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Metathesis in Oleochemistry
Mol, Johannes C.;Buffon, Regina;
Journal of the Brazilian Chemical Society , 1998, DOI: 10.1590/S0103-50531998000100002
Abstract: metathesis is an attractive reaction for the conversion of oleochemical feedstocks into useful chemical products. thus, metathesis of unsaturated fatty acid esters (the oleochemical raw materials) provides a convenient route to unsaturated diesters which can be used as intermediates for the production of polymers and specialty chemicals. cross-metathesis with olefins is a means to change the chain length of fatty acids and derivatives; cross-metathesis with ethene (ethenolysis) gives compounds with terminal double bonds, having a broad range of applications. ethenolysis of fatty oils or triglycerides allows the transformation of long-chain fatty acid triglycerides into fatty oils of lower molecular weight. several highly selective catalyst systems - homogeneous as well as heterogeneous - have proven to be successful for the metathesis of unsaturated esters. especially modified heterogeneous rhenium- and molybdenum-based catalysts have attracted much attention. considering catalyst activation and regeneration procedures, rhenium-based catalysts are to be preferred.
Organic-Inorganic Hybrid Silica Material Derived from a Monosilylated Grubbs-Hoveyda Ruthenium Carbene as a Recyclable Metathesis Catalyst  [PDF]
Guadalupe Borja,Roser Pleixats,Ramón Alibés,Xavier Catto?n,Michel Wong Chi Man
Molecules , 2010, DOI: 10.3390/molecules15085756
Abstract: The synthesis of a monosilylated Grubbs-Hoveyda ruthenium alkylidene complex is described, as well as the preparation and characterization of the corresponding material by sol-gel cogelification with tetraethoxysilane (TEOS) and the assay of this recyclable supported catalyst in ring-closing diene and enyne metathesis reactions under thermal and microwave conditions.
Extrudate versus Powder Silica Alumina as Support for Re2O7 Catalyst in the Metathesis of Seed Oil-Derivatives – A Comparison  [PDF]
Bassie B. Marvey
International Journal of Molecular Sciences , 2009, DOI: 10.3390/ijms10010213
Abstract: Self- and cross-metathesis of fatty acid methyl esters (FAMEs) was investigated using a silica alumina supported Re2O7 catalyst. Although a 3 wt% Re2O7/SiO2-Al2O3/SnBu4 is already active for the metathesis of unsaturated FAMEs, the results have shown that particle size of silica alumina support has a profound influence on its activity and selectivity. Consequently, high substrate conversions coupled with improved product yields (for mono- and diesters) and reaction rates were obtained upon using powder, as opposed to extrudate silica alumina as the support material. Diesters are platform compounds for the synthesis of polymers and fragrances. In this paper a comparative outline of the influence of particle size of silica alumina (extrudate versus powder) on catalytic performance of a 3 wt% Re2O7/SiO2-Al2O3/SnBu4 for self- and cross-metathesis of FAMEs is made. Low surface area and diffusion constraints associated with extrudates were identified as some of the factors leading to low catalytic activity and selectivity.
The intriguing modeling of cis–trans selectivity in ruthenium-catalyzed olefin metathesis
Naeimeh Bahri-Laleh,Raffaele Credendino,Luigi Cavallo
Beilstein Journal of Organic Chemistry , 2011, DOI: 10.3762/bjoc.7.7
Abstract: In this study we have investigated computationally the origin of the cis–trans selectivity in the Ru-catalyzed cross metathesis (CM) of a prototype monosubstituted olefin, i.e., propene. Our calculations suggest that the origin of the preferential formation of trans-olefins is in the product release step, which prevents the initially formed cis-olefin from escaping the metal, and returns it to the reaction pool until the trans-olefin is formed.
Dissecting the Bond Formation Process of $d^{10}$-Metal-Ethene Complexes with Multireference Approaches  [PDF]
Yilin Zhao,Katharina Boguslawski,Pawe? Tecmer,Corinne Duperrouzel,Gergely Barcza,?rs Legeza,Paul W. Ayers
Physics , 2015,
Abstract: The bonding mechanism of ethene to a nickel or palladium center is studied by the density matrix renormalization group algorithm, the complete active space self consistent field method, coupled cluster theory, and density functional theory. Specifically, we focus on the interaction between the metal atom and bis-ethene ligands in perpendicular and parallel orientations. The bonding situation in these structural isomers is further scrutinized using energy decomposition analysis and quantum information theory. Our study highlights the fact that when two ethene ligands are oriented perpendicular to each other, the complex is stabilized by the metal-to-ligand double-back-bonding mechanism. Moreover, we demonstrate that nickel-ethene complexes feature a stronger and more covalent interaction between the ligands and the metal center than palladium-ethene compounds with similar coordination spheres.
Synthesis of Tetrasubstituted Alkenes via Metathesis  [PDF]
Seung-Mann Paek
Molecules , 2012, DOI: 10.3390/molecules17033348
Abstract: Fully substituted olefin generation via metathesis is presented. Catalyst development, optimization of reaction conditions and substrate screening are included. In addition, asymmetric alkene metathesis, the cross metathesis reaction for this transformation and its application in natural products will be discussed.
The allylic chalcogen effect in olefin metathesis  [cached]
Yuya A. Lin,Benjamin G. Davis
Beilstein Journal of Organic Chemistry , 2010, DOI: 10.3762/bjoc.6.140
Abstract: Olefin metathesis has emerged as a powerful tool in organic synthesis. The activating effect of an allylic hydroxy group in metathesis has been known for more than 10 years, and many organic chemists have taken advantage of this positive influence for efficient synthesis of natural products. Recently, the discovery of the rate enhancement by allyl sulfides in aqueous cross-metathesis has allowed the first examples of such a reaction on proteins. This led to a new benchmark in substrate complexity for cross-metathesis and expanded the potential of olefin metathesis for other applications in chemical biology. The enhanced reactivity of allyl sulfide, along with earlier reports of a similar effect by allylic hydroxy groups, suggests that allyl chalcogens generally play an important role in modulating the rate of olefin metathesis. In this review, we discuss the effect of allylic chalcogens in olefin metathesis and highlight its most recent applications in synthetic chemistry and protein modifications.
Oligomerization of ethene on ZSM-5 catalyst
乙烯在ZSM-5催化剂上低聚反应规律的研究

丁雪,耿姗,刘富余,李春义,杨朝合,王国辉
燃料化学学报 , 2009,
Abstract: Oligomerization of ethene over ZSM-5 catalyst was investigated on a fixed bed micro-reactor.The catalytic performance of HZSM-5 zeolite was markedly affected by the reaction conditions.Moderate reaction conditions can suppress secondary reactions and enhance the production of propene and butene.A slow deactivation accompanied by changes in the product distributions was observed along with the reaction time,which can be attributed to the coke deposition in the HZSM-5 pores during reaction.The conversion of e...
Light-induced olefin metathesis  [cached]
Yuval Vidavsky,N. Gabriel Lemcoff
Beilstein Journal of Organic Chemistry , 2010, DOI: 10.3762/bjoc.6.127
Abstract: Light activation is a most desirable property for catalysis control. Among the many catalytic processes that may be activated by light, olefin metathesis stands out as both academically motivating and practically useful. Starting from early tungsten heterogeneous photoinitiated metathesis, up to modern ruthenium methods based on complex photoisomerisation or indirect photoactivation, this survey of the relevant literature summarises past and present developments in the use of light to expedite olefin ring-closing, ring-opening polymerisation and cross-metathesis reactions.
Synthesis and Characterization of Mesostructured Cellular Foam (MCF) Silica Loaded with Nickel Nanoparticles as a Novel Catalyst  [PDF]
Lilis Hermida, Ahmad Zuhairi Abdullah, Abdul Rahman Mohamed
Materials Sciences and Applications (MSA) , 2013, DOI: 10.4236/msa.2013.41007
Abstract:

This work investigated the possibility of incorporation of nickel into several mesostructured cellular foam (MCF) silica supports prepared at various aging times (1, 2, and 3 days) by using deposition-precipitation method followed by reducetion process and to look for the best support to obtain supported nickel catalyst with highest nickel loading and smallest size of nickel nanoparticles. Analyses using nitrogen adsorption-desorption, transmission electron microscopy (TEM), X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) showed that MCF silica prepared at aging time of 3 days was the best support as the corresponding nickel functionalized MCF catalyst had the highest nickel content (17.57 wt%) and the smallest size of nickel nanoparticles (1 - 2 nm) together with high porosity (window pore size of 90A). The result was attributed to the highest window pore size in the MCF support which allowed more nickel nanoparticles to be incorporated.

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