Carbon Scrambling upon Electron Impact in Methylquinolines and Methylpyridines

Abstract

<p>The mass spectra of some monomethylquinolines and monomethyl-pyridines all labeled with ¹³C in the exocyclic methyl group have been examined. Such studies were undertaken to provide more information about the possible intermediacy of ring-expanded species in the major fragmentation pathways of these compounds.</p> <p>In the case of the monomethylquinolines ¹³C labelling studies confirm the rearrangement of the M-1 ion to a ring-expanded species before loss of HCN. The results of the ¹³C labelling in the monomethyl-pyridines suggest that rearrangement of the majority of the molecular ions to a ring-expanded species does not occur in the process M→M-HCN.</p>