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Enantioselective separation of twelve pairs of enantiomers on polysaccharide‐based chiral stationary phases and thermodynamic analysis of separation mechanism
Author(s) -
Zhu Bolin,
Yao Yaqi,
Deng Miaoduo,
Jiang Zhen,
Li Qing
Publication year - 2018
Publication title -
electrophoresis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.666
H-Index - 158
eISSN - 1522-2683
pISSN - 0173-0835
DOI - 10.1002/elps.201800194
Subject(s) - chemistry , enantiomer , enthalpy , hexane , chromatography , enantioselective synthesis , phase (matter) , stereochemistry , organic chemistry , thermodynamics , physics , catalysis
The enantioseparation of twelve pairs of structurally related 1‐aryl‐1‐indanone derivatives was studied in the normal‐phase mode using three different polysaccharide‐type chiral stationary phases, namely Chiralpak IB, Chiralpak IC, and Chiralpak ID. n ‐Hexane/2‐propanol and n ‐hexane/ethanol were employed as mobile phases. Among all the investigated chiral columns, Chiralpak IC exhibited the most universal and the best enantioseparation ability toward all the racemates, particularly with the mobile phase composed of n ‐hexane/2‐propanol (90/10, v/v). Then the effects of column temperature on retention and enantioselectivity were examined in the range of 25–40°C. Satisfactory enantioseparation was obtained at ambient temperature. The natural logarithm of retention and separation factors (ln k and ln α ) versus the reciprocal of absolute temperature (1/ T ) (Van't Hoff plots) were found to be linear for all racemates, indicating that the retention and separation mechanisms were independent of temperature in the range investigated. Then, the thermodynamic parameters (ΔΔ H °, ΔΔ S °, and ΔΔ G °) were calculated from Van't Hoff plots. These values indicated that the solute transfer from the mobile to stationary phase was enthalpically favorable, and the process of enantioseparation was mainly enthalpy controlled. At last, the impact of small changes in molecular structures of the tested 1‐indanone derivatives on enantioseparation was also discussed.