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Is the collision induced loss of ethene from the (M – H + ) − ion of butyrophenone a γ-hydrogen rearrangement?

1986; NRC Research Press; Volume: 64; Issue: 4 Linguagem: Inglês

10.1139/v86-123

1480-3291

Michael B. Stringer, Dennis Underwood, John H. Bowie, John Holmes, Alexander A. Mommers, Jan E. Szulejko,

Analytical Chemistry and Chromatography

The (M – H + ) − ion of butyrophenone undergoes the following reactions on collisional activation: losses of CH 3 • , CH 4 , (C,H 5 • ), C 2 H 4 , C 3 H 7 • , (CO + CH 4 ), together with formation of C 6 H 5 − and C 4 H 5 O − . Labelling studies ( 13 C and 2 H) show that the losses of CH 3 • , C 3 H 7 • and the formation of C 6 H 5 − and C 4 H 5 O − are specific and occur without hydrogen scrambling. All other reactions involve prior or accompanying hydrogen rearrangement. In particular, the loss of C 2 H 4 is very complex: it involves loss of ethyl carbon atoms, but all hydrogen atoms are involved via specific rearrangement reactions. The phenyl–alkyl H rearrangements which are noted for this process occur after collisional activation of the (M – H + ) − ion.