ENANTIOSEPARATION OF AMINO-ACIDS AND AMINO-ALCOHOLS ON CHIRAL STATIONARY PHASES DERIVED FROM ALPHA-AMINO-ACID-DISUBSTITUTED AND PYRROLIDINYL-DISUBSTITUTED CYANURIC CHLORIDE

Three silica-based chiral stationary phases (CSPs) derived from L-alph a-amino acid- and pyrrolidinyl-disubstituted cyanuric chloride were pr epared. The alpha-amino acids norvaline, valine, and phenylalanine wer e selected as the chiral moiety of CSPs. These CSPs provide effective recognition and separation of enantiomers of both methyl esters of N-( 3,5-dinitrobenzoyl) amino acids, except that of proline, and N-(3,5-di nitrobenzoyl) amino alcohols by high-performance liquid chromatography . Amino acids, except phenylglycine, were generally separated more eff ectively than amino alcohols. Separation factors obtained for norephed rine on these CSPs, except CSP-2, are the best among reported values. Although the enantioselectivity depends mainly on three preferential i nteractions described previously which include a pi-pi interaction and two hydrogen-bonding interactions, steric interaction between substit uents attached to chiral centers of chiral selectands and chiral selec tors plays a significant role in the mechanism of chiral recognition. The phenyl ring in the phenylalanyl moiety of CSP-3 neither plays an e lectronic role in chiral recognition nor makes a significant contribut ion to chiral recognition. Comparison of chromatographic results shows that a CSP of a covalent type was more effective than the correspondi ng ionic type.