Reactions of excited molecules. II. Reactions of phenylhydrazones on electron impact

Electron impact data are presented for the phenylhydrazones of a series of aromatic ketones C6H5-CO-R (R = H, CH3, CD3, C2H5, C6H6), and are discussed in comparison with the results of thermal excitation. Whereas pyrolysis resulted in extensive four-centre migration of R to nitrogen, followed by (or synchronous with) cleavage of the N-X bond, the electron-impact breakdown is largely dominated by N-N bond cleavage. A semi-quantitative assessment is made of the rearrangements which do occur, and the stereochemistry of these and related reactions is discussed.