Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/3361
標題: Benzylation of 2-Methoxy-4-propenylphenol via Liquid-Liquid Phase-Transfer Catalysis
液-液相相間轉移催化2-甲氧基-4-丙烯基酚之苯甲化反應研究
作者: 王毓嵐
Wang, Yu-Lan
關鍵字: Phase-transfer catalysis;相間轉移催化反應;liquid-kiquid phase;Benzyl 2-methoxy-4- propenylphenyl ether;Aliquat 336;Kintics;interfacial tensio;液-液相;界面張力;反應動力學;醚化反應;苯甲基2-甲氧基-4-丙烯基苯基醚;氯化甲基三辛基銨
出版社: 化學工程學系
摘要: 
本研究探討的是以液液相間轉移催化2-甲氧基-4-丙烯基酚之苯甲化反應。操作條件有:觸媒種類效應、觸媒添加量效應、水量添加效應、不同反應溫度效應、不同攪拌速率效應、不同反應物比例效應以及不同溶劑效應等。另外還探討了導電度與界面張力的現象,並且進ㄧ步去研究反應機構及求得其反應動力學的速率常數。
隨著觸媒Aliquat 336和水相反應物的添加量增加,其界面張力也會跟著下降,這是因為其結構都與界面活性劑相似的關係。從實驗結果來看,加入相間轉移觸媒對反應速率的提升是很有幫助的,在不添加觸媒時其反應性是相當低的,當添加Aliquat 336的量增加時,反應速率也會隨之上升,並且可以用虛擬一階方式來描寫此一反應。在液-液相系統中,利用氯化甲基三辛基銨親油的特性,可將水相反應物質傳到油相,當轉速超過50 rpm時便可忽略兩相間之質傳阻力。而NaOH的量對系統反應是沒影響的。在不同有機溶劑的影響方面,使用MIBK在30分鐘後其產率便可達到86%,而使用極性較低之Hexane在30分鐘後產率只能大約60%。由實驗結果顯示最佳的2-甲氧基-4-丙烯基酚鈉鹽使用量為為水相反應物與2-甲氧基-4-丙烯基酚鈉鹽的莫耳比例為1.5,在45分鐘後產率可達84%。在這個系統內最適的水量為55毫升,過多和過少的水量都對反應有不好的影響。
在不同觸媒活性比較方面,其結果是Aliquat 336>TBPB>BTBAB>TBAI>TBAB>PEG400>PEG600,求得的活化能為Aliquat 336:17.522(kcal/mol);TBPB:21.652(kcal/mol);BTBAB:15.996(kcal/mol);TBAI :16.055(kcal/mol);TBAB:14.665(kcal/mol)。

The present study is to investigate the benzylation of 2-methoxy-4 -propenylphenol via liquid-liquid phase-transfer catalysis. The operating conditions for investigation include agitation speed, reaction temperatures, catalyst amounts, type of catalyst, type of organic solvent, molar ration of reactant, types of solvents, and so on. The electric conductivity and interfacial tension were also measured. The reaction mechanism and apparent reaction rate constants were obtained from the experimental results.
The interfacial tension of two phases will be dreacreased with Aliquat 336 adding to the organic phase and sodium 2-methoxy-4- propenylphenoxide in the aqueous phase. From the experimental data shown, the reaction rate was greatly enhanced by applying phase-transfer catalysts. Without the addition of any catalyst, the product yield is very low, while the reaction rate increases with increasing the amount of Aliquat 336 catalyst added, and the overall reaction rate can be well described by the pseudo-first-order kinetics. In a liquid-liquid phase transfer syatem, the aqueous phase reactant can be transported from aqueous-phase to organic-phase by the hydrophobic characters of catalyst Aliquat 336. When the agitation speed exceeds 50 rpm, the mass transfer resistance at the liquid-liquid interface can be ignored, and NaOH cannot influence the reaction rate. Effects of different organic solvents for Aliquat 336 were carried out, and above 86% of yield of benzyl 2-methoxy-4- propenylphenyl ether is easily achieved within 30 minutes using MIBK as the solvent, and above 60% of yield of product is obtained within 30 minutes using hexane as the solvent. An optimal quantity of sodium 2-methoxy-4- propenylphenoxide is located on 1.5 of the molar ratio of 2-methoxy-4-propenylphenoxide to benzyl bromide to give above 84% of yield of benzyl 2-methoxy-4-propylphenyl ether is within 30 minutes. The best condition is 55 ml of water in this system, neither much more nor less use of water is good for this system.
Different phase-transfer catalysts were employed to compare their catalytic efficiency, and the reactivity order was found : Aliquat 336>TBPB>BTBAB>TBAI>TBAB>PEG400>PEG600. The activation energies for five catalysts were: Aliquat 336: 17.522(kcal/mol);TBPB: 21.652(kcal/mol);BTBAB: 15.996(kcal/mol);TBAI : 16.055(kcal/mol);TBAB: 14.665(kcal/mol)
URI: http://hdl.handle.net/11455/3361
Appears in Collections:化學工程學系所

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