| In this paper,a homogeneous reaction model and an interfacial reaction?heterogeneous reaction?model are established for chiral extraction according to the location of the reaction.The kinetics of reactive extraction of enantiomers was studied and the related kinetic parameters were obtained,which would provide a thought for optimizing the condition of the extraction of enantiomers and a rational basis for the industrial amplification of the method.The main contents and results about the research are summarized as follows:1.Study on the kinetics of homogeneous reaction extraction of enantiomers: During the kinetic study of reactive extraction for separation of aromatic enantiomers and ketoconazole enantiomers with hydrophilic ?-cyclodextrin derivative as an extractant,the enantiomers can be dissolved in the organic phase and the aqueous phase,and the hydrophilic ?-cyclodextrin derivative was dissolved in the aqueous phase,thus homogeneous reaction model was chosen to describe the process of reactive extraction.And the homogeneous model is based on the following assumptions:?1?The mass transfer resistance of the liquid film is neglected in the “plateau region”,so the concentration of the reactants at the interface is consistent with that of the bulk phase;?2?the reaction occurs at the bulk of aqueous phase.Based on the homogeneous reaction model,the factors influencing the extraction rate such as the specific area,the initial concentrations of the chiral selector in the aqueous phase and the enantiomers in the organic phase were investigated respectively in a Lewis cell.The results shown that the reactions were a fast reaction at temperature of 278 K.The extraction reactions were first-order reaction for 2-phenylbutyric acid?2-PBA?,tropic acid?TA?,?-cyclopentyl mandelic acid??-CPMA?and ketoconazole?KTZ?enantiomers,and secondary-order reaction for hydroxyethyl-?-cyclodextrin or hydroxypropyl-?-cyclodextrin?HE-?-CD or HP-?-CD?.The reaction rate constants of?+?-2-PBA and?–?-2-PBA were 2.829 × 10-4 m6/?mol2·s?and 1.803 × 10-4 m6/?mol2·s?;the reaction rate constants of?+?-TA and?–?-TA were 4.041 × 10-3 m6/?mol2·s?and 3.124 × 10-3 m6/?mol2·s?;the reaction rate constants of?R?-?-CPMA and?S?-?-CPMA were 1.459 × 10-3 m6/?mol2·s?and 2.056 × 10-3 m6/?mol2·s?;the reaction rate constants of?+?-KTZ and?–?-KTZ were 2.067 × 10-3 m6/?mol2·s?and 1.716 × 10-3 m6/?mol2·s?,respectively.2.Study on the kinetics of the interfacial reaction extraction of enantiomers: During the kinetic study of reactive extraction for separation of clorprenaline?CPNL?enantiomers with butyl?D?-tartrate?DT?and boric acid?BA?as a combined extractant,the reactants exist in different liquid phase and can not transfer to the other liquid phase,thus the interfacial reaction?heterogeneous reaction?model was selected to describe the process of reactive extraction.The interface model is based on the following assumptions:?1?The mass transfer resistance of the liquid film is neglected in the “plateau region”,so the concentration of the reactants at the interface is consistent with that of the bulk phase;?2?the reaction occurs at the interface.Based on the interfacial reaction model,the factors that influence the initial reaction extraction rate of enantiomers,including the initial concentrations of the chiral selectors?BA and DT?and clorprenaline enantiomers were investigated respectively in a Lewis cell.The experimental results demonstrate that the extraction reaction is 0.6 order reaction for boric acid,0.8 order reaction for isobutyl D-tartrate,and 0.8 order reaction for clorprenaline enantiomers.The rate constants of?R?-CPNL and?S?-CPNL were 2.476 × 10-4 L1.53/?mol1.2 s?and 1.349 × 10-4 L1.53/?mol1.2 s?at 278 K,respectively. |
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