Chiral Recognition of <i>N</i>‐Phthaloyl, <i>N</i>‐Tetrachlorophthaloyl, and <i>N</i>‐Naphthaloyl α‐Amino Acids and Their Esters on Polysaccharide‐Derived Chiral Stationary Phases

Abstract

Enantiomeric separations of N-phthaloyl (N-PHT), N-tetrachlorophthaloyl (N-TCPHT), and N-naphthaloyl (N-NPHT) α-amino acids and their esters were examined on several kinds of polysaccharide-derived chiral stationary phases (CSPs). Resolution capability of CSPs was greater Chiralcel OF than the others for N-PHT and N-NPHT α-amino acids and their esters. In N-TCPHT α-amino acids and their esters, good enantioselectivities showed Chiralcel OG for N-TCPHT α-amino acids, Chiralpak AD for N-TCPHT α-amino acid methyl esters, and Chiralcel OD for N-TCPHT α-amino acid ethyl esters, respectively. From the results of liquid chromatography and computational chemistry, it is concluded that l-form is preferred and more retained with electrostatic interaction in case of interaction between N-PHT α-amino acid derivatives and Chiralcel OF, N-TCPHT α-amino acid derivatives and Chiralcel OD, and N-NPHT α-amino acid derivatives and Chiracel OF. On the other hand, d-form is preferred and more retained with van der Waals interaction in case of interaction between N-TCPHT α-amino acid ester derivatives and Chiralcel OG and Chiralpak AD.