Synthesis Of Magnetic Polymer Nanocomposite Supported-Pd Catalysts And Their Application

Palladium-catalyzed carbon-carbon cross-coupling reactions are powerful synthetic methods for the formation of carbon-carbon bonds in organic compounds. However, the expensive Palladium catalyst is difficult to be recycled, which cause huge waste and contaminate the products. Therefore, a variety of supported catalytic systems have been developed to solve these problems. However, compared with their homogeneous counterparts, the solid-supported catalysts often suffer from lower activity. It is highly desirable to developed new ones comparable to homogeneous catalysts in catalytic performance. The reasonable design of the magnetic polymer nanocomposite-supported catalysts is possible to achieve the target of good stability, high activity as well as excellent separation performance. In additional, the environmentally friendly catalytic system is becoming more and more necessary with development of green chemistry.Herein, two types of magnetic polymer nanocomposite supported-Pd catalysts Fe3O4@PUVS-Pd and Fe3O4@PUGM-PEI-Pd were prepared and their structures are identified by FT-IR, VSM, TEM and XPS etc. These catalysts exhibited excellent catalytic activity and recyclability for carbon-carbon cross-coupling reactions in water or solvent-free. Moreover, the two types of catalysts could be simply separated by using a permanent magnet. The main contents are summarized as follows:1. A new magnetically responsive heterogeneous palladium catalyst (Fe3O4@PUVS-Pd) was prepared by copolymerization of 4-vinyl pyridine (4-VP), sodium acrylate (SAA) and Fe3O4@undecylenic acid (UA). This catalyst exhibited not only high catalytic activity, but also good stability in the Heck and Suzuki reactions in water. The yields of corresponding products can be achieved 82-97% and 73-97%, respectively. Besides, it can be used consecutively for six runs.2. A novel type of magnetically responsive polymer nanocomposite-supported catalyst Fe3O4@PUGM-PEI-Pd was synthesized and then applied to the Sonogashira and Suzuki reactions in water. This catalyst exhibited excellent catalytic activity, stability and reusability in the Sonogashira and Suzuki coupling reactions. The yields of 81-97% and 70-97% were respectively obtained in the Sonogashira and Suzuki reactions. The Fe3O4@PUGM-PEI- Pd catalyst could be used seven runs without significant loss of catalytic activity.3. Fe3O4@PUVS-Pd was applied to catalysis the solvent-free Heck reaction. The yields of Heck reactions were about 90-96% in 40-180 min by using 0.09 mol% Pd. The catalyst can be easily recovered and used consecutively for seven runs with 84% yield still obtained at the seventh run.