离子液体两相不对称氢甲酰化催化反应的研究

A Study of Asymmetric Hydroformylation in Ionic Liquid Biphasic System

从(R)-BINAP出发制备水溶性磺酸钠盐配体(R)-BINAPS,采用离子液体[BMIM]BF4和[BMIM]PF6为介质,实现其Rh配合物对乙酸乙烯酯的两相不对称氢甲酰化反应.实验结果表明,在以[BMIM]BF4为介质的乙酸乙烯酯不对称氢甲酰化反应中,该催化剂在温和条件下显示出高于相应均相体系的产物ee值和异构醛选择性,并在6次循环使用中,反应产物的ee值、选择性和转化率均无明显改变;在离子液体体系中添加适当的甲苯时,油溶性配体(R)-BINAP与Rh组成的配合物催化剂亦可形成类似的两相反应体系,但其活性和选择性在重复使用中呈明显下降趋势.本文还考察了溶剂体系、膦铑比、温度、压力、时间等的影响,并尝试苯乙烯的两相不对称氢甲酰化反应.

A biphasic catalysis system composed of ionic liquids (ILs) and water-soluble chiral rhodium complex of (R)-BINAPS which was prepared by sulfonation of (R)-BINAP has been developed for the asymmetric hydroformylation of vinyl acetate under mild conditions. The catalyst system with BF4 showed higher ee value and iso-aldehyde selectivity as compared with the homogeneous counterpart without IL. The biphasic catalysis system could be reused at least six times without reducing activity, enetioselectivity and regioselectivity. Analogous biphasic catalysis system might be formed when using the chiral rhodium complex of (R)-BINAP dissolved in ILs and an additional solvent of toluene. But such system showed significant decreases in activity and enetioselectivity during the recycling use. The effects of molar ratio of ligand to rhodium, temperature, pressure and reaction time have been discussed. An attempt for the asymmetric hydroformylation of styrene with the biphasic catalysis system has also been made in the paper.