Influence of temperature on the enantioseparation of rolipram and structurally related racemates on Chiracel-OD

Abstract The temperature dependence of the chiral separations of rolipram and structurally related racemates was investigated in liquid chromatography with Chiralcel-OD as staionary phase. The thermodynamic data reveal that the enantioseparation of rolipram and two other racemates belong to the unusual case of entropy-controlled separations whereas for the remaining racemates the expected enthalpy-controlled separations were observed. In particular, at 20°C not even a partial separation is obtained for rolipram whereas a complete baseline resolution is achieved at 65°C.