D. Kuck et al., ELECTRON-IMPACT-INDUCED FRAGMENTATION OF LONG-LIVED C14H14-CENTER-DOT-DIPHENYLETHANE( IONS FROM DIBENZYL SULFONE AND 1,2), International journal of mass spectrometry and ion processes, 167, 1997, pp. 55-68
Citations number
51
Categorie Soggetti
Spectroscopy,"Physics, Atomic, Molecular & Chemical
Gaseous dibenzyl sulphone radical cations (1(.+)) expel SO2, forming C
14H14.+ ions, whose fragmentation is identical with that of the radica
l cations of 1,2-diphenylethane (2(.+)). Metastable ions [1 - SO2](.+)
and 2(.+) eliminate predominantly benzene to give C8H8.+, in competit
ion with the well-known benzyl cleavage. The [M - SO2](.+) ions from d
euterium-labelled isotopomers of 1 react in exactly the same way as 2(
.+) ions bearing the label in corresponding positions (e.g. C6H5CD2SO2
CD2C6H5.+ and C6H5CD2CD2C6H5.+). Benzene loss is initiated by migratio
n of a benzylic H atom, but does not occur by simple I,2-elimination;
rather, the C6H6 molecule incorporates an H atom from the other ring.
Both fragmentation reactions are preceded by slow interannular hydroge
n exchange, which involves preferentially the ortho positions of the r
ings; however, this exchange is coupled with a relatively fast intra-a
nnular hydrogen ring-walk by which the hydrogens at the meta and para
positions of the rings participate in the interannular exchange. The d
ata suggest that the extrusion of SO2 from ionized dibenzyl sulphone g
enerates a complex of a benzyl cation and a benzyl radical, which reco
mbine by bond formation between the benzylic alpha carbon atoms, but p
ossibly also by electrophilic attack of C6H5CH2+ at the various sites
of C6H5CH2.. (C) 1997 Elsevier Science B.V.