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Some ring opening reactions of cyclic siloxanes in organic solvents have been investigated. By the action of potassium hydroxide, hexaphenylcyclotrisiloxane and cis- and trans-trimethyltriphenylcyclotrisiloxane may all be converted into cyclotetrasiloxanes in good yield and, in the case of the latter two compounds, with a high degree of stereospecificity. By the action of hydrochloric acid, hexamethylcyclotrisiloxane is rapidly converted into octamethylcyclotetrasiloxane. The trimethyltriphenylcyclotrisiloxanes are much more resistant to the action of acids and conversion into cyclic tetramer is low.  相似文献   

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Summary We have obtained four new addition products of cyclic siloxanes containing the Si-H bond to unsaturated compounds of different classes. In the presence of chloroplatinic acid addition takes place according to the Farmer rule with formation of one adduct in each case.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12 p. 2230–2232, December, 1964  相似文献   

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Taking advantage of the strong nucleophilic properties of N-heterocyclic carbene (NHC), the efficient catalytic ring opening polymerization (ROP) of cyclotetrasiloxane D4 was achieved under mild conditions.  相似文献   

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Molecular inclusion complexes between cyclodextrins and cyclic siloxanes were prepared and characterized via a combination of liquid and solid state NMR, FT-IR, TGA, powder X-ray diffraction, SEM–EDS and elemental analyses. The crystalline complexes adopted the channel-type conformation. Depending from the size of both the cyclic sugar cavity and the silicon guest, various yields (between 0 and 41%) and host–guest molar ratios (between 1:1 and 4:1) were obtained. α-cyclodextrin (α-CD) and β-cyclodextrin (β-CD) were observed to form crystalline inclusion complexes only with D3 (cyclic dimethyltrisiloxane) due to steric effects, whereas the larger γ-cyclodextrin (γ-CD) formed inclusion complexes both with D3, D4 (cyclic dimethyltetrasiloxane) and D5 (cyclic dimethylpentasiloxane). This study is believed to be the first step towards the selective removal of cyclic siloxanes impurities from commercial PDMS preparations.  相似文献   

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The mass spectra of two silanes and two cyclic siloxanes of the general formulae HSi(CH3)2-C6H4? (CF2)n? C6H4(CH3)2SiH and (n = 2 and 3) are reported and discussed. Although some major differences are apparent between the spectra of the two silanes, the fragmentation patterns of the cyclic siloxanes are largely identical.  相似文献   

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Insertion reaction of methylphenylsilylene into SiO single bonds of cyclic siloxanes have been studied. Methylphenylsilylene is less reactive than dimethylsilylene. 1,1,3,3-Tetramethyl-2-oxo-1,3-disilacyclopentane is a more reactive silylene trapping reagent than hexamethylcyclotrisiloxane.  相似文献   

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