Kinetic Study for Biphasic Recognition Chiral Extraction of Naproxen Enantiomers with HydrophobicL-iso-butyl Tartrate and Hydrophilic Hydroxypropyl-β-Cyclodextrin

Abstract

The kinetics of biphasic recognition chiral extraction of naproxen (HA) enantiomers was investigated to determine the extraction mechanism, with hydrophobic L-iso-butyl tartrate (L-IBTA) in the organic phase and hydrophilic hydroxypropyl-β-cyclodextrin (HP-β-CD) in the aqueous phase. The two-phase homogeneous reaction model was selected over the interfacial reaction model, because there is a clear physical solubility of naproxen enantiomers in both the aqueous phase and the organic phase. The reactions between the HA enantiomers and L-iso-butyl tartrate in a stirred cell fall in Regime 3; the extraction is accompanied by two fast chemical reactions in the diffusion film. The reactions have been found to be first order with respect to HA enantiomers and second order with respect to L-IBTA. The forward rate constants for S-HA and R-HA are 1.26 × 10 −4 mol −2 m 6 s −1 and 2.52 × 10 −4 mol −2 m 6 s −1 , respectively. With the increase of HP-β-CD concentration in the aqueous phase, high enantioselectivity was obtained, but the extraction rates decreased. These data will be useful in the design of extraction processes.

Chiral Ionic Liquids: Structural Diversity, Properties and Applications in Selected Separation Techniques

“…The formation of "chiral selector-enantiomer" complexes [86] thanks to intermolecular interactions ("three-point model") is the basis of the final chiral recognition. The best-researched ELLE systems contain organic solvents and chiral selectors derived from β-cyclodextrin or tartaric acid [87][88][89][90][91][92]. However, nowadays, as recommended by green chemistry and sustainability [93,94], the use of volatile organic solvents should be limited.…”