Normal phase high-performance liquid chromatographic enantiomeric separation of chiral amines as naphthaldimine derivatives was performed on amylose and cellulose-derived chiral stationary phases (CSPs) using three naphthaldehyde derivatizing agents. The effect of the structural characteristics of both derivatizing agent types of naphthaldehydes and CSP types on enantiodiscrimination of chiral amines was investigated. The enantioselectivities and resolutions obtained on amylose-derived CSPs were greater than those on cellulose-derived CSPs, except for 2-hydroxynaphthaldimine derivatives on cellulose-derived CSPs. In particular, the most conformationally rigid and flexible, 2-hydroxynaphthaldimine and 2-naphthaldimine derivatives, among three kinds of naphthaldehyde-derived analytes afforded the greatest enantioseparation on conformationally rigid cellulose-derived and conformationally flexible amylose-derived CSPs, respectively. The developed analytical method was applied to the determination of enantiomeric purity for its broad applicability where the enantiomeric impurities of (R)- and (S)-α-methylbenzylamine reagents were found to be 0.63 and 0.55%, respectively. The described method would be useful for evaluating the enantiomers of various chiral amines.
Introduction
Experimental Methods
Results and Discussion
Conclusion