Mass spectra of some perfluoroalkyl and perfluoroalkylether substituted 1,2,4‐oxadiazoles

Electron impact fragmentation patterns were obtained for 1,4‐bis[(5‐perfluoro‐ n ‐heptyl)‐1,2,4‐oxadiazolyl]‐benzene, its perfluoroalkylether substituted analogue, 3,5‐bis(perfluoroalkyl)‐, 3,5‐bis(perfluoroalkylether)‐ and 3‐perfluoroalkylether‐5‐perfluoroalkyl‐1,2,4‐oxadiazoles. In the compounds containing the phenylene group the molecular ion constituted the base peak; the main process was the breakdown of the oxadiazole ring with concurrent liberation of the perfluoroalkyl or perfluoroalkylether nitrile molecule; cleavage of the fluorinated chain α to the oxadiazole ring was found to take place to a considerable degree. In the perfluorinated 1,2,4‐oxadiazoles cleavage β to the oxadiazole ring occurred preferentially; fragmentation of the ring itself took place to a limited degree only. The 3‐perfluoroalkylether‐5‐perfluoroalkyl‐1,2,4‐oxadiazole appeared to undergo the primary β‐cleavage exclusively at the perfluoroalkylether sidechain.