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題 名 | 液-液相相間轉移催化酚化鈉醚化反應之無機鈉鹽與鉀鹽效應=Effects of Inorganic Sodium and Potassium Salts on Etherification of Sodium Phenoxide by Liquid-Liquid Phase-Transfer Catalysis |
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作 者 | 楊鴻銘; 吳俊民; | 書刊名 | 興大工程學刊 |
卷 期 | 12:2 2001.07[民90.07] |
頁 次 | 頁109-117 |
分類號 | 460.02 |
關鍵詞 | 相間轉移觸媒; 醚化反應; 反應動力學; 鹽類效應; Phase-transfer catalysis; Etherification; Kinetics; Salt effect; |
語 文 | 中文(Chinese) |
中文摘要 | 本研究在探討以碘化四丁基銨為觸媒在液─液相系統中由酚化鈉與溴化丙烯合成丙烯基苯基醚,加入不同的鹽類及氫氧化鈉,瞭解其對觸媒中間體之生成及總反應速率的影響,並提出虛擬一次反應式來描述此反應之動力學。當攪拌速率在350rpm以上,反應速率為攪拌速率的弱函數關係;總反應速率隨著氫氧化鈉的增加而上昇,雖然有機相中觸媒中間體的濃度會減少,觸媒反應性會因為水合作用與水解─萃取作用的遲滯而使反應速率提高。而丙烯基苯基醚的產率隨著溴化鈉添加量增多而下降,因溴化鈉使反應性較高的中間產物碘化丙烯減少,但溴化鉀對於視反應速率常數的影響較為顯著。若在反應系統碘化鈉之添加量增多,會使觸媒中間體易再生成碘化四丁基銨,造成毒化觸媒的效應使反應速率隨之下降。當碳酸鈉添加量小時,反應速率不受影響,但添加量變大後,反應速率則會隨鹽類增多而變小;當加入硫酸鈉量小時,反應速率下降;而在添加量增多後,反應速率會略回昇,此速率之下降係因有機相中碘化丙烯之濃度變化在加入鹽類碳酸鈉與硫酸鈉後被抑制,以致總反應速率減慢。本研究對無機鹽類在液─液相相間轉移催化反應之效應獲得深入的瞭解。 |
英文摘要 | In the present study, the effects of inorganic salts on the formation of catalytic intermediate and the reaction rate for synthesizing allyl phenyl ether from the etherification of sodium phenoxide with allyl bromide by liquid-liquid phase-transfer catalysis were investigated using tetra-n-butylammonium iodide as the catalyst. The pseudo-first-order kinetics was proposed to describe the overall reaction successfully. The reaction rate exhibits a weak function of agitation speed when exceeding 200 rpm. The overall reaction rate increases with increasing NaOH added, although the concentration of the catalytic intermediate is decreased. This phenomenon is due to the hydration effect and the diminished hydrolysis-extraction of sodium phenoxide. The decrease of the product yield with increasing NaBr is resulted from the reduction of forming allyl iodide, which is a more reactive intermediate during the reaction. In addition, the effect of KBr on the reaction rate is more significant than that of NaBr. By adding extra NaI, the reaction rate would be reduced due to the re-formation of tetra-n-butylarmnonium iodide from the catalytic intermediate. Small amounts of sodium carbonate do not influence the reaction rate, however, the reaction rate decreases with larger amount of that added. By introducing a small amount of sodium sulfate, the reaction rate diminishes, but then increases and decreases subsequently for more sodium sulfate added. This is due to the formation of allyl iodide inhibited in the organic phase from extra sodium carbonate and sulfate, leading to the reduction of the overall reaction rate. The present study gives a detailed insight for salt effect in liquid-liquid phase-transfer catalysis. |
本系統中英文摘要資訊取自各篇刊載內容。