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Oxidative Coupling
Oxidative coupling in chemistry is a coupling reaction of two molecular entities through an oxidative process. Usually oxidative couplings are catalysed by a transition metal complex like in classical cross-coupling reactions, although the underlying mechanism is different due to the oxidation process that requires an external (or internal) oxidant. Many such couplings utilize dioxygen as the stoichiometric oxidant but proceed by electron transfer. C-C Couplings Many oxidative couplings generate new C-C bonds. Early examples involve coupling of terminal alkynes: :2 RC≡CH + 2 Cu(I) → RC≡C-C≡CR + 2 Cu + 2 H+ Aromatic coupling In oxidative aromatic coupling the reactants are electron-rich aromatic compounds. Typical substrates are phenols and typical catalysts are copper and iron compounds and enzymes, although Scholl demonstrated that high heat and a Lewis acid suffice. The first reported synthetic application dates back to 1868 with Julius Löwe and the sy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemistry
Chemistry is the scientific study of the properties and behavior of matter. It is a physical science within the natural sciences that studies the chemical elements that make up matter and chemical compound, compounds made of atoms, molecules and ions: their composition, structure, properties, behavior and the changes they undergo during chemical reaction, reactions with other chemical substance, substances. Chemistry also addresses the nature of chemical bonds in chemical compounds. In the scope of its subject, chemistry occupies an intermediate position between physics and biology. It is sometimes called the central science because it provides a foundation for understanding both Basic research, basic and Applied science, applied scientific disciplines at a fundamental level. For example, chemistry explains aspects of plant growth (botany), the formation of igneous rocks (geology), how atmospheric ozone is formed and how environmental pollutants are degraded (ecology), the prop ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ellagic Acid
Ellagic acid is a polyphenol found in numerous fruits and vegetables. It is the dilactone of hexahydroxydiphenic acid. Name The name comes from the French term ''acide ellagique'', from the word ''galle'' spelled backward because it can be obtained from ''noix de galle'' (galls), and to distinguish it from ''acide gallique'' ( gallic acid). The molecular structure resembles to that of two gallic acid molecules being assembled "head to tail" and bound together by a C–C bond (as in biphenyl, or in diphenic acid) and two lactone links (cyclic carboxylic esters). Metabolism Biosynthesis Plants produce ellagic acid from hydrolysis of tannins such as ellagitannin and geraniin. Biodegradation Urolithins are gut flora human metabolites of dietary ellagic acid derivatives. Ellagic acid has low bioavailability, with 90% remaining unabsorbed from the intestines until metabolized by microflora to the more bioavailable urolithins. History Ellagic acid was first discove ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrolysis Of Water
Electrolysis of water is using electricity to Water splitting, split water into oxygen () and hydrogen () gas by electrolysis. Hydrogen gas released in this way can be used as hydrogen fuel, but must be kept apart from the oxygen as the mixture would be extremely explosive. Separately pressurised into convenient 'tanks' or 'gas bottles', hydrogen can be used for oxyhydrogen welding and other applications, as the hydrogen / oxygen flame can reach approximately 2,800°C. Water electrolysis requires a minimum potential difference of 1.23 volts, although at that voltage external heat is also required. Typically 1.5 volts is required. Electrolysis is rare in industrial applications since hydrogen can be produced less expensively from fossil fuels. Most of the time, hydrogen is made by splitting methane (CH4) into carbon dioxide (CO2) and hydrogen (H2) via steam reforming. This is a carbon-intensive process that means for every kilogram of “grey” hydrogen produced, approximatel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxidative Coupling Of Methane
The oxidative coupling of methane (OCM) is a potential chemical reaction studied in the 1980s for the direct conversion of natural gas, primarily consisting of methane, into value-added chemicals. Although the reaction would have strong economics if practicable, no effective catalysts are known, and thermodynamic arguments suggest none can exist. Ethylene production The principal desired product of OCM is ethylene, the world's largest commodity chemical and the chemical industry's fundamental building block. While converting methane to ethylene would offer enormous economic benefits, it is a major scientific challenge. Thirty years of research failed to produce a commercial OCM catalyst, preventing this process from commercial applications. Ethylene derivatives are found in food packaging, eyeglasses, cars, medical devices, lubricants, engine coolants and liquid crystal displays. Ethylene production by steam cracking consumes large amounts of energy and uses oil and natural ga ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CuCl2 Naphthol Coupling
Copper(I) chloride, commonly called cuprous chloride, is the lower chloride of copper, with the formula CuCl. The substance is a white solid sparingly soluble in water, but very soluble in concentrated hydrochloric acid. Impure samples appear green due to the presence of copper(II) chloride (CuCl2). History Copper(I) chloride was first prepared by Robert Boyle and designated rosin of copper in the mid-seventeenth century from mercury(II) chloride ("Venetian sublimate") and copper metal: :HgCl2 + 2 Cu → 2 CuCl + Hg In 1799, Joseph Proust first differentiated two different chlorides of copper. He prepared CuCl (which he called white muriate of copper) by heating CuCl2 at red heat in the absence of air, causing it to lose half of its combined chlorine followed by removing residual CuCl2 by washing with water. An acidic solution of CuCl was formerly used to analyze carbon monoxide content in gases, for example in Hempel's gas apparatus where the CuCl absorbs the carbon mono ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Copper(II) Chloride
Copper(II) chloride, also known as cupric chloride, is an inorganic compound with the chemical formula . The monoclinic crystal system, monoclinic yellowish-brown anhydrous form slowly absorbs moisture to form the orthorhombic blue-green hydrate, dihydrate , with two water of crystallization, water molecules of hydration. It is industrially produced for use as a catalyst, co-catalyst in the Wacker process. Both the anhydrous and the dihydrate forms occur naturally as the rare minerals tolbachite and eriochalcite, respectively. Structure Anhydrous copper(II) chloride adopts a distorted cadmium iodide structure. In this structure, the copper centers are octahedral molecular geometry, octahedral. Most copper(II) compounds exhibit distortions from idealized Octahedral molecular geometry, octahedral geometry due to the Jahn-Teller effect, which in this case describes the localization of one electron, d-electron into a molecular orbital that is strongly antibonding molecular orbital, an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alexander Dianin
Aleksandr Pavlovich Dianin (; 20 April 1851 – 6 December 1918) was a Russian chemist from Saint Petersburg. He carried out studies on phenols and discovered a phenol derivative now known as bisphenol A and the accordingly named Dianin's compound. He was married to the adopted daughter of fellow chemist Alexander Borodin. In 1887, Dianin succeeded his father-in-law as chair of the Chemistry Department at the Imperial Medical-Surgical Academy in St. Petersburg (now the S.M. Kirov Military Medical Academy). Bisphenol A and Dianin's compound Dianin's method for preparing bisphenol A from 1891 remains the most widely-known approach to this important compound, though the method has been refined for industrial-scale synthesis. It involves the catalysed condensation of a 2:1 mixture of phenol and acetone in the presence of concentrated hydrochloric acid or sulfuric acid. The reaction proceeds readily at room temperature producing a crude product containing a great variety of side p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iron(III) Chloride
Iron(III) chloride describes the inorganic compounds with the formula (H2O)x. Also called ferric chloride, these compounds are some of the most important and commonplace compounds of iron. They are available both in anhydrous and in hydrated forms, which are both hygroscopic. They feature iron in its +3 oxidation state. The anhydrous derivative is a Lewis acid, while all forms are mild oxidizing agents. It is used as a water cleaner and as an etchant for metals. Electronic and optical properties All forms of ferric chloride are paramagnetic, owing to the presence of unpaired electrons residing in 3d orbitals. Although Fe(III) chloride can be octahedral or tetrahedral (or both, see structure section), all of these forms have five unpaired electrons, one per d-orbital. The high spin d5 electronic configuration requires that d-d electronic transitions are spin forbidden, in addition to violating the Laporte rule. This double forbidden-ness results in its solutions being ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
2-naphthol
2-Naphthol, or β-naphthol, is a fluorescent colorless (or occasionally yellow) crystalline solid with the formula C10H7OH. It is an isomer of 1-naphthol, differing by the location of the hydroxyl group on the naphthalene ring. The naphthols are naphthalene homologues of phenol, but more reactive. Both isomers are soluble in simple alcohols, ethers, and chloroform. 2-Naphthol is a widely used intermediate for the production of dyes and other compounds. Production Traditionally, 2-naphthol is produced by a two-step process that begins with the sulfonation of naphthalene in sulfuric acid:full-text PDF/ref> :C10H8 + H2SO4 → C10H7SO3H + H2O The sulfonic acid group is then cleaved in molten sodium hydroxide: :C10H7(SO3H) + 3 NaOH → C10H7ONa + Na2SO3 + 2 H2O Neutralization of the product with acid gives 2-naphthol. 2-Naphthol can also be produced by a method analogous to the cumene process. 2-Naphthol-derived dyes The Sudan dyes are popular dyes noted for being ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silver Oxide
Silver oxide is the chemical compound with the formula Ag2 O. It is a fine black or dark brown powder that is used to prepare other silver compounds. Preparation Silver oxide can be prepared by combining aqueous solutions of silver nitrate and an alkali hydroxide. This reaction does not afford appreciable amounts of silver hydroxide due to the favorable energetics for the following reaction: :( p''K'' = 2.875) With suitably controlled conditions, this reaction can be used to prepare Ag2O powder with properties suitable for several uses including as a fine grained conductive paste filler. Structure and properties Ag2O features linear, two-coordinate Ag centers linked by tetrahedral oxides. It is isostructural with Cu2O. It "dissolves" in solvents that degrade it. It is slightly soluble in water due to the formation of the ion and possibly related hydrolysis products. It is soluble in ammonia solution, producing active compound of Tollens' reagent. A slurry of Ag2O is readil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
