Kinetic study on biphasic recognition chiral extraction for separation of α-cyclohexyl-mandelic acid enantiomers

摘要

Chiral solvent extraction is a potentially attractive chiral separation technique. It is essential to know the intrinsic complexation kinetics for selection, design and operation of reactive extraction equipment and for reliable scale-up. The objective of this research is to study the kinetics of biphasic recognition chiral extraction of α-cyclohexyl-mandelic acid (α-CHMA) enantiomers using a modified Lewis cell. Results: The experimental results demonstrate that the extraction reaction kinetics is fast, and the reactions are first order with respect to α-CHMA and second order with respect to D-IBTA, with forward rate constants of 6.54 × 10 ~(-4) mol ~(-2) m ~6 s ~(-1) for S-α-CHMA and 6.84 × 10 ~(-4) mol ~(-2) m ~6 s ~(-1) for R-α-CHMA. With increase of HP-β-CD concentration in aqueous phase, enantioselectivity increases, while the overall mass transfer coefficients decrease. Conclusions: Sufficient enantioselectivity and fast kinetics of extraction can be obtained in the BRCE system at HP-β-CD concentration of 0.1 mol L ~(-1) and D-IBTA concentration of 0.2 mol L ~(-1). These data will be useful in the design of extraction processes.