Electron impact studies. LXIII. Negative-ion mass spectrometry of functional groups. Rearrangements of the nitrophthalic anhydrides

The negative-ion mass spectra of 3- and 4-nitrophthalic anhydride contain a series of rearrangement ions. One of these, an M-CO2 ion, is mainly produced by loss of CO from the anhydride unit together with an oxygen of the nitro group.