Enantioselective Partitioning of Racemic Ibuprofen in a Biphasic Recognition Chiral Extraction System

Abstract

Enantioselective partitioning of ibuprofen enantiomers in a biphasic recognition chiral extraction system was studied. A combination of hydrophobic L-isobutyl tartrate in organic phase and hydrophilic β-cyclodextrin derivative in aqueous phase is necessary to establish a biphasic recognition chiral extraction system. The studies performed involve an enantioselective extraction in a biphasic system, where ibuprofen enantiomers form four complexes with the β-cyclodextrin derivative in aqueous phase and the D(L)-isobutyl tartrate in organic phase, respectively. In these biphasic resolutions, the types and the concentrations of the extractants, pH and temperature all exert a considerable influence on the biphasic recognition process. Good enantioselectivities for ibuprofen enantiomers were obtained at pH≤2.5 and a ratio of 2∶1 of [L-isobutyl tartrate] to [HP-β-CD]. Biphasic recognition chiral extraction is of strong chiral separation ability, and may be very helpful to optimize the extraction systems and realize the large-scale production of enantiomers.

Chiral separation by enantioselective liquid–liquid extraction

“…136 Selectivities up to 2.49 were reported for these systems with the biphasic extraction system mentioned above. Tang and coworkers have further expanded the scope of substrates to phenylsuccinic acid (selectivity of 2.8), 137 and the chiral drugs flurbiprofen, 138 ibuprofen, 139 and zopiclone, 140 all with rather low selectivities below 1.5. Much lower but still reasonable selectivities of 1.46-1.85 were observed for the same substrates with a single extractant Cu(II)(C12Pro) 2 in the organic phase.…”