Silicon tetrabromide

Silicon stainless steels, 23 784 Silicon steel electrical sheets, 23 309 Silicon technology, 22 481 projection of, 22 23 It sensors based on, 22 266-269 Silicon tetrabromide... 

Silicon tetrabromide [7789-66-4], SiBr4, and tribromosilane [7789-57-3], SiHBr3, are used in a process to make high purity silicon (40). Stannous bromide [10031-24-0], SnBi, is claimed as a catalyst in preparing a lubricant antioxidant (41). Stannic bromide [7789-67-5], SnBr is used in the metallurgical separation of minerals (42). 

Aluminum bromide AlBr3 is used as a catalyst and parallels AICI3 in this role. Strontium and magnesium bromides are used to a limited extent m phamiacentical applications. Ammonium bromide is nsed as a flame retardant in some paper and textile applications potassium bromide is used in photography. Phosphorus tribromidc PBr3 and silicon tetrabromide SiBi4 are nsed as intermediates and catalysts, notably in the production of phosphite esters. 

Silicon tetrabromide SiBr,.. Silicon tetrachloride SiCL.. Silicon tetrafiuoride SiF.. . 

Silicobromoform is usually prepared by passing hydrogen bromide over heated silicon112,4,5 or a silicide such as copper silicide.3 The product, consisting of a mixture of silicon tetrabromide with a few per cent of tri- and dibromosilanes, is purified by shaking with mercury, if necessary, to remove any free bromine, and by fractional distillation. The use of metal silicides instead of silicon does not add appreciably to the yield of the bromoform and is not recommended in the following procedure. 

The crude gaseous products are condensed in the flask G, which is deeply immersed in a Dewar tube filled with alcohol, cooled to about — 30°C. by the addition of solid carbon dioxide. At lower temperatures, solid silicon tetrabromide tends to clog the delivery tube. The unchanged hydrogen bromide and hydrogen pass out of the system through a guard tube T of calcium chloride into the hood. 

Silicon, higher chlorides of, 42 Silicon tetrabromide, 38, 40 Silicon tetrachloride, 44 Silicopropane, octachloro, 44 Silicotungstic acid, 129 analysis, 131 ether complex, 131 Silver, metallic, 4 Silver chloride, reduction of, 3 Silver cyanamide, 98 Silver residues, purification of, 2 Sodium amalgam, 10 Sodium amide, 74 Sodium azide, purification of, 79 Sodium azidodithiocarbonate, 82 Sodium butoxide, 88 Sodium hypochlorite (solution), 90 Sodium iodate, 168 Sodium metaperiodate, 170 Sodium paraperiodate, chlorine method, 169 persulfate method, 170 Strontium amalgam, 11 Sulfur hexafluoride, 121 Sulfuryl chloride, 114... 

Silicon bromide, Si2Br6, 2 98 (See also Silicon tetrabromide) Silicon chlorides, higher, 1 42 Si2Cl6, 1 42 Si,Cl, 1 44... 

See also Silicon tetrachloride) Silicon compounds, halomethyl derivatives by the diazomethane method, 6 37, 39 nomenclature of, 2 265 organo-, 3 50 nomenclature of, 3 55 Silicon tetraacetate, 4 45 Silicon tetrabromide, 1 38, 40 Silicon tetrachloride, 1 44 Silicon tetrafluoride, 4 145 Silicooxalic acid, (H Si, ,), formation of, by disilicon hexa-bromide, 2 101... 

SiBr2H2 Silane, dibromo-, 1 38 SiBr3H Silane, tribromo-, 1 38, 41 SiBr4 Silicon tetrabromide, 1 38, 40... 

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. 

Spitzer, R., W. J. Howell, and V. Schomaker An Electron Diffraction Investigation of the Molecular Structures of Silicon Tetrabromide, Tri-bromosilane, and Dibromofluorosilane. T. Amer. chem. Soc. 64, 62—67 (1942). 

The more volatile silicon tetrachloride and silicon tetrabromide may be effectively separated on silicone oils coated on a polytetrafluoroethylene supports. Less volatile metal bromides generally require high-temperature stationary phases. Thus, the use of alkali bromide salts coated on silica as stationary phases with the use of bromine/nitrogen and boron tribromide/bromine/nitrogen mobile... 

SiBr4 SILICON TETRABROMIDE 1486 Sm203 DISAMARIUM TRIOXIDE (CUBIC) 1534... 

SiBr4[g] SILICON TETRABROMIDE (GAS) 1487 Sm203[M] DISAMARIUM TRIOXIDE (MONOCLINIC) 1535... 

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... 

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