Development of the antipode of the covalently bonded crown ether type chiral stationary phase for the advantage of the reversal of elution order

Chiral stationary phases, CSP 1 and CSP 2, with a reverse stereochemical configuration, were prepared by covalently bonding (+)- and (-)-(18-crown-6)-2,3,11,12-tetracarboxylic acid (18-C-6-TA) to silica gel, respectively. These CSPs were used to resolve the enantiomers of a-amino acids and primary amino compounds, affording reasonable and quite similar resolution behaviors except for the elution orders. The elution orders of the two enantiomers for the resolution of alpha-amino acids and other primary amino compounds were always opposite on the two CSPs. The reverse elution orders on the two CSPs with the antipode of the chiral selector were demonstrated to be very useful in the determination of the enantiomeric purity of optically enriched analytes.