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High‐Performance Liquid Chromatographic Enantioseparation of Cyclic β ‐Amino Acids on Zwitterionic Chiral Stationary Phases Based on Cinchona Alkaloids
Author(s) -
Ilisz István,
Gecse Zsanett,
Lajkó Gyula,
Forró Enikõ,
Fülöp Ferenc,
Lindner Wolfgang,
Péter Antal
Publication year - 2015
Publication title -
chirality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.43
H-Index - 77
eISSN - 1520-636X
pISSN - 0899-0042
DOI - 10.1002/chir.22458
Subject(s) - chemistry , enantiomer , cinchona , steric effects , chromatography , enthalpy , counterion , elution , chiral column chromatography , amino acid , organic chemistry , thermodynamics , enantioselective synthesis , ion , catalysis , physics , biochemistry
Stereoselective high‐performance liquid chromatographic separations of eight sterically constrained cyclic β ‐amino acid enantiomer pairs were carried out using the newly developed Cinchona alkaloid‐based zwitterionic chiral stationary phases Chiralpak ZWIX(+) and ZWIX(−). The effects of the mobile phase composition, the nature and concentrations of the acid and base additives, the counterions and temperature on the separations were investigated. The changes in standard enthalpy, Δ(Δ H °), entropy, Δ(Δ S °), and free energy, Δ(Δ G °), were calculated from the linear van't Hoff plots derived from the ln α vs. 1 / T curves in the studied temperature range (10–50°C). The values of the thermodynamic parameters depended on the nature of the selectors and the structures of the analytes. Unusual temperature behavior was observed on the ZWIX(−) column: decreased retention times were accompanied by increased separation factors with increasing temperature. On the ZWIX(+) column only enthalpically, whereas on the ZWIX(−) column both enthalpically and entropically driven separations were observed. The elution sequence was determined in all cases and was observed to be the opposite on ZWIX(+) and on ZWIX(−). Chirality 27:563 – 570, 2015 . © 2015 Wiley Periodicals, Inc.