Tetrachloride, silicon

Silicon tetrachloride. S1CI4 m.p. — TO C, b.p. 57°C. Colourless liquid (Si plus CI2 followed by distillation). Hydrolyses in moist air or in water. 

The formation of silicon carbide, SiC (carborundum), is prevented by the addition of a little iron as much of the silicon is added to steel to increase its resistance to attack by acids, the presence of a trace of iron does not matter. (Addition of silicon to bronze is found to increase both the strength and the hardness of the bronze.) Silicon is also manufactured by the reaction between silicon tetrachloride and zinc at 1300 K and by the reduction of trichlorosilane with hydrogen. 

In silicon tetrachloride, SiC, chlorine atoms can be replaced by methyl or other alkyl groups to give, for example, CHjSiClj and (CH3)2SiCl2. These two compounds are obtained when methyl... 

Silicon tetrachloride is a colourless liquid, b.p. 216.2 K, and again the molecule has a covalent structure. Silicon tetrachloride is hydrolysed by water ... 

The intermediates may be produced from silicon tetrachloride by interaction with the appropriate Grignard reagent, the composition of the product depending upon the proportions of the reactants ... 

Silicon tetrachloride from [SILICON COMPOUNDS - SILICON ITALIDES] (Vol 22) -use in cement mfg [CEMENp (Vol 5)... 

Silicon tetrachloride Silicon Tetrachloride Silicon tetrachloride... 

Both the Toth and Alcoa processes provide aluminum chloride for subsequent reduction to aluminum. Pilot-plant tests of these processes have shown difficulties exist in producing aluminum chloride of the purity needed. In the Toth process for the production of aluminum chloride, kaolin [1332-58-7] clay is used as the source of alumina (5). The clay is mixed with sulfur and carbon, and the mixture is ground together, pelletized, and calcined at 700°C. The calcined mixture is chlorinated at 800°C and gaseous aluminum chloride is evolved. The clay used contains considerable amounts of silica, titania, and iron oxides, which chlorinate and must be separated. Silicon tetrachloride and titanium tetrachloride are separated by distillation. Resublimation of aluminum chloride is requited to reduce contamination from iron chloride. 

Table 3. Physical Properties of Silicon Tetrachloride and Trichlorosilane ...

Silicon Tetrachloride. Most commercially available sihcon tetrachloride is made as a by-product of the production of alkylchlorosilanes and trichlorosilane and from the production of semiconductor-grade sihcon by thermal reduction of trichlorosilane. 

Silicate esters are used ia the production of coating and refractories and in some semiconductor manufacturing operations. A broad range of purity grades of silicon tetrachloride are available to meet the requirements of these different appHcations. 

P. K. Basu, Ph.D. dissertation, Depelopment of a Processfor the Manufacture of Silicone Tetrachloride from Rice Hulls, University of California, Berkeley,... 

The possibility of the existence of organosilicone compounds was first predicted by Dumas in 1840, and in 1857 Buff and Wohler found the substance now known to be trichlorosilane by passing hydrochloric acid gas over a heated mixture of silicone and carbon. In 1863 Friedel and Crafts prepared tetraethylsilane by reacting zinc diethyl with silicon tetrachloride. 

The reaction is carried out by first reacting the alkyl or aryl halide with magnesium shavings in an ether suspension and then treating with silicon tetrachloride (prepared by passing chlorine over heated silicon). With methyl chloride the following sequence of reactions occur ... 

The Grignard method was the first route used commercially in the production of silicone intermediates. Its great advantage is its extreme flexibility since a wide range of organic groups may be attached to the silicon in this method. Because of the need to use ether or other inflammable solvents considerable production hazards arise. On economic grounds the main drawbacks of the process are the multiplicity of steps and the dependence on silicon tetrachloride, which contains only 16% Si and is thus a rather inefficient source of this element. 

Under the most favourable reaction conditions when methyl chloride is used the crude product from the reaction tube will be composed of about 73.5% dimethyldichlorosilane, 9% trichloromethysilane and 6% chlorotrimethylsilane together with small amounts of other silanes, silicon tetrachloride and high boiling residues. 

This method depends on the reaction of an organic chloride with silicon tetrachloride in the presence of sodium, lithium or potassium. 

Attempts by Kao and others to enhance transparency by chemically removing impurities from glass met with little success the level of purity required was indeed comparable with that needed in silicon for integrated circuits. In the event, the required purification was achieved in the same way in which semiconductor-grade silicon is now manufactured, by going through the gas phase (silicon tetrachloride), which can be separated from the halides of impurity species because of dilTerences in vapour pressures. This breakthrough was achieved by R.D. Maurer and his... 

When this reaction has occuiTcd accidentally sufficient hydrogen chloride has been liberated to explosively burst the vessel. The purest form of hydrogen chloride is made by the action of water on silicon tetrachloride ... 

Chlor-siure, /. chloric acid. -sMureanhydrid, n. chloric anhydride, chlorine(V) oxide, -schwefel, n. sulfur chloride (esp. the monochloride). -silber, n. silver chloride, -sili-cium, n. silicon tetrachloride, -soda, /. = Chlornatron. -stickstoff, m. nitrogen chloride. -Strom, m. stream of chlorine, -strontium, n. strontium chloride, -suifonsaure, /. chlorosulfonic acid, chlorosulfuric acid, -toluol, n. chlorotoluene. -fibertrager, m. chlorine carrier. 

The combination of carbonylate dianions with silicon tetrachloride leads in high yields to the p-Si compounds 22-24. As already mentioned, the reaction can be performed either stepwise with isolation of the dichlorosilylene complex or in a one-pot procedure. The resulting products show a surprisingly high thermal... 

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