Kinetic study on reactive extraction for chiral separation of phenylsuccinic acid enantiomers

The kinetics of the extraction of phenylsuccinic acid (PSA) enantiomers by hydroxypropyl-beta-cyclodextrin (HP-beta-CD) in a modified Lewis cell was studied, in which HP-beta-CD dissolved in 0.1 mol L(-1) NaH(2)PO(4)/H(3)PO(4) buffer solution (pH=2.5) was selected as the chiral extractant. PSA enantiomers were extracted from organic phase to aqueous phase in the extraction module. The theory of extraction accompanied by a chemical reaction has been used to obtain the intrinsic kinetics of this extraction module. The different parameters affecting the extraction rate such as agitation speed, interfacial area, initial concentration of PSA enantiomers in organic phase as well as HP-beta-CD concentration in aqueous phase were separately studied. The experimental results demonstrate that the extraction reactions are fast. The reactions were found to be first order with respect to PSA and second order with respect to HP-beta-CD with forward rate constants of 3.4 x 10(-2) m(6) mol(-2) s(-1) R-PSA and 9.96 x 10(-3) m(6) mol(-2) s(-1) for S-PSA. These data will be useful in the design of extraction processes.