Preparation of Silicon Tetrachloride

Preparation of Silicon Tetrachloride. To prepare amorphous silicon, mix 2 g of dry quartz sand comminuted in an iron mortar with 3 g of powdered magnesium. Spill the mixture into a refractory test tube, secure it at an angle in a stand, and carefully heat first the entire tube, and then its bottom end more intensively until the mixture ignites. When the reaction ends, break the test tube, extract the product, crush it, and wash it in a fume cupboard, wear eye protection. ) with dilute hydrochloric acid until the flashes of light vanish. Filter off the silicon, wash it on the filter with distilled water, and dry it in the air. 

The products of the reaction between silicon(IV) oxide and powdered magnesium can also be used to prepare silicon tetrachloride without the separation of free silicon. 

Place the prepared silicon (or the product of reacting silicon(lV) oxide with magnesium) in a porcelain boat into quartz tube 1 of the apparatus shown in Fig. 111. Dry the apparatus and the silicon in a stream of dry carbon dioxide at 200 °C during one hour. Raise the temperature of the furnace to 400 C and use a chlorine stream instead of that of carbon dioxide. Perform chlorination during 

Collect the liquid silicon tetrachloride in a receiver flask provided with a calcium chloride tube or a wash bottle with a desiccator. Cool the receiver with a mixture of ice and table salt. 

For complete purification from chlorine, distil the silicon tetrachloride over copper shavings in an apparatus for distillation under atmospheric pressure (see Fig. 20) and collect the fraction boiling at 57-59 °C. First thoroughly dry the distillation apparatus with 

The contemporary process of silicon tetrachloride production is based on research by Martin, who in 1914 was the first to obtain silicon tetrachloride by chlorinating ferrosilicon with gaseous chlorine  

The chlorination of ferrosilicon was also used in the first USSR production of silicon tetrachloride, the credit for which goes to Academician K.A.Andrianov. 

The mechanism of SiCI4 formation is as follows. Silicon molecules, in which Si atoms are bonded by the forces of main valencies, are chlorinated under the influence of chlorine, with Si—Si bonds breaking up first. The chlorine atoms join the silicon atoms to form linear molecules of polychlo-rosilanes. Under continued influence of chlorine, the polychlorosilanes are broken up into lower-molecular chlorosilanes. 

Further chlorination breaks up all Si—Si bonds and forms SiCl4  

The silicides of other metals found in ferrosilicon are also chlorinated however, since the boiling point of silicon tetrachloride is low (57.7 °C), it can be easily distilled from secondary metal chlorides. 

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Martin, G. Researches on Silicon Compounds. Part VI. Preparation of Silicon Tetrachloride, Disilicon Hexachloride, and the Higher Chlorides of Silicon by the Action of Chlorine on 50 per cent. Ferrosilicon, Together with a Discussion on Their Mode of Formation. J. chem. Soc. [London] 105, 2836 (1914). 

The "conventional" methods for the preparation of SiC and Si3N4, the high temperature reaction of fine grade sand and coke (with additions of sawdust and NaCl) in an electric furnace (the Acheson process) for the former and usually the direct nitridation of elemental silicon or the reaction of silicon tetrachloride with ammonia (in the gas phase or in solution) for the latter, do not involve soluble or fusible intermediates. For many applications of these materials this is not necessarily a disadvantage (e.g., for the application of SiC as an abrasive), but for some of the more recent desired applications soluble or fusible (i.e., proces-sable) intermediates are required. 

Aminolysis of the corresponding halides is the preferred method for the synthesis of dialkylamino derivatives of boron,1 silicon,2 germanium,3 phosphorus,4 arsenic,5 and sulfur.6 (Dialkylamino) chlorosilanes are prepared stepwise by the reaction of silicon tetrachloride with dialkylamines. This method may be utilized equally well for the conversion of alkyl- or aryl-substituted halides [e.g., (CH3) SiCl4. ] or of oxide and sulfide halides (e.g., POCl3 or PSC13) to the corresponding dialkylamino compounds. 

Silicon tetraisothiocyanate is prepared from silicon tetrachloride and silver thiocyanate or, preferably, ammonium thiocyanate. The silicon tetraisothiocyanate used by the checkers was slightly yellow however, this did not affect the yield of product. 

Silane also may be prepared by the reaction of silicon tetrachloride with lithium aluminum hydride in ether ... 

Compounds where fluorine is bound directly to silicon may be prepared directly from sihcon tetrafluonde, obtained by treatment of silicon tetrachloride with antimony tnfluoride and an alkylhthium or lithium amide base [99,100] (equation 80)... 

Silicon tetrachloride is a raw stock for preparing ethers of orthosilicon acid and is used in the production of silicone polymers used to obtain highly thermostable plastics and synthetic lubricants, as well as high-quality electroinsulation. Silicon tetrachloride is also used to prepare superfine silicon dioxide (Aerosil). A mixture of silicon tetrachloride and... 

After the raw stock is prepared and the equipment is checked for her-meticity, the etherification of silicon tetrachloride is started. The process is carried out in etherificator 6, which is a cast iron enameled apparatus with a jacket. From batch boxes 2 and 3 the etherificator is simultaneously filled with anhydrous ethyl alcohol and silicon tetrachloride. Apart from anhydrous alcohol, the etherificator receives recirculating ethyl alcohol from batch box 4. In certain volume ratios (usually from 1 2.2 to 1 2.3) silicon tetrachloride and alcohol enter through siphons the lower part of the etherificator. The temperature of the process (30-40°C) is maintained by regulating the supply of the components. The pressure in the apparatus should not exceed 0.015-0.016 MPa. 

A variation of the method was described in 1884 by Pape, who used a mixture of silicon tetrachloride and propyl iodide with metallic zinc instead of preparing the zinc dipropyl separately. Another variation, exploited by Friedel and Ladenburg, eliminated the sealed tube by introducing metallic sodium along with the zinc alkyl and silicate ester ... 

Of the other methods for preparing organosilicon compounds, the Grignard and direct methods have been selected for further consideration here. This is not to say that the Wurtz synthesis and the meta-thetical reactions of silicon tetrachloride with alkyls of zinc and mer-... 

Silane, germane, and stannane can be synthesized by the reduction of a variety of silicon, germanium, or tin compounds with active metal hydrides. The general method described below, involving the lithium hydroaluminate (LiAlHi) reduction of silicon tetrachloride and tin (IV) chloride, is convenient for the eflficient preparation of 1-50 mmoles of silane and stannane. The method is easily adapted to the synthesis of the deuterio compounds, i.e., silane-d4, germane-dt, and stannane-d4, by... 

Diphenylsilicanediol and its condensation products have been studied by Kipping with interesting results. It may be prepared from S grams of silicon tetrachloride and 17 grams of phenyl magnesium bromide in the following manner ... 

Numerous patents have appeared in which benzoic anhydride has been prepared by the action of benzenesulfochloride upon sodium benzoate (14), by the action of chlorosulfonic acid upon potassium benzoate (15) by the action of silicon tetrachloride upon sodium benzoate (16) by the action of sulfuryl chloride upon a mixture of calcium benzoate and sodium sulfate or sodium chloride (17) by the action of sulfuryl chloride upon a mixture of 2 mols. of sodium benzoate and 1 mol. of calcium benzoate (18) by the action of sulfur dioxide and chlorine upon sodium benzoate (19) by the action of sulfuric anhydride upon a mixture of benzoic acid and sodium benzoate (20) by the action of a mixture of sulfuric anhydride and carbon tetrachloride on sodium benzoate. 

Some ceramic materials are not found widely or at all in nature, and thus are synthesized for use. To prepare more complex ceramic compositions such as perovskites of general structural formula ABO3, and ferrites, of formula MFc204, the individual oxides or salts of the cations A, B, and M are often combined as powders and then reacted at high temperature by a solid-state diffusion mechanism. Silicon nitride (Si3N4) can be manufactured from either the nitridation of silicon metal or from the reaction of silicon tetrachloride with ammonia. Silicon carbide (SiC) is obtained from the reduction of silica with a carbon containing source. 

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