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Novel Heterogeneous Catalysts

　We immobilized various metal catalysts into polystyrene based organic co-polymer with cross-linking moieties. Our catalysts can be synthesized based on two key techniques, microencapsulation (MC) and polymer incarceration (PI).

　Polymer and metal catalysts can be dissolved in good solvent of polymer and precipitates of both polymer and metal catalysts generate after addition of poor solvent for polymer. We call this phenomenon as microencapsulation (MC). This polymer precipitates can be heated under neat condition to make cross-link of polymer side chains and completely heterogeneous catalysts are obtained. In this solid, metal catalysts can be stabilized by weak but multiple interactions between metal and benzene rings in polymer. In addition, polymer backbone physically envelopes metal catalysts to prevent leaching from polymer matrix. We call this method as polymer incarceration (PI).

　Based on these techniques, we could immobilize various toxic and precious metal complexes such as, Sc, Os, Pd, and Ru. Recently we are focusing on encapsulation of metal nanoparticles including Au, Pt, Pd, Rh etc. to realize highly reactive and robust heterogeneous catalysts. We can achieve various types of reaction, such as aerobic oxidation, hydrogenation, cross-coupling, and even asymmetric reaction. Moreover these catalysts can be applied to tandem processes and flow systems. These catalysts can be reused by simple filtration and metal leaching into products are suppressed to realize truly practical and environmentally benign organic synthesis that fulfill the criteria of green sustainable chemistry.

Reviews:

  1. Tandem Oxidative Processes Catalyzed by Polymer-Incarcerated Multimetallic Nanoclusters with Molecular Oxygen
  2. Miyamura, H.; Kobayashi, S.
  3. Acc. Chem. Res. , 47, 1054 (2014). DOI: 10.1021/ar400224f
  1. Polymer-Incarcerated Metals: Highly Reactive, Recoverable, and Multifunctional Nanocluster Catalysts for Organic Synthesis
  2. Kobayashi, S.; Miyamura, H.
  3. Aldrichimica Acta , 46, 3-19 (2013). free
  1. Polymer-Incarcerated Metal(0) Cluster Catalysts
  2. Kobayashi, S.; Miyamura, H.
  3. Chem. Rec. , 10, 271 (2010). 10.1002/tcr.201000026

Topics

  1. Aerobic oxidation reactions catalyzed by Au nanoparticle catalysts (PI-Au)
  2. Size effect of Au nanoparticles on reactivity and selectivity
  3. Direct ester, amide and imine synthesis using molecular oxygen
  4. Cooperative catalytic system of metal nanoparticles and quinone derivatives as artificial enzyme
  5. Asymmetric synthesis using chiral metal nanoparticles
  6. Tandem reactions using multifunctional heterogeneous catalysts
  7. Application to flow systems
  8. Metal nanoparticle catalysts with NHC active cross-linker

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