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	Olefin metathesis (Site not responding. Last check: 2007-10-19)
		Olefin metathesis or transalkylidenation (in some literature, a disproportionation) is an organic reaction which involves redistribution of olefinic (alkene) bonds.
		Olefin metathesis was first used in petroleum reformation for the synthesis of higher olefins in the Shell higher olefin process (SHOP) under high pressure and high temperatures.
		Alkene metathesis is generally driven by the evolution of gaseous ethylene; and alkyne metathesis is driven by the evolution of acetylene.
	www.toolhost.com /Olefin_metathesis.html (559 words)

	Olefin metathesis - Patent 4490512
		This process simplifies olefin metathesis as acetylenes can be handled in the atmosphere, while ethylaluminum dichloride or related materials which have been used in the past instantaneously ignite when exposed to the atmosphere.
		According to the teachings of subject invention, olefin metathesis is accomplished by combining olefins and acetylenes and tungsten salts such as tungsten hexachloride.
		Another object of subject invention is to accomplish olefin metathesis in a simplified manner wherein acetylenes used as coinitiators can be handled in the atmosphere, unlike the compounds such as ethylaluminum dichloride or related materials used in the prior art.
	www.freepatentsonline.com /4490512.html (1870 words)

	Olefin metathesis (Site not responding. Last check: 2007-10-19)
		'''Olefin metathesis''' or transalkylidenation (in some literature a disproportionation) is a organic reaction which involves redistribution of olefinic bonds.
		center Olefin metathesis was first used in petroleum reformation for the synthesis of higher olefins in the Shell higher olefin process (SHOP) under high pressure and high temperatures.
		A metathesis reaction is a chain reaction involving a metal-carbene.
	olefin-metathesis.iqnaut.net (270 words)

	Ground-breaking synthesis
		For example, in the metathesis reaction involving two propylene molecules shown in Figure 2 (known as the Phillips triolefin process), one of the molecules trades its CH{-2} group for the CH{-3}CH group in the other in the presence of a catalyst to form butene and ethylene, a hitherto unknown transformation also called `disproportination' of propylene.
		The catalyst used in the metathesis reaction to produce the anti-cancer compound, in fact, is one of the catalysts discovered by Grubbs.
		Olefin metathesis now enables the creation of new carbon-carbon double bonds at or near room temperature in aqueous forms from starting materials that bear a variety of functional groups.
	www.flonnet.com /fl2223/stories/20051118001808400.htm (2278 words)

	Olefin metathesis coupling using ruthenium and osmium carbene complexes - Patent 5750815 (Site not responding. Last check: 2007-10-19)
		The high level metathesis activity of the carbene compounds of the present invention is observed when L and L.sup.1 are alkyl phosphines where the carbon backbone of at least one alkyl group of the alkyl phosphine is a secondary alkyl or cycloalkyl.
		Unlike most metathesis catalysts presently known which are poisoned by functional groups, the carbene compounds of the present invention are stable in the presence of a wide variety of functional groups including alcohol, thiol, ketone, aldehyde, ester, ether, amine, amide, nitro acid, carboxylic acid, disulfide, carbonate, carboalkoxy acid, isocyanate, carbodiimide, carboalkoxy, and halogen functional groups.
		One embodiment of this invention is an improved polymerization process comprising metathesis polymerization of a cyclic olefin by conducting the polymerization in the presence of a catalytic amount of a carbene compound of the present invention.
	www.freepatentsonline.com /5750815.html (6245 words)

	Olefin Metathesis and Metathesis Polymerization -- Books
		Olefin Metathesis and Metathesis Polymerization provides a broad, up-to-date account of the subject from its beginnings in 1957 to the latest applications in organic synthesis.
		In the last few years molybdenum carbene complexes and the air-and water-stable ruthenium carbene complexes have cme to the fore as very effective catalysts in the synthesis of numerous compounds of biologicial importance; also for the preparation of well-defined polymers and block copolymers of very narrow molecular weight distribution.
		Olefin Metathesis and Metathesis Polymerization provides a broad, up-to-date account of the subject from its beginnings around 1960 to the latest applications in organic synthesis.
	www.cadgate.com /book/un/123770459 (635 words)

	C&EN: COVER STORY - OLEFIN METATHESIS: THE EARLY DAYS
		Olefin metathesis was first observed in the 1950s by industrial chemists.
		This paper, everyone agrees, was the first to envision correctly a key role for metal carbenes in olefin metathesis and the events that lead to exchange of groups around carbon-carbon double bonds.
		That there is no such thing as a "Katz catalyst" for olefin metathesis may be the reason that he is not linked to the reaction.
	www.pubs.acs.org /cen/coverstory/8051/8051olefin2.html (3584 words)

	C&EN: COVER STORY - OLEFIN METATHESIS: BIG DEAL REACTION
		The power of olefin metathesis is that it transforms the carbon-carbon double bond, a functional group that is unreactive toward many reagents that react with many other functional groups.
		Olefin metathesis is "marvelous in the hands of the synthetic chemist," Nicolaou says.
		The buzz of olefin metathesis is heard not only in research labs among chemists applying the reaction to complex syntheses.
	pubs.acs.org /cen/coverstory/8051/8051olefin.html (2413 words)

	C&EN: COVER STORY - OLEFIN METATHESIS: THE EARLY DAYS
		In an attempt to explain olefin metathesis, Grubbs--who by then had moved to Michigan State University, East Lansing--proposed that the redistribution of groups around the double bonds was due to a rearranging metallacyclopentane intermediate [J. Am.
		When we submitted the paper, we thought we were proposing a new mechanism for olefin metathesis that involved metal carbenes.
		The work of Katz in 1975 was the first to unambiguously substantiate the carbene mechanism for the olefin metathesis reaction, says Nicolaou, who once was a postdoc in the Katz lab.
	pubs.acs.org /cen/coverstory/8051/8051olefin2.html (3584 words)

	ISOM Conference: Program
		The Organizing Committee is pleased to invite you to attend the 14th International Symposium on Olefin Metathesis and Related Chemistry to be held at the Massachusetts Institute of Technology in Cambridge (Boston), Massachusetts, from Sunday noon, August 5 through Thursday noon, August 9, 2001.
		Molybdenum or ruthenium olefin metathesis catalysts now been employed in a number of natural product syntheses, since the metathesis reaction is by definition a unique and efficient way to form a carbon-carbon double bond.
		Acetylene metathesis has also been shown to be useful in organic synthesis, although the number of examples at present lags far behind examples involving olefin metathesis.
	web.mit.edu /rrs/isom/level2/program.htm (263 words)

	VLU: Industrial Importance of Alkenes - Olefin Metathesis - ChemgaPedia
		Olefin metathesis has been used for several decades to convert alkenes without additional functional groups on an industrial scale.
		Since new custom-made catalysts were developed in the nineties, the olefin metathesis became a standard method of preparative organic chemistry.
		The homodimerization, that is the (in this case undesirable) dimerization of two molecules of the same type, is a fundamental problem of olefin metathesis, because the reactants have functional groups of the same kind, the multiple bonds.
	www.chemgapedia.de /vsengine/vlu/vsc/en/ch/12/oc/vlu_organik/alkene/indust_bedeut_alkene.vlu/Page/vsc/en/ch/12/oc/alkene/olefinmetathese/olefinmetathese.vscml.html (343 words)

	CHM333: Green Chemistry » Chemistry
		The example used in the mechanism, assuming the R groups are straight chains, is one of cross metathesis, where the groups attached to the double bonds are exchanged.
		Cross metathesis is used in processes such as olefin metathesis, where specific alkenes are made using different alkenes, along with other fine chemical production.
		Ring closing metathesis is used primarily in pharmaceuticals to create new or hard to produce chemicals for use in research and drugs.
	blogs.princeton.edu /chm333/f2005/group3/04_metathesis/01_chemistry (479 words)

	The Organometallic HyperTextBook: Ring-Opening Metathesis Polymerization (ROMP)
		Ring Opening Metathesis Polymerization (ROMP), a term coined by CalTech chemist Robert Grubbs, is a variant of the olefin metathesis reaction.
		The mechanism of the ROMP reaction involves an alkylidene catalyst and is identical to the mechanism of olefin metathesis with two important modifications.
		Olefins such as cyclohexenes or benzene have little or no ring strain and can not be polymerized because there is no thermodynamic preference for polymer versus monomer.
	www.ilpi.com /organomet/romp.html (806 words)

	Mechanism of Ru carbene mediated olefin metathesis
		The currently accepted mechanism for olefin metathesis by ruthenium carbenes is consistent with Chauvin's metallacyclobutane mechanism dicovered in 1971 [1].
		After the barrier less coordination of an olefin, the metallacyclobutane intermediate D is formed by a formal [2+2] cycloaddition.
		The mechanism is termed the trans dissociative mechanism because a) a (phosphane) ligand dissociates and b) the olefin coordinates trans to the secondary ligand L [2,3].
	folk.uio.no /chrisad/mech.html (147 words)

	Chemical & Engineering News: Latest News - Olefin Metathesis
		Olefin metathesis is already regarded as an important way to make carbon-carbon bonds, but the reaction could become even more practical, thanks to a new, highly active, water-soluble catalyst.
		Because olefin metathesis is widely used in industry, the reagent could make these processes more environmentally friendly and less expensive.
		In olefin metathesis, two carbon-carbon double bonds react to form two new carbon-carbon double bonds, exchanging substituents attached to the carbon atoms in the process.
	www.pubs.acs.org /cen/news/84/i10/8410notw7.html (310 words)

	FACULTY ::: Division of Chemistry and Chemical Engineering ::: CALTECH
		Catalysts for olefin metathesis have been the focus of the research over the past several years.
		The rules controlling the use of cross metathesis in organic synthesis is now opening its application in the synthesis of a variety of functional molecules.
		Recent methods have been developed that are being used to prepare cyclic olefins, alternating copolymers and multiblock copolymers with a broad array of functionality.
	www.cce.caltech.edu /faculty/grubbs/research.html (385 words)

	The Organometallic HyperTextBook: Olefin Metathesis
		The olefin metathesis reaction can be thought of as a reaction in which all the carbon-carbon double bonds in an olefin (alkene) are cut and then rearranged in a statistical fashion:
		The commonly accepted mechanism for the olefin metathesis reaction was proposed by Chauvin and involves a [2+2] cycloaddition reaction between a transition metal alkylidene complex and the olefin to form an intermediate metallacyclobutane.
		The mechanism of this reaction is identical to that of the olefin metathesis reaction except that the final step is not reversible.
	www.ilpi.com /organomet/olmetathesis.html (939 words)

	Ruthenium Runs Rings 'Round Organic Reactions
		Yet it is not without its uses in making large organic molecules, such as its remarkable ability to catalyze the chemical reaction known as olefin metathesis, which in recent years has become a standard tool of organic chemistry.
		Olefin metathesis is the reaction of two olefinic bonds, i.e.
		This is a type of reaction in which two linear olefins couple to form new linear olefins but in which the molecular fragments of the original two are scrambled.
	www.sciencewatch.com /jan-feb2001/sw_jan-feb2001_page5.htm (938 words)

	BSP :: Current Topics in Medicinal Chemistry Home Page
		Olefin metathesis is now widely considered as one of the most powerful synthetic tools.
		Scope and limitations of ring-closing metathesis to form medium and large rings are discussed and illustrated by the epothilone synthesis.
		A summary of the application of ruthenium catalyzed olefin cross-metathesis towards the synthesis of tocopherols (vitamin E) is given.
	www.bentham.org /ctmc/contabs/ctmc5-15.htm (909 words)

	DuPont :: 2005 Nobel Laureates Celebrate Contributions of DuPont Scientist To the Discovery of Olefin Metathesis
		Robert H. Grubbs and Richard R. Schrock, recipients of the 2005 Nobel Prize for Chemistry for the development of olefin metathesis, visited the DuPont Experimental Station here today to celebrate the contributions of Dr. Herbert S. Eleuterio, a retired DuPont chemist who was instrumental in the early stage development of this novel technology.
		The two scientists most responsible for the ubiquity of olefin metathesis and its wide-ranging applications are Drs.
		Olefin metathesis is an organic reaction which involves redistribution of double bonds, like exchanging dancing partners.
	sev.prnewswire.com /chemical/20060906/PHW03206092006-1.html (565 words)

	Process for making fatty acid nitriles and fatty amines by cross-metathesis of normal alpha olefins - Patent 6380420
		A process for preparing fatty amines by the cross-metathesis of normal alpha olefins and acrylonitrile to form an intermediate fatty acid nitrile which is hydrogenated to the corresponding fatty amine.
		The process of claim 12 wherein the cross metathesis product also includes an internal olefin of the general formula A--CH.dbd.CH--A. The process of claim 16 wherein the internal olefin is contacted with a metathesis catalyst in a metathesis zone under metathesis conditions to produce a normal alpha olefin.
		The process of claim 17 wherein the normal alpha olefin is recovered from the metathesis zone and is recycled to the cross-metathesis zone.
	www.freepatentsonline.com /6380420.html (3882 words)

	Olefin Metathesis / Grubbs Reaction
		Olefin Metathesis allows the exchange of substituents between different olefins - a transalkylidenation.
		Synthetically useful, high-yield procedures for lab use include ring closure between terminal vinyl groups, cross metathesis - the intermolecular reaction of terminal vinyl groups - and ring opening of strained alkenes.
		Ring opening metathesis can employ an excess of a second alkene (for example ethene), but can also be conducted as a homo- or co-polymerization reaction.
	www.organic-chemistry.org /namedreactions/olefin-metathesis.shtm (267 words)

	2005 Nobel Laureates in Chemistry (Site not responding. Last check: 2007-10-19)
		Metathesis reactions were first recognized in the 1950s but were poorly understood at the time.
		Metathesis is now a method of choice for the synthesis of pharmaceutical candidates.
		Metathesis is used daily in the chemical industry, mainly in the development of pharmaceuticals and of advanced plastic materials.
	www.acs.org /portal/a/c/s/1/feature_ent.html?id=c373e906c9e8606e8f6a17245d830100 (431 words)

	Spartanburg SC \| GoUpstate.com \| Spartanburg Herald-Journal (Site not responding. Last check: 2007-10-19)
		* Since its discovery, olefin metathesis has gained widespread use in research and industry for making products ranging from medicines and polymers to enhanced fuels.
		Olefin metathesis was first used in petroleum reformation for the synthesis of higher olefins from the products (Î±-olefins) from the Shell higher olefin process (SHOP) under high pressure and high temperatures.
		Alkene metathesis is synthetically equivalent to (and has replaced) a procedure of ozonolysis of an alkene to two ketone fragments followed by the reaction of one of them with a Wittig reagent.
	www.goupstate.com /apps/pbcs.dll/section?category=NEWS&template=wiki&text=olefin_metathesis (527 words)

	COC Contents and Abstracts, Vol 4, No. 6
		This account is devoted to a discussion of synthetic applications of olefin metathesis in carbohydrate chemistry.
		Olefin metathesis has emerged as a highly promising and exciting area in the contemporary organic synthesis of carbon-carbon bonds.
		Compared with the ring-closing metathesis, this variation of the theme has, to date, received much less attention from the scientific community despite the fact that it has proved to be of tremendous synthetic value in the area of organometallic chemistry.
	www.bentham.org /coc/contabs/COC4-6.html (636 words)

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