The mass spectra of some linear and branched methyl(vinyl)siloxanes Me3SiOS
i(Me)(R)(OSiMeVin)(n)Y (R = Vin, OSiMe3; Y = OSiMe3, Cl; n = 0-2) were stud
ied. The regularities of their fragmentation and an anomalously high probab
ility of elimination of the ethylene molecule to form the stable 1,3-dioxa-
2,4,6-trisilacyclohexane skeleton were revealed.