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Tris(trimethylsilyl)amine
Tris(trimethylsilyl)amine is the simplest tris(trialkylsilyl)amine which are having the general formula (R3Si)3N, in which all three hydrogen atoms of the ammonia are replaced by trimethylsilyl groups (-Si(CH3)3). Tris(trimethylsilyl)amine has been for years in the center of scientific interest as a stable intermediate in chemical nitrogen fixation (i. e. the conversion of atmospheric nitrogen N2 into organic substrates under normal conditions). Production Early attempts to prepare tris(trimethylsilyl)amine from ammonia and trimethylchlorosilane (TMS-Cl) were unsuccessful even at temperatures of 500 °C and in the presence of the base pyridine. The reaction of ammonia and trimethylchlorosilane stops at the stage of the doubly silylated product bis(trimethylsilyl)amine (usually referred to as hexamethyldisilazane, HMDS). Tris(trimethylsilyl)amine is obtained by reaction of the sodium salt of hexamethyldisilazane - from hexamethyldisilazane and sodium amide or from hexamet ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ammonia
Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogenous waste, particularly among aquatic organisms, and it contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to 45% of the world's food and fertilizers. Around 70% of ammonia is used to make fertilisers in various forms and composition, such as urea and Diammonium phosphate. Ammonia in pure form is also applied directly into the soil. Ammonia, either directly or indirectly, is also a building block for the synthesis of many pharmaceutical products and is used in many commercial cleaning products. It is mainly collected by downward displacement of both air and water. Although common in nature—both terrestrially and in the outer planets of the Solar System—and in wide use, ammonia is both caust ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cubane-type Cluster
A cubane-type cluster is an arrangement of atoms in a molecular structure that forms a cube. In the idealized case, the eight vertices are symmetry equivalent and the species has Oh symmetry. Such a structure is illustrated by the hydrocarbon cubane. With chemical formula , cubane has carbon atoms at the corners of a cube and covalent bonds forming the edges. Most cubanes have more complicated structures, usually with nonequivalent vertices. They may be simple covalent compounds or macromolecular or supramolecular cluster compounds. Examples Other compounds having different elements in the corners, various atoms or groups bonded to the corners are all part of this class of structures. Inorganic cubane-type clusters include selenium tetrachloride, tellurium tetrachloride, and sodium silox. Cubane clusters are common throughout bioinorganic chemistry. Ferredoxins containing e4S4iron–sulfur clusters are pervasive in nature. The four iron atoms and four sulfur atoms form an alter ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Synthese Von Hexachlorcyclotriphosphan
''Synthese'' () is a scholarly periodical specializing in papers in epistemology, methodology, and philosophy of science, and related issues. Its subject area is divided into four specialties, with a focus on the first three: (1) "epistemology, methodology, and philosophy of science, all broadly understood"; (2) "foundations of logic and mathematics, where 'logic', 'mathematics', and 'foundations' are all broadly understood"; (3) "formal methods in philosophy, including methods connecting philosophy to other academic fields"; and (4) "issues in ethics and the history and sociology of logic, mathematics, and science that contribute to the contemporary studies". As of 2022, according to Google Scholar's metrics ( h-5 index and h-5 index median), it is the top philosophy journal, but other metrics do not rank the journal as highly. Overview Published articles include specific treatment of methodological issues in science such as induction, probability, causation, statistics, symboli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trimer (chemistry)
In chemistry, a trimer (; ) is a molecule or polyatomic anion formed by combination or association of three molecules or ions of the same substance. In technical jargon, a trimer is a kind of oligomer derived from three identical precursors often in competition with polymerization. Examples Alkyne trimerisation In 1866, Marcellin Berthelot reported the first example of cyclotrimerization, the conversion of acetylene to benzene. This process was commercialized: : Nitrile trimerization Symmetrical 1,3,5-triazines are prepared by trimerization of certain nitriles such as cyanogen chloride or cyanimide. Cyanogen chloride and cyanogen bromide each trimerize at elevated temperatures over a carbon catalyst. The chloride gives cyanuric chloride: : The bromide has an extended shelflife when refrigerated. Like the chloride, it undergoes ab exothermic trimerisation to form cyanuric bromide. This reaction is catalyzed by traces of bromine, metal salts, acids and bases. For this reason ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polydispersity
In chemistry, the dispersity is a measure of the heterogeneity of sizes of molecules or particles in a mixture. A collection of objects is called uniform if the objects have the same size, shape, or mass. A sample of objects that have an inconsistent size, shape and mass distribution is called non-uniform. The objects can be in any form of chemical dispersion, such as particles in a colloid, droplets in a cloud, crystals in a rock, or polymer macromolecules in a solution or a solid polymer mass. Polymers can be described by molecular mass distribution; a population of particles can be described by size, surface area, and/or mass distribution; and thin films can be described by film thickness distribution. IUPAC has deprecated the use of the term ''polydispersity index'', having replaced it with the term ''dispersity'', represented by the symbol Đ (pronounced D-strokeStepto, R. F. T.; Gilbert, R. G.; Hess, M.; Jenkins, A. D.; Jones, R. G.; Kratochvíl P. (2009).Dispersity in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Poly(dichlorophosphazene)
Poly(dichlorophosphazene), also called dichlorophosphazine polymer or phosphonitrilechloride polymer, is a chemical compound with formula (PNCl2)''n''. It is an inorganic (hence carbon-free) chloropolymer, whose backbone is a chain of alternating phosphorus and nitrogen atoms, connected by alternating single and double covalent bonds. The compound can be prepared by polymerization of hexachlorophosphazene ((PNCl2)3) by heating to ca. 250 °C.Hans Rytger Kricheldorf (1991), ''Handbook of Polymer Synthesis''Mario Gleria, Roger De Jaeger (2004) ''Phosphazenes: A Worldwide Insight''Nova Publishers, 2004. 1047 pages. , 9781590334232 It is an "inorganic rubber" and the starting material for many other polymers with the -P=N- backbone (polyphosphazenes), which have important commercial uses. History Poly(dichlorophosphazene) was discovered by H. N. Stokes in the 19th century, and at that time its superior properties over natural rubber were already noted.H. N. Stokes (1895)''On ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Synthese Von Trichlor(trimethylsilyl)phosphoranimin
''Synthese'' () is a scholarly periodical specializing in papers in epistemology, methodology, and philosophy of science, and related issues. Its subject area is divided into four specialties, with a focus on the first three: (1) "epistemology, methodology, and philosophy of science, all broadly understood"; (2) "foundations of logic and mathematics, where 'logic', 'mathematics', and 'foundations' are all broadly understood"; (3) "formal methods in philosophy, including methods connecting philosophy to other academic fields"; and (4) "issues in ethics and the history and sociology of logic, mathematics, and science that contribute to the contemporary studies". As of 2022, according to Google Scholar's metrics ( h-5 index and h-5 index median), it is the top philosophy journal, but other metrics do not rank the journal as highly. Overview Published articles include specific treatment of methodological issues in science such as induction, probability, causation, statistics, symboli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hexane
Hexane () is an organic compound, a straight-chain alkane with six carbon atoms and has the molecular formula C6H14. It is a colorless liquid, odorless when pure, and with boiling points approximately . It is widely used as a cheap, relatively safe, largely unreactive, and easily evaporated non-polar solvent, and modern gasoline blends contain about 3% hexane. The term ''hexanes'' refers to a mixture, composed largely (>60%) of hexane, with varying amounts of the isomeric compounds 2-methylpentane and 3-methylpentane, and, possibly, smaller amounts of nonisomeric C5, C6, and C7 (cyclo)alkanes. These ''hexanes'' are cheaper than pure hexane and are often used in large-scale operations not requiring a single isomer (e.g., as cleaning solvent or for chromatography). Isomers Uses In industry, hexanes are used in the formulation of adhesive, glues for shoes, leather products, and roofing. They are also used to extract cooking oils (such as canola oil or soy oil) from seeds, for c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phosphorus Pentachloride
Phosphorus pentachloride is the chemical compound with the formula PCl5. It is one of the most important phosphorus chlorides, others being PCl3 and POCl3. PCl5 finds use as a chlorinating reagent. It is a colourless, water-sensitive and moisture-sensitive solid, although commercial samples can be yellowish and contaminated with hydrogen chloride. Structure The structures for the phosphorus chlorides are invariably consistent with VSEPR theory. The structure of PCl5 depends on its environment. Gaseous and molten PCl5 is a neutral molecule with trigonal bipyramidal geometry and (''D''3h) symmetry. The hypervalent nature of this species (as well as of , see below) can be explained with the inclusion of non-bonding molecular orbitals (molecular orbital theory) or resonance (valence bond theory). This trigonal bipyramidal structure persists in nonpolar solvents, such as CS2 and CCl4. In the solid state PCl5 is an ionic compound, formulated . In solutions of polar solvents, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monomer
In chemistry, a monomer ( ; ''mono-'', "one" + '' -mer'', "part") is a molecule that can react together with other monomer molecules to form a larger polymer chain or three-dimensional network in a process called polymerization. Classification Monomers can be classified in many ways. They can be subdivided into two broad classes, depending on the kind of the polymer that they form. Monomers that participate in condensation polymerization have a different stoichiometry than monomers that participate in addition polymerization: : Other classifications include: *natural vs synthetic monomers, e.g. glycine vs caprolactam, respectively *polar vs nonpolar monomers, e.g. vinyl acetate vs ethylene, respectively *cyclic vs linear, e.g. ethylene oxide vs ethylene glycol, respectively The polymerization of one kind of monomer gives a homopolymer. Many polymers are copolymers, meaning that they are derived from two different monomers. In the case of condensation polymerizations, the r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ChemistryOpen
''ChemistryOpen'' is a monthly peer-reviewed, open access, scientific journal covering all areas of chemistry and related fields. It is published by Wiley-VCH on behalf of Chemistry Europe. According to the ''Journal Citation Reports'', the journal has a 2021 impact factor The impact factor (IF) or journal impact factor (JIF) of an academic journal is a scientometric index calculated by Clarivate that reflects the yearly mean number of citations of articles published in the last two years in a given journal, as i ... of 2.630, ranking it 109th out of 179 journals in the category "Chemistry, Multidisciplinary". References External links *{{Official website, https://chemistry-europe.onlinelibrary.wiley.com/journal/21911363 Chemistry Europe academic journals Wiley-VCH academic journals English-language journals Chemistry journals Open access journals Monthly journals ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluoroform
Trifluoromethane or fluoroform is the chemical compound with the formula CHF3. It is one of the " haloforms", a class of compounds with the formula CHX3 (X = halogen) with C3v symmetry. Fluoroform is used in diverse applications in organic synthesis. It is not an ozone depleter but is a greenhouse gas. Synthesis About 20M kg/y are produced industrially as both a by-product of and precursor to the manufacture of Teflon. It is produced by reaction of chloroform with HF: :CHCl3 + 3 HF → CHF3 + 3 HCl It is also generated biologically in small amounts apparently by decarboxylation of trifluoroacetic acid. Historical Fluoroform was first obtained by Maurice Meslans in the violent reaction of iodoform with dry silver fluoride in 1894. The reaction was improved by Otto Ruff by substitution of silver fluoride by a mixture of mercury fluoride and calcium fluoride. The exchange reaction works with iodoform and bromoform, and the exchange of the first two halogen atoms by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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