Application of a cinchona alkaloid-based chiral anion-exchanger stationary phase for the direct high-performance liquid chromatographic enantioseparation of N-protected unusual phenylalanine analogs is reported. The N-benzyloxycarbonyl, N-3,5-dinitrobenzyloxycarbonyl, N-benzoyl and N-3,5-dinitrobenzoyl derivatives were well separable with high resolution. To achieve optimal separation of the enantiomers, the chromatographic conditions and temperature were varied. Linear van't Hoff plots were observed in the studied temperature range, 278-343 K, and the apparent changes in enthalpy, Δ(ΔH°), entropy, Δ(ΔS°), and Gibbs free energy, Δ(ΔG°), were calculated. The values of the thermodynamic parameters depended on the nature of the N-acyl groups, on the structures of the compounds, and especially on the nature of the substituent on C3 of phenylalanine.
- Chinchona alkaloid-based stationary phase
- Direct enantiometric separation
- Phenylalanine analogs
- Temperature effect
ASJC Scopus subject areas
- Analytical Chemistry
- Filtration and Separation