Resolution of Racemic Ofloxacin Based on Co-Technology of Bubble Fractionation and Extraction

A method of bubble fractionation, with the help of solvent extraction, was developed for the resolution of racemic ofloxacin (rac OFLX). In this method, dibenzoyl-L-tartaric (L-DBTA), di-(2-ethylhexyl) phosphoric acid (D2EHPA) and sodium lauryl sulfate (SDS) were used as chiral collector, co-extractant and foamer, respectively. Several important parameters influencing the resolution performances, such as pH in aqueous phase, concentration of OFLX, concentration of L-DBTA, concentration of SDS and volume ratio of D2EHPA to n-octanol in solution, were investigated. The optimal resolution conditions were obtained with the aqueous phase pH 7, volume ratio of D2EHPA to n-octanol 6/14 in organic phase, concentration of SDS 0.42 mg mL−1, concentration of OFLX 1.67 mg mL−1, and concentration of L-DBTA 0.11 g mL−1. Under the optimal extraction conditions, the enantiomeric excess value (e.e.%) was 60.08% and the enantioselectivity (α) was 5.58. It was found that the capacity of enantioselective separation can be greatly improved by the co-technology.