Preparation And Application Of Polymer-supported Metal Catalysts

In recent decades, homogeneous catalysts due to their high catalytic activity have been widely concerned and applied in the scientific community and industry. However, the homogeneous catalysts have the problems such as expensive cost, leaching problem and non-recyclability. Moreover, homogeneous catalysis generally use the heavy metal ion that would make the reaction system pollution of the product and the reaction process, and the catalyst could hardly reused. These drawbacks make the application of homogeneous catalysts in organic synthesis and industrial have a lot of restrictions. In order to overcome these drawbacks, the polymer-supported catalysts have been rapid developed recently. Polymer-supported catalysts have lots of advantages such as high catalytic activity, stereo selectivity, good stability, reusability and easy to handle. After the completion of the reaction, the catalyst could separate from the reaction mixture and the catalyst could be recovered and reused by simple filtration for the next run. The cost and pollution could be reduced efficiently to some extent.In this dissertation, using polymer such as polystyrene as support, followed by structure modification with different kinds of functional groups, a series of polymer-supported metal catalysts have been successfully prepared. Their application in Suzuki cross-coupling reaction, Heck reaction, Sonogashira reaction has been studied in detail. The results showed that polymer-supported palladium catalysts not only have good stability and catalytic activities, they also could be easily recovered and reused without significant loss of activities.The polymer-supported copper catalyst has been synthesized using Amberlyst21as support. The application in homocoupling of alkynes reaction has been well investigated. Results showed that the complex could catalyze the reaction efficiently within10-20min at the room temperature. The catalyst could reuse four times with significant loss in its activity.A novel polymer-supported carbene-rhdium complex was prepared via Click chemistry. Meanwhile, the reaction conditions such as solvent, base, catalyst loadings, time were optimized in detail, and a series of diol coupounds have been synthesized successfully. The catalyst could be reused for several times with a slightly decrease in its activity.On the basis of the earlier work, a series of polymer-supported silver complexes have been prepared via Click chemistry. The application of three component reaction of aromatic alkyne, aldehyde and imine at the room temperature has been investigated. The multi-component reaction and the heterogeneous catalyst have been combined successfully in the reaction system. Studies showed that the catalyst could effectively catalyze the reaction. Moreover, the catalyst could be recovered and reused several times after a simple filtration, washing and drying without significant loss of activity.