Imidazole grafting-type ionic liquid catalyst and preparation method and application

[0016] Example 1:

[0017] Add 1mol of methylimidazole and 1mol of chloropropyltriethoxysilane to 80mL of toluene solvent, stir and reflux until the layers are separated, and remove the lower viscous liquid (1-chloropropyl(triethoxysilyl)-3 -Methylimidazole chloride crude product), washed 3 times with ethyl acetate, and dried in vacuum. Add the obtained [Smim]Cl and 1mol potassium hydroxide to 80mL of anhydrous dichloromethane, stir vigorously for 10h at room temperature, filter off the precipitate, remove the solvent by rotary evaporation, wash 3 times with ether, and dry under vacuum at 70℃ for 10h . Add the obtained 2.3g ionic liquid to a 0.3mol silica gel carrier uniformly dispersed in 50mL of anhydrous toluene, stir and reflux for 12h, extract with dichloromethane for 10h, and vacuum dry at 70℃ for 10h to obtain heterogeneous grafted ions Liquid catalyst [Smim]OH/SiO 2 , The mass grafting amount of ionic liquid is 5%. The grafted ionic liquid catalyst of propylene oxide and imidazole was added to the 80mL reactor at a molar ratio of 1:1.8, and then filled with 2MPa CO 2. Under stirring conditions, the temperature was raised to 120°C, and the reaction was conducted for 8 hours. The product was centrifuged to settle, and the supernatant was taken for analysis by gas chromatography. The results are shown in Table 1.

[0018] Example 2:

[0019] Add 1mol of methylimidazole and 1mol of chloropropyltriethoxysilane to 100mL of toluene solvent, stir and reflux until the layers are separated, and remove the lower viscous liquid (1-chloropropyl(triethoxysilyl)-3 -Methylimidazole chloride crude product), washed 3 times with ethyl acetate, and dried in vacuum. Add the obtained [Smim]Cl and 1mol potassium hydroxide to 100mL of anhydrous dichloromethane, stir vigorously for 16h at room temperature, filter off the precipitate, remove the solvent by rotary evaporation, wash 3 times with ether, and dry under vacuum at 90℃ for 16h . Add the obtained 4.6g ionic liquid to a 0.3mol silica gel carrier uniformly dispersed in 70mL of anhydrous toluene, stir and reflux for 18h, extract with dichloromethane for 16h, and vacuum dry at 90℃ for 16h to obtain heterogeneous grafted ions Liquid catalyst [Smim]OH/SiO 2 , The mass grafting amount of ionic liquid is 10.5%. The grafted ionic liquid catalyst of propylene oxide and imidazole was added to the 80mL reactor at a molar ratio of 1:1, and then filled with 2MPa CO 2. Under stirring conditions, the temperature was raised to 120°C, and the reaction was conducted for 8 hours. The product was centrifuged to settle, and the supernatant was taken for analysis by gas chromatography. The results are shown in Table 1.

[0020] Example 3:

[0021] Add 1mol of methylimidazole and 1mol of chloropropyltriethoxysilane to 120mL of toluene solvent, stir and reflux until the layers are separated, and remove the lower viscous liquid (1-chloropropyl(triethoxysilyl)-3 -Methylimidazole chloride crude product), washed 3 times with ethyl acetate, and dried in vacuum. Add the obtained substance [Smim]Cl and 1mol potassium hydroxide to 120mL of anhydrous dichloromethane, stir vigorously for 20h at room temperature, filter off the precipitate, remove the solvent by rotary evaporation, wash 3 times with ether, and dry at 110°C under vacuum 20h. Add the obtained 9.1g ionic liquid to a 0.3mol silica gel carrier uniformly dispersed in 90mL of anhydrous toluene, stir and reflux for 20h, extract with dichloromethane for 18h, and vacuum dry at 110℃ for 20h to obtain heterogeneous grafted ions Liquid catalyst [Smim]OH/SiO 2 , The mass grafting amount of ionic liquid is 17%. The grafted ionic liquid catalyst of propylene oxide and imidazole was added to the 80mL reactor at a molar ratio of 1:1.4, and then filled with 2MPa CO 2. Under stirring conditions, the temperature was raised to 120°C, and the reaction was conducted for 8 hours. The product was centrifuged to settle, and the supernatant was taken for analysis by gas chromatography. The results are shown in Table 1.