Silicon reaction with hydrocarbon halides

The Direct Reaction of Hydrocarbon Halides with Elementary Silicon ... 

In practice vapours of the hydrocarbon halide, e.g. methyl chloride, are passed through a heated mixture of the silicon and copper in a reaction tube at a temperature favourable for obtaining the optimum yield of the dichlorosilane, usually 250-280°C. The catalyst not only improves the reactivity and yield but also makes the reaction more reproducible. Presintering of the copper and silicon or alternatively deposition of copper on to the silicon grains by reduction of copper (I) chloride is more effective than using a simple mixture of the two elements. The copper appears to function by forming unstable copper methyl, CUCH3, on reaction with the methyl chloride. The copper methyl then decomposes into free methyl radicals which react with the silicon. 

Thus the function of the copper catalyst in the synthesis of methyl-chlorosilanes seems to be to transport the free methyl groups and to prolong their life in the form of copper methyl, and also to transfer the chlorine from methyl chloride to silicon. It is probable that copper acts similarly in the reaction of other hydrocarbon halides with silicon, and that similar metals also may undergo the same cycle of reactions. 

Nonflammable gas. Chlorine pentafluoride is a highly reactive substance. It reacts explosively with water. Paper, cloth, wood, and other organic matter would burst into flames upon contact with the liquid or vapor of chlorine pentafluoride. Vigorous to violent reaction occurs with metals. Reactions with oxides, sulfides, halides, and carbides of metals are violent. It forms explosive mixtures with hydrogen, carbon monoxide, hydrocarbon gases, ammonia, phosphine, sulfur dioxide, and hydrogen sulfide. It reacts violently with sulfur, phosphorus, silicon compounds, charcoal, and mineral acids. 

The Reaction of Hydrocarbons with Silicon Halides by Passing the Mixed Vapors Through a Heated Tube. ... 

Consequently, in the early work with hydridosilicon derivatives, diethyl ether was normally used in the case of very volatile products, dimethyl ether offered some practical advantages. It was tacitly assumed that a polar solvent was essential in order to dissolve, at least partly, the transition-metal carbonyl derivative. More recently, however, it has become clear that alkanes, although nonpolar, provide a very suitable reaction medium, and can be used in cases where ethers, for example, are inimical to the products (8, 32, 306, 310). The hydrocarbon, besides acting as a diluent for the silicon halide, seems to assist the separation of alkali halide from the surface of the reacting transition-metal carbonyl salt. 

A somewhat similar process makes use of the gas-phase reaction of aliphatic hydrocarbons with a silicon halide14 at a high temperature. Thus a mixture of silicon tetrachloride and an aliphatic hydrocarbon may be heated to a temperature above 450° (but below the temperature of thermal decomposition of the hydrocarbon) to produce organosilicon halides. 

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