The enantiomers of four unusual, rather rigid isoxazoline-fused 2-aminocyclopentanecarboxylic acids were directly separated on a quinine- or a quinidine-based zwitterionic ion-exchanger as chiral selector. The effects of the mobile phase composition, the structures of the analytes and temperature on the separations were investigated. Experiments were performed at constant mobile phase composition in the temperature range 10-50. °C to study the effects of temperature, and thermodynamic parameters were calculated from plots of ln α versus 1/. T. Some mechanistic aspects of the chiral recognition process are discussed with respect to the structures of the analytes. It was found that the enantiomer separations were in most cases predominantly enthalpy-driven, but entropically-driven separations were also observed. The sequence of elution of the enantiomers was determined in all cases.
- Chiralpak ZWIX columns, van't Hoff analysis, Unusual temperature effects
- Cinchona alkaloid-based chiral stationary phases
- Column liquid chromatography
- Isoxazoline-fused 2-aminocyclopentanecarboxylic acids
ASJC Scopus subject areas
- Analytical Chemistry
- Organic Chemistry