Kinetics of Synthesis of Dibenzyl Glycol under Phase-Transfer Catalysis Conditions

• Main Authors: Chia-Ning Chi, 祁家寧
• Other Authors: Yao-Hsuan Tseng
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/36427264996693225934

碩士 === 國立臺灣科技大學 === 化學工程系 === 99 === 　　In this study, 1,2-bis(benzyloxy)ethane was synthesized by reacting benzyl bromide with ethylene glycol under phase transfer catalysis. In the experiment, the reactor was a 100 mL three-necked flask, added an appropriate amount of reactant, deionized water, organic solvents, potassium hydroxide and the catalyst for reaction. Detailed investigation was made for: effect of agitation speed, amount of water, organic solvents, catalysts, organic solvent types, phase transfer catalyst types, alkali concentration, alkali salt type, mole ratio of reactant, temperature and ultrasonic wave. The reaction kinetics by high performance liquid layer chromatography (HPLC), gas chromatography mass spectrometer (GC / MS), nuclear magnetic resonance (NMR) and elemental analysis (EA) to analyze this results to find the optimal reaction conditions. 　　The results show that (a) The reaction type as an SN2 reaction. (b) The pseudo steady-state hypothesis and two-film theory are successfully applied to describe the reaction behaviors. (c) The reaction was effectively enhanced in the mild conditions via phase-transfer catalysis. The reaction via phase-transfer catalyst could avoid by-product was produce at higher temperature. (d) A threshold value of two-phase mass-transfer rate would exist in the phase transfer catalytic reactions. All reaction systems were identified as the extraction mechanism. The reaction was organic reaction controlled when the agitation speed was higher than the threshold value. (e) The reaction rate is increase with the increase in agitation speed, temperature, amount of catalyst and organophilicity of the active catalyst. (f) The significant binary interactions in affecting the reaction rate, agitation speed-amount of KOH , agitation speed-reaction temperature, and amount of PTC-amount of KOH, are found with using fractional factorial design method. The reasons for these interactions are : distribution and concentration of active catalyst, viscosity and surface tension of liquid, and hydration number of active catalyst.