反应萃取分离2-苯基丁酸对映体的动力学

Kinetics of reaction extraction separation of 2-phenylbutyric acid enantiomers

通过恒界面池法进行了羟乙基-β-环糊精反应萃取2-苯基丁酸对映体的动力学研究。采用双膜理论和均相反应模型描述了萃取过程的相际传质机理,并考察了搅拌速率、界面面积、对映体初始浓度和萃取剂初始浓度等因素对2-苯基丁酸对映体的萃取动力学的影响。实验结果表明羟乙基-β-环糊精与2-苯基丁酸对映体之间的包合反应属于"快反应";2-苯基丁酸对映体反应分级数为1,羟乙基-β-环糊精反应分级数为2;(+)-2-苯基丁酸和(–)-2-苯基丁酸在278 K下的反应速率常数分别为2.829×10^(-4)、1.803×10^(-4) m6·mol^(-2)·s^(-1)。该萃取动力学研究为大规模生产中的反应萃取过程的设计和操作以及设备的设计和过程强化提供了科学的依据。

Kinetics research on the reactive extraction of 2-phenylbutyric acid enantiomers using hydroxyethyl-β-cyclodextrin（HE-β-CD） as extractant was performed in a Lewis cell. A homogeneous reaction model and a two-film theory were employed to describe the mass transfer mechanism of the reactive extraction process. The process parameters affecting the initial extraction rate, including agitation speed, interfacial area, pH value of aqueous phase, initial concentration of 2-phenylbutyric acid（2-PBA） enantiomers and initial concentration of extractant, were separately studied. The results showed that the reaction between hydroxyethyl-β-cyclodextrin and 2-phenylbutyric acid was a fast reaction. It was found that the reaction was first order in 2-phenylbutyric acid and second order in hydroxyethyl-β-cyclodextrin. The forward rate constants for the extraction of（＋）-2-phenylbutyric acid and（–）-2-phenylbutyric acid were 2.829×10-4 and 1.803×10-4m6·mol-2·s-1, respectively. The results were useful for the design and operation of reactive extraction process in large-scale production, and provide scientific basis for equipment design and process intensification.