- Electrochemical synthesis of symmetrical difunctional disilanes as precursors for organofunctional silanes
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Difunctional disilanes of the general type XR2SiSiR2X (1-5) (X = OMe, H; R = Me, Ph, H) have been synthesized by electrolysis of the appropriate chlorosilanes XR2SiCl in an undivided cell with a constant current supply and in the absence of any complexing agent. Reduction potentials of the chlorosilane starting materials derived from cyclic voltammetry measurements were used to rationalize the results of preparative electrolyses. Organofunctional silanes of the general formula MeO(Me 2)SiC6H4Y (6a-c, 7) were subsequently obtained by the reaction of sym-dimethoxytetramethyldisilane (1) with NaOMe in the presence of p-functional aryl bromides BrC6H4Y (Y = OMe, NEt2, NH2).
- Grogger, Christa,Loidl, Bernhard,Stueger, Harald,Kammel, Thomas,Pachaly, Bernd
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p. 105 - 110
(2007/10/03)
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- Cleavage of siloxanes with organyltrifluoro- and diorganyldifluorosilanes
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Hexamethyldisiloxane is cleaved with organyltrifluoro- or diorganyldifluorosilanes as low as 20 deg C in the absence of catalysts to from earlier unknown 1,1,1-trimethyl, 3-organyl-3,3-difluoro- or 1,1,1-trimethyl-, 3,3-diorganyl-3-difluorodisiloxanes with the general formula R4-nSiFn-1OSi(CH3)3 (n = 2-3) in 57-97percent yield.The Si-O bond in 1,1,3,3-tetramethyldisiloxane is broken with organyltrifluoro- or diorganyldifluorosilanes in a similar manner but more slowly to give 1,1-dimethyl-, 3-organyl-, 3,3-difluoro- or 1,1-dimethyl, 3,3-diorganyl-, 3-fluorodisiloxanes with the general formula R4-nSiFn-1OSiH(CH3)2 (n = 2-3) in 50-70percent yield.The reaction of phenyltrifluorosilane with 1,1,1,3,3,5,5,5-octamethyltrifluorosiloxane leads to 1,1,1,3,3-pentamethyl-, 5,5-difluoro-, 5-phenyltrisiloxane, whereas the reaction with tetrakis (trimethylsiloxy)siloxane gives tri(trimethylsiloxy)difluoro(phenyl)silane.Even under normal conditions of storage, the cleavage products disproportionate readily in different directions.The ability of these compounds to disproportionation depends on the nature of the substituents attached to the silicon atom and the number of fluorine atoms in the molecule.
- Voronkov, M.G.,Basenko, S.V.,Gebel, I.A.,Vitkovskii, V.Yu.,Mirskov, R.G.
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- The synthesis and properties of (CH2F)SiH3 and related monofluoromethylsilanes
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The reduction of (CFCl2)SiCl3 by LiAlH4, Me3SnH, and (nBu)3SnH has been studied.The compound (CH2F)SiH3 (I) and all the compounds of the series (CFCl2-mHm)SiCl3-nHn, m = 0, 1 and n = 0-3 were detected and characterized by NMR spectroscopy.Conditions for the synthesis of I, (CHFCl)SiH3 (IX) and (CFCl2)SiH3 (V) with acceptable yields have been optimized.These novel compounds were studied by 1H, 19F, 13C and 29Si NMR spectroscopy; their infrared and Raman spectra were recorded and assigned with the assistance of a normal coordinate analysis of 1 and its isotopomer (CD2F)SiD3.The thermolyses of I, IX and (CHF2)SiH3 (X) which start at about 120, 200 and 180 deg C, respectively, have been studied.Whereas I decomposes by a migration of F from C to Si, compound X undergoes elimination of the carbene CHF, insertion of which into SiH bonds ultimately gives CH3Si derivatives.
- Buerger, H.,Moritz, P.
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p. 293 - 308
(2007/10/02)
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