Mass spectra of α-diketones. I. Non-enolized α-diketones

Abstract

The mass spectra of a series of a-diketones are reported and discussed. Fragmentation patterns have been substantiated by exact mass measurements, metastable ions, and in two cases, by deuterium labelling studies. The McLafferty rearrangement is not observed in the spectra of aliphatic α-diketones; fragmentation proceeds by α-cleavage. The fragmentation modes of those cyclic α-diketones studied depend largely on the ring size. Molecular ions are observed in all spectra.