Gas chromatography and mass spectrometry of bis(alkylamino)- s-Triazines

Abstract

The retention behaviour of 22 2-chloro, 2-methoxy- and 2-methylthio-4,6-bis(alkylamino)triazines was studied on four gas chromatographic columns with different polarities. The most polar stationary phase Carbowax 20M, was found to be the best suited for the separation of these compounds. The differences in the retention indices of the same triazines on columns with different polarities were found to be proportional to the p K a values and the dipole moments of these compounds. Electron-impact mass spectra and deduced fragmentation schemes are given. The stability of the compounds under electron impact increases in the order chloro < methoxy < methylthio derivatives. Chemical-ionization mass spectra, using methane as reagent gas, are tabulated. It has been found that the ease of fragmentation of the protonated molecular ions of chlorotriazines is related to the low proton affinity of the leaving neutral HCl group. In the isobutane chemical-ionization mass spectra all triazines exhibited the protonated molecular ion as the base peak with only relatively minor fragmentations.