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Alkane Metathesis
Alkane metathesis is a class of chemical reaction in which an alkane is rearranged to give a longer or shorter alkane product. It is similar to olefin metathesis, except that olefin metathesis cleaves and recreates a carbon-carbon double bond, but alkane metathesis operates on a carbon-carbon single bond. Examples and catalysts Alkane metathesis is catalyzed by metal-containing compounds or complexes. One such class of catalyst systems, discovered and developed by the group of Jean-Marie Basset, comprises tantalum hydride supported on silica (SiO2)TaH at temperatures of 25°C to 200°C. These systems catalyze the conversion of ethane to give methane, propane and traces of butane. Cross metathesis can also take place, for example methane and propane can react to give two molecules of ethane. Ethane reacts with toluene to give ethylbenzene and xylene. The reaction involves metallocyclobutane intermediates just as in olefin metathesis. Dual-catalyst systems have also been developed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemical Reaction
A chemical reaction is a process that leads to the chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the positions of electrons in the forming and breaking of chemical bonds between atoms, with no change to the nuclei (no change to the elements present), and can often be described by a chemical equation. Nuclear chemistry is a sub-discipline of chemistry that involves the chemical reactions of unstable and radioactive elements where both electronic and nuclear changes can occur. The substance (or substances) initially involved in a chemical reaction are called reactants or reagents. Chemical reactions are usually characterized by a chemical change, and they yield one or more products, which usually have properties different from the reactants. Reactions often consist of a sequence of individual sub-steps, the so-called elementary reactions, and the information on the precise co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ethylbenzene
Ethylbenzene is an organic compound with the formula . It is a highly flammable, colorless liquid with an odor similar to that of gasoline. This monocyclic aromatic hydrocarbon is important in the petrochemical industry as an reaction intermediate in the production of styrene, the precursor to polystyrene, a common plastic material. In 2012, more than 99% of ethylbenzene produced was consumed in the production of styrene. Occurrence and applications Ethylbenzene occurs naturally in coal tar and petroleum. The dominant application of ethylbenzene is its role as an intermediate in the production of polystyrene. Catalytic dehydrogenation of ethylbenzene gives hydrogen and styrene: : → C6H5CH=CH2 + As of May 2012, more than 99% of all the ethylbenzene produced is used for this purpose. Ethylbenzene hydroperoxide, a reagent and radical initiator, is produced by autoxidation of ethylbenzene: :C6H5CH2CH3 + O2 → C6H5CH(O2H)CH3 Niche uses Ethylbenzene is added to gasoline ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alkene Metathesis
Olefin metathesis is an organic reaction that entails the redistribution of fragments of alkenes (olefins) by the scission and regeneration of carbon-carbon double bonds. Because of the relative simplicity of olefin metathesis, it often creates fewer undesired by-products and hazardous wastes than alternative organic reactions. For their elucidation of the reaction mechanism and their discovery of a variety of highly active catalysts, Yves Chauvin, Robert H. Grubbs, and Richard R. Schrock were collectively awarded the 2005 Nobel Prize in Chemistry. Catalysts The reaction requires metal catalysts. Most commercially important processes employ heterogeneous catalysts. The heterogeneous catalysts are often prepared by in-situ activation of a metal halides (MClx) using organoaluminium or organotin compounds, e.g. combining MClx–EtAlCl2. A typical catalyst support is alumina. Commercial catalysts are often based on molybdenum and ruthenium. Well-defined organometallic compo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cycloalkanes
In organic chemistry, the cycloalkanes (also called naphthenes, but distinct from naphthalene) are the monocyclic saturated hydrocarbons. In other words, a cycloalkane consists only of hydrogen and carbon atoms arranged in a structure containing a single ring (possibly with side chains), and all of the carbon-carbon bonds are single. The larger cycloalkanes, with more than 20 carbon atoms are typically called ''cycloparaffins''. All cycloalkanes are isomers of alkenes. The cycloalkanes without side chains are classified as small (cyclopropane and cyclobutane), common (cyclopentane, cyclohexane, and cycloheptane), medium ( cyclooctane through cyclotridecane), and large (all the rest). Besides this standard definition by the International Union of Pure and Applied Chemistry (IUPAC), in some authors' usage the term ''cycloalkane'' includes also those saturated hydrocarbons that are polycyclic. In any case, the general form of the chemical formula for cycloalkanes is C''n''H2( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Syngas
Syngas, or synthesis gas, is a mixture of hydrogen and carbon monoxide, in various ratios. The gas often contains some carbon dioxide and methane. It is principly used for producing ammonia or methanol. Syngas is combustible and can be used as a fuel. Historically, it has been used as a replacement for gasoline, when gasoline supply has been limited; for example, wood gas was used to power cars in Europe during WWII (in Germany alone half a million cars were built or rebuilt to run on wood gas). Production Syngas is produced by steam reforming or partial oxidation of natural gas or liquid hydrocarbons, or coal gasification. Steam reforming of methane is an endothermic reaction requiring 206 kJ/mol of methane: : In principle, but rarely in practice, biomass and related hydrocarbon feedstocks could be used to generate biogas and biochar in waste-to-energy gasification facilities. The gas generated (mostly methane and carbon dioxide) is sometimes described as ''syngas'' but its co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diesel Fuel
Diesel fuel , also called diesel oil, is any liquid fuel specifically designed for use in a diesel engine, a type of internal combustion engine in which fuel ignition takes place without a spark as a result of compression of the inlet air and then injection of fuel. Therefore, diesel fuel needs good compression ignition characteristics. The most common type of diesel fuel is a specific fractional distillate of petroleum fuel oil, but alternatives that are not derived from petroleum, such as biodiesel, biomass to liquid (BTL) or gas to liquid (GTL) diesel are increasingly being developed and adopted. To distinguish these types, petroleum-derived diesel is sometimes called petrodiesel in some academic circles. In many countries, diesel fuel is standardised. For example, in the European Union, the standard for diesel fuel is EN 590. Diesel fuel has many colloquial names; most commonly, it is simply referred to as ''diesel''. In the United Kingdom, diesel fuel for on-road us ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alan S
Alan may refer to: People *Alan (surname), an English and Turkish surname *Alan (given name), an English given name ** List of people with given name Alan ''Following are people commonly referred to solely by "Alan" or by a homonymous name.'' * Alan (Chinese singer) (born 1987), female Chinese singer of Tibetan ethnicity, active in both China and Japan * Alan (Mexican singer) (born 1973), Mexican singer and actor *Alan (wrestler) (born 1975), a.k.a. Gato Eveready, who wrestles in Asistencia Asesoría y Administración * Alan (footballer, born 1979) (Alan Osório da Costa Silva), Brazilian footballer * Alan (footballer, born 1998) (Alan Cardoso de Andrade), Brazilian footballer *Alan I, King of Brittany (died 907), "the Great" * Alan II, Duke of Brittany (c. 900–952) *Alan III, Duke of Brittany(997–1040) * Alan IV, Duke of Brittany (c. 1063–1119), a.k.a. Alan Fergant ("the Younger" in Breton language) * Alan of Tewkesbury, 12th century abbott *Alan of Lynn (c. 1348–1423), 1 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maurice Brookhart
Maurice S. Brookhart (born 1942) is an American chemist, and professor of chemistry at the University of Houston since 2015. Brookhart received his bachelor's degree from Johns Hopkins University in 1964. He received his PhD in 1968 from the University of California, Los Angeles, in physical organic chemistry where his thesis advisor was Saul Winstein. After an NSF postdoctoral fellowship at the University of California, Los Angeles in 1968 and a NATO postdoctoral fellowship at Southampton University, England. In 1969, he joined the faculty of the University of North Carolina, where he stayed until 2015, when he joined the University of Houston as a professor of Chemistry. His research group is noted for its research in the general area of synthetic and mechanistic organometallic chemistry. A recent major thrust has been the development of post-metallocene catalysts based upon late transition metal (Ni and Pd) complexes for olefin coordination polymerization. They carry ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Richard R
Richard is a male given name. It originates, via Old French, from Old Frankish and is a compound of the words descending from Proto-Germanic ''*rīk-'' 'ruler, leader, king' and ''*hardu-'' 'strong, brave, hardy', and it therefore means 'strong in rule'. Nicknames include " Richie", "Dick", " Dickon", " Dickie", "Rich", " Rick", " Rico", " Ricky", and more. Richard is a common English, German and French male name. It's also used in many more languages, particularly Germanic, such as Norwegian, Danish, Swedish, Icelandic, and Dutch, as well as other languages including Irish, Scottish, Welsh and Finnish. Richard is cognate with variants of the name in other European languages, such as the Swedish "Rickard", the Catalan "Ricard" and the Italian "Riccardo", among others (see comprehensive variant list below). People named Richard Multiple people with the same name * Richard Andersen (other) * Richard Anderson (other) * Richard Cartwright (disambiguati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pincer Ligand
In chemistry, a transition metal pincer complex is a type of coordination complex with a pincer ligand. Pincer ligands are chelating agents that binds tightly to three adjacent coplanar sites in a meridional configuration. The inflexibility of the pincer-metal interaction confers high thermal stability to the resulting complexes. This stability is in part ascribed to the constrained geometry of the pincer, which inhibits cyclometallation of the organic substituents on the donor sites at each end. In the absence of this effect, cyclometallation is often a significant deactivation process for complexes, in particular limiting their ability to effect C-H bond activation. The organic substituents also define a hydrophobic pocket around the reactive coordination site. Stoichiometric and catalytic applications of pincer complexes have been studied at an accelerating pace since the mid-1970s. Most pincer ligands contain phosphines.Jensen, C. M., "Iridium PCP pincer complexes: ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
