DIRECT SEPARATION OF ALPHA-HYDROXY ACID ENANTIOMERS BY LIGAND-EXCHANGE CHROMATOGRAPHY

Direct separation of several alpha-hydroxy acid racemic mixtures was p erformed by the aid of ligand exchange chromatography using L-hydroxyp roline chemically bound to silica stationary phase and aqueous solutio ns of copper (II) sulphate as a mobile phase. The elution order of the D- and L-enantiomers of alpha-hydroxy acids is interpreted in terms o f a modified Davankov's rule. Several aspects of the Davankov's model of selectand-Cu(II)-selector ternary complexes are discussed based on the theoretical calculations within the quantum mechanical semiempiric al and density functional theories. (C) 1998 Wiley-Liss, Inc.