Electron impact studies. CVIII. Negative-ion mass spectra of the oxime group

Abstract

Molecular anions derived from Ar-CH=NOH systems fragment by the process [MI- → [M-H₂O]- to yield pronounced peaks corresponding to [ArCN]-. Molecular anions from Ar(CH₂)_nC(NOH)Ph (n = 0-2) also eliminate H₂O, but the mechanisms are often complex. Possible mechanisms for some of these eliminations are suggested after consideration of the + E spectra of non-decomposing [M?H₂O]- ions. A characteristic cyclization/retro process of o-O₂NC₆H₄-CH=CH-C(NOH)R molecular anions produces CHO-CR=N-O- as the major product anion.