohols continues as a result of the important role these intermediates serve in drug design. These hydrogenation reactions have been remarkably developed in homogeneous catalytic system since the groundbreaking discovery disclosed by Noyori and co-workers. However, the recuperation of homogeneous catalysts is still a problem. We succeed in heterogeneous enantioselective hydrogenation of aromatic ketones, with enantioselectivity up to 98%, catalyzed by supported catalysts. However, the two-dimensional limitation of supported catalysts partly restricted the further optimization of catalytic system. Nanometal/ionic liquid system, with characterization of nanometal three-dimensional rotational freedom, have advantage in catalysts recuperation and catalysts optimization. In this project, nanometal particle size and morphology control will be carried out through the optimization of ionic liquid structure, metal precursor and reduction condition. Then modifier will be introduced to the nanometal/ionic liquid system. Chemoselective and enantioselective catalytic hydrogenation of aromatic ketones will be carried out in the presence and absence of modifier. Characterization technology, including TEM, XPS, XRD, IR and UV, and computational technology will be carried out to analyze the influence of ionic liquid structure, size and morphology of nanometal and modifier on catalysts. Furthermore, the relationship between the nature of catalytic center and the catalytic property will be discussed in detail. On the basis of research mentioned above, nanometal/ionic liquid catalysts with high efficient and good synthetic potential will be developed in the field of selective hydrogenation of aromatic ketones.

芳香酮选择性加氢是合成药物中间体的有效途径之一，但目前获得较好发展的均相催化体系难以实现催化剂回收。我们前期应用负载催化剂在芳香酮多相选择性加氢上取得了较好的成果，但负载催化体系难以突破二维表面的束缚制约了其对芳香酮加氢选择性的调控。纳米金属/离子液体系结合了均相催化易实现催化剂调控和负载多相催化易实现催化剂循环使用的优势。本项目以离子液结构、金属前体种类及还原条件等对三维旋转的纳米金属（钌、铑等）粒径和形貌调控为基础，进而通过引入修饰剂对纳米金属表面环境进行调节，考察催化剂在芳香酮加氢化学选择性和对映选择性方面性能；运用谱学表征及模拟计算分析离子液结构、纳米金属粒径和形貌、修饰剂对芳香酮选择性加氢三维催化活性中心的调控，深入了解催化活性中心特性与催化反应活性及选择性间的联系。为建立高效、易调控且具有较强应用价值的芳香酮选择性加氢催化体系提供有益探索。

本项目严格按照项目计划书执行，通过调变离子液结构、金属前体种类、还原条件及稳定剂结构，制备出具有不同粒径和形貌的纳米金属/离子液催化剂，并对这些催化剂进行了表征。考察了催化体系中各种因素对芳香酮、喹啉类化合物、芳香醛、芳香硝基化合物等化学选择性加氢的影响；将手性修饰剂引入纳米金属/离子液催化剂中并用于芳香酮、α-酮酯的化学选择性和对映选择性加氢反应。结合谱学表征、实验结果及模拟分析阐释了离子液结构、纳米金属粒径与形貌、修饰剂等对化学选择性和对映选择性加氢三维催化活性中心的影响，分析了催化过程中的配体加速作用，多中心协同作用等。基本得到了预期结果，基本实现了本项目的研究目的。