Showing papers on "Metathesis published in 1983"
Patent•
20 Jun 1983
TL;DR: The co-metathesis reaction of triglycerides having fatty acid esters containing isolated carbon-carbon double bonds and ethylene produces modified triglycerides and alpha-olefins as mentioned in this paper.
Abstract: The co-metathesis reaction of triglycerides having fatty acid esters containing isolated carbon-carbon double bonds and ethylene produces modified triglycerides and alpha-olefins. The reaction occurs at an ethylene partial pressure of about 200 to 550 psig in the presence of a catalytically effective amount of a metathesis catalyst at a temperature of about 100° F. to 500° F.
81 citations
TL;DR: In this paper, the formation d'un nouveau complexe W(=CRH)(OCH 2 R) 2 Br + Ga 2 Br 7 − and utilise ce complexe pour catalyser la metathese du cis-pentene-2
Abstract: On etudie la formation d'un nouveau complexe W(=CRH)(OCH 2 R) 2 Br + Ga 2 Br 7 − et on utilise ce complexe pour catalyser la metathese du cis-pentene-2
71 citations
TL;DR: Etude des reactions de M 2 (OR) 6 et du dimethylcyanamide, donnant des composes d'addition 1:1, MO 2 (OCH 2 −t-Bu) 6 (η−NCNMe 2 ) as mentioned in this paper.
Abstract: Etude des reactions de M 2 (OR) 6 et du dimethylcyanamide, donnant des composes d'addition 1:1, MO 2 (OR) 6 (μ−NCNMe 2 ). Structure moleculaire de MO 2 (OCH 2 −t-Bu) 6 (η−NCNMe 2 )
49 citations
TL;DR: In this paper, the authors studied the influence of several parameters on the activity of the catalyst with methyl oleate (methyl-Z-9-octadecenoate) as substrate, and the use of a nonpolar solvent and a cocatalyst of general formula SnR 4, in which R is a linear alkyl group, provided optimal reaction conditions.
36 citations
TL;DR: In this paper, the rate of reaction is found to depend upon the molecular characteristics of the esters, the amount of supported rhenium oxide and upon the surface properties of the aluminas.
34 citations
TL;DR: In this article, the experimental equilibrium composition appeared to deviate considerably from the composition calculated from thermochemical tables, due to inaccurate values of the standard enthalpy of formation for cis - and trans -2-butene.
27 citations
TL;DR: In this article, an alternating ring-opened copolymer of the two enantiomers, with an all-cis, head-tail, syndiotactic structure was revealed by the 13C n.m.r spectrum of the polymer and its hydrogenated product.
Abstract: Polymerization of racemic 1-methylbicyclo[2.2.1]hept-2-ene(1) using ReCl5 as catalyst yields an alternating ring-opened copolymer of the two enantiomers, with an all-cis, head-tail, syndiotactic structure as revealed by the 13C n.m.r. spectrum of the polymer and its hydrogenated product.
26 citations
TL;DR: In this paper, the initial carbene for ethene or propene metathesis over active fixed Mo catalysts with well defined reaction sites is formed by a 1,2-hydrogen shift via a molybdenum-n-alkenyl intermediate.
Abstract: It is indicated that the initial carbene for ethene or propene metathesis over active fixed Mo catalysts with well defined reaction sites is formed by a 1,2-hydrogen shift via a molybdenum–n-alkenyl intermediate.
23 citations
Patent•
21 Mar 1983TL;DR: In this article, a supported tungsten oxide or supported molybdenum oxide is treated with elemental Tungsten, silicon or antimony, and the composition is useful as a metathesis catalyst.
Abstract: A supported tungsten oxide or supported molybdenum oxide is treated with elemental tungsten, silicon or antimony. The composition is useful as a metathesis catalyst.
16 citations
11 citations
TL;DR: The structure of rhenium(VII) oxide on alumina at loadings of 5 and 17.5% closely resembles that of crystalline Rhenium oxide as mentioned in this paper.
Abstract: The structure of rhenium(VII) oxide on alumina at loadings of 5 and 17.5% closely resembles that of crystalline rhenium(VII) oxide.
TL;DR: The reaction of (CO)5WC(C6H5)2 with ethyl vinyl ether in benzene or pentane yields predominantly the two metathesis products 1,1-diphenyl-ethylene and 1-ethoxy-2,2-Diphenylethylene along with some 1-ethyloxy-1,2,3-cyclopropane as discussed by the authors.
TL;DR: Under certain conditions the photolysis of α,α-disubstituted cyclobutanones give terminal olefinic esters as discussed by the authors, and a two-stage thermal photochemical metathesis is described.
TL;DR: With the catalyst Mo(NO)2Cl2(PPh3)2+ EtAlCl2, cis-and trans-cyclo-octenes give respectively cis- and trans-polyoctenes; cyclic and acyclic olefins have a similar stereochemical behaviour in metathesis but, depending on the strain of the ring, the expected retention of configuration of the starting olefin may be attenuated as discussed by the authors.
Abstract: With the catalyst Mo(NO)2Cl2(PPh3)2+ EtAlCl2, cis- and trans-cyclo-octenes give respectively cis- and trans-polyoctenes; cyclic and acyclic olefins have a similar stereochemical behaviour in metathesis but, depending on the strain of the ring, the expected retention of configuration of the starting olefin may be attenuated.
Patent•
13 Jan 1983
TL;DR: In this paper, a method for the co-dismutation of a feedstock comprising functional olefins is presented, where the feedstock which has at least one terminally unsaturated ester is dismuted using a hybrid metathesis catalyst composition which has a tungsten halide and an organometallic compound of the formula R 3 R'M.
Abstract: The present invention is a method for the (co)dismutation of a feedstock comprising functional olefins. The feedstock, which has at least one terminally unsaturated ester, is dismuted using a hybrid metathesis catalyst composition which has a tungsten halide and an organometallic compound of the formula R 3 R'M wherein, R 1 is a group selected from an alkyl and an aryl group, R is a group selected from R 1 and a hydrogen atom, and M is a metal atom capable of exhibiting more than one oxidation state, on a support. The activity of this heterogeneous catalyst composition for dismuting terminally unsaturated ester is vastly superior to the corresponding homogeneous systems.
03 Jun 1983
TL;DR: In this paper, the cis-trans isomerization of polybutadiene double bonds during metathesis degradation using WCl6/(CH3)4Sn catalyst system has been estimated kinetically along with productive met athesis.
Abstract: The cis-trans isomerization of polybutadiene double bonds during metathesis degradation using WCl6/(CH3)4Sn catalyst system has been estimated kinetically along with productive metathesis. The isomerization was followed both for noncrosslinked and for crosslinked polybutadiene. Ninety-six percent cis-1, 4 units are found to isomerize into ca. 75% trans-1, 4 units. The rate of stereomutation is found to be different in the presence and absence of a low-molecular-weight olefin. The results are explained with the help of a stereo model originally proposed by Katz (Advances in Organometallic Chemistry, Academic, New York, 1977, Vol. 16.)
Patent•
13 Oct 1983
TL;DR: In this article, an improved process for the metathesis of alkenyl esters utilizing substantially reduced catalyst levels is provided, where a tungsten hexachloride/tetraalkyltin catalyst is used.
Abstract: An improved process for the metathesis of alkenyl esters utilizing substantially reduced catalyst levels is provided. For the process, an alkenyl ester of the formula ##STR1## where R is hydrogen or alkyl, R* is tertiary alkyl or an aromatic group, and n is an integer from 2 to 20 is reacted with a tungsten hexachloride/tetraalkyltin catalyst.
TL;DR: In this paper, cyclooctene was polymerized in benzene at temperatures ranging from 10 to 80°C. The polymerization was initiated with the metathesis catalyst WCl6/C2H5)AlCl2/C 2H5OH for initial monomer concentrations varying from 0.11 to 4.0 mol/L.
Abstract: Cyclooctene was polymerized in benzene at temperatures ranging from 10 to 80°C. The polymerization was initiated with the metathesis catalyst WCl6/C2H5)AlCl2/C2H5OH for initial monomer concentrations varying from 0.11 to 4.0 mol/L. Polymerization products obtained from the metathesis reaction and the alkylation of benzene were found. The metathesis products consisted of a high molecular weight polymer and cyclic oligomers of cyclooctene. The double bond content was the same as in the monomer. The alkylation products were characterized by the presence of an aromatic nucleus and a low double bond content. Benzene was found to react with the double bond of cyclooctene and the cyclic dimer. It may also lead to the formation of saturated oligomer consisting of short chains of cyclooctyl units. Their presence is not temperature dependent and increases with decreasing initial monomer concentrations. For initial monomer concentrations above 1.0 mol/L, the alkylation reaction cannot be detected.
TL;DR: The first example of a catalyst for the heterogeneous metathesis of functionalized olefins is Re 2 O 7 /Al 2 O 3, promoted by a small amount of an alkyltin compound.
Abstract: The metathesis of olefins bearing functional groups provides potential routes to many valuable compounds. Most methathesis catalysts, however, are easily poisoned by polar compounds; so far, only a few catalyst systems have proven to be active in metathesizing functionalized olefins. In the homogeneous metathesis of these substrates the catalyst system WCl 6 -(CH 3 ) 4 Sn is still the best known. In addition to its well-known application in the conversion of unsaturated oxygen-containing olefins, such as (fatty) acid esters and unsaturated ethers, its effectiveness for the homogeneous metathesis of unsaturated nitriles has recently been proven. The first example of a catalyst for the heterogeneous metathesis of functionalized olefins is Re 2 O 7 /Al 2 O 3 , promoted by a small amount of an alkyltin compound. The system Re 2 O 7 /Al 2 O 3 -(CH 3 ) 4 Sn is active — and very selective — in the metathesis of unsaturated acid esters and other hetero-atom containing olefins, even in situations where homogeneous systems fail. To be of interest for the chemical industry it is, however, necessary to develop catalysts which are more active and more stable than the catalysts known at the moment.
TL;DR: In this article, various functionalized disubstituted acetylenes, including esters, are prepared metathetically with high selectivity on molybdenum based homogeneous catalytic systems.
Abstract: Various functionalized disubstituted acetylenes, including esters, are prepared metathetically with high selectivity on molybdenum based homogeneous catalytic systems; this procedure is a useful tool for the synthesis of acetylenes, wnich can provide cis- or trans-olefins by further selective hydiogenation.
TL;DR: In this paper, a comparison of the catalytic activity in olefin metathesis with the time dependence of the electrical conductivity does not give any evidence for a direct relationship between the ionic species formed during the reaction of the starting components and the catalytically active centres.
TL;DR: In this paper, a metathesis reaction with WCl 6 /Sn(CH 3 ) 4 and 4-octene was investigated, and products and by-products were identified by GC/MS using several evaluation methods.
TL;DR: In this paper, the mechanism of the chain process of opening of the cyclo-olefines under the influence of carbene complexes and the formation of active centres on breakdown of the organometallic compounds of the transitional metals have been examined.
Abstract: The mechanism of the chain process of opening of the cyclo-olefines under the influence of carbene complexes and the mechanism of the formation of active centres on breakdown of the organometallic compounds of the transitional metals have been examined. The possibility of using the reactions of metathesis for obtaining new polymeric and oligomeric materials is illustrated. The nature of the active centres on polymerization of the dienes under the influence of the individual organometallic compounds of the transitional metals (Ni, Cr, Ti, Mo, W, Nd) and the mechanism of stereoregulation is considered. The results of the investigations to develop a new process of obtaining impact resistant poiystyrene based on anionic polymerization are discussed. New approaches to the solution of the problem of synthesizing “ideal” general purpose elastomers are outlined. The results of investigations into the dehydrogenation of the various polymers by quinones are generalized.
TL;DR: A detailed study of the monometallic initiation of the polymerization of cyclopentene by WCI6 has shown that the kinetics of polymerization are extremely complex and the complexity is associated with the formation of a heterogeneous system as mentioned in this paper.
Patent•
27 Dec 1983
TL;DR: In this paper, a combination of a Mo compound and an organometallic compound of group IVA or IIIA in the periodic table is used as a catalyst to effect the metathesis of a alpha,beta-unsaturated carboxylic ester to give the starting material of nylon 66 in high yield.
Abstract: PURPOSE:A combination of a Mo compound and an organometallic compound of group IVA or IIIA in the periodic table is used as a catalyst to effect the metathesis of a alpha,beta-unsaturated carboxylic ester to give the titled compound used as a starting material of nylon 66 in high yield. CONSTITUTION:After an alpha,beta-unsaturated carboxylic ester of the formula (R is H, 1-3C alkyl, aromatic group; R is 1-3C alkyl, aromatic group) is subjected to aging in the presence of a catalyst of a Mo compound such as MoCl3 or MoBr3, preferably in a solvent such as chlorobenzene at 25-80 deg.C for 10-40min, an organometallic compound of group IVA or IIIA is added as a cocatalyst to effect metathesis under atmospheric or lower pressure in an inert gas atmosphere at 40-200 deg.C, preferably 100-160 deg.C, to give the objective a 2-butene-1,4- dicarboxylic diester.