Base Effect of Synthesizing Partially Substituted- (phenoxy) cyclotriphosphazene by Triphase Catalysis
| Autor: | Chang-Lin Lee, 李忠錂 |
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| Rok vydání: | 1999 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 87 Phase-transfer catalysis is usually applied for synthesizing an organic compound, in the organic-aqueous phases. However, the separation and rease of the catalyst in the reaction system need to encounter. In this study, the substitution reaction of hexachlorocyclotriphosphazene and phenol was investigated using polymer supported ammonium salt in the batch reactor and total recycle fixed bed reactor. The concentration of base, reactants and catalyst, temperature and the kinds of catalyst were studied to obtain the optimum reaction condition. The relative reaction-rate constants and activation eneries were also calculated. According to the experimental result, same conclusions are listed as following: (1) psendo-first-order reaction-rate constant was increased with increasing temperature, the concentrations of base and phase-transfer catalyst. (2) The arrherius activation energy for this substitution reaction had a minimum value, the particle diffusion resistance of reactant from bulk solution to active site was main an factor in increasing apparent reactivity. The Arrherius activition energy was decreased by decreasing the particle size of triphase catalyst. It is demonstrated that the particle diffusion is an important factor in enhancing reaction rate. (3) The substitution degree of hexachlorotricyclophosphazene reacting phenol was increased with increasing base concentration. However, the substitution procedures for the first and the second substitution products were complete. The finding denstrated the particle diffusion can not be neglected in this reaction system. (4) The reaction rate of phosphazene replaced reaction in batch reactor was rapid than that in total recycle fixed-bed reaction. The product yield of the first to the third substitution reaction was decreased by decreaing recycle ratio of effluent to recycle stream. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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