Enantioselective liquid-liquid extraction of DL-mandelic acid using chiral diphosphine ligands as extractants

In order to expand the application range of chiral diphosphine ligands, (S)-BINAP, (S)-SEGPHOS, and (S)-MeO-BIPHEP were employed as extractants to recognize DL-mandelic acid. The results indicated that (S)-SEGPHOS-Cu exhibited considerable ability to recognize DL-mandelic acid with operational enantioselectivity (alpha) of 2.677. The process of extraction of DL-mandelic acid using (S)-SEGPHOS-Cu as extractant was systematically investigated. Performance factor (pf) was adopted to comprehensively evaluate the extraction. After optimization by response surface methodology (RSM), the optimal extraction condition is temperature of 5.5 degrees C, (S)-SEGPHOS-Cu concentration of 3.0 mmol/L, and pH of 8.0. And the predicted and experimental maximum values of pf were 0.26374 and 0.26839, respectively.