Enantioselective extraction of mandelic acid enantiomers by L-dipentyl tartrate and β-cyclodextrin as binary chiral selectors

A new binary chiral selector system effective for the enantioselective extraction of racemic mandelic acid is presented. While L-dipentyl tartrate and beta-cyclodextrin had a very low enantioselectivity as single selectors, a preferential extraction of D-mandelic acid to the organic phase was found in the binary selector system. Using decanol as organic solvent and pH of a phoshate buffer equal to 2.3, the distribution coefficients of D-and L-mandelic acids as high as 14.9 and 7.0, respectively, and the enantioselectivity value of 2.1 were found at optimum concentration of beta-cyclodextrin.