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Olefin 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] |
Reaction Scheme Of The Olefin Metathesis
Reaction may refer to a process or to a response to an action, event, or exposure: Physics and chemistry *Chemical reaction *Nuclear reaction *Reaction (physics), as defined by Newton's third law * Chain reaction (other). Biology and medicine *Adverse drug reaction *Allergic reaction *Reflex, neural reaction *Hypersensitivity, immune reaction * Intolerance (other) * Light reaction (other). Psychology *Emotional, reaction * Reactivity (behaviour) *Proactivity, opposite of reactive behaviour *Reactive attachment disorder. Politics and culture *Reactionary, a political tendency * Reaction video *Commentary (other). Proper names and titles * ''Reaction'' (album), a 1986 album by American R&B singer Rebbie Jackson ** "Reaction" (song), the title song from the Rebbie Jackson album *"Reaction", a single by Dead Letter Circus *ReAction GUI, a GUI toolkit used on AmigaOS * Reaction.life, a political news and commentary website edited by Iain Marti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organometallic
Organometallic chemistry is the study of organometallic compounds, chemical compounds containing at least one chemical bond between a carbon atom of an organic molecule and a metal, including alkali, alkaline earth, and transition metals, and sometimes broadened to include metalloids like boron, silicon, and selenium, as well. Aside from bonds to organyl fragments or molecules, bonds to 'inorganic' carbon, like carbon monoxide (metal carbonyls), cyanide, or carbide, are generally considered to be organometallic as well. Some related compounds such as transition metal hydrides and metal phosphine complexes are often included in discussions of organometallic compounds, though strictly speaking, they are not necessarily organometallic. The related but distinct term " metalorganic compound" refers to metal-containing compounds lacking direct metal-carbon bonds but which contain organic ligands. Metal β-diketonates, alkoxides, dialkylamides, and metal phosphine complexes are r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neohexene
Neohexene is the hydrocarbon compound with the chemical formula . It is a colorless liquid, with properties similar to other hexenes. It is a precursor to commercial synthetic musk perfumes. Preparation and reactions Neohexene is prepared by ethenolysis of diisobutene, an example of a metathesis reaction: :\ce + \longrightarrow \ce + \ce It is a building block to synthetic musks by its reaction with ''p''-cymene. It is also used in the industrial preparation of terbinafine Terbinafine, sold under the brand name Lamisil among others, is an antifungal medication used to treat pityriasis versicolor, fungal nail infections, and ringworm including jock itch and athlete's foot. It is either taken by mouth or applied to .... In the study of C-H activation, neohexene is often used as a hydrogen acceptor.{{cite journal, last1 = Liu, first1 = Fuchen, last2 = Pak, first2 = Esther B., last3 = Singh, first3 = Bharat, last4 = Jensen, first4 = Craig M., last5 = Goldman, first5 = ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alpha-olefins
In organic chemistry, alpha-olefins (or α-olefins) are a family of organic compounds which are alkenes (also known as olefins) with a chemical formula , distinguished by having a double bond at the primary or alpha (α) position.''Petrochemicals in Nontechnical Language'', 3rd Edition, Donald L. Burdick and William L. Leffler, This location of a double bond enhances the reactivity of the compound and makes it useful for a number of applications. Classification There are two types of alpha-olefins, branched and linear (or normal). The chemical properties of branched alpha-olefins with a branch at either the second (vinylidene) or the third carbon number are significantly different from the properties of linear alpha-olefins and those with branches on the fourth carbon number and further from the start of the chain. Examples of linear alpha-olefins are propene, 1-butene and 1-decene. An example of a branched alpha-olefin is isobutylene. Production A variety of methods are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shell Higher Olefin Process
The Shell higher olefin process (SHOP) is a chemical process for the production of linear alpha olefins via ethylene oligomerization and olefin metathesis invented and exploited by Royal Dutch Shell.''Industrial Organic Chemistry'', Klaus Weissermel, Hans-Jurgen Arpe John Wiley & Sons; 3rd 1997 The olefin products are converted to fatty aldehydes and then to fatty alcohols, which are precursors plasticizers and detergents. The annual global production of olefines through this method is over one million tonnes.Keim, W. (2013), ''Oligomerization of Ethylene to α-Olefins: Discovery and Development of the Shell Higher Olefin Process (SHOP)''. Angew. Chem. Int. Ed., 52: 12492–12496. History The process was discovered by chemists at Shell Development Emeryville in 1968. At the time ecological considerations demanded the replacement of branched fatty alcohols used widely in detergents, by linear fatty alcohols because the biodegradation of the branched compounds was slow, causing f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Olefin Conversion Technology
Olefin Conversion Technology, also called the Phillips Triolefin Process, is the industrial process that interconverts propylene with ethylene and 2-butenes. The process is also called the ethylene to propylene (ETP) process. In ETP, ethylene is dimerized to 1-butene, which is isomerized to 2-butenes. The 2-butenes are then subjected to metathesis with ethylene. Rhenium- and molybdenum-containing heterogeneous catalysis are used. Nowadays, only the reverse reaction is practiced, i.e., the conversion of ethylene and 2-butene to propylene: :CH2=CH2 + CH3CH=CHCH3 → 2 CH2=CHCH3 The technology is founded on an olefin metathesis reaction discovered at Phillips Petroleum Company. The originally described process employed catalysts molybdenum hexacarbonyl, tungsten hexacarbonyl Tungsten hexacarbonyl (also called tungsten carbonyl) is the chemical compound with the formula W(CO)6. This complex gave rise to the first example of a dihydrogen complex.Kubas, G. J., Metal Dihydrogen a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heterogeneous Catalyst
In chemistry, heterogeneous catalysis is catalysis where the phase of catalysts differs from that of the reactants or products. The process contrasts with homogeneous catalysis where the reactants, products and catalyst exist in the same phase. Phase distinguishes between not only solid, liquid, and gas components, but also immiscible mixtures (e.g. oil and water), or anywhere an interface is present. Heterogeneous catalysis typically involves solid phase catalysts and gas phase reactants. In this case, there is a cycle of molecular adsorption, reaction, and desorption occurring at the catalyst surface. Thermodynamics, mass transfer, and heat transfer influence the rate (kinetics) of reaction. Heterogeneous catalysis is very important because it enables faster, large-scale production and the selective product formation. Approximately 35% of the world's GDP is influenced by catalysis. The production of 90% of chemicals (by volume) is assisted by solid catalysts. The chemical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Grubbs' Catalyst
Grubbs catalysts are a series of transition metal carbene complexes used as catalysts for olefin metathesis. They are named after Robert H. Grubbs, the chemist who supervised their synthesis. Several generations of the catalyst have been developed. Grubbs catalysts tolerate many functional groups in the alkene substrates, are air-tolerant, and are compatible with a wide range of solvents. For these reasons, Grubbs catalysts have become popular in synthetic organic chemistry. Grubbs, together with Richard R. Schrock and Yves Chauvin, won the Nobel Prize in Chemistry in recognition of their contributions to the development of olefin metathesis. First-generation catalyst In the 1960s, ruthenium trichloride was found to catalyze olefin metathesis. Processes were commercialized based on these discoveries. These ill-defined but highly active homogeneous catalysts remain in industrial use. The first well-defined ruthenium catalyst was reported in 1992. It was prepared from RuCl2(P ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ligand
In coordination chemistry, a ligand is an ion or molecule (functional group) that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's electron pairs, often through Lewis bases. The nature of metal–ligand bonding can range from covalent to ionic. Furthermore, the metal–ligand bond order can range from one to three. Ligands are viewed as Lewis bases, although rare cases are known to involve Lewis acidic "ligands". Metals and metalloids are bound to ligands in almost all circumstances, although gaseous "naked" metal ions can be generated in a high vacuum. Ligands in a complex dictate the reactivity of the central atom, including ligand substitution rates, the reactivity of the ligands themselves, and redox. Ligand selection requires critical consideration in many practical areas, including bioinorganic and medicinal chemistry, homogeneous catalysis, and environmental c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chelation
Chelation is a type of bonding of ions and molecules to metal ions. It involves the formation or presence of two or more separate coordinate bonds between a polydentate (multiple bonded) ligand and a single central metal atom. These ligands are called chelants, chelators, chelating agents, or sequestering agents. They are usually organic compounds, but this is not a necessity, as in the case of zinc and its use as a maintenance therapy to prevent the absorption of copper in people with Wilson's disease. Chelation is useful in applications such as providing nutritional supplements, in chelation therapy to remove toxic metals from the body, as contrast agents in MRI scanning, in manufacturing using homogeneous catalysts, in chemical water treatment to assist in the removal of metals, and in fertilizers. Chelate effect The chelate effect is the greater affinity of chelating ligands for a metal ion than that of similar nonchelating (monodentate) ligands for the same metal. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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