手性修饰的介孔树脂材料负载铂催化剂上丙酮酸乙酯的不对称氢化反应

Asymmetric Hydrogenation of Ethyl Pyruvate on Chirally Modified Pt Catalysts Supported on Periodic Mesoporous Resols

采用氯铂酸和二氯四氨合铂为前体通过浸渍法分别制备了介孔树脂材料FDU-14负载的质量分数为5%的铂催化剂Pt/FDU-14,并利用XRD,TEM,N2气吸附和CO化学吸附等手段对催化剂进行了表征.考察了经过手性分子辛可尼定修饰后的Pt/FDU-14催化剂在丙酮酸乙酯不对称氢化反应中的催化性能.以氯铂酸为前体制备的Pt/FDU-14催化剂因其具有较小的铂粒子和较高的分散度而表现出较高的活性,乙酸溶剂中的初始活性(TOF)可以达到21902mol/(mol.h);而以二氯四氨合铂为前体制备的Pt/FDU-14催化剂则具有较强的手性诱导能力,乙酸溶剂中(R)-(+)-乳酸乙酯的光学选择性可以达到81.4%e.e..更重要的是,由于FDU-14具有较强的疏水性,Pt/FDU-14催化剂在水溶剂中也表现出较高的催化性能,并且还可以重复使用10次以上.

5.0% （Mass fraction） Pt catalysts supported on FDU-14, a kind of periodic mesoporous resols, were prepared by an impregnation method using two different Pt precursors, H2PtCl6 and Pt（ NH3 ） 4Cl2. These Pt/FDU-14 catalysts were characterized by XRD, N2-sorption, TEM and CO chemisorption. The Pt/FDU-14 catalysts can be effectively applied in the asymmetric hydrogenation of ethyl pyruvate after chirally modified with cinchonidine. The Pt/FDU-14 catalysts derived from H2PtCl6 afforded better conversions of ethyl pyruvate due to higher Pt dispersion and smaller Pt particle size, the initial activity （TOF） reaching 21092 mol/（ mol · h） in acetic acid. While the Pt/FDU-14 catalysts derived from Pt（ NH3 ）4Cl2 exhibited higher chiral induction ability and as high as 81.4% e.e. value of （R）-（ ＋ ）-ethyl lactate was achieved in acetic acid. Due to the strong hydrophobicity of FDU-14 with pure organic framework, Pt/FDU-14 also worked well in water and can be recycled easily for more than 10 times without distinct loss of activity or enantioselectivity.