Enantioseparation of sulphoxide compounds with cellulose-based chiral stationary phase

Six sulphoxide compounds were enantioseparated with a cellulose-based chiral stationary phase, Chiralcel OD-H, in the normal-phase mode. The effects of the amount of polar alcohol in the mobile phase and the column temperature on the retention and enantioseparation were studied. It showed that the substance containing electron-withdrawing substituent in the aromatic ring exhibited low enantioseparation. Methyl phenyl sulphoxide, ethyl phenyl sulphoxide and methyl 3-methoxyphenyl sulphoxide can be baseline separated; the separation factors are 1.351, 1.369. and 1.151 respectively when n-hexane/2-propanol (92.5 : 7.5, V/V) was used as eluent, at a flow rate of 1.0 mL/min at 25 degrees C. The retention times were in 26 min. The mechanism of chiral recognition was discussed further by thermodynamic method.