Mass spectrometry of cycloheptatriene derivatives. III —skeletal rearrangements in the molecular ion of 7‐cyano‐7‐methylcycloheptatriene and in some of its fragment ions

It is shown by carbon and deuterium labelling experiments that a substantial part of the molecular ions of 7‐cyano‐7‐methylcycloheptatriene has rearranged to a tolylacetonitrile, both in the ion source and in the second field free region. The evidence follows from a comparative study of α‐methylbenzylcyanide, o ‐ and p ‐tolylacetonitriles and their labelled analogues. The decomposing [M — CH 3 ] + ion from 7‐cyano‐7‐methylcycloheptatriene presumably has a cyanomethylphenyl cation, instead of a cyanotropylium structure.