- Synthesis of high-purity heptamethylchlorocyclotetrasiloxane
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The procedures of preparation of heptamethylcyclotetrasiloxane (CH3)7Si4O4H in a 60% yield, its exhaustive purification, and its chlorination to form (CH3)7Si4O4Cl in a quantitative yield were developed. The composition of heptamethylchlorocyclotetrasiloxane and the content of alkali and heavy metal impurities in this compound, permissible for materials used in electronics, were determined by elemental analysis, gas-liquid chromatography, flame photometry, and atomic absorption analysis.
- Martynova,Voronkov
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p. 921 - 922
(2007/10/03)
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- Synthesis of organosiloxanes with reactive groups at silicon atoms
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The heterofunctional condensation of (dihydroxy)organodisiloxanes and -trisiloxanes with vinyl(hydro)organodichlorosilanes was studied with the purpose of preparing α,ω-dichloroorganosiloxanes with reactive Si-H and Si-CH=CH2 groups. During the isolation, 1,9-dichloro-1,9-dihydropentamethyloctasiloxane disproportionates with the elimination of (dichloro)methylsilane to form heptamethylcyclotetrasiloxane. A series of cyclotetra-, cyclohexa-, and cyclooctasiloxanes with Si-H and Si-CH=CH2 groups was obtained by the condensation of α,ω-dihydroxyorganosiloxanes with α,ω-(dichloro)divinyl(dihydro)organosiloxanes.
- Makarova,Astapova,Lavrukhin
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p. 914 - 919
(2007/10/03)
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- SYNTHESIS OF SPIROCYCLOSILOXANES BY FLASH VACUUM PYROLYSIS OF 2,7-DIMETHYL-2,3:7,8-DIEPOXY-5-SILASPIRONONANE AND CYCLOSILOXANES
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Flash vacuum pyrolysis (FVP) of 2,7-dimethyl-2,3:7,8-diepoxy-5-silaspirononane with cyclotetra- or cyclopenta-siloxanes (D4 or D5) leads to products which apparently result from transannular insertion of or an equivalent synthon into Si-O single bonds of D4 or D5: 2,4,6,8,10-pentasila-1,3,5,7,9,11-hexaoxaspiroundecane (D2QD2) and 2,4,6,8,10,12-hexasila-1,3,5,7,9,11,13-heptaoxaspirotridecane (D3QD2) respectively.The scope of this reaction has been explored with substituted cyclotetrasiloxanes such as heptamethylcyclotetrasiloxane, vinylheptamethylcyclotetrasiloxane, phenylheptamethylcyclotetrasiloxane, and chloromethylheptamethylcycloterasiloxane.In all cases, substituted spirocyclosiloxane products (D2QDDx) were obtained. 29Si NMR has proved particularly useful for the assignment of structure of these spirocyclosiloxanes.
- Juengst, Clifford D.,Weber, William P.,Manuel, Georges
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p. 187 - 194
(2007/10/02)
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