Abstract-The m a s spectra of tetrazole, al1 isomers of mononiethyl-and dimethyltetrazole, several trifluoromethyl substituted tetrazoles, as well as deuterated analogs, were recorded. Loss of N, was the important fragmentation of the molecular ions of tetrazole and 2-niethyl substituted tetrazoles; however, HN2 loss was more important for 1-methyl substituted tetrazoles. The l-methyltetrazoles showed molecular ion peaks while the 2-methyltetrazoles exhibited an unprecedented [M + 11 peak with no molecular ion.NUMEROUS papers have recently appeared on the mass spectral fragmentation of various azoles including pyrroles,l imidazoles2 and pyrazoles? A brief report4 on the metastable transitions of s-triazole has appeared, but no detailed study of substituted triazoles has been reported. A study of the tetrazoles was missing untii the recent work of Fraser and H a g~e ,~ who reported the primary fragmentations of several 1-and 2-methyl-5-aryltetrazoles. They showed that the position of N-methyl substitution of 5-aryltetrazoles could be differentiated by mass spectrometry. With 1-methyl substitution the loss of a fragment of m/e 42 (N3 or CH,N,) was important while loss of N, was only 6 % of the base peak. In contrast, with 2-methyl substitution [M -N,] was the base peak.It is desired to report here a thorough study of the mass spectral fragmentation of tetrazole (1), 1-methyl-(11), 2-methyl-(III), 5-methyl-(IV), 1 ,5-dimethyl-(V), 2,5-dimethyl-(VI), 5-trifluoromethyl-(VII), 1 -methyl-5-trifluoromethyl-(VIII), 2-methyl-5-trifluoromethyitetrazole (IX), and several deuterated analogs (X) to (XIV).For the purposes of discussing the fragmentations observed, the tetrazoles studied fa11 into three structural categories, i.e. 2-methyl substitution, 1-methyl substitution, and those unsubstituted on nitrogen. The cleavages of the molecular ion [MI can be represented schematically for this discussion by a wiggly line bisecting the molecular ion into two fragments with the charge being retained on the portion * National Rescarch Council Postdoctoral Research Associate.
