Preparation Of New Organic Functional Materials For Organic Reactions And Catalysis In Aqueous Media

The concept of energy conservation driven by green chemistry exerts strong influence on the design for modern industrial catalysis: on one hand, to overcome the shortcomings of homogeneous catalyst in separation and recycling via immobilization, which diminishes the pollution problems that heavy metals may cause and cuts down the economic waste; on the other hand, the use of the water as a non-toxic, cheap and available reaction system not only reduce costs but protect the environment.Given a large number of silanols in the traditional silicon-based heterogeneous catalyst, it is hard to further increase the support hydrophobicity. Decrease in activity is often observed after homogeneous catalysts immobilization. Meanwhile, the silicon material itself is susceptible to destruction in some chemical environment particularly important for organic synthesis such as alkaline conditions. The mesoporous polymer materials and graphene have recently won widespread concerns. These organic materials have high surface areas, readiness for functionalization and high stability, which make them ideal supports for heterogeneous catalysts.The solvent evaporation induced self-assembly procedure, in-situ reduction technique, sacrificing template method are used to prepare a series of organic functional materials with specific structure and morphology, which are applied to catalyze a series of water-media green organic synthesis. The goal is to develop efficient catalysts that is similar with/superior to homogenous catalysts in activity result; easy to reuse; and compatible for different chemical environments. By analyzing the catalytic performance and material characterization, the relationship between the efficiency and structure is investigated. The detailed descriptions are listed as follows:1. Urea-functionalized mesoporous polymers (Urea-MPs) were synthesized through a surfactant-directed urea-phenol-formaldehyde oligomers self-assembly approach. The as-prepared urea-MPs material exhibited superior catalytic activity than parent urea in water-medium Knoevenagel condensation reactions and could be used repetitively for seven times. The excellent activity could be attributed to the synergic effect derived from the secondary amine with the surface phenolic groups that generated the acid-base cooperative catalytic behavior. Meanwhile, the urea functional groups embedded in the mesopore wall could effectively inhibit the leaching of active species and thus obtained the relatively good durability.2. By using in-built functional groups on the urea-functionalized mesoporous polymer materials (Urea-MPs), the metal salt solutions such as PdCl₂, HAuCl₄ and AgNO₃ were reduced and anchored within the channels. In this system, Urea-MPs acted as a reducing agent, stabilizer and size control agent without any additional reagents and surface modification. In the Suzuki carbon-carbon coupling reactions between boric acid and benzene halide under the alkaline conditions, the Urea-MPs after the incorporation of Pd nanoparticles (Urea-MPs-Pd) showed high activity and stability, and can be separated and recycled.3. Improved Hummers Method was used to prepare the graphite oxide (GO). Layered structure graphene-MnO2 composite (GMC) was prepared by chemical replacement with KMnO4 of graphene at low temperature. Optimal synthesis condition was investigated by examining the influence of reaction time and solution acidity on the product. 3-cyano pyridine oxidation reaction and phemethylol oxidization were used as probes, in which GMC show high catalytic activities. Meanwhile, the process of GMC formation and the growth mechanism were explored.