Chiral separation of α-cyclohexyl-mandelic-acid by aqueous two phase system combined with Cu2-β-cyclodextrin complex

Based on the Polyethylene glycol (PEG)-salt aqueous two phase system (ATPS), a novel, green and economical approach was proposed for the chiral separation and determination of α-cyclohexyl-mandelic-acid (CHMA). The result showed that this new technique has good chiral recognition ability for CHMA. The separation factor, α, was affected by various factors, including the molecular weight of PEG, pH, temperature, the amount of Cu2-β-cyclodextrin, which influenced on either the formation of the host–guest complex or the distribution of the complex. In this work, Cu2-β-cyclodextrin was inclined to recognize R-CHMA. Under the optimum conditions, α could reached 1.36 after just one step extraction. This method has explored a new path for preparative separation of racemic compounds.

Schematic representation of the ATPS chiral extraction for CHMA enantiomers.Figure optionsDownload as PowerPoint slideHighlights
► ATPS was introduced for the resolution of α-cyclohexyl–mandelic-acid enantiomers.
► Cu2-β-CD inclined to prefer monovalent ionic state of R-CHMA than that of S-CHMA.
► Cu2-β-CD was introduced as a selector for the resolution of (R, S)-CHMA.
► Under the optimal condition, α could reach 1.36 after just one step extraction.