Synthesis,Characterization And Catalytical Performance Of Porous Polymerized Organocatalysts

Small organic molecular catalysts, providing an alternative to metal-and enzyme-catalyzed transformations due to their distinct activity and selectivity, have become another class of important catalysts. They have been attracting continuous attention over the last decade because they are easily prepared, simply handled, and being insensitive to water or air. Despite fruitful advancements in academia, like many homogeneous catalytic systems, they cannot be more extensively applied because of low catalytic efficiency and difficulties in separation of the catalysts from the products. More importantly, the ammount of organocatalysts are too large. To solve this problem, the immobilization of the organocatalysts with insoluble solid supports is applied.In Charpter I, common porous supports of catalysts including inorganic mesoporous silica, organic-inorganic hybrid metal organic frameworks (MOFs) and porous organic polymers have been introduced. Notably, the mesoporous silica support is difficult to modify due to the simply chemical compositions and normally sensitive to the alkaline media; the MOFs usually have relatively low stability; the polystyrene support often has relatively low surface area. These shortcomings strongly hinder their applications in heterogeneous catalysis. However, the porous organic polymers synthesized via "Bottom-Up" methods can introduce the organocatalysts as the building structure into the polymers. Based on the above consideration, we show an alternative route for preparing highly active and excellently recyclable organocatalysts with hierarchical porosity, which could efficiently function as a combination of both catalyst and support. The porous polymerized organocatalysts (PPOs) with high surface area, large pore volume, hierarchical porosity, superior chemical stability have been directly and rationally synthesized via a mild solvothermal polymerization reaction of the corresponding vinyl-functionalized organocatalyst monomers. In Charpter III, the porous polymerized TEMPO (PPO-TEMPO) with has been successfully synthesized from the polymerization of vinyl-functionalized TEMP monomers under solvothermal conditions and subsequent oxidations to generate the stable free radicals. The PPO-TEMPO shows high activities and excellent recyclabilities in selective oxidations of a variety of alcohols to the corresponding aldehydes or ketones.In Charpter IV, using the proline as raw materials, porous polymerized catalysts of prolinol and2-(fluorodiphenylmethyl) pyrrolidine (PPO-DPP and PPO-FBMP) are synthesized via the same methods. The PPO-DPP together with BH3can generate the PPO-CBS catalyst for the asymmetry reduction of ketones, but unfortunately, low ee values were obtained. The catalytial research of PPO-DPP and PPO-FBMP are still under investigation.The PPOs catalyst synthesized in this work might open a new door for developing heterogeneous catalysts with high activity and good recyclability in the future.