The mass spectrometric behaviour of dimethylcyclosiloxanes

The fragmentations of [(CH₃)₂SiO]_n, (D_n), where n = 4, 5, 6, 7, 8, 9, 10, 12 and 15 are reported. The behaviour of these compounds under electron-impact is governed by the size of the siloxane ring. Rings smaller than D6 have base peaks corresponding to [M – 15]⁺ ions; larger rings all show base peaks of m/e 73 [Si(CH₃)₃]⁺. A transannular mechanism previously applied only to D₅ and D₆ is extended and modified to account for the behaviour of larger rings. A ring con-traction mechanism is proposed which leads to the formation of smaller rings and doubly charged ions. A new transannular mechanism is proposed to account for the production of [M – 177]⁺ and [M – 193]⁺ ions.     

Synthesis of dimethylcyclosiloxanes in the active medium

The process of condensation of dimethyldiethoxysilane in the active medium in a presence of acetyl chloride, trifluoroacetic acid, and sulfocationites has been investigated. Their impact on the rate and selectivity of the process has been estimated. The prospects of the application of sulfocationites for the polycondensation of dimethyldiethoxysilane in anhydrous acetic acid with an 99% yield have been demonstrated.     

Telomerization of vinyltrimethylsilane with alcohols

Conclusions The telomerization of vinyltrimethylsilane by ethanol is accompanied to a larger extent by rearrangement of MeCH(OH)CH₂·CHSiMe₃ radicals with 1,3-hydrogen atom migration and leads to the formation of secondary and tertiary silicon-containing alcohols as well as the products of their dehydration.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2179–2182, September, 1988.The author expresses his gratitude to V. I. Dostovalova and L. I. Sheveleva for participating in carrying out this study.     

Telomerization of ethylene with ethylal

Conclusions The telomerization of ethylene with ethylal goes at the-C-H bond of the ethoxyl group to give the telomers CH₂(OC₂H₅)OCH(CH₃)(CH₂CH₂)n^H·Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2786–2788, December, 1978.     

Telomerization of styrene with bromotrichloromethane

The photo-initiated reactions between styrene and bromotrichloromethane have been studied at 30. The analysis of the telomer products by gel permeation chromatography has been refined since the previously published work; the relative proportions of several smaller telomers have been estimated. The results show a considerable increase in the magnitude of the transfer constant over the first few propagation steps of the reaction, with a limiting value after the incorporation of three monomer units into the growing polymer radical.