ISSN print edition: 0366-6352
ISSN electronic edition: 1336-9075
Registr. No.: MK SR 9/7
Enantioseparation of mandelic acid enantiomers in ionic liquid aqueous two-phase extraction systems
Yan Yue, Xin-Yu Jiang, Jing-Gang Yu, and Ke-Wen Tang
College of Chemistry and Chemical Engineering, Central South University, Changsha, 410083, Hunan, China
Abstract: In the past decade, ionic liquids have received great attention owing to their potential as green solvent alternatives to conventional organic solvents. In this work, hydrophobic achiral ionic liquids (1-butyl-3-methylimidazolium-hexafluorophosphate([bmim][PF6]), 1-octyl-3-methylimidazolium tetrafluoroborate([omim][BF4])) were used as solvents in chiral liquid-liquid extraction separation of mandelic acid (MA) enantiomers with β-cyclodextrin (β-CD) derivatives as hydrophilic chiral selectors preferentially forming complexes with (R)-enantiomers. Factors affecting the separation efficiency were optimised, namely the type of the extraction solvents and β-CD derivatives, concentrations of the β-CD derivatives and MA enantiomers, pH, and temperature. Excellent enantioseparation of MA enantiomers was achieved in the ionic liquid aqueous two-phase extraction systems under the optimal conditions of pH 2.5 and temperature of 5°C with the maximum enantioselectivity (α) of 1.74. The experimental results demonstrated that the ionic liquid aqueous two-phase extraction systems with a β-CD derivative as the chiral selector have a strong chiral recognition ability, which might extend the application of ionic liquids in chiral separation.
Keywords: ionic liquids – enantioseparation – mandelic acid enantiomers – extration
Full paper is available at www.springerlink.com.
Chemical Papers 68 (4) 465–471 (2014)