Has A Temperature-controlled Two-phase Nature Of The Dual-cation Type Alkaline Ionic Liquid Synthesis In Organic Reactions

Nowdays, it is very important to develop green chemistry, especially the synthesis of non-toxic, enviromental and recoverable catalysts. Both the traditional homogeneous and heterogeneous catalysts have some drawbacks. So the development of a new catalytic system is in urgent need.Seven new ionic liquids ([PEG400-DPIL]Cl,[PEG800-DPIL]Cl,[PEG1000-DPIL]Cl,[PEG800-DEIL]Cl,[PEG1000-DEIL]Cl,[PEG8oo-DPIL]BF4,[PEG800-DPIL]PF6) were synthesized via a simple method in this paper. Some of them were identified by 1H NMR,13C NMR,IR,MS,TG-DSC. After inspection, it was found that [PEG800-DPIL]Cl/cylcohexane/isoproponal system had the thermoergulated biphasic properties, when the volume ratio of cyclohexane and isopropanol was 3:1 (V (cyclohexane):V (isopropanol)= 3:1), the system could turn to be homogeneous phase at relatively high temperature and biphase at room temperature. Applications of [PEG800-DPIL]Cl/cylcohexane/isoproponal system in Knoevenagel condensation reaction were carried out. It was found that these reactions were completed in 10～60 min with high yields and the catalyst could be simply recovered. The recovered ionic liquid [PEG8oo-DPIL]Cl could be reused for four times without noticeably loss of catalytic activity, which indicates that [PEG800-DPIL]Cl is a very efficient catalyst.[PEG800-DPIL]Cl could also been used as catalyst in the reaction of four-component Hantzsch reaction under solvent-free condition at 60℃. Most of the reactions went to completion in only 10～30 min with 5mol% ionic liquid and afforded excellent yields from 70% to 95%. The catalyst can be reused for at least eight times without further treatment and with no weight or activity loss.In all, seven PEG-linked dicationic basic ionic liquids were synthesized and investigated in this paper. It was found that [PEG800-DPIL]Cl/cylcohexane/isoproponal system had the thermoergulated biphasic properties. This system has combined advantages of homogeneous and heterogeneous catalysis. They could be used as green reaction solvents as well as basic catalysts. This opinion is of important theoritcial value and application prospect.