An original chiral selector, namely the prop-2-enyl 3α-(N-phenylcarbamate)-7α,12α-dihydroxy-5β-cholan-24-oate, is bonded onto the silica surface by three different grafting modes. The influence of the total structure of the chiral stationary phases (CSPs) on enantioseparation is studied. These CSPs are prepared in two steps. In the first step, the silica surface is reacted with one of the following reagents: 1) (3-mercaptopropyl)trimethoxysilane, yielding a rather monomeric support, 2) chlorodimethylsilane, leading to a monomeric material, or 3) triethoxysilane, affording a polymeric packing. In the second step, the chiral selector is bonded onto the modified silica structures to provide the corresponding stationary phases SH, CDS, and TES, respectively. The CSP SH shows the poorest column performance. CSPs CDS and TES show similar mass transfer kinetics; this highlights the good behaviour of the polymeric packing. CSP TES displays globally the highest enantioselectivity and is found to be extremely stable despite its use over months. The silanization reaction with triethoxysilane provides a suitable support for chiral stationary phases. 2155

The suitability of cyclocholates as chiral selectors in gas chromatography has been evaluated. We present the synthesis and characterization of two cyclocholates, viz. 3α,7α‐diacetoxycyclo[3]cholate and 3α,7α‐diacetoxycylo[4]cholate. Mixtures of these new selectors with polysiloxanes were tested as chiral stationary phases in capillary gas chromatography. Several enantiomer separations of common racemates were achieved with the 3α,7α‐diacetoxycyclo[3]cholate at 10% in OV‐1701 (w/w). It was shown that column efficiency was strongly dependent on temperature and that enantioselectivity was very sensitive to column conditioning. This chromatographic behavior suggested that cyclocholates were only dispersed in polysiloxane. Thus, it was assumed that chiral discrimination occurred via enantioselective adsorption interactions of enantiomers at the surface of the solid chiral selector dispersed in the polysiloxane matrix OV‐1701.