The Investigation Of Cross-Coupling Reactions Catalyzed By An Ultrasmall Pd Nanoparticles Supported On Polyaniline

The transition metal-catalyzed cross-coupling reactions are one of the most effective ways to construct the C-C bond in organic synthesis and many of them have become classical name reactions, including Kumada, Negishi, Suzuki, Stille, Hiyama, Heck and Sonogashira cross-coupling reactions. For a long time, the transition metal-catalyzed reactions are one of the hot topics. They are much-efficient, and break the bottle neck of the traditional methods in organic synthesis. However, during the continuous progresses of the transition metal-catalyzed reactions, the defects began to emerge, such as the unrecoverable catalysts, requirement of ligands and the harsh conditions. With the rapid development of nanotechnology, the application and development of nano-metal catalysis in organic synthesis is mature now.Our group mainly focused much on green synthesis and recently the polyaniline supported catalysts attracted our interest. This dissert reported several Pd@PAN-catalyzed cross-couplings, which include:1. Investigations on the clean preparations of the Pd@PAN catalyst.We prepared the Pd@PAN catalyst using air as the clean oxidant instead of the traditionally employed persulfates and obtained more uniform Pd nanoparticles. The experimental results of the Suzuki reactions showed this catalyst had very high activity.2. Pd@PAN-catalyzed Heck reaction.We applied the above catalyst in the Heck reaction. The experiment result showed that the catalyst had much higher activity and catalyzed the Heck reactions with very high efficiency. Compared with reported references, the reactions had much higher TON and wider application scope for substrates. The catalyst was also recyclable and could be reused for at least 8 times.3. Pd@PAN-catalyzed Sonogashira reaction.To the best of our knowledge, the Pd@PAN-catalyzed Sonogashira reaction was not reported by references yet. We recently successfully applied the above catalyst in Sonogashira reactions and greatly expand the application scope of this kind of catalyst.In this dissert, the morphology of catalyst observed by transmission electron microscope, the content of palladium supported by catalyst tested by ICP, all of the structures identified by NMR, GC-MS, IR.In conclusion, the above results showed that the slow growth of Pd@PAN catalyst oxidized by the air instead of the persulfates had better stability and reactivity, and could efficiently catalyze a series of classic coupling reaction under mild condition, with low-loading, ligand-free and easy recovery. Therefore, this nano-metal material we have developed has broad applied prospects.