Electron‐impact studies—LX Negative‐ion mass spectrometry of functional groups skeletal‐rearrangements in aryl nitro compounds

The molecular anions of nitrobenzenes containing an electron‐withdrawing substituent eliminate NO· via a skeletal rearrangement process in the order ortho > para > meta. An ortho substituted nitrobenzene may eliminate a neutral molecule after the loss of NO· Hydrogen‐rearrange‐ment processes, hydrogen‐scrambling processes, and unusual concerted eliminations are noted in certain spectra. Isomeric nitrobenzenes are generally more readily differentiated by negative‐ion than positive‐ion mass spectrometry.