Organosilanes silicon halides

Organosilanes, especially dimethyldichlorosilane (M2), are important chemicals used in the silicone industries. The direct reaction of silicon with an organic halide to produce the corresponding organosilanes as a gas-solid-solid catalytic reaction was first disclosed by Rochow [1]. In the reaction, a copper-containing precursor first reacts with silicon particles to form the catalytically active component, which is a copper-silicon alloy, the exact state of which is still under discussion. As the reaction proceeds. Si in the alloy is consumed, which is followed by the release of copper. This copper diffuses into the Si lattice to form new reaction centers until deactivation occurs. The main reaction of the direct process is ... 

It is a palladium-catalyzed cross-coupling reaction between organosilanes (vinyl, ethynyl and allylsilanes) and organic halides (aryl, vinyl and allyl halides). Allylpal-ladium chloride dimmer [( ri -C3H5PdCl)2] and either tris(diethylamino)sulfonium difluorotrimethylsilicate (TASF) or tetra-n-butylammonium fluoride (TBAF) are used as catalysts. Fluoride ion acts as an activator for the coupling, forming an intermediate hypervalent anionic silicon species, which can then transmetallate with palladium as a preliminary reaction to coupling. 

Extensive rate studies on aluminum-halide-catalyzed redistributions of organosilanes support a mechanism in which polarization of alkyl silicon bonds and an associative step are essential ... 

Direct Process. The preparation of organosilanes by the direct process, first reported in 1945, is the primary method used commercially (142,143). Organosilanes in the United States, France, Germany, Japan, and the CIS are prepared by this method, including CH SiHC, (CH3)2SiHCl, and CTRSiHCL. Those materials are utilized as polymers and reactive intermediates. The synthesis involves the reaction of alkyl halides, eg, methyl and ethyl chloride, with silicon metal or silicon alloys in a fluidized bed at 250—450°C ... 

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