Separation of racemic R-3-pyridyl sulfoxide on chiral stationary phase by high performance liquid chromatography

A series of racemic R-3-pyridyl sulfoxides were successfully separated by a cellulose derivative based chiral stationary phase ( OB-H) under normal - phase high performance liquid chromatography ( HPLC) conditions. Through investigation on the influence of the percentage of iso-propanol in the mobile phase and the column temperature on the resolution, the chromatographic conditions were optimized. As the percentage of iso-propanol in the mobile phase increased, the capacity factors k' and the resolution factors R. of the series of racemic sulfoxides all decreased except for compound M which had a branched chain. The influence of temperature on resolution was not obvious. As far as the solutes were considered, a long carbon chain or a branched chain both can decrease the interaction of solutes with the stationary phase, so the capacity factors k' and the resolution factors R. of the enantiomers would decrease, too. The results show that this chiral stationary phase exhibits good stereoselectivity to the series of racemic sulfoxide enantiomers. And the best resolution condition is 30% iso-propanol in the mobile phase and the column temperature at 25 degrees C..