METASTABLE ION STUDY OF ORGANOSILICON COMPOUNDS .6. TRIETHOXYMETHYLSILANE AND TETRAETHOXYSILANE

The fragmentations of triethoxymethylsilane ((C2H5O)3SiCH3 (1)) and te traethoxysilane ((C2H5O)4Si (3)) induced by electron impact were inves tigated by mass-analysed ion kinetic energy (MIKE) spectrometry and a deuterium-labelling study. These molecular ions begin to fragment by t he loss of methyl, ethyl and/or ethoxy radicals. Almost complete scram bling of methylene hydrogen takes place in these resultant intermediat e ions, prior to the elimination of acetaldehyde molecule. The fragmen tations of [1]+. and [3]+. were compared with those of the correspondi ng carbon analogues, 1,1,1-triethoxyethane ((C2H5O)3CCH3 (2)) and tetr aethoxymethane ((C2H5O)4C (3)), respectively.