Separation of flurbiprofen enantiomers by biphasic recognition chiral extraction

Abstract

Based on our previous work, this paper reports enantioselective partitioning of flurbiprofen enantiomers in a biphasic recognition chiral extraction (BRCE) system combining a hydrophobic l-tartrate in organic phase and hydrophilic β-cyclodextrin derivative in aqueous phase which preferentially recognize R-enantiomer and S-enantiomer, respectively. The studies performed involve an enantioselective extraction in a biphasic system, where flurbiprofen enantiomers form four complexes with β-cyclodextrin derivative and l-tartrate, respectively. In these biphasic resolutions, the concentrations of the extractants and flurbiprofen enantiomers, the types of organic solvents and extractants, pH and temperature all exert a considerable influence on the biphasic recognition process. The maximum enantioselectivity for flurbiprofen enantiomers is 1.24 at the pH of 2.5, 5 °C, the flurbiprofen initial concentration of 0.0001 mol/L and the ratio of 2:1 of [ l- iso-butyl tartrate] to [TM-β-CD]. By changing the monophasic recognition chiral extraction (MRCE) system into BRCE system, the enantioselectivities are greatly improved. Biphasic recognition chiral extraction is of strong chiral separation ability, and can be hopeful for separations of various enantiomers at a large-scale.