Skeletal rearrangements in mass spectra. Part I. Bis‐aryl compounds

Examination of a large number of spectra indicates that bis‐unsaturated compounds commonly undergo a skeletal rearrangement in which part or all or the bridging moiety is eliminated, often with concomitant loss of hydrogen atoms. The spectra of labeled azobenzene, diphenyl sulfide, and their p,p′‐dimethyl derivatives show that scrambling of hydrogen atoms precedes or accompanies such rearrangements, in contrast to the loss of a p‐methyl group from the latter derivatives. These results are rationalized in terms of the radical site formed on one unsaturated functional group attacking the polarizable π‐electrons of the other unsaturated group.