Mass spectrometry of pyrazolium salts

A series of pyrazolium bromides were investigated by field desorption, field ionization and electron impact mass spectrometry. Dealkylation was found to be the predominant thermal decomposition. The nature of the substituents controls the pyrazole formed. The application of field ionization was found to facilitate the interpretation of the thermolytic decomposition products. Field ionization and electron impact mass spectra of N-phenylpyrazole and N-benzylpyrazole were obtained.