Mass spectra of 1,2,4-triazoles: A novel skeletal rearrangement

Abstract

The mass spectra of 3-chloro-4,5-dipheny1-4H-1,2,4-triazole (I), 3-amino-4,5-diphenyl-4H-1,2,4-triazole (2) and 3-chloro-5-(5'-chloro-2'-thienyl)-4-phenyl-4H-l,2,4-triazole (3) revealed a novel skeletal rearrangement involving the migration of the 3-substituent to the C 5 carbon of the triazole ring followed by a concerted loss of nitrogen and benzonitrile.Mass spectral studies on heterocycles brought to light several skeletal rearrangements. Of these, the most extensively investigated ones were the formation of the fluorenyl cation from a number of diary1 five-membered heterocycles1 and the ring expansion of alkyl-substituted heter~cycles.~ Investigations on the mass spectra of 1,2,4-triazoles were only of recent ~r i~i n .~-~ The methyl and phenyl derivatives of 1,2,4-triazoline-3-thiones were found to be the most complex in their mass spectral behaviour, the other derivatives of this parent triazole system being relatively simpler.During the course of our investigations on 1,2,4-triazoles, we had occasion to examine the mass spectra of three triazoles (1)-(3). All three revealed a novel skeletal rearrangement, as evidenced from the following discussion.The molecular ion peaks were found to be the base peaks in the case of (2) and (3), whereas with (I), the parent ion was the second most abundant in the spectrum (the

Synthesis and growth regulatory activity of pyrazolesulfanyl‐ and isoxazolesulfanyl‐1H‐[1,2,4]triazoles and their azinyl derivatives

“…Value of 9.0–9.1 ppm for H‐5 in 1 H NMR spectra allows excluding 2‐N substitution [28], but do not make a choice between 1‐N and 4‐N substitutions. In some cases, by means of mass spectra a substitution position in triazole cycle can be established [29–31]. However, in mass spectra of synthesized compounds 4 , the molecular fragments, which allow answering this question, were not detected.…”