Abstract
N-Acyl amino acid esters are the typical optically active stationary phase for gas chromatographic separation of amine enantiomers, and carbonyl-bis-(aminoacid esters) are the useful phases for the separation of amine enantiomers. However, these phases suffer from relatively high column bleeding which limits the working temperature to 110°C and 125°C, respectively. In order to overcome this disadvantage, we prepared some new s-triazine derivatives of amino acid esters. It was found that these new phases give good properties in relation to enantiomer separation and thermal stability. For example, N, N', N''-[2, 4, 6-(1, 3, 5-triazine] trilyl)-tris-(L-valine isopropyl ester) exhibits excellent property for the separation of both amino acid and amine enantiomers. Moreover, its maximum permissible operating temperature (about 150°C) is considerablly higher than those of all published phases containing amino acid ester groups. Its low melting point {(6768)°C (uncorr.)} is also convenient which enables the column to be used over a larger temperature range. It is very noticeable that these new stationary phases, which have no-CO-NH-groups, give essentially the same separation as N-acyl amino acid esters or carbonyl-bis-(amino acid esters). This fact siggests that -N=C-NH-C- groups make a contribution to resolution of enantiomers in these new phases.
