Silicon tetrabromide, reaction

Tribromosilane, HSiBr3, is obtained together with silicon tetrabromide by the reaction of crystalline silicon with hydrogen bromide. As in the reaction with HC1, the amount of SiBr4 increases when the temperature is raised (31% at 360°C, 55% at 470°C and 80% at 700 °C)90. 

The reactions of a-chloromethyl ethers ROCH2CI (R = Me, Et, or Bu) with powdered tin at 20—80 °C afford low yields of the dihalides (ROCH2)2-SnCIg. Dimethyltin dichloride may be prepared in 75—80 % yield by heating tin with methyl chloride in hexamethylphosphoramide at 140—150 C. Silicon tetrabromide is obtained by bromination of pure or commercial silicon, or ferrosilicon, in the presence of Cu, CuBr, or CuBr2 at 350—600 °C. Optimum yields are obtained at 500 C. A 97 % yield of germanium tetrachloride is obtained when vitreous germanium dioxide is treated with... 

The reactions of silicon tetrahalides with polyhalometal organic compounds may also be used preparatively. For example, the reactions of silicon tetrachloride (Eq. 3.71) or silicon tetrafluoride (Eq. 3.72) with pentachlorophenylmagnesium chloride [185], silicon tetrachloride with pentafluorophenyllithium [186] (Eq. 3.73) and silicon tetrabromide with phenylmercury trichloromethane [187] (Eq. 3.74) have been reported. 

A highly explosive liquid [1]. Early attempts failed to isolate it but prepared numerous other explosive compounds. Reaction of dichlorine hexoxide with silicon tetrachloride or tetrabromide gave an explosive solid, apparently a perchlorato oligosiloxane. Silver perchlorate and silicon tetrahalides in ether gave explosive volatile organics, perhaps ethyl perchlorate. Replacing ether by acetonitrile as solvent, a solid (di)acetonitrile adduct of the tetraperchlorate precipitated, described as exceptionally explosive even in the smallest quantities [2],... 

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