Influence of the kind of the alcoholic modifier on chiral separation of 4-substituted-pyrrolidin-2-ones using amylose based chiral stationary phase

The enantioselective separation of 4-substituted-pyrrolidin-2-ones was inve stigated on a silica-based amylose tris (3,5-dimetfiylphenylcarbamate) (Chi ralpak AD) using. normal phase methodology with a mobile phase consisting o f n-hexane-alcohol (ethanol, 1-propanol or 2-propanol) in various percentag e. Effects of variation of concentration of alcohol and the nature of aliph atic alcohols in the mobile phase were studied. In a general manner, for th e ten compounds analysed, the retention times increased and the separations factors were improved on changing the alcohol modifier from 2-propanol to ethanol. The effects of substitution were analysed. Baseline separation was easily obtained in many cases with a maximum resolution factor of 11.