Electron impact-induced rearrangements of substituted 1-phenylpropynes

The primary ion mass spectra of the C9H8 isomers indene and 1-phenylpropyne were remarkably similar. Examination of ion and metastable peak intensities and their energy spectrum indicate that their common M-1 (C9H7+) fragment ion has the same structure. The mass spectra of several substituted phenylpropynes were also similar to that of the parent hydrocarbon below mass m/e 115 but showed no substituent or kinetic effect. The mass spectra of 1-phenylpropyne-d3 clearly shows H/D randomization in the molecular ion and linear ion structures are proposed.