| Traditional ionic liquids sometimes encounter problems of separation when the product was polar and contained many heteroatoms, while catalysts supported on Merrifield resin and magnetic polymer spheres have distinct advantages of separation, so novel kinds of imidazolium ionic liquids combined magnetism and acidity have been designed, synthesized and applied to catalyze the esterification of tributyl citrate.The structure and properties of the novel ionic liquids were investigated by X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), ~1H nuclear magnetic resonance (~1HNMR) and differential scanning calorimetry (DSC). The results of FT-IR and ~1HNMR, as well as XRD, have indicated that the structures were agreed with what we have expected. On the basis of TGA data, the thermal stability of the resulting samples was all excellent, which will not degrade until 200℃.From the magnetic curve of magnetic imidazolium ionic liquid supported on Merrifield resin, we can see that the saturation magnetization is 2460 emu/g, while remanence and coercivity are 606.788emu/g and 254.9Oe, respectively.In the meantime, we learned the appearance of the samples via optical microscope, and through sedimentation experiment, the rate and effect of the magnetic separation of the magnetic sample were studied.Finally, the catalytic activities of short alkyl chain, long alkyl chain, solid supported, carboxyl functional, esterificated and magnetic packed ionic liquids were explored and compared. The results implied that, the longer the alkyl chain is, the more activity it is; the structure of solid supporter, the introduction of carboxyl and ester group will all help to improve the activity of the resulting samples. In addition, the magnetic sample exhibits the best catalytic activity among all the catalysts we have used in this study.
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