Application of cellulose and amylose arylcarbamates as chiral selectors in counter-current chromatography

Here we studied the applicability of cellulose and amylose tris(3,5-dimethylphenylcarbamate) as chiral selectors for the separation of enantiomers by counter-current chromatography (CCC). A variety of organic/aqueous biphasic solvent systems and eight racemic analytes of acidic, neutral, and basic nature were tested for this purpose. Classical elution mode and pH-zone-refining displacement conditions were used. Partial enantioseparation of pindolol and warfarin was achieved in methyl isobutyl ketone (MIBK)/aqueous solution and methyl tert-butyl ether (MTBE)/aqueous solution, respectively. For these two racemates enantiomeric excess values from 84% to 97% were achieved under the best conditions tested. However, resolution by CCC was not achieved for propranolol, naproxen and N-(3,5-dinitrobenzoyl)-(+/-)-leucine, easily separated in HPLC by the same selectors.