Enantioselective Extraction of Racemic Ofloxacin by Di(2-Ethylhexyl)phosphoric Acid and Tartaric Acid Derivatives as Mixed Complex Chiral Selectors

Abstract

The distribution behavior of ofloaxcin (OFLX) enantiomers in a two-phase system was examined using a new mixed complex chiral selector consisting of di(2-ethylhexyl) phosphoric acid (D2EHPA) and two tartaric acid derivatives with n-octanol as diluents. The influence of composition of mixed complex chiral selector, initial concentration of OFLX, pH of aqueous phase and temperature was investigated. A maximum enantioselectivity of 2.43 was obtained when the molar concentration ratio of L-(-)-DBTA to L-(-)-DTTA is 2:3 L-(-)-DTTA concentration 0.18 mol/L, L-(-)-DBTA concentration 0.12mol/L) and the pH of aqueous phase is 6.86 at 25°C, with D D and D L up to a relative high value of 10.2 and 4.20, respectively. The results indicated a useful way of searching new efficient chiral selectors and it was proved also helpful to optimize the extraction systems and realize the large-scale production of the pure isomer of racemic mixtures with extraction methods.