| Summary: | 碩士 === 國立中興大學 === 化學工程學系 === 90 === The objectives of the present study are to apply phase-transfer catalytic technique in synthesizing benzyl benzoate by conducting nucleophilic substitutions in the organic solution in solid-liquid and liquid-liquid system. The operating conditions for investigation include agitation speeds , reaction temperatures, catalyst amounts, types of solvents, molar ratio of reactants, type of phase-transfer catalysts, volume ratio of aqueous to solvent , and so on. The reaction mechanism and apparent reaction rate constants were obtained from the experimental results.
It will decrease interficial tension of two phases,while Aliquat 336 added to organic phase and sodium benzoate added to aquenous phase. Aliquat 336 is widely used as the fibers soften in textile industry. In liquid-liquid phase transfer system, the aqueous-phase reactant can be transported from aqueous-phase to organic-phase by the hydrophobic characters of catalytic Alliquat 336. The Aliquat 336 can catalyze sodium benzoate and benzyl bromide into esterification. The the formation of intermediate (PhCOOQ) and its the effects of the change on operating conditions were all investigate.
The experimental results show that the more the amounts of catalyst, the faster the synthesizing reaction rate will be. Effects of different organic solvents for Aliquat 336 are carried out, and above 95% yield of benzyl benzoate is easily achieved within 3 hours as using chlorobenzene as the solvent. The kinetics of pseudo-first-order reaction can be applied to describe the overall reaction rate successfully.
In the other quaternary ammonium system, the product selectivity and kinetics of sodium benzoate with benzyl bromide to produce benzyl benzoate via liquid-liquid phase-transfer catalysis were explored. When the agitation speed exceeds 200 rpm，the mass transfer resistance at the liquid-liquid interface can be ignored. Different phase-transfer catalysts were employed to compare their catalytic efficiency , and the reactivity order was found： Aliquat 336 > TBPB > TBAI > TBAHS > TBAB > PEG series.
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