Direct resolution of alpha-amino acid enantiomers by ligand exchange: stereoselection mechanism on silica packings coated with a chiral polymer.
A chiral polymer easily obtained by treatment of a linear polyacrylamide with L-proline was adsorbed on a silica support treatment of a linear polyacrylamide with L-proline. After complexation with copper(II), and in spite of a rather low efficiency due to slow ligand exchange, such packing are very convenient for the resolution of amino acid enantiomers eluted in water (relative retention, k'L/k'D, higher than 2 may be observed). Other eluents may also be used. The chiral polymer was studied in solution by potentiometry and nuclear magnetic resonance spectroscopy (13C relaxation measurement). A model of the complex involved in the stereoselection is proposed which accounts for the chromatographic results obtained.
D000588:Amines / Q000032:analysis*; D002852:Chromatography, Ion Exchange / Q000379:methods*
D000588:Amines