Silicon industry

Nevertheless Kipping made a number of contributions of value to the modem silicone industry. In 1904 he introduced the use of Grignard reagents for the preparation of chlorosilanes and later discovered the principle of the inter-molecular condensation of the silane diols, the basis of current polymerisation practice. The term silicone was also given by Kipping to the hydrolysis products of the disubstituted silicon chlorides because he at one time considered them as being analogous to the ketones. 

Silicon for the chemical industry is usually purified to 98.5% by leaching the powdered 96-97% material with water. Very pure Si for semiconductor applications is obtained either from SiCU (made from the chlorination of scrap Si) or from SiHCls (a byproduct of the silicone industry, p. 338). These volatile compounds are... 

Organosilanes, especially dimethyldichlorosilane (M2), are important chemicals used in the silicone industries. The direct reaction of silicon with an organic halide to produce the corresponding organosilanes as a gas-solid-solid catalytic reaction was first disclosed by Rochow [1]. In the reaction, a copper-containing precursor first reacts with silicon particles to form the catalytically active component, which is a copper-silicon alloy, the exact state of which is still under discussion. As the reaction proceeds. Si in the alloy is consumed, which is followed by the release of copper. This copper diffuses into the Si lattice to form new reaction centers until deactivation occurs. The main reaction of the direct process is ... 

In the papers presented in the two days of the Munich Silicon Days, representatives from many lands describe what is new and what has been going on in the silicone industry. I join with Prof. Midler in commending these papers, now in book form, to the student and the practitioner in this new, very different, and very exciting field. 

This contribution to the broad field of organosilicon chemistry including molecules and materials, marks a very unusual anniversary, the existence of which effectively contradicts a historical statement by the famous organosilicon pioneer F. S. Kipping, who believed 80 years ago that organosilicon chemistry would never gain industrial and commercial importance. Fifty years after the invention of the Miiller-Rochow process, the silicon industry achieved an annual worldwide turnover of US 4.700.000.000. This proves impressively that the basic process - independently developed by R. Muller and E. G. Rochow in 1941/2 - can be considered to be the most important innovation for organosilicon research work in industry and university. 

Other markets for char include iron, steel, and sili-con/ferro-silicon industries. Char can be used as a reducing agent in direct reduction of iron. Ferro-silicon and metallurgical-grade silicon metal are produced carbothermally in electric furnaces. Silica is mixed with coke, either iron ore or scrap steel (in the case of ferro-silicon), and sawdust or charcoal in order to form a charge. The charge is then processed by the furnace to create the desired product. Char can be substituted for the coke as a source of reducing carbon for this process. Some plants in Norway are known to have used coal-char in the production of silicon-based metal products as late as mid-1990.5 The use of char in this industry is not practiced due to lack of char supply. 

Silicone industry, history of, 22 547—548 Silicone latex sealants, 22 34—35 Silicone liquid-injection-molded (LIM) rubber... 

The example of the first category is the formation of alkyl- and arylchlorosilanes in the so-called direct process (DP). The process was discovered over 60 years ago by Rochow in the United States, and, independently, by Muller in Germany, and it is still the most important reaction in organosilicon chemistry. In fact, it is at the very basis of the silicone industry, being the primary source of organochlorosilane precursors (mostly methylchlorosilanes, comprising over 90% of the total) in the production of silicone oligomers and polymers. 

Chandra, G. Maxim, L. D. Sawano, T. The Silicone Industry and its Environmental Impact. In The Handbook of Environmental Chemistry Vol. 3 Antropogenic Compounds, Part H Chandra, G., Ed. Springer Berlin, 1997 Chapter 12, pp 295-319. 

USA Silicone Environmental Health and Safety Council (SEHSC) Europe Centre Europeen des Silicones (CES) Japan Silicone Industry Association of Japan (SIAJ) Global Global Silicones Council (GSC). 

Refining. In order to produce silicon that meets the requirements of the chemical, ie, silicones, and primary aluminum markets, the silicon produced in the arc furnace requires further purification. The quality of silicon for the chemical silicones industry is critical with respect to the levels of aluminum and calcium present, and the primary aluminum grade of silicon requires low levels of calcium, iron, and phosphorus. The impurity requirements for the secondary aluminum market are not as stringent, so long as the silicon content is >98.5%. 

Cyclic siloxanes are important precursors in the silicon industry, being formally dimers or trimers of silanone (R2Si=0), a known intermediate. Cyclic siloxanes have been synthesized by four routes, the conventional methods being the condensation of silanediol or the hydrolysis of species such as halosilanes or aminosilanes (Scheme l)16-20. Alternatively, oxidation of disilene by triplet oxygen (equation l)21-27 or oxidation of oxadisiliranes by singlet oxygen (equation 2)28-31 may be utilized. 

After more than fifty years of industrial use, the direct reaction of methyl chloride with silicon, which underlies the entire silicone industry, is not understood. Promising recent experiments on this process are likely to be continued, and should at least settle the question of the nature of the intermediates. Are silylenes important in the process, either in the gas phase or at the silicon surface ... 

Until recently, it was thought that polysilanes would be either intractable or unstable. In his famous book, Eugene G. Rochow, the father of the silicone industry, dismissed poly silane polymers in this way ... 

Each year sees more and more silicone elastomers used in the production of thermostable rubbers, and silicone polymers of various composition used for nonmetal composites. At present there are few industries where silicone polymers and materials based on them are not used to a greater or lesser extent. With that in mind, it is small wonder that the silicone industry is gathering such momentum ah over the world. 

S, N or P. The silicones industry is largely based on the hydrolysis of chlorosilanes, while the formation of silicas is often achieved by hydrolysis of alkoxysilanes. 

Finally, Vycor devitrifies far less than fused silica. Therefore, if you do not require ultrapure baking environments (similar to those demanded in the silicon industry), furnace tubes made from Vycor may be cheaper in the long run than those made from less expensive fused silica. 

Methyl chloride is the only chlorinated methane with good growth. The principal use for methyl chloride is in the manufacture of chlorosilanes (89%) for the silicone industry. Other smaller uses are for methyl cellulose ether, quaternary ammonium compounds, herbicides, and butyl rubber. 

Today s silicone industry is based on the direct reaction, which does not require a preformed organometallic reagent and a flammable solvent and... 

Recent studies on the direct reaction of elemental silicon with alkyl chlorides such as methyl chloride, activated alkyl chlorides, polychloro-methanes, (chloromethyl)silanes, (dichloromethyl)silanes, etc. are summarized in this review. In the direct reaction of elemental silicon with activated alkyl chlorides and polychloromethanes, the decomposition of the reactants can be suppressed and the production of polymeric carbosilanes reduced by adding hydrogen chloride to the reactants. These reactions provide a variety of new organosilicon compounds containing Si-H and Si- Cl functionalities, which should find considerable application in the silicone industry. 

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