Studies on the syntheses of azole derivatives—V: The mass spectra of 1,2,4‐triazoles and oxadiazoles (studies on the syntheses of heterocyclic compounds—CCCLXXIV )

The electron‐impact induced fragmentation of twenty 3‐alkyl‐1‐phenyl‐Δ 2 ‐1,2,4‐triazolin‐5‐ones, three 1‐phenyl‐1,2,4‐triazolin‐3,5‐diones and ten 2‐alkyl‐4‐phenyloxadiazolin‐5‐ones has been studied by conventional mass spectrometry. The major cleavages take place in the 1‐phenyl‐Δ 2 ‐1,2,4‐triazolin‐5‐one nucleus, producing three major fragment ions. 4‐Phenyloxadiazolin‐5‐ones exhibit a similar fragmentation pattern to 1‐phenyl‐Δ 2 ‐1,2,4‐triazolin‐5‐ones. Furthermore, several additional fragmentation processes are observed in the case of specific 1,2,4‐triasolines.