Mass spectra of aromatic and acetylenic compounds. Part VI. The electron impact-induced rearrangements of substituted phenylacetylenes

Abstract

The mass spectra of [²H₁]phenylacetylene shows 100% H/D randomisation in the molecular ion prior to expulsion of an acetylene fragment. In analogous benzene-substituted phenylacetylenes 70–100% H/D randomisation occurs in the molecular ion or some subsequent fragment. Symmetrical intermediates are proposed to account for the scrambling and it seems likely that carbon–carbon bond fission takes place prior to formation of these intermediates.