Unusual separation of 1-phenyl-3-methyl-5-pyrazolone derivatives of aldoses by capillary zone electrophoresis

The 1-phenyl-3-methyl-5-pyrazolone (PMP) derivatives of aldoses showed unusual behavior in capillary zone electrophoresis in neutral buffers, giving excellent separation. Examination of the mi ration behavior of the PMP derivatives of aldopentoses and aldohexoses indicated that the derivatives of epimers having the 2,3-trans hydroxyl groups migrated faster than those having the 2,3-cis hydroxyl groups. This phenomenon can be explained by intramolecular ring formation by hydrogen bonding between the carbonyl group in the pyrazolone ring and the hydroxyl groups at C-2 and C-3 in the carbohydrate moiety. The 2,3-trans disposition will be favorable for ring formation and thereby cause reduction of the negative charge due to suppressed enolization. (C) 1997 Elsevier Science B.V.