Synthesis of Allyl Phenyl Ether by Liquid-Liquid-Solid Phase Transfer Catalysis─Comparison of the Polymer and Inorganic Supports

• Main Authors: Hsien-Ting Chung, 鍾協廷
• Other Authors: Hung-Shan Weng
• Format: Others
• Language: zh-TW
• Published: 2003
• Online Access: http://ndltd.ncl.edu.tw/handle/42306943632332651687

碩士 === 國立成功大學 === 化學工程學系碩博士班 === 91 === In this study, several kinds of trialkylamines were immobilized on chloromethylated polystyrene polymer, silica gel and alumina to prepare triphase catalysts. These catalysts were then employed for catalyzing the etherification reaction of allyl bromide (the organic reactant) and sodium phenolate (the aqueous reactant). In the experiments, phenetole has a configuration similar to the organic product, allyl phenyl ether, was used as an organic solvent for the purpose of simulating a reaction system with the organic product as a solvent. An optimal catalyst was selected basing on the activity, selectivity and stability. Subsequently, for preventing the catalysts from the destruction by the stirrer, ultrasonic vibration was imposed on the reactor. The effect of ultrasonic vibration on the performance of catalyst was investigated. Finally, the etherification reaction was carried out in a batch reactor and a continuous-flow stirred vessel reactor in which the organic product was used as a solvent, and the ultrasonic vibration was imposed in addition to a slow mechanical stirring. By this study, an optiomal catalyst and a proper way of stirring were found. This thesis is composed of four parts. In the first part, several kinds of trialkylamines were immobilized on the polymeric support and used as the catalysts for catalyzing the etherification reaction. Experiment results show that the immobilization of trialkylamine is influenced by the length of the alkyl group in the trialkylamine molecules. The amount of trialkylamine immobilized is less when the length of alkyl group is longer. For catalyzing the reaction between allyl bromide and sodium phenolate, the catalyst immobilizing tri-n-propylamine is the best, tri-n-butylamine the second, triethylamine the next, and tri-n-pentylamine the worst. When the amount of sodium phenolate is larger than that of allyl bromide, the conversion of allyl bromide will be higher, and the reaction is of the pseudo-first order. In the second part, the inorganic compounds (silica and alumina) were functionalized first and then used as the supports for immobilizing the trialkylamines. The inorganic supported catalyst has a high mechanical strength, can sustain even at high temperatures and can not be easily destroyed at a high stirring speed. Its stability is higher than the polymeric supported catalyst. The experimental result shows that it is true. The shortcoming of inorganic supported catalyst is its low activity and selectivity. In addition, the rate of catalyzing allyl bromide will be slow down in the later period of the reaction. These shortcomings can not be improved by changing the operation conditions. So comparing to the polymeric supported catalyst, the inorganic supported catalyst is a worse choice. In order to mitigate the decay of catalyst due to the destruction by the mechanical stirrer and to improve the contacting pattern between the catalyst particles and the organic and aqueous phases for increasing the reaction rate, three mixing modes were compared in the third part of this study, namely, mechanical stirring, mechanical stirring with the imposition of ultrasonic vibration, and stirring with a magnetic bar. The experimental results show that the decay of the catalyst is indeed mitigated when the ultrasonic vibration is imposed on the reaction mixture which is agitated by a mechanical stirrer at a slow speed. The result also reveals the activity and the stability of the catalyst become the worst when the magnetic bar is employed for stirring. In the last part, the etherification reaction was carried out in a batch reactor and in a continuous-flow stirred vessel reactor (CFSVR) with the organic product, allyl phenyl ether, as the solvent. The catalysts and the operation conditions were selected and determined by referring the results obtained in the preceding parts. The polymeric supported tri-n-propylamine was used as the catalyst while the SiO2-supported tri-n-butylamine catalyst was tested for comparison. The mechanical stirring at a low agitation speed with the imposition of ultrasonic vibration was adopted for agitating the reacting mixture. The results reveal that the activity of polymeric supported catalyst is higher than that of SiO2-supported catalyst, and the conversion of allyl bromide declines only slightly during a long-period operation.