Derivatives of cholesterol cinnamate: A comparison of the separations of geometrical isomers when used as gas chromatographic stationary phases

Four para-substituted cholesterol cinnamates were synthesized and evaluated for utility as gas chromatograph (GC) liquid crystal stationary phases. The capability of the phases to separate olefinic geometrical isomers was found to be dependent on the position of the olefinic bond. When unsaturation occurred at positions four carbons or greater from the terminal methyl of the compounds investigated, the relative ability of the phases to separate geometrical isomers was p-Cl > p-Me > cholesterol cinnamate > p-MeO derivative > p-NO₂. When unsaturation occurred at positions four carbons or less from the terminal methyl the relative ability of the para-derivatives of cholesterol cinnamate to separate geometrical isomers was reversed.