有机胺功能化离子液体中离子型铑(Ⅲ)配合物催化的1-辛烯两相氢甲酰化反应

考察了离子型+3价铑配合物1a和2a作为催化剂前体在1-辛烯氢甲酰化反应中的催化行为. 实验结果表明, 在无助剂存在下, 配合物1a和2a表现出较差的催化性能, 而廉价低毒的有机叔胺助剂如三乙胺或N-甲基哌啶可以显著提升配合物1a和2a的催化性能, 可获得800 h^-1以上的转化频率(TOF). 当以哌啶功能化离子液体PEmim]BF₄兼作助剂和溶剂时, 不仅可以促进配合物1a和2a对氢甲酰化反应的活性和选择性, 还可实现“离子液体-有机”两相氢甲酰化反应, 使得锁定在PEmim]BF₄离子液体相中的配合物1a(或2a)催化剂得以简单两相分离和回收循环使用, 但在5次循环使用过程中锁定在PEmim]BF₄中的催化剂存在向有机相流失和失活的问题, 导致产物壬醛的收率逐渐下降.

Biphasic Hydroformylation of 1-Octene Catalyzed by Ionic Rh(Ⅲ)-complex in the Presence of Tertiary Amine Functionalized Ionic Liquid†

The ionic Rh(Ⅲ)-complexes 1a and 2a exhibited poor catalytic performance for hydroformylation of 1-octene without the presence of any auxiliary additive. The involvement of cheap and low-toxic tertiary amines such as Et₃N or N-methylpiperidine could dramatically boost the catalytic performance of compounds 1a and 2a up to turnover frequency(TOF) of 800 h^-1. When piperidinyl-functionalized ionic liquid of PEmim]BF₄ was dually used as the additive and the solvent, not only the positive roles of N-methylpiperidine in spurring up the activity of compounds 1a and 2a were embodied, but also the easy recovery and recycling of compounds 1a(or 2a)in PEmim]BF₄ were fulfilled in biphasic hydroformylation. The TOFs of compounds 1a and 2a in PEmim]BF₄ were gradually decreased in the course of the recycling uses due to the leaching and deactivation of the catalysts.