Fragmentation reactions of the trimethylsilyl adducts of C6 ketones

Abstract

AbstractThe unimolecular (metastable ion) and collision‐induced fragmentation reactions of the trimethylsilyl cation adducts of six C6 ketones have been studied by tandem mass spectrometry. A major unimolecular fragmentation channel involves regeneration of the trimethylsilyl cation; other fragmentation channels involve elimination of (CH3)3SiOH, C5H10, C4H8 and C3H6 from the adduct ions. Some mechanistic detail has been obtained from a study of the adducts with deuterium‐containing ketones, and the reactions observed are compared with the fragmentation reactions of the protonated ketones. Collision‐induced dissociation (CID) of the adduct ion results in predominant formation of (CH3)3Si+. However, in the high energy (6 keV) CID new minor reaction channels, involving elimination of alkanes, CH4 to C4H10, become accessible. It is concluded that tandem mass spectrometry of the trimethylsilyl adducts provides only limited ability to distinguish between isomeric ketones.