手性溶液萃取分离氧氟沙星对映体

目的研究氧氟沙星对映体在手性环境中的萃取分配行为,为外消旋体膜萃取拆分提供理论和设计依据。方法以0.25 mol·L^-1 L-二苯甲酰酒石酸醇溶液为有机相,含0.14 g·L^-1氧氟沙星的0.1 mol·L^-1磷酸氢二钠/磷酸缓冲液为水相,考察了pH对氧氟沙星对映体在水-有机相分配系数(K)和分离因子(α)的影响,研究了不同碳数醇的溶剂化效应,同时运用中空纤维膜对氧氟沙星外消旋体进行初步分离。结果以癸醇为溶剂,pH 6.86时,L-二苯甲酰酒石酸对氧氟沙星外消旋体萃取分配系数大于4.7,α达1.18;用中空纤维支载液膜双有机相逆流分级萃取技术,11个22 cm长膜器串联,产品光学纯度达90%以上。结论L-二苯甲酰酒石酸在醇溶剂中对磷酸氢二钠缓冲液中的RS-氧氟沙星对映体有较强的立体选择性,其中癸醇的效果最好,pH对K和α有较大影响,综合K和α值,取pH 6.86时,手性萃取效果最佳;利用高效中空纤维膜,可使RS氧氟沙星对映体得到不同程度的分离。

SEPARATION OF OFLOXACIN ENANTIOMERS BY EXTRACTION WITH SOLVENT CONTAINING CHIRAL SELECTOR

AIMDistribution behavior of ofloxacin enantiomers was examined in the aqueous and organic solvent of a two-phase system containing a chiral selector, and the theory was provided for separation of racemic mixtures by solvent extraction. METHODSAlcohol containing 0.25 mol·L^-1 L-dibenzoyltartaric acid (L-DBTA), was used as organic phase, and Na₂HPO₄ buffer solution containing 0.14 g·L^-1 ofloxacin, was used as aqueous phase. The influence of pH on partition coefficient (K) and separation factor (α), was investigated in aqueous-organic phases. Significant enantioselectivity was observed with alcohols of different carbon number as solvents. Ofloxacin enantiomers were separated with hollow fiber membrane. RESULTSThe values of K for R and S enantiomers were all above 4.7, and α was up to 1.18, when racemic ofloxacins were extracted with L-DBTA in decanol at pH 6.86; the optical purity of the product in the outflow is above 90% through 11 hollow fiber membrane modules with 22 cm length. CONCLUSION L-DBTA in alcohol solvents is of strong enantioselectivity for racemic ofloxacins in Na₂HPO₄ buffer solution. pH and alcohol solvents are of big influence on K and α, and decanol and pH 6.86 are good for separation; a different degree of separation can be obtained by adjusting transfer unit numbers.