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Silane
Silane is an inorganic compound with chemical formula, . It is a colourless, pyrophoric, toxic gas with a sharp, repulsive smell, somewhat similar to that of acetic acid. Silane is of practical interest as a precursor to elemental silicon. Silane with alkyl groups are effective water repellents for mineral surfaces such as concrete and masonry. Silanes with both organic and inorganic attachments are used as coupling agents. Production Commercial-scale routes Silane can be produced by several routes. Typically, it arises from the reaction of hydrogen chloride with magnesium silicide: : Mg2Si + 4 HCl -> 2 MgCl2 + SiH4 It is also prepared from metallurgical-grade silicon in a two-step process. First, silicon is treated with hydrogen chloride at about 300 °C to produce trichlorosilane, HSiCl3, along with hydrogen gas, according to the chemical equation : Si + 3 HCl -> HSiCl3 + H2 The trichlorosilane is then converted to a mixture of silane and silicon tetrachloride: : ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silicon
Silicon is a chemical element with the symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic luster, and is a tetravalent metalloid and semiconductor. It is a member of group 14 in the periodic table: carbon is above it; and germanium, tin, lead, and flerovium are below it. It is relatively unreactive. Because of its high chemical affinity for oxygen, it was not until 1823 that Jöns Jakob Berzelius was first able to prepare it and characterize it in pure form. Its oxides form a family of anions known as silicates. Its melting and boiling points of 1414 °C and 3265 °C, respectively, are the second highest among all the metalloids and nonmetals, being surpassed only by boron. Silicon is the eighth most common element in the universe by mass, but very rarely occurs as the pure element in the Earth's crust. It is widely distributed in space in cosmic dusts, planetoids, and planets as various forms of silicon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Disilane
Disilane is a chemical compound with chemical formula Si2H6 that was identified in 1902 by Henri Moissan and Samuel Smiles (1877–1953). Moissan and Smiles reported disilane as being among the products formed by the action of dilute acids on metal silicides. Although these reactions had been previously investigated by Friedrich Woehler and Heinrich Buff between 1857 and 1858, Moissan and Smiles were the first to explicitly identify disilane. They referred to disilane as ''silicoethane''. Higher members of the homologous series SinH2n+2 formed in these reactions were subsequently identified by Carl Somiesky (sometimes spelled "Karl Somieski") and Alfred Stock. At standard temperature and pressure, disilane is a colourless, acrid gas. Disilane and ethane have similar structures, although disilane is much more reactive. Other compounds of the general formula Si2X6 (X = hydride, halide, alkyl, aryl, and mixtures of these groups) are called disilanes. Disilane is a group 14 hydri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trichlorosilane
Trichlorosilane is an inorganic compound with the formula HCl3Si. It is a colourless, volatile liquid. Purified trichlorosilane is the principal precursor to ultrapure silicon in the semiconductor industry. In water, it rapidly decomposes to produce a siloxane polymer while giving off hydrochloric acid. Because of its reactivity and wide availability, it is frequently used in the synthesis of silicon-containing organic compounds. Production Trichlorosilane is produced by treating powdered metallurgical grade silicon with blowing hydrogen chloride at 300 °C. Hydrogen is also produced, as described in the chemical equation: :Si + 3 HCl → HCl3Si + H2 Yields of 80-90% can be achieved. The main byproducts are silicon tetrachloride (chemical formula SiCl4), hexachlorodisilane (Si2Cl6) and dichlorosilane (H2SiCl2), from which trichlorosilane can be separated by distillation. It is also produced from silicon tetrachloride: :Si + 3 SiCl4 + 2 H2 → 4 HCl3Si Applicatio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vinylsilane
Vinylsilane refers to an organosilicon compound with chemical formula CH2=CHSiH3. It is a derivative of silane (SiH4). The compound, which is a colorless gas, is mainly of theoretical interest. Substituted vinylsilanes More commonly used than the parent vinylsilane are vinyl-substituted silanes with other substituents on silicon. In the area of organic synthesis, vinylsilanes are useful intermediates. In the area of polymer chemistry and materials science, vinyltrimethoxysilane or vinyltriethoxysilane serve as monomers and coupling agents. Preparation Vinylsilanes are often prepared by hydrosilylation of alkynes. They can be made by the reaction of alkenyl lithium and Grignard reagents with chlorosilane Chlorosilanes are a group of reactive, chlorine-containing chemical compounds, related to silane and used in many chemical processes. Each such chemical has at least one silicon-chlorine bond. Trichlorosilane is produced on the largest scale. The p ...s. In some cases d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trisilane
Trisilane is the silane with the formula H2Si(SiH3)2. A liquid at standard temperature and pressure, it is a silicon analogue of propane. The contrast with propane however trisilane ignites spontaneously in air. Synthesis Trisilane was characterized by Alfred Stock having prepared it by the reaction of hydrochloric acid and magnesium silicide. This reaction had been explored as early as 1857 by Friedrich Woehler and Heinrich Buff, and further investigated by Henri Moissan and Samuel Smiles in 1902. Decomposition The key property of trisilane is its thermal lability. It degrades to silicon films and SiH4 according to this idealized equation: :Si3H8 → Si + 2 SiH4 In terms of mechanism, this decomposition proceeds by a 1,2 hydrogen shift that produces disilanes, normal and isotetrasilanes, and normal and isopentasilanes. Because it readily decomposes to leave films of Si, trisilane has been explored a means to apply thin layers of silicon for semiconductors and similar ap ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phenylsilane
Phenylsilane, also known as silylbenzene, a colorless liquid, is one of the simplest organosilanes with the formula C6 H5 SiH3. It is structurally related to toluene, with a silyl group replacing the methyl group. Both of these compounds have similar densities and boiling points due to these similarities. Phenylsilane is soluble in organic solvents. Synthesis and reactions Phenylsilane is produced in two steps from Si(OEt)4. In the first step, phenylmagnesium bromide is added to form Ph−Si(OEt)3 via a Grignard reaction. Reduction of the resulting Ph−Si(OEt)3 product with LiAlH4 affords phenylsilane. :Ph−MgBr + Si(OEt)4 → Ph−Si(OEt)3 + MgBr(OEt) :4 Ph−Si(OEt)3 + 3 LiAlH4 → 4 Ph−SiH3 + 3 LiAl(OEt)4 Uses Phenylsilane can be used to reduce tertiary phosphine oxides to the corresponding tertiary phosphine. :P(CH3)3O + PhSiH3 → P(CH3)3 + PhSiH2OH The use of phenylsilane proceeds with retention of configuration at the phosphine. For example, cyclic chiral ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silicon Tetrachloride
Silicon tetrachloride or tetrachlorosilane is the inorganic compound with the formula SiCl4. It is a colourless volatile liquid that fumes in air. It is used to produce high purity silicon and silica for commercial applications. Preparation Silicon tetrachloride is prepared by the chlorination of various silicon compounds such as ferrosilicon, silicon carbide, or mixtures of silicon dioxide and carbon. The ferrosilicon route is most common. In the laboratory, can be prepared by treating silicon with chlorine at : : It was first prepared by Jöns Jakob Berzelius in 1823. Brine can be contaminated with silica when the production of chlorine is a byproduct of a metal refining process from metal chloride ore. In rare occurrences, the silicon dioxide in silica is converted to silicon tetrachloride when the contaminated brine is electrolyzed. Reactions Hydrolysis and related reactions Like other chlorosilanes, silicon tetrachloride reacts readily with water: :SiCl4 + 2 H2O → S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Disproportionation
In chemistry, disproportionation, sometimes called dismutation, is a redox reaction in which one compound of intermediate oxidation state converts to two compounds, one of higher and one of lower oxidation states. More generally, the term can be applied to any desymmetrizing reaction of the following type, regardless of whether it is a redox or some other type of process: :2A -> A' + A'' Examples *Mercury(I) chloride disproportionates upon UV-irradiation: :Hg2Cl2 → Hg + HgCl2 *Phosphorous acid disproportionates upon heating to give phosphoric acid and phosphine: :4 → 3 H3PO4 + PH3 *Desymmetrizing reactions are sometimes referred to as disproportionation, as illustrated by the thermal degradation of bicarbonate: :2 → + H2CO3 :The oxidation numbers remain constant in this acid-base reaction. This process is also called autoionization. *Another variant on disproportionation is radical disproportionation, in which two radicals form an alkene and an alkane. : Reverse ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silicon Tetrafluoride
Silicon tetrafluoride or tetrafluorosilane is a chemical compound with the formula Si F4. This colorless gas is notable for having a narrow liquid range: its boiling point is only 4 °C above its melting point. It was first prepared in 1771 by Carl Wilhelm Scheele by dissolving silica in hydrofluoric acid., later synthesized by John Davy in 1812. It is a tetrahedral molecule and is corrosive. Preparation is a by-product of the production of phosphate fertilizers wet process production, resulting from the attack of HF (derived from fluorapatite protonolysis) on silicates, which are present as impurities in the phosphate rocks. The hydrofluoric acid and silicon dioxide (SiO2) react to produce hexafluorosilicic acid: : 6 HF + SiO2 → H2SiF6 + 2 H2O In the laboratory, the compound is prepared by heating barium hexafluorosilicate (Ba iF6 above whereupon the solid releases volatile , leaving a residue of . : Alternatively, sodium hexafluorosilicate () may also ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyrophoricity
A substance is pyrophoric (from grc-gre, πυροφόρος, , 'fire-bearing') if it ignites spontaneously in air at or below (for gases) or within 5 minutes after coming into contact with air (for liquids and solids). Examples are organolithium compounds and triethylborane. Pyrophoric materials are often water-reactive as well and will ignite when they contact water or humid air. They can be handled safely in atmospheres of argon or (with a few exceptions) nitrogen. Class D fire extinguishers are designated for use in fires involving pyrophoric materials. A related concept is hypergolicity, in which two compounds spontaneously ignite when mixed. Uses The creation of sparks from metals is based on the pyrophoricity of small metal particles, and pyrophoric alloys are made for this purpose. The sparking mechanisms in lighters and various toys, using ferrocerium; starting fires without matches, using a firesteel; the flintlock mechanism in firearms; and spark testing fe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnesium Silicide
Magnesium silicide, Mg2Si, is an inorganic compound consisting of magnesium and silicon. As-grown Mg2Si usually forms black crystals; they are semiconductors with n-type conductivity and have potential applications in thermoelectric generators. Crystal structure Mg2Si crystallizes in the antifluorite structure. In the face-centered cubic lattice Si centers occupy the corners and face-centered positions of the unit cell and Mg centers occupy eight tetrahedral sites in the interior of the unit cell. The coordination numbers of Si and Mg are eight and four, respectively. Synthesis It can be produced by heating silicon dioxide, SiO2, found in sand, with excess magnesium. The process first forms silicon metal and magnesium oxide, and, if an excess of SiO2 is used, then elemental silicon is formed: :2 Mg + SiO2 → 2 MgO + Si If an excess of Mg is present, Mg2Si is formed from the reaction of the remaining magnesium with the silicon: :2 Mg + Si → Mg2Si These reactions p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plumbane
Plumbane, PbH4, is a metal hydride and group 14 hydride composed of lead and hydrogen. Plumbane is not well characterized or well known, and it is thermodynamically unstable with respect to the loss of a hydrogen atom. Derivatives of plumbane include lead tetrafluoride, PbF4, and tetraethyllead, (CH3CH2)4Pb. History Until recently, it was uncertain whether plumbane had ever actually been synthesized, although the first reports date back to the 1920s and in 1963, Saalfeld and Svec reported the observation of by mass spectrometry. Plumbane has repeatedly been the subject of Dirac– Hartree–Fock relativistic calculation studies, which investigate the stabilities, geometries, and relative energies of hydrides of the formula MH4 or MH2. Properties Plumbane is an unstable colorless gas and is the heaviest group IV hydride. Furthermore, plumbane has a tetrahedral (Td) structure with an equilibrium distance between lead and hydrogen of 1.73 Å. By weight percent, the compositi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
