Fragmentation paths of hydrazonyl halides upon electron impact; simulation of nitrilimine formation

Abstract

The mass spectra of diaromatic hydrazonyl halides with substituents in the C- and N-aryl rings (Ia–h), and NN-disubstituted hydrazonyl chlorides (VI)–(VIII) have been examined and a comparison with chemical behaviour in solution has bean attempted. The main reactions of the hydrezonyl halides are expulsion of a halogen radical or dehydrohalogenation to give [M– X]⁺ and [M– HX]⁺˙ ions, respectively. The hydrazonyl chlorides derived from 2-, 3-, and 4-nitrophenylhydrazines all show abundant [C₇H₅O]⁺ ions which indicate migration of the nitrogroup prior to fragmentation. The NN-disubstituted hydrazonyl chlorides react by expulsion of a chlorine radical and by cleavage of the hydrazonyl N–N bond to give [M- Cl]⁺ and [R¹R²N]⁺ ions, respectively. Hydrogen rearrangement accompanying decomposition also takes place.