Enantioselective Extraction of Mandelic Acid Enantiomers Using Ester Alcohol L-tartarate as Chiral Selector

Distribution behavior of mandelic acid enantiomers was examined in an aqueous-organic solvent of a two-phase system containing L-tartarate. The influences of pH, length of alkyl chain of Ltartarate, organic solvent, concentration of phosphate salt and time of chiral extraction on partition coefficient (k) and separation factor (α) were investigated, respectively. With the rise of pH, k decreases, but α increases. With the addition of length of alkyl chain of L-tartarate, k and α decrease. The organic solvent and concentration of phosphate salt also have a bigger influence on k and α. A new binary chiral selector system is presented, effective for the enantioselective extraction of racemic mandelic acid. The distribution coefficients of Dand L-mandelic acid as high as 14.9 and 7.0, respectively, and the enantioselectivity value of 2.1 were found. Keyword—Mandelic acid enantiomers, Ltartarate, chiral extraction, binary chiral selector.