Gas chromatographic resolution of enantiomeric amphetamines and related amines : I. Structural effects on some diastereomer separations

Abstract

Eight structurally related enantiomeric primary amines including several amphetamines were resolved as diastereomers by gas chromatography. Optically active acylated amino acid chlorides were reacted with the amine racemates to yield volatile diastereomers which were chromatographed on polar and on nonpolar columns. Selectivity of diastereomeric pair separations was found to be dependent on substitution at the chiral centers of both the amino acids and the amines. Baseline resolution was achieved on a 6-ft. diethylene glycol succinate column at 200° for seven of the eight amines. The polar stationary phases yielded higher relative separation factors than the nonpolar phase in all cases for the same chromatographic conditions. The effect of varying the perfluoroacyl group of the amino acid resolving agent from trifluoroacetyl to pentafluoropropionyl to heptafluorobutyryl was to significantly decrease the retention times without significantly decreasing these separation factors.