Design, Preparation Of Magnetic Nanoparticles Supported Chiral Ionic Liquid And Its Application In Asymmetric Michael Addition

Recent years, ionic liquids as a kind of green medium used as reaction solventand catalyst, become one of the hot spot in the field of organic synthesis. The chiralionic liquids due to its dual characteristic of both solvent and chiral catalystsgradually become the focus of researches on the asymmetric synthesis. Magneticnanoparticles has magnetic character of recycling and reuse, has been widely used inmechanical, chemical, biological, pharmaceutical, and other fields. In combinationwith the advantages of ionic liquids and magnetic nanoparticles, this paper designedand prepared cyclohexanediamine derivatives based nanoparticles supported chiralionic liquids, used in catalytic asymmetric Michael addition reaction.First of all, a series of acidic ionic liquids were prepared to catalyze thepreparation of nitroolefins. UV was used to compare the acidity of the ionic liquids.With the reaction of nitromethane and benzaldehyde as templates, we found the mostacidic [SFHEA][HSO4] showed the best effect, with the dosage of20mol%ionicliquid,110℃, without any solvent, expanding substrate. The ionic liquid can be usedfor five times, no significant decrease in yields was observed.Secondly, the cyclohexanediamine derivatives based nanoparticles supportedchiral ionic liquid was prepared and used in catalytic asymmetric Michael additionreaction. At the same time, in order to verify the role of imidazole ring in ionic liquid,a control catalyst with no imidazole ring was prepared. The physical and chemicalproperties and structure of the magnetic carrier and catalyst have been characterizedusing X-ray diffraction (XRD), transmission electron microscopy (TEM),thermogravimetric (TG), infrared and magnetic testing methods.Finally, with the reaction of isobutyl aldehyde and nitrobenzene ethylene astemplate, the designed catalyst was used for the catalytic reaction, proved that thecatalytic activity of ionic liquid containing imidazole ring. Through a series ofconditions optimization, found butyl aldehyde and nitrobenzene ethylene feeding ratioof4:1,20mol%of catalyst,20mol%of additive (DMAP), in water, the reactioneffect is the best. The reaction time is greatly shortened compared with the literatures,the enantioselectivity is high and the catalyst can be reused for five times, with no significant decrease in effect. The possible reaction mechanism was presented basedon several references and our experiment.Above all, the cyclohexanediamine derivatives based nanoparticles supportedchiral ionic liquid was prepared, and it showed high efficient in asymmetric Michaeladdition reaction. The basic additives can significantly improve reaction rate, and thecatalyst can be recycled to reuse. The catalyst may get more extensive applicationthrough further work.