Silicon sodium coupling reaction

Boron-containing organosilicon polymers have also been synthesized via a sodium coupling reaction of silicon and boron halides or alkyl boron halides in hydrocarbon solvents [37]. On pyrolysis, mixed ceramics comprising SiC, SiBjt, and Si-(B, C) can be obtained. 

Sodium Condensation. The coupling of an organic halide and a silicon halide by reaction with metallic sodium (the so-called Wurtz reaction) vras first applied by Pape in 1884. Silicon tetrachloride and isoamyl or isobutyl chloride were found to react with sodium at reflux temperatures when a little ethyl acetate was added to get the reaction started ... 

The sodium condensation reaction of a,co-bis(chlorosilyl)-substituted compounds and the coupling reaction of dilithio derivatives of compounds bearing 7t-electron systems with dichlorosilanes offer a convenient route to various silicon containing polymers. However, the polymers prepared by these methods always contain a small proportion of siloxy units in the polymer backbone, which would interrapt the electron delocalisation. Therefore, new synthetic routes to organosilicon polymers have been developed in which no alkali metal halide condensations are involved [6, 7]. We report syntheses of organosilicon... 

Wurtz coupling reactions of chlorosilanes are the main route to the silicon-silicon bonded compounds. For example, hexamethyldisilane can be prepared by refluxing trimethylchlorosilane with lithium sand in THF (97%). Lithium may be substituted by sodium by using a mixture of HMPA-THF as the solvent. Linear and branched oligosilanes can be prepared by the same method (equations 55-57). 

Isomerically pure vinyl halides are important starting materials for preparation of the corresponding vinyl lithium species (see Section 7.1) and for use in Pd-catalyzed coupling reactions (see Section 7.10). Halogenation of vinylsilanes offers a valuable route for the synthesis of both (E)- and (Z)-vinyl halides. These reactions involve addition of the halogen to the double bond, followed by elimination of the silicon and halide moieties. The stereochemical outcome of the reaction will depend on both the mode of addition and the mode of elimination. For example, bromination of (Z)-vinylsilanes with bromine in CH2CI2 proceeds via an anti-addition. Treatment of the bromine adduct with sodium methoxide results in anti-desilicobromination. The conversion of the vinylsi-lane into the vinylbromide occurs with overall inversion of the double bond stereochemistry. " ... 

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