Thermoregulated Polyether Ionic Liquid And Its Applications In Transition Metal Catalysis

In this paper, the quarternary ammonium salts ionic liquids modified with poly-(ethylene glycol) chain (Scheme I) are synthesized by reaction of methylsulfonate of polyethylene glycol with triethylamine.The solubility of these ionic liquids in different organic solvents is investigated under different temperature. It is found that these ionic liquids possess the thermoregulated function of "mono-phase under high temperature, bi-phase under room temperature". A novel concept (Thermoregulated Ionic Liquid Biphasic Catalysis, TRILC) based on the thermoregulated function of ionic liquids for separating catalyst from the reaction mixture is proposed.The hydrogenation reaction of cyclohexene catalyzed by Ru/TPPTS complex is investigated as a test reaction. The effects of temperature on the reaction conversion and recycling efficiency of Ru/TPPTS complex are throughout investigated. The experimental results indicate that the hydrogenation of cyclohexene take place with TRILC system. With a system composition of 1mL heptane, 2mL toluene, 1g IL750(n=16), (ie.20.0 wt% heptane, 50.7 wt% toluene, 29.3 wt% IL750), under the optimum condition of T=60℃, P=2.5MPa, TPPTS/Ru=5(molar ratio), S/Ru=1500(molar ratio), t=5h, the conversion of cyclohexene is 100%. After recycling for ten times, almost no loss in the catalyst activity has been observed. It indicates that TRILC system is characterized by homogeneous catalysis coupled with two-phase separation.Meanwhile, the hydroformylation of cyclohexene catalyzed by Rh/TPPTS complex and Rh/phosphite complex are successfully conducted in TRILC system, which expand the application range of TRILC system.