Mass spectra of benzotriazoles. Correlation with thermolytic and photolytic fragmentations

Abstract

The mass spectra of some alkyl, aryl and acyl benzotriazoles are reported and discussed on the basis of their thermolytic and photolytic fragmentation products. All benzotriazoles so far studied lose a molecule of nitrogen to give the intermediate radical cations upon electron-impact. Subsequently cyclization and a hydrogen migration lead them to the molecular ions of thermolytic and photolytic fragmentation products. A general rule for predicting the possibility of 1-3 hydrogen migration, based on a knowledge of the electronic state of the radical cation is proposed.