Studies in mass spectrometry. III-formation of a common intermediate in the primary fragmentation process of 1-phenylcyclobutene and of 2-phenyl-1,3-butadiene

The mass spectra of the title compounds show peaks corresponding to the primary fragmentation of H, CH3 and (H2 + C2H2). Kinetic study suggests that the molecular ion of 1‐phenylcyclobutene and 2‐phenyl‐1,3‐butadiene loses H and CH3 through formation of a common intermediate. This is confirmed by appearance potential and ionisation potential measurements, fragmentation of deuterium labelled compounds and the corrected Z values.