Phase-Transfer Catalytic Reaction of 2,4,6-Tribromophenol and α-Bromxylene Initiated by Hydroxide Ion at High Alkalinity

本研究主要探討α-溴化二甲苯(-o-,-p-,-m-)和2,4,6-三溴(ArOH)在鹼性水溶液和有機溶劑中之二相介質進行相間轉移觸媒催化反應，如攪拌速率、觸媒(QBr)用量、有機溶劑種類、有機相反應物之位相(orientation)與溫度等操作變數對2,4,6-三溴酚之轉化率之影響，逐一做深入探討。雖然在高鹼濃度情況下，轉化率（或反應速率）展現出奇異現象，但仍獲得極高之轉化率。在高鹼固體量下，反應物轉化率隨著攪拌速率之增加而降低，吾人利用有機溶劑會受到鹼性物質濃度影響之事實進行解釋此奇異現象，而首先鹼性物質會影響到有機溶劑之極性及路易士鹼(Lewis base)之特性，此二種因素影響了有機溶劑及反應物與活性中間體之溶劑分解作用(Solvolysis)。在整個反應過程中，2,4,6-三溴酚氧化四丁基銨鹽(ArOQ)在有機相中之濃度一直保持常數，而活性中間體之濃度及活性都會影響到轉化率，而活性中間體(ArOQ)在二相間之質量傳送阻力若與有機相反應速率之大小做比較是可以省略的，本研究利用熱力學之性質和溶劑分解作用可以圓滿解釋動力學數據。

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並列摘要

In this work, the phase transfer catalytic reactions of α-bromoxylene (-o-, -p- and -m-) and 2,4,6-tribromophenol for producing α-bromoxyl-2,4,6-tribromophenoxide were carried out in an alkaline solution of KOH/organic solvent two-phase medium. High conversion is obtained only under high concentration of alkali, though the conversion (or the reaction rate) exhibits a peculiar phenomenon at high concentration of alkali. Here, the conversion is decreased with the increase in the agitation speed of low speed region for a high content of alkali solid in the two-phase solution. The characteristics of the organic solvents, which are affected by the concentration of alkali compound, are used to explain this phenomenon of the conversion. The concentration of alkaline compound directly influences the polarity and the characteristics of the Lewis base of the organic solvent. These two important factors affect the solvolysis of organic solvent and reactant or the activated intermediate. The concentration of tetrabutylammonium 2,4,6-tribromophenoxide (ArOQ) stays constant through the course of reaction. Both the concentration of the active intermediate (ArOQ) and its activity are important in affecting the conversion. The resistance of mass transfer of ArOQ between two phases is negligible compared to the rate of organic-phase reaction. Thermodynamic properties in conjunction with the solvolysis effect was used to explain the kinetic data satisfactorily.

並列關鍵字

Phase-transfer catalysis ； Solvolysis ； Polarity ； Lewis base ； Organic solvents ； High alkalinity

國際替代計量

Phase-Transfer Catalytic Reaction of 2,4,6-Tribromophenol and α-Bromxylene Initiated by Hydroxide Ion at High Alkalinity

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