Chiral discrimination of the enantiomers of δ-phenyl-δ-valerolactone by cellulose triacetate: A chromatographic and microcalorimetric study of the thermodynamics

The resolution of racemic δ-phenyl-δ-valerolactone by chromatography on cellulose triacetate CTA I results in one of the best separations of optical antipodes observed so far on this chiral stationary phase. The thermodynamics of the stereoselective interaction of the enantiomers of δ-phenly-δ-valerolactone have been studied by chromatography at different temperatures and by direct microcalorimetric investigations of the complexation with CTA I. This analysis suggests that the separation process is mainly controlled thermodynamically and that kinetic effects, if any, play a minor role. Microcalorimetric titration experiments indicate that specific (optimum) complexation sites on CTA I for the stronger retained enantiomer of δ-phenly-δ-valerolactone are rapidly saturated, whereas the first eluted enantiomer seems to interact much less selectively with defined interaction sites on the chiral polymer matrix. © 1993 Wiley-Liss, Inc.