ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Chiral separation of α-cyclohexylmandelic acid enantiomers using ionic liquid/salt aqueous two-phase system

Lei-Lei Chen, Fen-Fang Li, and Zhi-Jian Tan

School of Chemistry and Chemical Engineering, Central South University, Changsha, 410083, China

E-mail: lfflqq@mail.csu.edu.cn

Abstract: In this paper, an ionic liquid-based aqueous two-phase system (ILATPS) was applied to the chiral separation of α-cyclohexylmandelic acid (α-CHMA) enantiomers with hydroxypropyl-β- cyclodextrin (HP-β-CD) as the chiral selector. Several influencing parameters were investigated including the types and concentration of ionic liquids, the amount of phase-forming salt, temperature, mixing time, pH, and the content of HP-β-CD. The results showed that not all ILATPS had the ability to chirally recognise the selected enantiomers and that [C₄mim]BF₄/(NH₄)₂SO₄-based ATPS possessed the best enantioseparation ability of the investigated ILATPSs. Under optimal conditions, the separation factor (α) attained 1.59 in a single-step extraction. ILATPS is much “greener” than other liquid-liquid extraction systems, showing its potential for application to the chiral separation.

Keywords: ionic liquid-based aqueous two-phase system – chiral recognition – enantiomers – HP-β- CD – α-cyclohexylmandelic acid

Full paper is available at www.springerlink.com.

DOI: 10.1515/chempap-2015-0162

Chemical Papers 69 (11) 1465–1472 (2015)