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Polysilyne
Polysilynes are organosilicon compounds with the formula Sisub>n. Although their name suggests a relationship to alkynes, polysilynes are a class of silicon-based random network polymers primarily composed of tetrahedral silicon centers, each connected to one carbon and three Si centers. These compounds are prepared by Wurtz coupling of alkyltrichlorosilanes (RSiCl3): :3 Na + RSiCl3 → Sisub>n + 3 NaCl The methyl and hexyl derivatives have been described. Poly(methylsilyne) (PMSy) is a dark yellow powder. With some solvents (tetrahydrofuran, ether, toluene etc.) it forms a colloidal suspension that is clear and non-viscous, which may then be deposited as a film or coating on various substrates. Upon thermolysis, poly(methylsilyne) decomposes to silicon carbide Silicon carbide (SiC), also known as carborundum (), is a hard chemical compound containing silicon and carbon. A semiconductor, it occurs in nature as the extremely rare mineral moissanite, but has been mas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Poly(methylsilyne)
Polysilynes are organosilicon compounds with the formula Sisub>n. Although their name suggests a relationship to alkynes, polysilynes are a class of silicon-based random network polymers primarily composed of tetrahedral silicon centers, each connected to one carbon and three Si centers. These compounds are prepared by Wurtz coupling of alkyltrichlorosilanes (RSiCl3): :3 Na + RSiCl3 → Sisub>n + 3 NaCl The methyl and hexyl derivatives have been described. Poly(methylsilyne) (PMSy) is a dark yellow powder. With some solvents (tetrahydrofuran, ether, toluene etc.) it forms a colloidal suspension that is clear and non-viscous, which may then be deposited as a film or coating on various substrates. Upon thermolysis, poly(methylsilyne) decomposes to silicon carbide Silicon carbide (SiC), also known as carborundum (), is a hard chemical compound containing silicon and carbon. A semiconductor, it occurs in nature as the extremely rare mineral moissanite, but has been mas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organosilicon Compound
Organosilicon compounds are organometallic compounds containing carbon–silicon chemical bond, bonds. Organosilicon chemistry is the corresponding science of their preparation and properties. Most organosilicon compounds are similar to the ordinary organic compounds, being colourless, flammable, hydrophobic, and stable to air. Silicon carbide is an ''inorganic chemistry, inorganic'' compound. History In 1846 Von Ebelman's had synthesized Tetraethyl orthosilicate (Si(OC2H5)4). In 1863 Friedel and Crafts managed to make the first organosilieon compound with C-Si bonds which gone byound the syntheses of orthosilicic acid esters. The same year they also described a «polysilicic acid ether» in the preparation of Ethanol, ethyl- and methyl-o-silicic acid. The early extensive research in the field of organosilicon compounds was pioneerd in the beginning of 20th century by Frederic Kipping. He also had coined the term «silicone» (akin to ketones) in relation to these materials ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wurtz Coupling
In organic chemistry, the Wurtz reaction, named after Charles Adolphe Wurtz, is a coupling reaction whereby two alkyl halides are treated with sodium metal to form a higher alkane. : 2 R−X + 2 Na → R−R + 2 NaX The reaction is of little value except for intramolecular versions. A related reaction, which combines alkyl halides with aryl halides is called the Wurtz–Fittig reaction. Mechanism The reaction proceeds by an initial metal–halogen exchange, which involves this idealized stoichiometry: : R−X + 2 M → RM + MX This step involves the intermediacy of radical species R·. This step resembles the formation of a Grignard reagent. These RM intermediates have been isolated in several cases. The organometallic intermediate next reacts with the alkyl halide forming a new carbon–carbon covalent bond. : RM + RX → R−R + MX The process resembles an SN2 reaction, but the process is probably complex, which may explain the inefficiency of the reaction. Exampl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tetrahydrofuran
Tetrahydrofuran (THF), or oxolane, is an organic compound with the formula (CH2)4O. The compound is classified as heterocyclic compound, specifically a cyclic ether. It is a colorless, water-miscible organic liquid with low viscosity. It is mainly used as a precursor to polymers. Being polar and having a wide liquid range, THF is a versatile solvent. Production About 200,000 tonnes of tetrahydrofuran are produced annually. The most widely used industrial process involves the acid-catalyzed dehydration of 1,4-butanediol. Ashland/ISP is one of the biggest producers of this chemical route. The method is similar to the production of diethyl ether from ethanol. The butanediol is derived from condensation of acetylene with formaldehyde followed by hydrogenation. DuPont developed a process for producing THF by oxidizing ''n''-butane to crude maleic anhydride, followed by catalytic hydrogenation. A third major industrial route entails hydroformylation of allyl alcohol followed by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Toluene
Toluene (), also known as toluol (), is a substituted aromatic hydrocarbon. It is a colorless, water-insoluble liquid with the smell associated with paint thinners. It is a mono-substituted benzene derivative, consisting of a methyl group (CH3) attached to a phenyl group. As such, its systematic IUPAC name is methylbenzene. Toluene is predominantly used as an industrial feedstock and a solvent. As the solvent in some types of paint thinner, permanent markers, contact cement and certain types of glue, toluene is sometimes used as a recreational inhalant and has the potential of causing severe neurological harm. History The compound was first isolated in 1837 through a distillation of pine oil by the Polish chemist Filip Walter, who named it ''rétinnaphte''. In 1841, French chemist Henri Étienne Sainte-Claire Deville isolated a hydrocarbon from balsam of Tolu (an aromatic extract from the tropical Colombian tree ''Myroxylon balsamum''), which Deville recognized as similar to Wa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thermolysis
Thermal decomposition, or thermolysis, is a chemical decomposition caused by heat. The decomposition temperature of a substance is the temperature at which the substance chemically decomposes. The reaction is usually endothermic as heat is required to break chemical bonds in the compound undergoing decomposition. If decomposition is sufficiently exothermic, a positive feedback loop is created producing thermal runaway and possibly an explosion or other chemical reaction. Decomposition temperature definition A simple substance (like water) may exist in equilibrium with its thermal decomposition products, effectively halting the decomposition. The equilibrium fraction of decomposed molecules increases with the temperature. Examples * Calcium carbonate (limestone or chalk) decomposes into calcium oxide and carbon dioxide when heated. The chemical reaction is as follows: ::CaCO3 → CaO + CO2 :The reaction is used to make quick lime, which is an industrially important product. : ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silicon Carbide
Silicon carbide (SiC), also known as carborundum (), is a hard chemical compound containing silicon and carbon. A semiconductor, it occurs in nature as the extremely rare mineral moissanite, but has been mass-produced as a powder and crystal since 1893 for use as an abrasive. Grains of silicon carbide can be bonded together by sintering to form very hard ceramics that are widely used in applications requiring high endurance, such as car brakes, car clutches and ceramic plates in bulletproof vests. Large single crystals of silicon carbide can be grown by the Lely method and they can be cut into gems known as synthetic moissanite. Electronic applications of silicon carbide such as light-emitting diodes (LEDs) and Cat's whisker detector, detectors in early radios were first demonstrated around 1907. SiC is used in semiconductor electronics devices that operate at high temperatures or high voltages, or both. Natural occurrence Naturally occurring moissanite is found in only minut ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silanes
Silanes refers to diverse kinds of charge-neutral silicon compounds with the formula . The R substituents can any combination of organic or inorganic groups. Most silanes contain Si-C bonds, and are discussed under organosilicon compounds. Examples: *Silane , the parent. *Binary silicon-hydrogen compounds (which are sometimes called silanes also) includes silane itself but also compounds with Si-Si bonds including disilane and longer chains. *Silanes with one, two, three, or four Si-H bonds are called hydrosilanes. Silane itself is the parent member. Examples: triethylsilane () and triethoxysilane (). *Polysilanes are organosilicon compounds with the formula . They include all binary silicon-hydrogen compounds except the parent, although these tend to be less useful because they are fragile. Attracting more interest, are the organic derivatives such as polydimethylsilane and dodecamethylcyclohexasilane *Chlorosilanes have Si-Cl bonds. Examples: trichlorosilane () and tetrachlo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
