Metastable ion study of organosilicon compounds. Part IX. CH3COOSi(CH3)3 and CF3COOSi(CH3)3

Article abstract of DOI:10.1016/S0022-328X(96)06241-9

The unimolecular metastable dissociation of trimethylsilyl acetate, CH₃COOSi(CH₃)₃ (1), and its fluorine analogue, trimethylsilyl trifluoroacetate, CF₃COOSi(CH₃)₃ (2), upon electron impact have been investigated by means of a B/E linked scan, high resolution data, and D-labeling. The results are compared with those of the carbon analogue, tert-butyl acetate, CH₃COOC(CH₃)₃ (3). No molecular ion of any of these compounds can be observed, but loss of CH₃ occurs exclusively from the trimethylsilyl or tert-butyl groups. The fragmentation of 1^+. is slightly different from that of 3^+., and quite different from that of 2^+.. In the case of 3^+., (CH₃)₂C=O is eliminated from [3-CH₃]⁺, giving rise to the peak at m/z 43, but the loss of (CH₃)2Si=O does not occur from [1-CH₃]⁺. In the case of 2^+., an interesting fluorine atom (F) migration is observed.