FRAGMENTATION OF METASTABLE MOLECULAR-IONS OF ACETYLANISOLES

The spontaneous unimolecular dissociation reactions of the molecular ions of ortho-, meta- and para-acetylanisoles have been investigated by mass-analyzed ion kinetic energy spectrometry, high resolution mass spectrometry and deuterium labelling. Losses of CH3. from the molecular ions of all isomers occur exclusively from the acetyl group. The loss of CH3. for the o-isomer consists of two processes, i.e. one of them is a simple cleavage, and the other is a rearrangement. The latter is not observed for the m- and p-isomers. The loss of H2O from the molecular ion is also unique for the o-isomer, and the fragmentation mechanism is also explored.