Kinetic studies in mass spectrometry–VII: Competing cleavage and rearrangement processes in molecular ion decomposition reactions

Apparently competing cleavage and rearrangement reactions in a series of molecular ions have been studied by ionization and appearance potential methods, and by determination of the electron energy dependence of both normal and metastable daughter ion peak intensities. The processes investigated were (i) [M CH 3 ] vs. [M CH 2 O] in anisole; (ii) [M OC 6 H 5 ] vs. [M CO] in phenyl ether; (iii) [M NO 2 ] vs. [M NO] in nitrobenzene; (iv) [M C 3 H 7 ] vs. [M C 2 H 4 ] in butyrophenone: (v) [M C 3 H 7 ] vs. [M C 3 H 6 ] in n ‐butylbenzene; (vi) [M CH 2 OH] vs. [M CH 2 O] in 2‐phenylethanol; (vii) [M CH 3 CO 2 ] vs. [M CH 2 CO] in benzyl acetate; and (viii) [M C 4 H 9 O] vs. [M C 4 H 7 ] in n ‐butylbenzoate. The results are interpreted in terms of k vs. E curves with very different frequency factors for the two reaction types. Appearance potentials of metastable ions for the rearrangement reactions have also been measured.