Studies On The Synthesis And Properties Of Novel Supported Catalysts Based On Fibers

Supported catalysis is one of the most effective ways to achieve the catalyst recycling and simplify the operation. Exploring the reliable, efficient and inexpensive materials as supports, and immobilizing the homogeneous catalysts onto them to acquire higher activity and selectivity in the supported catalytic reactions have received increasing attention of the chemical workers. This dissertation focuses on the "green chemistry", and starting from the development of novel, economic, high efficient and environmentally-benign catalytic systems, to demonstrate a series of catalytic methods based on common synthons of polypropylene fiber and polyacrylonitrile fiber.The polypropylene chain of polypropylene fiber contains a large amount of tertiary carbon atoms, which can be used as the effectively modified sites for immobilization via the free radical reactions. In the first section of this paper(chapters, 2 and 3), a sulfonic acid-functionalized polypropylene fiber was synthesized by chlorosulfonation and hydrolysis, and the functionalized fiber was used in the three components Biginelli reaction, the results show that the reaction proceeded smoothly even with only 1 mol% catalyst loading and 25 different types of 3,4-dihydropyrimidin-2-(1H)-ones/-thiones were synthesized successfully. And on this basis, we further used the polypropylene fiber to design and synthesize the supported ionic liquid for the first time, through graft copolymerization, onium salt-forming and acidification, a novel class of different anion-substituted fiber-supported acidic pyridine onium salt ionic liquids were prepared and used to catalyze the dehydration of fructose to 5-hydroxymethylfurfural(HMF), and excellent catalytic performance was obtained in terms of 86.2% and 84.7% HMF yields in DMSO and mixed-aqueous solvent of water-methyl isobutyl ketone(MIBK) under 100 oC for only 30 and 45 min, respectively.The polyacrylonitrile fiber contains a lot of cyano and methoxycarbonyl groups, which can be easily immobilized by ammoniation. In the second section of this paper(chapters, 4 to 8), we first utilized the ammoniation of polyacrylonitrile fiber and polyethylene polyamine to obtain the polyamine-functionalized fiber, and the polyamine-functionalized fiber was used as the heterogeneous base catalyst and supported phase-transfer catalyst to synthesize a number of substituted iminocoumarins(yields 82-96%) and sulfones(yield up to 96%) in aqueous systems via Knoevenagel condensation-cyclization and nucleophilic substitution, respectively. Moreover, a series of polyacrylonitrile fiber-supported ethyl ammonium nitrate-type ionic liquids were prepared by acidification on the ethylenediamine-functionalized fiber, and the fiber-supported ionic liquids were used to mediate the Friedel-Crafts alkylation of indoles, it turned out that the reaction can proceed smoothly in water(yields 87-96%) and almost no reactions in organic solvents, accordingly, a "release and catch" catalytic mechanism was proposed. Based on the above work, the polyamine-functionalized fiber was acidized with methanesulfonic acid to afford the polyacrylonitrile fiber-supported poly(ammonium methanesulfonate)s, which was used as the Br?nsted acid catalysts in different types of solvents such as polar protic solvent, non-polar solvent, water and polar aprotic solvents as well as mixed-aqueous solvent to efficiently mediate Biginelli reaction(yields 81-94%), Pechmann condensation reaction(yield up to 95%), Friedel-Crafts alkylation of indoles(yields 81-96%) and conversion of fructose to HMF(yield up to 85%), respectively. In addition, based on the polyamine-functionalized fiber, four types of fiber-supported polyammoniums were prepared and used in combination with metal halides to study the concerted catalytic activities for the conversion of sucrose to HMF in mixed-aqueous systems, the results show that the fiber catalyst incorporates protonic acid groups that promote the hydrolysis of the glycosidic bond to convert sucrose into glucose and fructose, and then catalyzes fructose dehydration to HMF, while the ammonium moiety may promote synergetically with SnCl4 for the isomerization of glucose to fructose, after the optimization of reaction conditions, the yield of HMF could reach 72.8%, besides, the synergistic catalytic system also effective for fructose, glucose, inulin and starch. Finally, the tertiary amine-functionalized fiber was used to chelate copper salt, and a fiber-supported copper catalyst was prepared and verified to efficiently mediate the Glaser coupling reaction, with only 2 mol% catalyst loading, air as the oxidant in ethyl acetate at room temperature, the reaction proceeded smoothly to afford near to quantitative yields for the synthesis of a range of diynes.According to the detailed characterization of fiber samples at different stages and the studies on the catalytic performance of the above-mentioned sulfonic acid-functionalized fiber, fiber-supported ionic liquids, polyamine-functionalized fiber, fiber-supported ammonium salts and fiber-supported transition metal, the reliability of the fiber catalysts in the preparation process and the changes of the fiber catalysts during the catalytic process were fully demonstrated. Moreover, the corresponding fiber-supported catalytic systems with mild conditions, high catalytic activity and simple post-processing, and the fiber catalysts can be reused for several times as well as all of the above catalytic systems can be effectively scaled up, and comparing with the results reported in the literatures, which further provide indications of the green fiber catalysts with superior activities and also demonstrate their potential applications in the industrial production, furthermore, the fiber-mediated catalytic system opening a new avenue to achieve the fixed-bed reactors for continuous synthesis in the chemical industry.