Tetrachlorosilane hydrolysis

Tetrachlorosilane was added to aqueous ethanol (the presence of water was accidental). There was no proper stirring during this operation, which led to the formation of two liquid layers of compounds that did not react. The very fast and exothermic reaction of the alcoholysis-hydrolysis of chlorosilane started violently and the large compoundion of hydrogen chloride caused the reactor to detonate. 

When 2,4-dioxopyrido[l,2-a]pyrimidines 391 were treated dropwise in acetonitrile with tetrachlorosilane in 1,2-dichloroethane in the presence of sodium iodide at room temperature, 2-acetamido-3,4-dihydro-2//-pyridopyrimidin-4-ones 396 were obtained after work-up [92MJ24 93IJC(B)637]. In the first step iodotrichlorosilane was formed, and 1,2-addition of iodotrichlorosilane to a 2-carbonyl group of pyridopyrimidine 391 led to the formation of a-iodosilyl esters 392, which reacted with acetonitrile. After the rearrangement of adduct 393 and a further reaction with a second mole of iodotrichlorosilane, the hydrolysis of disylylated intermediates 395 yielded 2-acetamido-3,4-dihydro-2//-pyridopyrimidin-4-ones 396 (see Scheme 24). 

Keywords trichlorosilane, tetrachlorosilane, direct process, direct process residue, characterization, shock-sensitive, hydrolysis, pyrophoric... 

The most important process for the manufacture of pyrogenic silicas is flame hydrolysis in which tetrachlorosilane is decomposed in an oxyhydrogen flame ... 

There are numerous industrial products of colloidal silicas in various forms. The methods of industrial synthesis and main applications are briefly surveyed as follows. Ultra-fine particles of nanometer order such as aerosil (commercial name) are produced by the hydrolysis of tetrachlorosilane in air. A similar material can be obtained from oxidation of tetralkoxysilane in a gas phase. The former is used as a thixotropic additive of composite materials, heat insulator and etc. 

The hydrolysis of the chlorosilane blend is usually carried out in a diluent to moderate the hydrolysis reaction. Too much tri- or tetrachlorosilane or too little solvent may cause the reaction mixture to gel or the product to become prematurely insoluble. Low-molecular-weight alcohols are used to control the degree of condensation by forming alkoxysilanes rather than silanols. The alkoxysilanes are later converted to siloxanes at a controlled rate during processing. The hydrolysis reaction is quite complicated and still requires further study [74-77]. 

D AerosU. 200, a commercial sdica gel (Degussa, Inc.). The preparation involves flame hydrolysis of dry tetrachlorosilane into non-porous, spherical particles. 

X-ray crystallographic work on silicates has helped to explain the apparent complexity of the so-called silicic acids . Orthosilicic acid, H4Si04, can be made by the hydrolysis of tetrachlorosilane (silicon tetrachloride). 

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