Preparation Of Magnetic Nanoparticles Supported Transition Metal Catalysts And Their Applications In Organic Reactions

Catalyst plays an important role in modern chemical industry, and catalysis is an important way to make reactions efficientl. The supported catalyst can solve the weaknesses of homogeneous catalyst, such as difficult separation and recycling, polluting the products. So the supported catalyst attracts much attention. Magnetic nanoparticles can be efficiently separated via an external magnet, and the surface is easily to be functionalized, which is in favor of grafting active substance. In addition, the magnetic nanoparticles are very small, so it can be uniformly dispersed in the solution and fully contacted with the reactants, which will greatly improve the reaction rate. Thus, it is very significant to develop magnetic nanoparticles supported metal catalysts.Herein, the silica coated Fe3O4 was chosen as the support, and it was modified by introducing azide group. Then metal complexes could be successfully grafting onto the support through "Click" reaction. By this method, two novel magnetic nanoparticles supported catalysts Mn@MNP and Cu@MNP were prepared. The two catalysts were characterized by FT-IR, TEM, XRD, TGA, VSM and ICP-AES.The as-prepared catalyst Mn@MNP was found to be an efficient catalyst for the oxidation of alcohols. Only 0.2 mol% Mn was needed for the oxidation of alcohols to prepare corresponding aldehydes or ketones with high yield and selectivity, when the reaction was carried out in DMSO under 110℃ using t-butyl hydroperoxide as oxidant. The Mn@MNP could be recovered with an external magnet and reused after washing and drying. It could be recycled for five times without significant loss of catalytic activity.The as-prepared catalyst Cu@MNP was found to be an efficient catalyst for the ammonolysis of aryl halides. When the reaction was carried out in DMSO under 100℃ using potassium carbonate as base,3 mol% Cu could efficiently catalyze the ammonolysis of various aryl iodides and aryl bromides to prepare anilines with high yield (83-97%). After recycling for six times, the yield decreased only 9%, which indicated the good reusability of the catalyst.The as-prepared catalysts are according with the strategy of green chemistry because of the advantages of eco-friendly, easy to recycle and good reusability.