RESOLUTION OF AMINO-ACID RACEMATES ON BORATE-GELLED GUARAN-IMPREGNATED SILICA-GEL THIN-LAYER CHROMATOGRAPHIC PLATES

Borate-gelled guaran-impregnated silica gel TLC plates act as a very g ood chiral chromatographic media. Tetracoordinated boron is complexed to the cis-OH pairs in guaran polysaccharide, creating a chiral enviro nment around boron. The complexed boron can undergo a ligand-exchange reaction or stereoselective dual H-bonding to a bis-oxygen or N,O-liga nd, such as conformationally favourable glycol, alpha-hydroxy acids an d alpha-amino acids. These reactions, due to chiral selectivity, resul t in a difference in the migration rates of the enantiomers of a racem ic mixture on a TLC plate. This provided a simple, rapid and effective method for the resolution of alpha-amino acid racemates.