Temperature effects on the chromatographic behaviour of racemic 2-amidotetralins on a Whelk-O 1 stationary phase in super- and subcritical fluid chromatography

The chromatographic behaviour of thirty structurally related racemic 2-amidotetralins on a cis-(3R, 4S)-Whelk-O 1 stationary phase was investigated at five different temperatures between 50 and -15 degrees C using super- or subscritical fluid chromatography (SFC/SubFC). Generally, low selectivity factors were observed for this class of analytes on this stationary phase. In particular, phenyl and benzyl substituted analogues were strongly retained, probably due to strong pi-pi interactions with the chiral selector molecule, but the enantioselectivity was low. This also counts for the two p-iodo substituted methoxy analogues, although here steric effects may be responsible for the high capacity factors. In about 10% of the cases, a decrease in the (surrounding) temperature of the column did not result in an improved selectivity. Only four compounds out of thirty could not be resolved under the given conditions.