Ortho effects in organic molecules on electron impact: 18—Novel hydrogen transfer from the methoxy group to acetylenic carbon in 2-methoxyphenylacetylene and 2-methoxydiphenylacetylenes

The transfer of a hydrogen from the ortho methoxy group to the acetylenic carbon in 2-methoxyphenylacetylene under electron impact conditions affords the rearranged molecular ion corresponding to 2H-1-benzopyran. Similar processes leading to cyclic products are also noticed in 2-methoxydiphenylacetylenes. The ion structures and the mechanism of fragmentations are established through high-resolution data, collision-induced decomposition, mass-analysed ion kinetic energy spectra, B/E linked scan spectra, D-labelling and chemical substitution.