SBA-16负载手性M-Salen催化苯乙酮不对称加氢

Homogeneous chiral catalysts have shown distinguished catalytic properties in asymmetric hydrogenation of prochiral ketones to optically active chiral alcohols. The precious metal complexes used as catalysts are difficult to separate from the substrate and productions, which is neither economic and causes serious environmental pollution. Therefore, increasing demand has been generated for the preparation of heterogeneous catalysts. SBA-16 is highly ordered porous silica with large mesopores arranged in body centered cubic (BCC) Im3m symmetry. Its large cages can accommodate metal complexes of large molecular size, whereas the smaller pore entrances may prevent leaching of the metal complex confined in the mesoporous cages. In this program, the cage-like mesoporous silica SBA-16 will be synthesized and introduced in asymmetric catalysis system as support. Various of heterogeneous catalysts will be synthesised through several strategies and be characterized detailedly. In the whole study, the catalytic asymmetric hydrogenation of acetophenone and its derivatives acts as a probe reaction. The match between the central metal, ligand, carrier and the substrate, and the synthesis process, the structural properties and the catalytic activity of the chiral catalyst will be investigated. This program aims to discover the reasonable synthetic route of SBA-16 supported heterogeneous asymmetric catalyst.

在均相体系中，前手性酮不对称加氢获得了良好的催化效果。其催化剂大多是贵金属配合物，在反应过程中这些配合物难与底、产物分离，既不经济又造成严重环境污染。"均相催化剂-多相化"是解决这一问题的重要手段。本项目拟以SBA-16介孔分子筛材料作为载体，分别通过："原位合成法"、"自由配体"法、"瓶中造船"法等不同手段，将配位能力较强的手性Salen配体与钌、铑、钯、铱等贵金属配合物固载在SBA-16纳米的、三维的、规则的、大体积的超笼中,制备系列多相不对称加氢催化剂，并对其结构进行详细表征。以苯乙酮及其衍生物催化不对称加氢反应作为探针，考察载体、配体、中心金属等与底物的匹配能力；考察该类手性催化剂的合成工艺、结构性能及催化活性，寻找SBA-16负载型多相不对称催化剂合理的合成路线。

(1) 本项目以水热合成法制备了具有Im3m结构的SBA-16介孔分子筛材料，通过调节pH值、陈化和晶化时间及温度、模板剂和硅源的比例、无机添加剂的量和种类，制备结构规整的、超笼和孔道大小可调变的纯硅SBA-16，并通过离子交换、浸渍法、原位沉积法等方法将非硅骨架金属铝引入SBA-16中，制得非硅杂化的Al-SBA-16，当硅铝比在90:10以下时SBA-16的拓扑结构依然保持，而且铝原子都进入到SBA-16的骨架中(见图1.1 Al-SBA-16粉末的XRD衍射图)；然后采用“自由配体”法、“瓶中造船”法和“硅烷化试剂修饰”等封装的方法将Ru基催化活性和对映选择性良好的手性Salen配合物负载于SBA-16超笼中，制得效果良好的多相不对称催化剂；考察了催化剂的催化活性，以及活性组分与底物的匹配性能、中心金属与Salen的匹配性能、温度和反应时间、氢气压力等的综合效应；应用XRD、NMR、FTIR、UV-vis、低温氮吸附等测试手段，对催化剂进行了表征。.(2) 在理论计算方面我们也取得了一定的成果：以甲胺为吸附物种，计算了甲胺在Ru(0001)面的吸附与解离；研究了甲醇在Co3O4表面的氧化；探讨了CO对于碱性溶液中金催化甲醇氧化的影响。.(3) 研究成果在具有一定影响力的国际期刊上发表学术论文3篇；申请国家发明专利3项；申请省级项目1项。