Studies in mass spectrometry. II—A common intermediate in the primary fragmentation process of α‐phenylmethylenecylopropane

The variation of Z = [(F) + ]/[(M) +· ] vs electron energy for the loss of H · and CH 3 · from the molecular ion of 2‐phenylmethylenecyclopropane (I) and α‐phenylmethylenecyclopropane (II) suggests that they both rearrange to a common intermediate before fragmentation occurs. The structure of the intermediate is discussed with regard to the xperimental values found for the Z ratios and to the mass spectra of deuterium labelled compounds.