Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/3407
標題: 第三液相相間轉移觸媒合成鄰-硝基苯辛醚之醚化反應動力學研究
KINETICS FOR SYNTHESIZING O-NITROPHENYL OCTYL ETHER VIA THIRD-LIQUID PHASE-TRANSFER CATALYSIS
作者: 林俵任
Lin, Piao-Jen
關鍵字: Phase-transfer catalysis
相間轉移觸媒
Third-liquid phase
Catalytic intermediate
Interfacial tensions
Enhancement ratio
o-Nitrophenyl octyl ether
o-Nitrophenol sodium salt
1-Bromooctane
第三液相觸媒系統
觸媒中間體
界面張力
增益比率
鄰-硝基苯辛醚
鄰-硝基酚化鈉
1-溴辛烷
出版社: 化學工程學系
摘要: 本論文係應用第三液相相間轉移觸媒催化的新合成方法,進行鄰-硝基酚化鈉與1-溴辛烷之醚化反應合成產物鄰-硝基苯辛醚,其用途為核廢料中萃取放射性元素鎝-99之萃取劑、葡萄糖中分離出單糖的分離疏水膜材料等。研究內容包括形成第三液相之最佳條件、第三液相中觸媒中間體隨操作條件的變化情形、三液相之液-液界面特性分析、觸媒催化活性、合成鄰-硝基苯辛醚之醚化反應動力學研究及第三液相系統觸媒的回收方法、效率及其製程。 第三液相主要是水相反應物與相間轉移觸媒經離子交換反應形成之觸媒中間體,於特定條件下自水相中析出,且因其難溶於有機相而自成一相,即為第三液相,介於有機相與水相之間。使用溴化四丁基鏻(TBPB)為觸媒,形成第三液相之體積與TBPB的用量呈線性關係增加,但若以硫酸氫化四丁基銨(TBAHS)為觸媒則其體積呈非線性增加。第三液相中的觸媒中間體含量會隨添加劑氫氧化鈉之用量提高而增加,當氫氧化鈉用量為0.07莫耳時可使91.2%的觸媒集中於第三液相,此將有利於反應快速進行;而使用低極性正庚烷與甲苯,在適當操作條件下可順利形成第三液相,其體積約為1.7~2毫升,高極性氯苯則會使第三液相消失;若增加水及甲苯用量皆會使第三液相體積隨之減少,過多水量亦會使第三液相消失,而在水量10~80毫升皆能形成第三液相。 第三液相觸媒系統中,其液-液間的界面張力會受觸媒中間體含量的影響,使用較親油性的TBPB為觸媒時,其第三液相/水相間的界面張力介於6.4~10.3 mN/m,高於使用較親水性的TBAHS介於4.0~7.7 mN/m;而使用TBPB之有機相/第三液相的界面張力則介於3.2~3.6 mN/m之間,小於使用TBAHS之介於4.0~4.5 mN/m;至於使用親水、親油特性介於上述兩種觸媒間之溴化四丁基銨(TBAB),其液-液界面張力大小亦介於此兩種觸媒之間。當提高水相中氫氧化鈉的濃度,導致有機相/第三液相及第三液相/水相間的界面張力皆隨之增加;至於水相反應物鄰-硝基酚化鈉用量小於0.03莫耳時,第三液相/水相間之界面張力先隨其用量提高而增加,在其用量大於0.03莫耳時則隨之遞減。 本研究亦合成與定量出第三液相中觸媒中間體,深入探討在不同條件下的觸媒中間體含量及其隨反應時間的變化情形。在批式反應器進行三液相之催化反應,當攪拌速率為200 rpm以上即可忽略相與相間之質傳阻力;在反應溫度80℃及使用觸媒TBPB,反應時間三小時即可獲得超過98﹪以上之產物產率;同時可得第三液相中觸媒中間體的增益比率( )與有機相中產物之產率( )的關係式為 , 為第三液相中觸媒中間體的初始增益比率, 為觸媒中間體增益比率的下降速率,再配合實驗數據推導出符合本醚化反應的動力學模式,求取各種操作條件下之視反應速率常數kapp,其動力方程式表示為 ,並探討不同反應條件下,各變因對視反應速率的影響。 使用第三液相觸媒催化系統之優點為減少副產物產生及觸媒能再回收使用。本論文探討三種回收程序之效率優劣,可分為更新有機溶劑之回收程序與無更新有機溶劑之回收程序,其中以不更新有機溶劑並持續加入定量的水相反應物與有機相反應物之回收程序效果較佳。本研究之結果可作為本反應系統之製程方法設計的基礎。
The novel method for synthesizing o-nitrophenyl octyl ether used as extracting technetium-99 from nuclear waste was investigated in a batch reactor via third-liquid phase-transfer catalysis (PTC). The subject matter of this research contains the optimum condition of third-liquid phase formed, the variation of catalytic intermediate (ArOQ) with operation conditions in third-liquid phases, the analysis of interfacial characteristics between tri-liquid phase, the activity of catalyst, kinetics for synthesizing o-nitrophenyl octyl ether, the method of recovery for the catalyst. The aqueous reactant reacts with PTC firstly to form the ArOQ, and then that transfers from the aqueous phase with difficult dissolving in organic phase at some conditions to form third-liquid phase between organic and aqueous phase. The volume of third-liquid phase formed increases linearly with increasing the amount of tetra-n-butylphosphonium bromide (TBPB) employed, but that increases non-linearly with increasing the amount of tetra-n-butylammonium hydrogen sulfate (TBAHS). A more amount of NaOH can effectively gather more amount of ArOQ in third-liquid phase, and there was 91.2% of PTC gathered in third-liquid phase at 0.07 mol of NaOH, leading to the reactivity higher than at a lower amount of ArOQ. The volume of third-liquid phase decreases with increasing the amount of water or toluene, and third-liquid phase would be formed at 10~80 mL of water. The interfacial tension, affected by ArOQ and the hydrophilicity or lipophilicity of PTC, between the aqueous/third-liquid phases was 6.4~10.3 mN/m using TBPB more than 4.0~7.7 mN/m using TBAHS, and 3.2~3.6 mN/m using TBPB less than 4.0~4.5 mN/m using TBAHS for the third-liquid/toluene interface. The character of tetrabutylammonium bromide (TBAB) lies between TBPB and TBAHS leading to the interfacial tension in both phase also lying between those two catalysts. The interfacial tension between third-liquid/aqueous phases reduces when the usage of aqueous reactant exceeds 0.003 mol. This exhibits that increasing the aqueous reactant can promote the formation of ArOQ, leading to the resistance of transport gradually diminished. In this dissertation, ArOQ in third-liquid phase was successfully synthesized, and the variations of which with reaction time were quantified. The resistance of mass transportation can be neglected when the agitation speed was more than 200 rpm. The product yield greater than 98% was obtained within three hours of reaction using TBPB as the PTC at 80℃. The relation of the enhancement ratio (η) of ArOQ in third-liquid phase and the product yield in the organic phase is , where is the initial enhancement ratio of ArOQ in the third-liquid phase, and is the consumption rate of enhancement ratio. Correlating the experimental data, we have pseudo-first-order kinetic model to well describe the overall reaction successfully, as shown in equation , and the apparent reaction rate constants (kapp) are obtained and studied with different reaction conditions. Reducing side-product and recovering PTC are the advantage of third-liquid phase-transfer catalysis. Three types of recoverable procedure were discussed, in which, the efficiency of the recoverable procedure of non-renew organic solvent and fixed amounts of aqueous and organic reactant added is better than others. The results of this reaction system can provide referrals in designing the fabrication processes.
URI: http://hdl.handle.net/11455/3407
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