Enantioselective Liquid–Liquid Extraction of Racemic Ibuprofen by l-Tartaric Acid Derivatives

Abstract

Enantioselective liquid–liquid extraction (ELLE) of racemic ibuprofen enantiomers was studied by using l-tartaric acid derivatives as chiral extractants in the organic phase. The chiral recognition mechanism of two ibuprofen enantiomers with l-tartaric acid esters was preliminarily investigated using density functional theory. The calculated binding energy of the (R)-ibuprofen/l-tartaric acid dihexyl ester complex (−64.32 kJ·mol–1) is higher than that of the (S)-ibuprofen/l-tartaric acid dihexyl ester complex (−39.74 kJ·mol–1). The influences of the type and concentration of the l-tartaric acid ester, the type of organic solvent, and the pH of the aqueous phase in the ELLE process were experimentally studied. The results showed that l-tartaric acid dipentyl ester was the best chiral extractant for racemic ibuprofen. The distribution coefficient and separation factor were best with polar organic solvents at low pH. Under the optimum conditions (0.2 mol·L–1 l-tartaric acid dipentyl ester in the organic phase and decanol as the solvent), the maximum enantioselectivity of racemic ibuprofen enantiomers was over 1.2.