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Sample records for ruthenium-based olefin metathesis

  1. Consequences of the electronic tuning of latent ruthenium-based olefin metathesis catalysts on their reactivity

    PubMed Central

    Pump, Eva; Pazio, Aleksandra E; Woźniak, Krzysztof; Cavallo, Luigi

    2015-01-01

    Summary Two ruthenium olefin metathesis initiators featuring electronically modified quinoline-based chelating carbene ligands are introduced. Their reactivity in RCM and ROMP reactions was tested and the results were compared to those obtained with the parent unsubstituted compound. The studied complexes are very stable at high temperatures up to 140 °C. The placement of an electron-withdrawing functionality translates into an enhanced activity in RCM. While electronically modified precatalysts, which exist predominantly in the trans-dichloro configuration, gave mostly the RCM and a minor amount of the cycloisomerization product, the unmodified congener, which preferentially exists as its cis-dichloro isomer, shows a switched reactivity. The position of the equilibrium between the cis- and the trans-dichloro species was found to be the crucial factor governing the reactivity of the complexes. PMID:26425202

  2. Ruthenium-based olefin metathesis catalysts bearing pH-responsive ligands: External control of catalyst solubility and activity

    NASA Astrophysics Data System (ADS)

    Balof, Shawna Lynn

    2011-12-01

    Sixteen novel, Ru-based olefin metathesis catalysts bearing pH responsive ligands were synthesized. The pH-responsive groups employed with these catalysts included dimethylamino (NMe2) modified NHC ligands as well as N-donor dimethylaminopyridine (DMAP) and 3-(o-pyridyl)propylidene ligands. These pH-responsive ligands provided the means by which the solubility and/or activity profiles of the catalysts produced could be controlled via acid addition. The main goal of this dissertation was to design catalyst systems capable of performing ring opening metathesis (ROMP) and ring closing metathesis (RCM) reactions in both organic and aqueous media. In an effort to quickly gain access to new catalyst structures, a template synthesis for functionalized NHC ligand precursors was designed, in addition to other strategies, to obtain ligand precursors with ancillary NMe2 groups. Kinetic studies for the catalysts produced from these precursors showed external control of catalyst solubility was afforded via protonation of the NMe2 groups of their NHC ligands. Additionally, this protonation afforded external control of catalyst propagation rates for several catalysts. This is the first known independent external control for the propagation rates of ROMP catalysts. The incorporation of pH-responsive N-donor ligands into catalyst structures also provided the means for the external control of metathesis activity, as the protonation of these ligands resulted in an increased initiation rate based on their fast and irreversible dissociation from the metal center. The enhanced external control makes these catalysts applicable to a wide range of applications, some of which have been explored by us and/or through collaboration. Three of the catalysts designed showed remarkable metathesis activity in aqueous media. These catalysts displayed comparable RCM activity in aqueous media to a class of water-soluble catalysts reported by Grubbs et al., considered to be the most active catalyst for

  3. Olefin metathesis in air

    PubMed Central

    Piola, Lorenzo; Nahra, Fady

    2015-01-01

    Summary Since the discovery and now widespread use of olefin metathesis, the evolution of metathesis catalysts towards air stability has become an area of significant interest. In this fascinating area of study, beginning with early systems making use of high oxidation state early transition metal centers that required strict exclusion of water and air, advances have been made to render catalysts more stable and yet more functional group tolerant. This review summarizes the major developments concerning catalytic systems directed towards water and air tolerance. PMID:26664625

  4. Microwave-Assisted Olefin Metathesis

    NASA Astrophysics Data System (ADS)

    Nicks, François; Borguet, Yannick; Sauvage, Xavier; Bicchielli, Dario; Delfosse, Sébastien; Delaude, Lionel; Demonceau, Albert

    Since the first reports on the use of microwave irradiation to accelerate organic chemical transformations, a plethora of papers have been published in this field. In most examples, microwave heating has been shown to dramatically reduce reaction times, increase product yields, and enhance product purity by reducing unwanted side reactions compared to conventional heating methods. The present contribution aims at illustrating the advantages of this technology in olefin metathesis and, when data are available, at comparing microwave-heated and conventionally heated experiments

  5. Methods for suppressing isomerization of olefin metathesis products

    DOEpatents

    Firth, Bruce E.; Kirk, Sharon E.; Gavaskar, Vasudeo S.

    2015-09-22

    A method for suppressing isomerization of an olefin metathesis product produced in a metathesis reaction includes adding an isomerization suppression agent to a mixture that includes the olefin metathesis product and residual metathesis catalyst from the metathesis reaction under conditions that are sufficient to passivate at least a portion of the residual metathesis catalyst. The isomerization suppression agent is phosphorous acid, a phosphorous acid ester, phosphinic acid, a phosphinic acid ester or combinations thereof. Methods of refining natural oils are described.

  6. Methods for suppressing isomerization of olefin metathesis products

    DOEpatents

    Firth, Bruce E.; Kirk, Sharon E.

    2015-10-27

    A method for suppressing isomerization of an olefin metathesis product produced in a metathesis reaction includes adding an isomerization suppression agent that includes nitric acid to a mixture that includes the olefin metathesis product and residual metathesis catalyst from the metathesis reaction under conditions that are sufficient to passivate at least a portion of the residual metathesis catalyst. Methods of refining a natural oil are described.

  7. Enantioselective Olefin Metathesis with Cyclometalated Ruthenium Complexes

    PubMed Central

    2015-01-01

    The success of enantioselective olefin metathesis relies on the design of enantioenriched alkylidene complexes capable of transferring stereochemical information from the catalyst structure to the reactants. Cyclometalation of the NHC ligand has proven to be a successful strategy to incorporate stereogenic atoms into the catalyst structure. Enantioenriched complexes incorporating this design element catalyze highly Z- and enantioselective asymmetric ring opening/cross metathesis (AROCM) of norbornenes and cyclobutenes, and the difference in ring strain between these two substrates leads to different propagating species in the catalytic cycle. Asymmetric ring closing metathesis (ARCM) of a challenging class of prochiral trienes has also been achieved. The extent of reversibility and effect of reaction setup was also explored. Finally, promising levels of enantioselectivity in an unprecedented Z-selective asymmetric cross metathesis (ACM) of a prochiral 1,4-diene was demonstrated. PMID:25137310

  8. Preparation of cadmium selenide-polyolefin composites from functional phosphine oxides and ruthenium-based metathesis.

    PubMed

    Skaff, Habib; Ilker, M Firat; Coughlin, E Bryan; Emrick, Todd

    2002-05-22

    Cadmium selenide nanoparticles, prepared by known methods, were stabilized with functional phosphine oxide 1, then used to support the polymerization of cyclic olefins radially outward from the surface by ruthenium-catalyzed ring-opening metathesis polymerization (ROMP). The conversion of compound 1 into the new metathesis catalyst 3 by carbene exchange and the subsequent polymerization of cyclic olefins were observed spectroscopically by (1)H NMR to afford for example CdSe-polycyclooctene composite 6. Transmission electron micrographs on thin films of these composites showed good nanoparticle dispersion. This is in stark contrast to the substantial nanoparticle aggregation observed when similar polymerizations were performed in the presence of conventional TOPO-covered nanoparticles. The methods reported here to prepare composite product 6 are applicable to other cyclic olefins, and suggest that this chemistry will be useful for incorporating CdSe nanoparticles into a wide variety of polymer matrices.

  9. An Electronic Rationale for Observed Initiation Rates in Ruthenium-Mediated Olefin Metathesis: Charge Donation in Phosphine And N-Heterocyclic Carbene Ligands

    SciTech Connect

    Getty, K.; Delgado-Jaime, M.U.; Kennepohl, P.

    2009-06-01

    Ru K-edge XAS data indicate that second generation ruthenium-based olefin metathesis precatalysts (L = N-heterocyclic carbene) possess a more electron-deficient metal center than in the corresponding first generation species (L = tricyclohexylphosphine). This surprising effect is also observed from DFT calculations and provides a simple rationale for the slow phosphine dissociation kinetics previously noted for second-generation metathesis precatalysts.

  10. Thermally Stable, Latent Olefin Metathesis Catalysts

    PubMed Central

    Thomas, Renee M.; Fedorov, Alexey; Keitz, Benjamin K.

    2011-01-01

    Highly thermally stable N-aryl,N-alkyl N-heterocyclic carbene (NHC) ruthenium catalysts were designed and synthesized for latent olefin metathesis. These catalysts showed excellent latent behavior toward metathesis reactions, whereby the complexes were inactive at ambient temperature and initiated at elevated temperatures, a challenging property to achieve with second generation catalysts. A sterically hindered N-tert-butyl substituent on the NHC ligand of the ruthenium complex was found to induce latent behavior toward cross-metathesis reactions, and exchange of the chloride ligands for iodide ligands was necessary to attain latent behavior during ring-opening metathesis polymerization (ROMP). Iodide-based catalysts showed no reactivity toward ROMP of norbornene-derived monomers at 25 °C, and upon heating to 85 °C gave complete conversion of monomer to polymer in less than 2 hours. All of the complexes were very stable to air, moisture, and elevated temperatures up to at least 90 °C, and exhibited a long catalyst lifetime in solution at elevated temperatures. PMID:22282652

  11. Iron(III)-catalysed carbonyl-olefin metathesis

    NASA Astrophysics Data System (ADS)

    Ludwig, Jacob R.; Zimmerman, Paul M.; Gianino, Joseph B.; Schindler, Corinna S.

    2016-05-01

    The olefin metathesis reaction of two unsaturated substrates is one of the most powerful carbon-carbon-bond-forming reactions in organic chemistry. Specifically, the catalytic olefin metathesis reaction has led to profound developments in the synthesis of molecules relevant to the petroleum, materials, agricultural and pharmaceutical industries. These reactions are characterized by their use of discrete metal alkylidene catalysts that operate via a well-established mechanism. While the corresponding carbonyl-olefin metathesis reaction can also be used to construct carbon-carbon bonds, currently available methods are scarce and severely hampered by either harsh reaction conditions or the required use of stoichiometric transition metals as reagents. To date, no general protocol for catalytic carbonyl-olefin metathesis has been reported. Here we demonstrate a catalytic carbonyl-olefin ring-closing metathesis reaction that uses iron, an Earth-abundant and environmentally benign transition metal, as a catalyst. This transformation accommodates a variety of substrates and is distinguished by its operational simplicity, mild reaction conditions, high functional-group tolerance, and amenability to gram-scale synthesis. We anticipate that these characteristics, coupled with the efficiency of this reaction, will allow for further advances in areas that have historically been enhanced by olefin metathesis.

  12. Metathesis process for preparing an alpha, omega-functionalized olefin

    DOEpatents

    Burdett, Kenneth A.; Mokhtarzadeh, Morteza; Timmers, Francis J.

    2010-10-12

    A cross-metathesis process for preparing an .alpha.,.omega.-functionalized olefin, such as methyl 9-decenoate, and an .alpha.-olefin having three or more carbon atoms, such as 1-decene. The process involves contacting in a first reaction zone an .alpha.-functionalized internal olefin, such as methyl oleate, and an .alpha.-olefinic monomer having three or more carbon atoms, such as 1-decene, with a first metathesis catalyst to prepare an effluent stream containing the .alpha.,.omega.-functionalized olefin, such as methyl 9-decenoate, an unfunctionalized internal olefin, such as 9-octadecene, unconverted reactant olefins, and optionally, an .alpha.,.omega.-difunctionalized internal olefinic dimer, such as dimethyl 9-octadecen-1,18-dioate; separating said effluent streams; then contacting in a second reaction zone the unfunctionalized internal olefin with ethylene in the presence of a second metathesis catalyst to obtain a second product effluent containing the .alpha.-olefinic monomer having three or more carbon atoms; and cycling a portion of the .alpha.-olefinic monomer stream(s) to the first zone.

  13. Synthesis of interlocked molecules by olefin metathesis

    NASA Astrophysics Data System (ADS)

    Clark, Paul Gregory

    A large body of work in the Grubbs group has focused on the development of functional-group tolerant ruthenium alkylidene catalysts that perform a number of olefin metathesis reactions. These catalysts have seen application in a wide range of fields, including classic total synthesis as well as polymer and materials chemistry. One particular family of compounds, interlocked molecules, has benefitted greatly from these advances in catalyst stability and activity. This thesis describes several elusive and challenging interlocked architectures whose syntheses have been realized through the utilization of different types of ruthenium-catalyzed olefin metathesis reactions. Ring-closing olefin metathesis has enabled the synthesis of a [c2]daisy-chain dimer with the ammonium binding site near the cap of the dimer. A deprotonated DCD possessing such a structural attribute will more forcefully seek to restore coordinating interactions upon reprotonation, enhancing its utility as a synthetic molecular actuator. Dimer functionalization facilitated incorporation into linear polymers, with a 48% size increase of an unbound, extended analogue of the polymer demonstrating slippage of the dimer units. Ongoing work is directed at further materials studies, in particular, exploring the synthesis of macroscopic networks containing the DCD units and analyzing the correlation between molecular-scale extension-contraction manipulations and resulting macro-scale changes. A "clipping" approach to a polycatenated cyclic polymer, a structure that resembles a molecular "charm bracelet", has been described. The use of ring-opening metathesis polymerization of a carbamate monomer in the presence of a chain transfer agent allowed for the synthesis of a linear polymer that was subsequently functionalized and cyclized to the corresponding cyclic analogue. This cyclic polymer was characterized through a variety of techniques, and subjected to further functionalization reactions, affording a cyclic

  14. Mesoporous Molecular Sieves Based Catalysts for Olefin Metathesis and Metathesis Polymerization

    NASA Astrophysics Data System (ADS)

    Balcar, Hynek; Čejka, Jiří

    Heterogeneous catalysts for olefin metathesis using different types of (i) siliceous mesoporous molecular sieves, and (ii) organized mesoporous alumina as supports are reported. The catalysts were prepared either by spreading of transition metal oxidic phase on the support surface or by immobilizing transition metal compounds (mostly organometallic) on the support. The activity of these catalysts in various types of metathesis reactions (i.e. alkene and diene metathesis, metathesis of unsaturated esters and ethers, RCM, ROMP and metathesis polymerization of alkynes) was described. The main advantages of these catalysts consist generally in their high activity and selectivity, easy separation of catalysts from reaction products and the preparation of products free of catalyst residue. The examples of pore size influence on the selectivity in metathesis reactions are also given.

  15. Theory-assisted development of a robust and Z-selective olefin metathesis catalyst.

    PubMed

    Occhipinti, Giovanni; Koudriavtsev, Vitali; Törnroos, Karl W; Jensen, Vidar R

    2014-08-07

    DFT calculations have predicted a new, highly Z-selective ruthenium-based olefin metathesis catalyst that is considerably more robust than the recently reported (SIMes)(Cl)(RS)RuCH(o-OiPrC6H4) (3a, SIMes = 1,3-dimesityl-4,5-dihydroimidazol-2-ylidene, R = 2,4,6-triphenylbenzene) [J. Am. Chem. Soc., 2013, 135, 3331]. Replacing the chloride of 3a by an isocyanate ligand to give 5a was predicted to increase the stability of the complex considerably, at the same time moderately improving the Z-selectivity. Compound 5a is easily prepared in a two-step synthesis starting from the Hoveyda-Grubbs second-generation catalyst 3. In agreement with the calculations, the isocyanate-substituted 5a appears to be somewhat more Z-selective than the chloride analogue 3a. More importantly, 5a can be used in air, with unpurified and non-degassed substrates and solvents, and in the presence of acids. These are traits that are unprecedented among highly Z-selective olefin metathesis catalysts and also very promising with respect to applications of the new catalyst.

  16. Homobimetallic Ruthenium-N-Heterocyclic Carbene Complexes For Olefin Metathesis

    NASA Astrophysics Data System (ADS)

    Sauvage, Xavier; Demonceau, Albert; Delaude, Lionel

    In this chapter, the synthesis and catalytic activity towards olefin metathesis of homobimetallic ruthenium (Ru)-alkylidene, -cyclodiene or -arene complexes bearing phosphine or N-heterocyclic carbene (NHC) ligands are reviewed. Emphasis is placed on the last category of bimetallic compounds. Three representatives of this new type of molecular scaffold were investigated. Thus, [(p-cymene)Ru(m-Cl)3RuCl (h2-C2H4)(L)] complexes with L = PCy3 (15a), IMes (16a), or IMesCl2 (16b) were prepared. They served as catalyst precursors for cross-metathesis (CM) of various styrene derivatives. These experiments revealed the outstanding aptitude of complex 16a (and to a lesser extent of 16b) to catalyze olefin metathesis reactions. Contrary to monometallic Ru-arene complexes of the [RuCl2(p-cymene)(L)] type, the new homobimetallic species did not require the addition of a diazo compound nor visible light illumination to initiate the ring-opening metathesis of norbornene or cyclooctene. When diethyl 2,2-diallylmalonate and N,N-diallyltosylamide were exposed to 16a,b, a mixture of cycloisomerization and ring-closing metathesis (RCM) products was obtained in a nonselective way. Addition of phenylacetylene enhanced the metathetical activity while completely repressing the cycloisomerization process.

  17. Refining of plant oils to chemicals by olefin metathesis.

    PubMed

    Chikkali, Samir; Mecking, Stefan

    2012-06-11

    Plant oils are attractive substrates for the chemical industry. Their scope for the production of chemicals can be expanded by sophisticated catalytic conversions. Olefin metathesis is an example, which also illustrates generic issues of "biorefining" to chemicals. Utilization on a large scale requires high catalyst activities, which influences the choice of the metathesis reaction. The mixture of different fatty acids composing a technical-grade plant oil substrate gives rise to a range of products. This decisively determines possible process schemes, and potentially provides novel chemicals and intermediates not employed to date.

  18. Highly Z-Selective Metathesis Homocoupling of Terminal Olefins

    PubMed Central

    Jiang, Annie J.; Zhao, Yu; Schrock, Richard R.; Hoveyda, Amir H.

    2009-01-01

    Mo and W MonoAryloxide-Pyrrolide (MAP) olefin metathesis catalysts can couple terminal olefins to give as high as >98% Z-products in moderate to high yields with as little as 0.2% catalyst. Results are reported for 1-hexene, 1-octene, allylbenzene, allyltrimethylsilane, methyl-10-undecenoate, methyl-9-decenoate, allylB(pinacolate), allylOBenzyl, allylNHTosyl, and allylNHPh. It is proposed that high Z-selectivity is achieved because a large aryloxide only allows metallacyclobutanes to form that contain adjacent cis substituents and because isomerization of Z-product to E-product can be slow in that same steric environment. PMID:19919135

  19. Enhanced Olefin Cross Metathesis Reactions: The Copper Iodide Effect

    PubMed Central

    Voigtritter, Karl; Ghorai, Subir

    2011-01-01

    Copper iodide has been shown to be an effective co-catalyst for the olefin cross metathesis reaction. In particular, it has both a catalyst stabilizing effect due to iodide ion, as well as copper(I)-based phosphine-scavenging properties that apply to use of the Grubbs-2 catalyst. A variety of Michael acceptors and olefinic partners can be cross-coupled under mild conditions in refluxing diethyl ether that avoid chlorinated solvents. This effect has also been applied to chemistry in water at room temperature using the new surfactant TPGS-750-M. PMID:21528868

  20. Synthesis of terminal alkenes from internal alkenes and ethylene via olefin metathesis

    DOEpatents

    Schrodi, Yann

    2016-02-09

    This invention relates generally to olefin metathesis, and more particularly relates to the synthesis of terminal alkenes from internal alkenes using a cross-metathesis reaction catalyzed by a selected olefin metathesis catalyst. In one embodiment of the invention, for example, a method is provided for synthesizing a terminal olefin, the method comprising contacting an olefinic substrate comprised of at least one internal olefin with ethylene, in the presence of a metathesis catalyst, wherein the catalyst is present in an amount that is less than about 1000 ppm relative to the olefinic substrate, and wherein the metathesis catalyst has the structure of formula (II) ##STR00001## wherein the various substituents are as defined herein. The invention has utility, for example, in the fields of catalysis, organic synthesis, and industrial chemistry.

  1. Synthesis of terminal alkenes from internal alkenes and ethylene via olefin metathesis

    DOEpatents

    Schrodi, Yann

    2013-07-09

    This invention relates generally to olefin metathesis, and more particularly relates to the synthesis of terminal alkenes from internal alkenes using a cross-metathesis reaction catalyzed by a selected olefin metathesis catalyst. In one embodiment of the invention, for example, a method is provided for synthesizing a terminal olefin, the method comprising contacting an olefinic substrate comprised of at least one internal olefin with ethylene, in the presence of a metathesis catalyst, wherein the catalyst is present in an amount that is less than about 1000 ppm relative to the olefinic substrate, and wherein the metathesis catalyst has the structure of formula (II) ##STR00001## wherein the various substituents are as defined herein. The invention has utility, for example, in the fields of catalysis, organic synthesis, and industrial chemistry.

  2. Synthesis of terminal alkenes from internal alkenes and ethylene via olefin metathesis

    DOEpatents

    Schrodi, Yann

    2015-09-22

    This invention relates generally to olefin metathesis, and more particularly relates to the synthesis of terminal alkenes from internal alkenes using a cross-metathesis reaction catalyzed by a selected olefin metathesis catalyst. In one embodiment of the invention, for example, a method is provided for synthesizing a terminal olefin, the method comprising contacting an olefinic substrate comprised of at least one internal olefin with ethylene, in the presence of a metathesis catalyst, wherein the catalyst is present in an amount that is less than about 1000 ppm relative to the olefinic substrate, and wherein the metathesis catalyst has the structure of formula (II) ##STR00001## wherein the various substituents are as defined herein. The invention has utility, for example, in the fields of catalysis, organic synthesis, and industrial chemistry.

  3. Synthesis of terminal alkenes from internal alkenes and ethylene via olefin metathesis

    DOEpatents

    Schrodi, Yann [Agoura Hills, CA

    2011-11-29

    This invention relates generally to olefin metathesis, and more particularly relates to the synthesis of terminal alkenes from internal alkenes using a cross-metathesis reaction catalyzed by a selected olefin metathesis catalyst. In one embodiment of the invention, for example, a method is provided for synthesizing a terminal olefin, the method comprising contacting an olefinic substrate comprised of at least one internal olefin with ethylene, in the presence of a metathesis catalyst, wherein the catalyst is present in an amount that is less than about 1000 ppm relative to the olefinic substrate, and wherein the metathesis catalyst has the structure of formula (II) ##STR00001## wherein the various substituents are as defined herein. The invention has utility, for example, in the fields of catalysis, organic synthesis, and industrial chemistry.

  4. Ruthenium olefin metathesis catalysts featuring unsymmetrical N-heterocyclic carbenes.

    PubMed

    Paradiso, Veronica; Bertolasi, Valerio; Costabile, Chiara; Grisi, Fabia

    2016-01-14

    New ruthenium Grubbs' and Hoveyda-Grubbs' second generation catalysts bearing N-alkyl/N-isopropylphenyl N-heterocyclic carbene (NHC) ligands with syn or anti backbone configuration were obtained and compared in model olefin metathesis reactions. Different catalytic efficiencies were observed depending on the size of the N-alkyl group (methyl or cyclohexyl) and on the backbone configuration. The presence of an N-cyclohexyl substituent determined the most significant reactivity differences between catalysts with syn or anti phenyl groups on the backbone. In particular, anti catalysts proved highly efficient, especially in the ring-closing metathesis (RCM) of encumbered diolefins, while syn catalysts showed low efficiency in the RCM of less hindered diolefins. This peculiar behavior, rationalized through DFT studies, was found to be related to the high propensity of these catalysts to give nonproductive metathesis events. Enantiopure anti catalysts were also tested in asymmetric metathesis reactions, where moderate enantioselectivities were observed. The steric and electronic properties of unsymmetrical NHCs with the N-cyclohexyl group were then evaluated using the corresponding rhodium complexes. While steric factors proved unimportant for both syn and anti NHCs, a major electron-donating character was found for the unsymmetrical NHC with anti phenyl substituents on the backbone.

  5. Molybdenum chloride catalysts for Z-selective olefin metathesis reactions

    NASA Astrophysics Data System (ADS)

    Koh, Ming Joo; Nguyen, Thach T.; Lam, Jonathan K.; Torker, Sebastian; Hyvl, Jakub; Schrock, Richard R.; Hoveyda, Amir H.

    2017-01-01

    The development of catalyst-controlled stereoselective olefin metathesis processes has been a pivotal recent advance in chemistry. The incorporation of appropriate ligands within complexes based on molybdenum, tungsten and ruthenium has led to reactivity and selectivity levels that were previously inaccessible. Here we show that molybdenum monoaryloxide chloride complexes furnish higher-energy (Z) isomers of trifluoromethyl-substituted alkenes through cross-metathesis reactions with the commercially available, inexpensive and typically inert Z-1,1,1,4,4,4-hexafluoro-2-butene. Furthermore, otherwise inefficient and non-stereoselective transformations with Z-1,2-dichloroethene and 1,2-dibromoethene can be effected with substantially improved efficiency and Z selectivity. The use of such molybdenum monoaryloxide chloride complexes enables the synthesis of representative biologically active molecules and trifluoromethyl analogues of medicinally relevant compounds. The origins of the activity and selectivity levels observed, which contradict previously proposed principles, are elucidated with the aid of density functional theory calculations.

  6. A Ruthenium Catalyst for Olefin Metathesis Featuring an Anti-Bredt N-Heterocyclic Carbene Ligand

    PubMed Central

    Martin, David; Marx, Vanessa M.

    2016-01-01

    A ruthenium complex bearing an “anti-Bredt” N-heterocyclic carbene was synthesized, characterized and evaluated as a catalyst for olefin metathesis. Good conversions were observed at room temperature for the formation of di- and tri-substituted olefins by ring-closing metathesis. It also allowed for the ring-opening metathesis polymerization of cyclooctadiene, as well as for the cross-metathesis of cis-1,4-diacetoxy-2-butene with allyl-benzene, with enhanced Z/E kinetic selectivity over classical NHC-based catalysts. PMID:27594819

  7. Olefin metathesis for effective polymer healing via dynamic exchange of strong carbon-carbon bonds

    DOEpatents

    Guan, Zhibin; Lu, Yixuan

    2015-09-15

    A method of preparing a malleable and/or self-healing polymeric or composite material is provided. The method includes providing a polymeric or composite material comprising at least one alkene-containing polymer, combining the polymer with at least one homogeneous or heterogeneous transition metal olefin metathesis catalyst to form a polymeric or composite material, and performing an olefin metathesis reaction on the polymer so as to form reversible carbon-carbon double bonds in the polymer. Also provided is a method of healing a fractured surface of a polymeric material. The method includes bringing a fractured surface of a first polymeric material into contact with a second polymeric material, and performing an olefin metathesis reaction in the presence of a transition metal olefin metathesis catalyst such that the first polymeric material forms reversible carbon-carbon double bonds with the second polymeric material. Compositions comprising malleable and/or self-healing polymeric or composite material are also provided.

  8. Aromatizing olefin metathesis by ligand isolation inside a metal-organic framework.

    PubMed

    Vermeulen, Nicolaas A; Karagiaridi, Olga; Sarjeant, Amy A; Stern, Charlotte L; Hupp, Joseph T; Farha, Omar K; Stoddart, J Fraser

    2013-10-09

    The aromatizing ring-closing metathesis has been shown to take place inside an extended porous framework. Employing a combination of solvent-assisted linker exchange and postsynthesis modification using olefin metathesis, the noninterpenetrated SALEM-14 was formed and converted catalytically into PAH-MOF-1 with polycyclic aromatic hydrocarbon (PAH) pillars. The metal-organic framework in SALEM-14 prevents "intermolecular" olefin metathesis from occurring between the pillars in the presence of the first generation Hoveyda-Grubbs catalyst, while favoring the production of a PAH, which can be released from the framework under acidic conditions in dimethylsulfoxide.

  9. Beyond catalyst deactivation: cross-metathesis involving olefins containing N-heteroaromatics

    PubMed Central

    Lafaye, Kevin; Bosset, Cyril; Nicolas, Lionel

    2015-01-01

    Summary Alkenes containing N-heteroaromatics are known to be poor partners in cross-metathesis reactions, probably due to catalyst deactivation caused by the presence of a nitrogen atom. However, some examples of ring-closing and cross-metathesis involving alkenes that incorporate N-heteroaromatics can be found in the literature. In addition, recent mechanistic studies have focused on the rationalization of nitrogen-induced catalysts deactivation. The purpose of this mini-review is to give a brief overview of successful metathesis reactions involving olefins containing N-heteroaromatics in order to delineate some guidelines for the use of these challenging substrates in metathesis reactions. PMID:26664645

  10. Sunflower-based Feedstocks in Nonfood Applications: Perspectives from Olefin Metathesis

    PubMed Central

    Marvey, Bassie B.

    2008-01-01

    Sunflower (Helianthus annuus L.) oil remains under-utilised albeit one of the major seed oils produced world-wide. Moreover, the high oleic sunflower varieties make the oil attractive for applications requiring high temperature processes and those targeting the C=C double bond functionality. Herein an overview of the recent developments in olefin metathesis of sunflower-based feedstocks is presented. The improved performance of olefin metathesis catalysts leading to high turnover numbers, high selectivity and catalyst recyclability, opens new opportunities for tailoring sunflower-based feedstocks into products required for possible new niche market applications. Promising results in biofuel, biopolymers, fragrances and fine chemicals applications have been reported. PMID:19325810

  11. Biopolymer-supported ionic-liquid-phase ruthenium catalysts for olefin metathesis.

    PubMed

    Clousier, Nathalie; Filippi, Alexandra; Borré, Etienne; Guibal, Eric; Crévisy, Christophe; Caijo, Fréderic; Mauduit, Marc; Dez, Isabelle; Gaumont, Annie-Claude

    2014-04-01

    Original ruthenium supported ionic liquid phase (SILP) catalysts based on alginates as supports were developed for olefin metathesis reactions. The marine biopolymer, which fulfills most of the requisite properties for a support such as widespread abundance, insolubility in the majority of organic solvents, a high affinity for ionic liquids, high chemical stability, biodegradability, low cost, and easy processing, was impregnated by [bmim][PF6 ] containing an ionically tagged ruthenium catalyst. These biosourced catalysts show promising performances in ring-closing metathesis (RCM) and cross-metathesis (CM) reactions, with a high level of recyclability and reusability combined with a good reactivity.

  12. Olefin Metathesis in Homogeneous Aqueous Media Catalyzed by Conventional Ruthenium Catalysts

    PubMed Central

    Binder, Joseph B.; Blank, Jacqueline J.; Raines, Ronald T.

    2008-01-01

    Olefin metathesis in aqueous solvents is sought for applications in green chemistry and with the hydrophilic substrates of chemical biology, such as proteins and polysaccharides. Most demonstrations of metathesis in water, however, utilize exotic complexes. We have examined the performance of conventional catalysts in homogeneous water–organic mixtures, finding that the second-generation Hoveyda–Grubbs catalyst has extraordinary efficiency in aqueous dimethoxyethane and aqueous acetone. High (71–95%) conversions are achieved for ring-closing and cross metathesis of a variety of substrates in these solvent systems. PMID:17949009

  13. The Olefin Metathesis Reactions Combined with Organo-Iron Arene Activation Towards Dendrimers, and Polymers

    NASA Astrophysics Data System (ADS)

    Astruc, Didier; Martinez, Victor

    The subjects treated in the two lectures of the North Atlantic Treaty Organization (NATO) summer course are (1) the combination of arene activation and perfunctionalization using organo-iron chemistry with olefin metathesis incuding metathesis of dendritic polyolefin molecules; (2) the synthesis of metallodendritic benzylidene complexes that catalyse ring-opening metathesis polymerization (ROMP) under ambient conditions and the formation of dendritic stars; (3) the use of stoichiometric and catalytic electron-transfer processes with standard reservoirs of electrons (reductants) or electron holes (oxidants) iron complexes to achieve noteworthy metathesis reactions or synthesize compounds that are useful in metathesis. Only the two first topics are treated in this chapter, and interested readers can find references concerning the third aspect called in the introduction and subsequently cited in the reference list.

  14. Nonproductive events in ring-closing metathesis using ruthenium catalysts.

    PubMed

    Stewart, Ian C; Keitz, Benjamin K; Kuhn, Kevin M; Thomas, Renee M; Grubbs, Robert H

    2010-06-30

    The relative TONs of productive and nonproductive metathesis reactions of diethyl diallylmalonate are compared for eight different ruthenium-based catalysts. Nonproductive cross metathesis is proposed to involve a chain-carrying ruthenium methylidene. A second more-challenging substrate (dimethyl allylmethylallylmalonate) that forms a trisubstituted olefin product is used to further delineate the effect of catalyst structure on the relative efficiencies of these processes. A steric model is proposed to explain the observed trends.

  15. Z-Selective Olefin Metathesis on Peptides: Investigation of Side-Chain Influence, Preorganization, and Guidelines in Substrate Selection

    PubMed Central

    2015-01-01

    Olefin metathesis has emerged as a promising strategy for modulating the stability and activity of biologically relevant compounds; however, the ability to control olefin geometry in the product remains a challenge. Recent advances in the design of cyclometalated ruthenium catalysts has led to new strategies for achieving such control with high fidelity and Z selectivity, but the scope and limitations of these catalysts on substrates bearing multiple functionalities, including peptides, remained unexplored. Herein, we report an assessment of various factors that contribute to both productive and nonproductive Z-selective metathesis on peptides. The influence of sterics, side-chain identity, and preorganization through peptide secondary structure are explored by homodimerization, cross metathesis, and ring-closing metathesis. Our results indicate that the amino acid side chain and identity of the olefin profoundly influence the activity of cyclometalated ruthenium catalysts in Z-selective metathesis. The criteria set forth for achieving high conversion and Z selectivity are highlighted by cross metathesis and ring-closing metathesis on diverse peptide substrates. The principles outlined in this report are important not only for expanding the scope of Z-selective olefin metathesis to peptides but also for applying stereoselective olefin metathesis in general synthetic endeavors. PMID:25102124

  16. Amphiphilic Cellulose Ethers Designed for Amorphous Solid Dispersion via Olefin Cross-Metathesis.

    PubMed

    Dong, Yifan; Mosquera-Giraldo, Laura I; Taylor, Lynne S; Edgar, Kevin J

    2016-02-08

    The design of cellulose ether-based amphiphiles has been difficult and limited because of the harsh conditions typically required for appending ether moieties to cellulose. Olefin cross-metathesis recently has been shown to be a valuable approach for appending a variety of functional groups to cellulose ethers and esters, provided that an olefin handle for metathesis can be attached. This synthetic pathway gives access to these functional derivatives under very mild conditions and at high efficiency. Modification of ethyl cellulose by metathesis to prepare useful derivatives, for example, for solubility and bioavailability enhancement of drugs by amorphous solid dispersion (ASD), has been limited by the low DS(OH) of commercial ethyl cellulose derivatives. This is problematic because ethyl cellulose is otherwise a very attractive substrate for synthesis of amphiphilic derivatives by olefin metathesis. Herein we explore two methods for opening up this design space for ether-based amphiphiles, for example, permitting synthesis of more hydrophilic derivatives. One approach is to start with the more hydrophilic commercial methyl cellulose, which contains much higher DS(OH) and therefore is better suited for introduction of high DS of olefin metathesis "handles". In another approach, we explored a homogeneous one-pot synthesis methodology from cellulose, where controlled DS of ethyl groups was introduced at the same time as the ω-unsaturated alkyl groups, thereby permitting complete control of DS(OH), DS(Et), and ultimately DS of the functional group added by metathesis. We describe the functionalized derivatives available by these successful approaches. In addition, we explore new methods for reduction of the unsaturation in initial metathesis products to provide robust methods for enhancing product stability against further radical-catalyzed reactions. We demonstrate initial evidence that the products show strong promise as amphiphilic matrix polymers for amorphous

  17. Olefin Ring Closing Metathesis and Hydrosilylation Reaction in Aqueous Medium by Grubbs Second Generation Ruthenium Catalyst

    EPA Science Inventory

    The Grubbs second generation ruthenium catalyst was shown to catalyze various olefin ring closing metathesis and hydrosilylation reactions in aqueous medium. Reactions proceeded in pure water without any additives or co-solvents, in a short period of time. We found that inhomogen...

  18. Nobel Chemistry in the Laboratory: Synthesis of a Ruthenium Catalyst for Ring-Closing Olefin Metathesis--An Experiment for the Advanced Inorganic or Organic Laboratory

    ERIC Educational Resources Information Center

    Greco, George E.

    2007-01-01

    An experiment for the upper-level undergraduate laboratory is described in which students synthesize a ruthenium olefin metathesis catalyst, then use the catalyst to carry out the ring-closing metathesis of diethyl diallylmalonate. The olefin metathesis reaction was the subject of the 2005 Nobel Prize in chemistry. The catalyst chosen for this…

  19. "Click" and Olefin Metathesis Chemistry in Water at Room Temperature Enabled by Biodegradable Micelles.

    PubMed

    Lipshutz, Bruce H; Bošković, Zarko; Crowe, Christopher S; Davis, Victoria K; Whittemore, Hannah C; Vosburg, David A; Wenzel, Anna G

    2013-11-12

    The two laboratory reactions focus on teaching several concepts associated with green chemistry. Each uses a commercial, nontoxic, and biodegradable surfactant, TPGS-750-M, to promote organic reactions within the lipophilic cores of nanoscale micelles in water. These experiments are based on work by K. Barry Sharpless (an azide-alkyne "click" reaction) and Robert Grubbs (an olefin cross-metathesis reaction); both are suitable for an undergraduate organic laboratory. The copper-catalyzed azide-alkyne [3+2] cycloaddition of benzyl azide and 4-tolylacetylene is very rapid: the triazole product is readily isolated by filtration and is characterized by thin-layer chromatography and melting point analysis. The ruthenium-catalyzed olefin cross-metathesis reaction of benzyl acrylate with 1-hexene is readily monitored by thin-layer chromatography and gas chromatography. The metathesis experiment comparatively evaluates the efficacy of a TPGS-750-M/water medium relative to a traditional reaction performed in dichloromethane (a common solvent used for olefin metathesis).

  20. “Click” and Olefin Metathesis Chemistry in Water at Room Temperature Enabled by Biodegradable Micelles

    PubMed Central

    Lipshutz, Bruce H.; Bošković, Zarko; Crowe, Christopher S.; Davis, Victoria K.; Whittemore, Hannah C.; Vosburg, David A.; Wenzel, Anna G.

    2013-01-01

    The two laboratory reactions focus on teaching several concepts associated with green chemistry. Each uses a commercial, nontoxic, and biodegradable surfactant, TPGS-750-M, to promote organic reactions within the lipophilic cores of nanoscale micelles in water. These experiments are based on work by K. Barry Sharpless (an azide–alkyne “click” reaction) and Robert Grubbs (an olefin cross-metathesis reaction); both are suitable for an undergraduate organic laboratory. The copper-catalyzed azide–alkyne [3+2] cycloaddition of benzyl azide and 4-tolylacetylene is very rapid: the triazole product is readily isolated by filtration and is characterized by thin-layer chromatography and melting point analysis. The ruthenium-catalyzed olefin cross-metathesis reaction of benzyl acrylate with 1-hexene is readily monitored by thin-layer chromatography and gas chromatography. The metathesis experiment comparatively evaluates the efficacy of a TPGS-750-M/water medium relative to a traditional reaction performed in dichloromethane (a common solvent used for olefin metathesis). PMID:24324282

  1. Stereoselective synthesis of macrocyclic peptides via a dual olefin metathesis and ethenolysis approach.

    PubMed

    Mangold, Shane L; Grubbs, Robert H

    2015-08-01

    Macrocyclic compounds occupy an important chemical space between small molecules and biologics and are prevalent in many natural products and pharmaceuticals. The growing interest in macrocycles has been fueled, in part, by the design of novel synthetic methods to these compounds. One appealing strategy is ring-closing metathesis (RCM) that seeks to construct macrocycles from acyclic diene precursors using defined transition-metal alkylidene catalysts. Despite its broad utility, RCM generally gives rise to a mixture of E- and Z-olefin isomers that can hinder efforts for the large-scale production and isolation of such complex molecules. To address this issue, we aimed to develop methods that can selectively enrich macrocycles in E- or Z-olefin isomers using an RCM/ethenolysis strategy. The utility of this methodology was demonstrated in the stereoselective formation of macrocyclic peptides, a class of compounds that have gained prominence as therapeutics in drug discovery. Herein, we report an assessment of various factors that promote catalyst-directed RCM and ethenolysis on a variety of peptide substrates by varying the olefin type, peptide sequence, and placement of the olefin in macrocycle formation. These methods allow for control over olefin geometry in peptides, facilitating their isolation and characterization. The studies outlined in this report seek to expand the scope of stereoselective olefin metathesis in general RCM.

  2. Stereoselective synthesis of macrocyclic peptides via a dual olefin metathesis and ethenolysis approach

    PubMed Central

    Mangold, Shane L.

    2015-01-01

    Macrocyclic compounds occupy an important chemical space between small molecules and biologics and are prevalent in many natural products and pharmaceuticals. The growing interest in macrocycles has been fueled, in part, by the design of novel synthetic methods to these compounds. One appealing strategy is ring-closing metathesis (RCM) that seeks to construct macrocycles from acyclic diene precursors using defined transition-metal alkylidene catalysts. Despite its broad utility, RCM generally gives rise to a mixture of E- and Z-olefin isomers that can hinder efforts for the large-scale production and isolation of such complex molecules. To address this issue, we aimed to develop methods that can selectively enrich macrocycles in E- or Z-olefin isomers using an RCM/ethenolysis strategy. The utility of this methodology was demonstrated in the stereoselective formation of macrocyclic peptides, a class of compounds that have gained prominence as therapeutics in drug discovery. Herein, we report an assessment of various factors that promote catalyst-directed RCM and ethenolysis on a variety of peptide substrates by varying the olefin type, peptide sequence, and placement of the olefin in macrocycle formation. These methods allow for control over olefin geometry in peptides, facilitating their isolation and characterization. The studies outlined in this report seek to expand the scope of stereoselective olefin metathesis in general RCM. PMID:26509000

  3. Nobel Prize in Chemistry. Development of the Olefin Metathesis Method in Organic Synthesis

    NASA Astrophysics Data System (ADS)

    Casey, Charles P.

    2006-02-01

    The 2005 Nobel Prize in Chemistry was awarded to Yves Chauvin of the Institut Français du Pétrole, Robert H. Grubbs of CalTech, and Richard R. Schrock of MIT "for development of the metathesis method in organic synthesis". The discoveries of the laureates provided a chemical reaction now used daily in the chemical industry for the efficient and more environmentally friendly production of important pharmaceuticals, fuels, synthetic fibers, and many other products. This article tells the story of how olefin metathesis became a truly useful synthetic transformation and a triumph for mechanistic chemistry, and illustrates the importance of fundamental research. See JCE Featured Molecules .

  4. Bis(Cyclic Alkyl Amino Carbene) Ruthenium Complexes: A Versatile, Highly Efficient Tool for Olefin Metathesis.

    PubMed

    Gawin, Rafał; Kozakiewicz, Anna; Guńka, Piotr A; Dąbrowski, Paweł; Skowerski, Krzysztof

    2017-01-19

    The state-of-the-art in olefin metathesis is application of N-heterocyclic carbene (NHC)-containing ruthenium alkylidenes for the formation of internal C=C bonds and of cyclic alkyl amino carbene (CAAC)-containing ruthenium benzylidenes in the production of terminal olefins. A straightforward synthesis of bis(CAAC)Ru indenylidene complexes, which are highly effective in the formation of both terminal and internal C=C bonds at loadings as low as 1 ppm, is now reported.

  5. Bis(Cyclic Alkyl Amino Carbene) Ruthenium Complexes: A Versatile, Highly Efficient Tool for Olefin Metathesis

    PubMed Central

    Gawin, Rafał; Kozakiewicz, Anna; Guńka, Piotr A.; Dąbrowski, Paweł

    2016-01-01

    Abstract The state‐of‐the‐art in olefin metathesis is application of N‐heterocyclic carbene (NHC)‐containing ruthenium alkylidenes for the formation of internal C=C bonds and of cyclic alkyl amino carbene (CAAC)‐containing ruthenium benzylidenes in the production of terminal olefins. A straightforward synthesis of bis(CAAC)Ru indenylidene complexes, which are highly effective in the formation of both terminal and internal C=C bonds at loadings as low as 1 ppm, is now reported. PMID:27943616

  6. Ru complexes of Hoveyda–Grubbs type immobilized on lamellar zeolites: activity in olefin metathesis reactions

    PubMed Central

    Žilková, Naděžda; Kubů, Martin; Mazur, Michal; Bastl, Zdeněk; Čejka, Jiří

    2015-01-01

    Summary Hoveyda–Grubbs type catalysts with cationic tags on NHC ligands were linker-free immobilized on the surface of lamellar zeolitic supports (MCM-22, MCM-56, MCM-36) and on mesoporous molecular sieves SBA-15. The activity of prepared hybrid catalysts was tested in olefin metathesis reactions: the activity in ring-closing metathesis of citronellene and N,N-diallyltrifluoroacetamide decreased in the order of support MCM-22 ≈ MCM-56 > SBA-15 > MCM-36; the hybrid catalyst based on SBA-15 was found the most active in self-metathesis of methyl oleate. All catalysts were reusable and exhibited low Ru leaching (<1% of Ru content). XPS analysis revealed that during immobilization ion exchange between Hoveyda–Grubbs type catalyst and zeolitic support occurred in the case of Cl− counter anion; in contrast, PF6 − counter anion underwent partial decomposition. PMID:26664629

  7. Linker-free, silica-bound olefin-metathesis catalysts: applications in heterogeneous catalysis.

    PubMed

    Cabrera, José; Padilla, Robin; Bru, Miriam; Lindner, Ronald; Kageyama, Takeharu; Wilckens, Kristina; Balof, Shawna L; Schanz, Hans-Jörg; Dehn, Richard; Teles, J Henrique; Deuerlein, Stephan; Müller, Kevin; Rominger, Frank; Limbach, Michael

    2012-11-12

    A set of heterogenized olefin-metathesis catalysts, which consisted of Ru complexes with the H(2)ITap ligand (1,3-bis(2',6'-dimethyl-4'dimethyl aminophenyl)-4,5-dihydroimidazol-2-ylidene) that had been adsorbed onto a silica support, has been prepared. These complexes showed strong binding to the solid support without the need for tethering groups on the complex or functionalized silica. The catalysts were tested in the ring-opening-ring-closing-metathesis (RO-RCM) of cyclooctene (COE) and the self-metathesis of methyl oleate under continuous-flow conditions. The best complexes showed a TON>4000, which surpasses the previously reported materials that were either based on the Grubbs-Hoveyda II complex on silica or on the classical heterogeneous Re(2)O(7)/B(2)O(3) catalyst.

  8. Self-selection in olefin cross-metathesis: the effect of remote functionality.

    PubMed

    McNaughton, Brian R; Bucholtz, Kevin M; Camaaño-Moure, Ana; Miller, Benjamin L

    2005-02-17

    Olefin cross-metathesis (CM) is potentially an attractive method for generating dynamic combinatorial libraries (DCLs). In order for the CM reaction to be useful for DCL production, the course of the reaction and product distribution must be relatively insensitive to functionality remote from the reacting centers. We report on the CM of a series of allyl- and homoallylamides that are strongly dependent on remote functionality. This includes an unusual example of a cis-selective CM. [Reaction: see text

  9. Ruthenium indenylidene “1st generation” olefin metathesis catalysts containing triisopropyl phosphite

    PubMed Central

    Guidone, Stefano; Nahra, Fady; Slawin, Alexandra M Z

    2015-01-01

    Summary The reaction of triisopropyl phosphite with phosphine-based indenylidene pre-catalysts affords “1st generation” cis-complexes. These have been used in olefin metathesis reactions. The cis-Ru species exhibit noticeable differences with the trans-Ru parent complexes in terms of structure, thermal stability and reactivity. Experimental data underline the importance of synergistic effects between phosphites and L-type ligands. PMID:26425210

  10. Solvent-free cyclization of linear dienes using olefin metathesis and the Thorpe-Ingold effect

    SciTech Connect

    Forbees, M.D.E.; Myers, T.L.; Maynard, H.D.; Schulz, G.R. ); Patton, J.T.; Smith, D.W. Jr.; Wagener, K.B. )

    1992-12-30

    The olefin metathesis reaction is of great synthetic utility in polymer chemistry. The recent development of ring-opening (ROMP) and acyclic diene (ADMET) metathesis polymerization reactions has opened new avenues for the synthesis of novel polymeric materials. Recently the authors used ADMET to synthesize several photochemically active poly(keto olefins) using the catalyst Mo(CHCMe[sub 2]Ph)(NAr)(OCMe(CF[sub 3])[sub 2])[sub 2] (Ar = 2,6-diisopropylphenyl) (1) developed by Schrock and co-workers in 1990. In the course of that work, they discovered that neat samples of highly substituted dienes will cyclize quantitatively via metathesis to give difunctional five- and seven-membered rings instead of the expected linear polymer. Examples of substituted diene cyclizations by metathesis even in the presence of a solvent are rare. Their systematic exploitation in organic synthesis has therefore been limited to two recent studies by Fu and Grubbs, who cyclized several substituted diene ethers, amines, and amides to unsaturated oxygen and nitrogen heterocycles. Cyclization of unsubstituted dienes in various solvents has been reported, but complete conversion occurred in only a few cases. Formation of cyclic alkene oligomers from back-biting during the ROMP reaction is also known. The reactions reported here are unusual in that they are intermolecular between catalyst and substrate, yet can give 100% yield of product solely from the monomer in the absence of solvent. 13 refs.

  11. Synthesis of all-hydrocarbon stapled α-helical peptides by ring-closing olefin metathesis.

    PubMed

    Kim, Young-Woo; Grossmann, Tom N; Verdine, Gregory L

    2011-06-01

    This protocol provides a detailed procedure for the preparation of stapled α-helical peptides, which have proven their potential as useful molecular probes and as next-generation therapeutics. Two crucial features of this protocol are (i) the construction of peptide substrates containing hindered α-methyl, α-alkenyl amino acids and (ii) the ring-closing olefin metathesis (RCM) of the resulting resin-bound peptide substrates. The stapling systems described in this protocol, namely bridging one or two turns of an α-helix, are highly adaptable to most peptide sequences, resulting in favorable RCM kinetics, helix stabilization and promotion of cellular uptake.

  12. The generation of efficient supported (Heterogeneous) olefin metathesis catalysts

    SciTech Connect

    Grubbs, Robert H

    2013-04-05

    Over the past decade, a new family of homogeneous metathesis catalysts has been developed that will tolerate most organic functionalities as well as water and air. These homogeneous catalysts are finding numerous applications in the pharmaceutical industry as well as in the production of functional polymers. In addition the catalysts are being used to convert seed oils into products that can substitute for those that are now made from petroleum products. Seed oils are unsaturated, contain double bonds, and are a ready source of linear hydrocarbon fragments that are specifically functionalized. To increase the number of applications in the area of biomaterial conversion to petrol chemicals, the activity and efficiency of the catalysts need to be as high as possible. The higher the efficiency of the catalysts, the lower the cost of the conversion and a larger number of practical applications become available. Active supported catalysts were prepared and tested in the conversion of seed oils and other important starting materials. The outcome of the work was successful and the technology has been transferred to a commercial operation to develop viable applications of the discovered systems. A biorefinery that converts seed oils is under construction in Indonesia. The catalysts developed in this study will be considered for the next generation of operations.

  13. Liquid-phase synthesis of bridged peptides using olefin metathesis of a protected peptide with a long aliphatic chain anchor.

    PubMed

    Aihara, Keisuke; Komiya, Chiaki; Shigenaga, Akira; Inokuma, Tsubasa; Takahashi, Daisuke; Otaka, Akira

    2015-02-06

    Bridged peptides including stapled peptides are attractive tools for regulating protein-protein interactions (PPIs). An effective synthetic methodology in a heterogeneous system for the preparation of these peptides using olefin metathesis and hydrogenation of protected peptides with a long aliphatic chain anchor is reported.

  14. Poly(fluoroalkyl acrylate)-bound ruthenium carbene complex: a fluorous and recyclable catalyst for ring-closing olefin metathesis.

    PubMed

    Yao, Qingwei; Zhang, Yiliang

    2004-01-14

    The synthesis of a fluorous olefin metathesis catalyst derived from the Grubbs second-generation ruthenium carbene complex is described. The air stable fluorous polymer-bound ruthenium carbene complex 1 shows high reactivity in effecting the ring-closing metathesis of a broad spectrum of diene and enyne substrates leading to the formation of di-, tri-, and tetrasubstituted cyclic olefins in minimally fluorous solvent systems (PhCF3/CH2Cl2, 1:9-1:49 v/v). The catalyst can be readily separated from the reaction mixture by fluorous extraction with FC-72 and repeatedly reused. The practical advantage offered by the fluorous catalyst is demonstrated by its sequential use in up to five different metathesis reactions.

  15. Development of a Method for the Preparation of Ruthenium Indenylidene-Ether Olefin Metathesis Catalysts

    PubMed Central

    Jimenez, Leonel R.; Tolentino, Daniel R.; Gallon, Benjamin J.; Schrodi, Yann

    2012-01-01

    The reactions between several derivatives of 1-(3,5-dimethoxyphenyl)-prop-2-yn-1-ol and different ruthenium starting materials [i.e., RuCl2(PPh3)3 and RuCl2(pcymene)(L), where L is tricyclohexylphosphine di-t-butylmethylphosphine, dicyclohexylphenylphosphine, triisobutylphosphine, triisopropylphosphine, or tri-npropylphosphine] are described. Several of these reactions allow for the easy, in-situ and atom-economic preparation of olefin metathesis catalysts. Organic precursor 1-(3,5-dimethoxyphenyl)-1-phenyl-prop-2-yn-1-ol led to the formation of active ruthenium indenylidene-ether complexes, while 1-(3,5-dimethoxyphenyl)-prop-2-yn-1-ol and 1-(3,5-dimethoxyphenyl)-1-methyl-prop-2-yn-1-ol did not. It was also found that a bulky and strong σ-donor phosphine ligand was required to impart good catalytic activity to the new ruthenium complexes. PMID:22580400

  16. Evolution of Catalytic Stereoselective Olefin Metathesis: From Ancillary Transformation to Purveyor of Stereochemical Identity

    PubMed Central

    2015-01-01

    There have been numerous significant advances in catalytic olefin metathesis (OM) during the past two decades. Such progress has transformed this important set of reactions to strategically pivotal processes that generate stereochemical identity while delivering molecules that cannot be easily prepared by alternative routes. In this Perspective, an analysis of the origin of the inception of bidentate benzylidene ligands for Ru-based OM catalysts is first presented. This is followed by an overview of the intellectual basis that culminated in the development of Mo-based diolates and stereogenic-at-Ru complexes for enantioselective OM. The principles accrued from the study of the latter Ru carbenes and Mo alkylidenes and utilized in the design of stereogenic-at-Mo, -W, and -Ru species applicable to enantioselective and Z-selective OM are then discussed. The influence of the recently introduced catalytic OM protocols on the design of synthesis routes leading to complex organic molecules is probed. The impact of a better understanding of the mechanistic nuances of OM toward the discovery of stereoselective catalysts is reviewed as well. PMID:24720633

  17. Origins of initiation rate differences in ruthenium olefin metathesis catalysts containing chelating benzylidenes.

    PubMed

    Engle, Keary M; Lu, Gang; Luo, Shao-Xiong; Henling, Lawrence M; Takase, Michael K; Liu, Peng; Houk, K N; Grubbs, Robert H

    2015-05-06

    A series of second-generation ruthenium olefin metathesis catalysts was investigated using a combination of reaction kinetics, X-ray crystallography, NMR spectroscopy, and DFT calculations in order to determine the relationship between the structure of the chelating o-alkoxybenzylidene and the observed initiation rate. Included in this series were previously reported catalysts containing a variety of benzylidene modifications as well as four new catalysts containing cyclopropoxy, neopentyloxy, 1-adamantyloxy, and 2-adamantyloxy groups. The initiation rates of this series of catalysts were determined using a UV/vis assay. All four new catalysts were observed to be faster-initiating than the corresponding isopropoxy control, and the 2-adamantyloxy catalyst was found to be among the fastest-initiating Hoveyda-type catalysts reported to date. Analysis of the X-ray crystal structures and computed energy-minimized structures of these catalysts revealed no correlation between the Ru-O bond length and Ru-O bond strength. On the other hand, the initiation rate was found to correlate strongly with the computed Ru-O bond strength. This latter finding enables both the rationalization and prediction of catalyst initiation through the calculation of a single thermodynamic parameter in which no assumptions about the mechanism of the initiation step are made.

  18. Evolution of a total synthesis of (-)-kendomycin exploiting a Petasis-Ferrier rearrangement/ring-closing olefin metathesis strategy.

    PubMed

    Smith, Amos B; Mesaros, Eugen F; Meyer, Emmanuel A

    2006-04-19

    A convergent stereocontrolled total synthesis of (-)-kendomycin (1) has been achieved. The synthesis proceeds with a longest linear sequence of 21 steps, beginning with commercially available 2,4-dimethoxy-3-methylbenzaldehyde (12). Highlights of the synthesis include an effective Petasis-Ferrier union/rearrangement tactic to construct the sterically encumbered tetrahydropyran ring, a ring-closing metathesis to generate the C(4a-13-20a) macrocycle, an effective epoxidation/deoxygenation sequence to isomerize the C(13,14) olefin, and a biomimetic quinone-methide-lactol assembly to complete the synthesis.

  19. Introduction of all-hydrocarbon i,i+3 staples into alpha-helices via ring-closing olefin metathesis.

    PubMed

    Kim, Young-Woo; Kutchukian, Peter S; Verdine, Gregory L

    2010-07-02

    The introduction of all-hydrocarbon i,i+3 staples into alpha-helical peptide scaffolds via ring-closing olefin metathesis (RCM) between two alpha-methyl,alpha-pentenylglycine residues incorporated at i and i+3 positions, which lie on the same face of the helix, has been investigated. The reactions were found to be highly dependent upon the side-chain stereochemistry of the amino acids undergoing RCM. The i,i+3 stapling system established here provides a potentially useful alternative to the well-established i,i+4 stapling system now in widespread use.

  20. An S(N)Ar approach to sterically hindered ortho-alkoxybenzaldehydes for the synthesis of olefin metathesis catalysts.

    PubMed

    Engle, Keary M; Luo, Shao-Xiong; Grubbs, Robert H

    2015-04-17

    A three-step procedure has been developed for preparing ortho-alkoxybenzaldehydes from ortho-fluorobenzaldehydes that tolerates the use of sterically hindered sodium alkoxide nucleophiles. The protocol is modular and operationally convenient. The ortho-alkoxybenzaldehyde products can be converted in one additional step to ortho-alkoxystyrenes by a Wittig reaction. These styrenes are precursors to the chelating benzylidene moiety in a proposed series of novel ruthenium complexes for use in olefin metathesis. Chelation with three representative styrenes has been demonstrated.

  1. Rationalizing current strategies to protect N-heterocyclic carbene-based ruthenium catalysts active in olefin metathesis from C-H (de)activation.

    PubMed

    Poater, Albert; Bahri-Laleh, Naeimeh; Cavallo, Luigi

    2011-06-21

    Defending second generation Ru-catalysts in olefin metathesis from C-H (de)activation reactions requires precise catalyst design strategies. Computer simulations are used here to rationalize precisely the role of the currently used catalyst structural modifications, and the way these modifications cooperate.

  2. Synthesis and Catalytic Activity of Ruthenium-Indenylidene Complexes for Olefin Metathesis: Microscale Experiments for the Undergraduate Inorganic or Organometallic Laboratories

    ERIC Educational Resources Information Center

    Pappenfus, Ted M.; Hermanson, David L.; Ekerholm, Daniel P.; Lilliquist, Stacie L.; Mekoli, Megan L.

    2007-01-01

    A series of experiments for undergraduate laboratory courses (e.g., inorganic, organometallic or advanced organic) have been developed. These experiments focus on understanding the design and catalytic activity of ruthenium-indenylidene complexes for olefin metathesis. Included in the experiments are the syntheses of two ruthenium-indenylidene…

  3. Ligand Exchange-Mediated Activation and Stabilization of a Re-Based Olefin Metathesis Catalyst by Chlorinated Alumina.

    PubMed

    Gallo, Alessandro; Fong, Anthony; Szeto, Kai C; Rieb, Julia; Delevoye, Laurent; Gauvin, Régis M; Taoufik, Mostafa; Peters, Baron; Scott, Susannah L

    2016-10-05

    Extensive chlorination of γ-Al2O3 results in the formation of highly Lewis acidic surface domains depleted in surface hydroxyl groups. Adsorption of methyltrioxorhenium (MTO) onto these chlorinated domains serves to activate it as a low temperature, heterogeneous olefin metathesis catalyst and confers both high activity and high stability. Characterization of the catalyst reveals that the immobilized MTO undergoes partial ligand exchange with the surface, whereby some Re sites acquire a chloride ligand from the modified alumina while donating an oxo ligand to the support. More specifically, Re LIII-edge EXAFS and DFT calculations support facile ligand exchange between MTO and Cl-Al2O3 to generate [CH3ReO2Cl(+)] fragments that interact with a bridging oxygen of the support via a Lewis acid-base interaction. According to IR and solid-state NMR, the methyl group remains intact, and does not evolve spontaneously to a stable methylene tautomer. Nevertheless, the chloride-promoted metathesis catalyst is far more active and productive than MTO/γ-Al2O3, easily achieving a TON of 100 000 for propene metathesis in a flow reactor at 10 °C (compared to TON < 5000 for the nonchlorinated catalyst). Increased activity is a consequence of both a larger fraction of active sites and a higher intrinsic activity for the new sites. Increased stability is tentatively attributed to a stronger interaction between MTO and chlorinated surface regions, as well as extensive depletion of the Brønsted acidic surface hydroxyl population. The reformulated catalyst represents a major advance for Re-based metathesis catalysts, whose widespread use has thus far been severely hampered by their instability.

  4. High selectivity production of propylene from 2-butene: non-degenerate pathways to convert symmetric olefins via olefin metathesis.

    PubMed

    Mazoyer, Etienne; Szeto, Kai C; Basset, Jean-Marie; Nicholas, Christopher P; Taoufik, Mostafa

    2012-04-14

    The first example of propylene production from 2-butene in promising yield is described by reacting trans-2-butene over tungsten hydrides precursor W-H/Al(2)O(3) at 150 °C and different pressures in a continuous flow reactor. The tungsten carbene-hydride active site operates as a "bi-functional catalyst" through the disfavoured 2-butene isomerisation on W-hydride and 2-butenes/1-butene cross-metathesis on W-carbene.

  5. Orthogonal ring-closing alkyne and olefin metathesis for the synthesis of small GTPase-targeting bicyclic peptides

    PubMed Central

    Cromm, Philipp M.; Schaubach, Sebastian; Spiegel, Jochen; Fürstner, Alois; Grossmann, Tom N.; Waldmann, Herbert

    2016-01-01

    Bicyclic peptides are promising scaffolds for the development of inhibitors of biological targets that proved intractable by typical small molecules. So far, access to bioactive bicyclic peptide architectures is limited due to a lack of appropriate orthogonal ring-closing reactions. Here, we report chemically orthogonal ring-closing olefin (RCM) and alkyne metathesis (RCAM), which enable an efficient chemo- and regioselective synthesis of complex bicyclic peptide scaffolds with variable macrocycle geometries. We also demonstrate that the formed alkyne macrocycle can be functionalized subsequently. The orthogonal RCM/RCAM system was successfully used to evolve a monocyclic peptide inhibitor of the small GTPase Rab8 into a bicyclic ligand. This modified peptide shows the highest affinity for an activated Rab GTPase that has been reported so far. The RCM/RCAM-based formation of bicyclic peptides provides novel opportunities for the design of bioactive scaffolds suitable for the modulation of challenging protein targets. PMID:27075966

  6. Synthesis of the EF-ring of ciguatoxin 3C based on the [2,3]-Wittig rearrangement and ring-closing olefin metathesis.

    PubMed

    Goto, Akiyoshi; Fujiwara, Kenshu; Kawai, Ayako; Kawai, Hidetoshi; Suzuki, Takanori

    2007-12-20

    The EF-ring segment of ciguatoxin 3C, a causative toxin of ciguatera fish poisoning, was synthesized in three major steps: 1,4-addition for the C20O-C27 bond connection, chirality transferring anti selective [2,3]-Wittig rearrangement for the construction of the anti-2-hydroxyalkyl ether part, and ring-closing olefin metathesis for the F-ring formation.

  7. 2005 Nobel Prize in Chemistry: Development of the Olefin Metathesis Method in Organic Synthesis

    ERIC Educational Resources Information Center

    Casey, Charles P.

    2006-01-01

    The 2005 Nobel Prize in Chemistry was awarded "for the development of the metathesis method in organic synthesis". The discoveries of the laureates provided a chemical reaction used daily in the chemical industry for the efficient and more environmentally friendly production of important pharmaceuticals, fuels, synthetic fibers, and many other…

  8. Shell Higher Olefins Process.

    ERIC Educational Resources Information Center

    Lutz, E. F.

    1986-01-01

    Shows how olefin isomerization and the exotic olefin metathesis reaction can be harnessed in industrial processes. Indicates that the Shell Higher Olefins Process makes use of organometallic catalysts to manufacture alpha-olefins and internal carbon-11 through carbon-14 alkenes in a flexible fashion that can be adjusted to market needs. (JN)

  9. A Well-Defined, Silica-Supported Tungsten Imido Alkylidene OlefinMetathesis Catalyst

    SciTech Connect

    Rhers, Bochra; Salameh, Alain; Baudouin, Anne; Quadrelli, ElsjeA.; Taoufik, Mostafa; Coperet, Christophe; Lefebvre, Frederic; Basset,Jean-Marie; Solans-Monfort, Xavier; Eisenstein, Odile; Lukens, Wayne W.; Lopez, Lordes.P.H.; Sinha, Amritanshu; Schrock, Richard R.

    2006-06-13

    The reaction of [W(=NAr)(=CHtBu)(CH2tBu)2](1; Ar =2,6-iPrC6H3) with a silica partially dehydroxylated at 700oC, SiO2-(700),gives syn-[(_SiO)W(=NAr)(=CHtBu)(CH2tBu)](2) as a major surface species,which was fully characterized by mass balance analysis, IR, NMR, EXAFS,and DFT periodic calculations. Similarly, complex 1 reacts with[(c-C5H9)7Si7O12SiOH]to give [(SiO)W(=NAr)(=CHtBu)(CH2tBu)](2m), whichshows similar spectroscopic properties. Surface complex 2 is a highlyactive propene metathesis catalyst, which can achieve a TON of 16000within 100 h, with only a slow deactivation.

  10. Z-Selective Olefin Metathesis Reactions Promoted by Tungsten Oxo Alkylidene Complexes

    PubMed Central

    Peryshkov, Dmitry V.; Schrock, Richard R.; Takase, Michael K.; Müller, Peter; Hoveyda, Amir H.

    2011-01-01

    Addition of LiOHMT (OHMT = O-2,6-dimesitylphenoxide) to W(O)(CH-t-Bu)(PMe2Ph)2Cl2 led to WO(CH-t-Bu)Cl(OHMT)(PMe2Ph) (4). Subsequent addition of Li(2,5-Me2C4H2N) to 4 yielded yellow W(O)(CH-t-Bu)(OHMT)(Me2Pyr)(PMe2Ph) (5). Compound 5 is a highly effective catalyst for the Z-selective coupling of selected terminal olefins (at 0.2% loading) to give product in >75% yield with >99% Z configuration. Addition of two equivalents of B(C6F5)3 to 5 led to catalyst activated at the oxo ligand by B(C6F5)3. 5.B(C6F5)3 is a highly active catalyst that produces thermodynamic products (~20% Z). PMID:22107254

  11. Self-healing polymers---The importance of choosing an adequate healing monomer, and the olefin metathesis polymerization of agricultural oils

    NASA Astrophysics Data System (ADS)

    Mauldin, Timothy C.

    Modern society's immense and ill-fated reliance on petrochemical-based polymeric materials will likely necessitate a shift in polymer production paradigms in the near future. The work presented herein attempts to address this issue via a two-pronged approach. First, efforts to improve the duration of composite materials by incorporation of a self-healing function are discussed, the fruitful application of which can potentially reduce or eliminate the massive carbon footprints associated with the repair/replacement of damaged materials. And second, polymeric materials derived predominately from natural and renewable feedstock---namely vegetable oils---are developed. Early microcapsule-based self-healing materials utilized dicyclopentadiene-filled microcapsules and Grubbs' olefin metathesis catalyst to initiate the healing mechanism. However, the patent-protected catalyst, made from the precious metal ruthenium and sometimes costly ligands, will likely never be inexpensive and therefore limit large-scale applications. Hence, clever approaches to reduce the healing catalyst loading in self-healing polymers are of great interest. To this end, our efforts have revolved around solving the problem of the relatively inefficient use of Grubbs' catalyst during the healing mechanism. Given that the mismatch of the olefin metathesis polymerization and Grubbs' catalyst dissolution (in monomer) kinetics is a known cause of this inefficient use of the catalyst, we attempted to tune the "latency" (i.e. pot life) of the olefin metathesis polymerization to ensure more complete dissolution of catalyst in monomer. In an alternative approach to improving efficient catalyst dissolution, we developed a simple model to predict relative dissolution rates of Grubbs' catalyst in a small library of healing monomers. This model was shown experimentally to be able to aid in the selection of, for example, reactive monomer additives that can yield impressive improvements in catalyst dissolution

  12. Ring-expanding olefin metathesis: a route to highly active unsymmetrical macrocyclic oligomeric co-salen catalysts for the hydrolytic kinetic resolution of epoxides.

    PubMed

    Zheng, Xiaolai; Jones, Christopher W; Weck, Marcus

    2007-02-07

    In the presence of the third generation Grubbs catalyst, the ring-expanding olefin metathesis of a monocyclooct-4-en-1-yl functionalized salen ligand and the corresponding Co(II)(salen) complex at low monomer concentrations results in the exclusive formation of macrocyclic oligomeric structures with the salen moieties being attached in an unsymmetrical, flexible, pendent manner. The TOF-MALDI mass spectrometry reveals that the resulting macrocyclic oligomers consist predominantly of dimeric to tetrameric species, with detectable traces of higher homologues up to a decamer. Upon activation under aerobic and acidic conditions, these Co(salen) macrocycles exhibit extremely high reactivities and selectivities in the hydrolytic kinetic resolution (HKR) of a variety of racemic terminal epoxides under neat conditions with very low catalyst loadings. The excellent catalytic properties can be explained in terms of the new catalyst's appealing structural features, namely, the flexible oligomer backbone, the unsymmetrical pendent immobilization motif of the catalytic sites, and the high local concentration of Co(salen) species resulting from the macrocyclic framework. This ring-expanding olefin metathesis is suggested to be a simple way to prepare tethered metal complexes that are endowed with key features--(i) a high local concentration of metal complexes and (ii) a flexible, single point of attachment to the support--that facilitate rapid and efficient catalysis when a bimetallic transition state is required.

  13. Ruthenium—Arene Complexes Derived from NHC•CO2 and NHC•CS2 Zwitterionic Adducts and Their Use in Olefin Metathesis

    NASA Astrophysics Data System (ADS)

    Delaude, Lionel; Demonceau, Albert

    A range of imidazol(in)ium-2-carboxylates and -dithiocarboxylates bearing alkyl or aryl groups on their nitrogen atoms were prepared by reacting the corresponding N-heterocyclic carbenes (NHCs) with either carbon dioxide or carbon disulfide. All the zwitterionic products were characterized by various analytical techniques, including thermogravimetric analysis (TGA). Their ability to act as NHC ligand precursors for in situ catalytic applications was investigated in the ruthenium-promoted ring-opening metathesis polymerization (ROMP) of cyclo-octene. Upon exposure to the [RuCl2(p-cymene)]2 dimer, the NHC CO2 adducts readily dissociated to generate [RuCl2(p-cymene)(NHC)] complexes that were highly active catalyst precursors for olefin metathesis. Conversely, the NHC CS2 betaines retained their zwitterionic nature and led to new cationic complexes of the [RuCl(p-cymene)(NHC CS2)]+PF6 - type that were devoid of any significant catalytic activity in the reaction under consideration

  14. Carboxylate-Assisted C(sp3)–H Activation in Olefin Metathesis-Relevant Ruthenium Complexes

    PubMed Central

    2015-01-01

    The mechanism of C–H activation at metathesis-relevant ruthenium(II) benzylidene complexes was studied both experimentally and computationally. Synthesis of a ruthenium dicarboxylate at a low temperature allowed for direct observation of the C–H activation step, independent of the initial anionic ligand-exchange reactions. A first-order reaction supports an intramolecular concerted metalation–deprotonation mechanism with ΔG⧧298K = 22.2 ± 0.1 kcal·mol–1 for the parent N-adamantyl-N′-mesityl complex. An experimentally determined ΔS⧧ = −5.2 ± 2.6 eu supports a highly ordered transition state for carboxylate-assisted C(sp3)–H activation. Experimental results, including measurement of a large primary kinetic isotope effect (kH/kD = 8.1 ± 1.7), agree closely with a computed six-membered carboxylate-assisted C–H activation mechanism where the deprotonating carboxylate adopts a pseudo-apical geometry, displacing the aryl ether chelate. The rate of cyclometalation was found to be influenced by both the electronics of the assisting carboxylate and the ruthenium ligand environment. PMID:24731019

  15. Alkene Metathesis and Renewable Materials: Selective Transformations of Plant Oils

    NASA Astrophysics Data System (ADS)

    Malacea, Raluca; Dixneuf, Pierre H.

    The olefin metathesis of natural oils and fats and their derivatives is the basis of clean catalytic reactions relevant to green chemistry processes and the production of generate useful chemicals from renewable raw materials. Three variants of alkene metathesis: self-metathesis, ethenolysis and cross-metathesis applied to plant oil derivatives will show new routes to fine chemicals, bifunctional products, polymer precursours and industry intermediates.

  16. Enantioselective synthesis of 5-epi-citreoviral using ruthenium-catalyzed asymmetric ring-closing metathesis.

    PubMed

    Funk, Timothy W

    2009-11-05

    Chiral ruthenium olefin metathesis catalysts can perform asymmetric ring-closing reactions in > or = 90% ee with low catalyst loadings. To illustrate the practicality of these reactions and the products they form, an enantioselective total synthesis of 5-epi-citreoviral was completed by using an asymmetric ring-closing olefin metathesis reaction as a key step early in the synthesis. All of the stereocenters in the final compound were set by using the chiral center generated by asymmetric olefin metathesis.

  17. Remarkably Efficient Microvawe-Assisted Cross-Metathesis of Lipids in Solvent Free Conditions.

    PubMed

    Ullah, Aman; Arshad, Muhammad

    2017-02-28

    Catalytic transformation of renewable feed stocks into fine chemicals is in high demands and olefin metathesis is one of the sophisticated tools for biomass conversion. Nevertheless, the large scale viability of such processes depends on the conversion efficiency, energy efficiency, catalytic activity, selective conversion into desired products and environmental footprint of the process. Thus, conversions of renewables using simple, swift, and efficient methods are desirable. A microwave-assisted ethenolysis and alkenolysis (using 1-5 hexadiene) of canola oil and methyl esters derived from canola oil (COME) and waste/recycled cooking oil (WOME) was carried out using ruthenium based catalytic systems. A systematic study using 1st and 2nd generation Grubbs (G1, G2) and Hoveyda-Grubbs (HG1 & HG2) catalysts was carried out. Among all ruthenium catalysts, HG2 was found to be highly active in the range of 0.002-0.1 mol% loadings. The conversions proved to be highly efficient with outstanding values of turnover numbers (TONs) and turnover frequencies (TOFs). The TONs for ethenolysis of COME (~1.5 million), direct ethenolysis of canola oil (~0.6 million), more than 1 million for WOME and above 1.6 million for cross metathesis of 1,5-hexadiene with COME were achieved. The ethenolysis of commercial methyl oleate was also performed leading to TONs ~1.2 million and TOFs 20,300 s-1 under microwave conditions.

  18. Increased functionality of methyl oleate using alkene metathesis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A series of alkene cross metathesis reactions were performed using a homogeneous ruthenium based catalyst. Using this technology, a variety of functional groups can be incorporated into the biobased starting material, methyl oleate. Trans-stilbene, styrene, methyl cinnamate and hexen-3-ol were all s...

  19. Organometallic chemistry: A new metathesis

    NASA Astrophysics Data System (ADS)

    Hennessy, Elisabeth T.; Jacobsen, Eric N.

    2016-08-01

    Carbonyls and alkenes, two of the most common functional groups in organic chemistry, generally do not react with one another. Now, a simple Lewis acid has been shown to catalyse metathesis between alkenes and ketones in a new carbonyl olefination reaction.

  20. CH3-ReO3 on gamma-Al2O3: understanding its structure, initiation,and reactivity in olefin metathesis

    SciTech Connect

    Salameh, Alain; Joubert, Jerome; Baudouin, Anne; Lukens, Wayne; Delbecq, Francoise; Sautet, Philippe; Basset, Jean Marie; Coperet,Christophe

    2007-01-20

    Me-ReO3 on gamma-alumina: understanding the structure, theinitiation and thereactivity of a highly active olefin metathesiscatalyst Heterolytic splitting of the C-H bond of the methyl group ofCH3ReO3 on AlsO reactive sites of alumina as a way to generate the activesite of CH3ReO3 supported on gamma-Al203.

  1. Cis-Selective Ring-Opening Metathesis Polymerization with Ruthenium Catalysts

    PubMed Central

    Keitz, Benjamin K.; Fedorov, Alexey; Grubbs, Robert H.

    2012-01-01

    Using a C-H activated, ruthenium-based metathesis catalyst, the cis selective ROMP of several monocyclic alkenes, as well as norbornene and oxanorbornene-type monomers is reported. The cis content of the isolated polymers depended heavily on monomer structure and temperature. By lowering the temperature, cis content as high as 96% could be obtained. PMID:22239675

  2. Tandem Ring-Opening-Ring-Closing Metathesis for Functional Metathesis Catalysts.

    PubMed

    Nagarkar, Amit A; Yasir, Mohammad; Crochet, Aurelien; Fromm, Katharina M; Kilbinger, Andreas F M

    2016-09-26

    Use of a tandem ring-opening-ring-closing metathesis (RORCM) strategy for the synthesis of functional metathesis catalysts is reported. Ring opening of 7-substituted norbornenes and subsequent ring-closing metathesis forming a thermodynamically stable 6-membered ring lead to a very efficient synthesis of new catalysts from commercially available Grubbs' catalysts. Hydroxy functionalized Grubbs' first- as well as third-generation catalysts have been synthesized. Mechanistic studies have been performed to elucidate the order of attack of the olefinic bonds. This strategy was also used to synthesize the ruthenium methylidene complex.

  3. Ru-Based Z-Selective Metathesis Catalysts with Modified Cyclometalated Carbene Ligands†

    PubMed Central

    Bronner, Sarah M.; Herbert, Myles B.; Patel, Paresma R.; Marx, Vanessa M.; Grubbs, Robert H.

    2014-01-01

    A series of cyclometalated Z-selective ruthenium olefin metathesis catalysts with alterations to the N-heterocyclic carbene (NHC) ligand were prepared. X-Ray crystal structures of several new catalysts were obtained, elucidating the structural features of this class of cyclometalated complexes. The metathesis activity of each stable complex was evaluated, and one catalyst, bearing geminal dimethyl backbone substitution, was found to be comparable to our best Z-selective metathesis catalyst to date. PMID:25346842

  4. Building Indenylidene-Ruthenium Catalysts for Metathesis Transformations

    NASA Astrophysics Data System (ADS)

    Clavier, Hervé; Nolan, Steven P.

    Ruthenium-mediated olefin metathesis has emerged as an indispensable tool in organic synthesis for the formation carbon-carbon double bonds, attested by the large number of applications for natural product synthesis. Among the numerous catalysts developed to mediate olefin metathesis transformations, ruthenium-indenylidene complexes are robust and powerful pre-catalysts. The discovery of this catalyst category was slightly muddled due to a first mis-assignment of the compound structure. This report provides an overview of the synthetic routes for the construction of the indenylidene pattern in ruthenium complexes. The parameters relating to the indenylidene moiety construction will be discussed as well as the mechanism of this formation

  5. Lewis basicity modulation of N-heterocycles: a key for successful cross-metathesis.

    PubMed

    Lafaye, Kevin; Nicolas, Lionel; Guérinot, Amandine; Reymond, Sébastien; Cossy, Janine

    2014-10-03

    Cross-metathesis involving N-heteroaromatic olefinic derivatives is disclosed. The introduction of an appropriate substituent on the heteroaromatic ring decreases the Lewis basicity of the nitrogen atom, thus preventing the deactivation of the ruthenium-centered catalyst. The reaction is quite general in terms of both N-heterocycles and olefinic partners.

  6. Induction of Olefin Metathesis by Acetylenes.

    DTIC Science & Technology

    1980-11-20

    essentially that of 2. The acetylene is thus an activator, but unlike the organometallic co- catalysts like C2 H5A1C1 2 , which it replaces, it is unique in...J.C.; Moulijn, J.A. Adv. Catal. 1975, 24, 131. (4) Some of the results were discussed at the 3rd NSF Workshop on Organo - metallic Chemistry, Pingree

  7. Catalytic Intramolecular Ketone Alkylation with Olefins by Dual Activation.

    PubMed

    Lim, Hee Nam; Dong, Guangbin

    2015-12-07

    Two complementary methods for catalytic intramolecular ketone alkylation reactions with unactivated olefins, resulting in Conia-ene-type reactions, are reported. The transformations are enabled by dual activation of both the ketone and the olefin and are atom-economical as stoichiometric oxidants or reductants are not required. Assisted by Kool's aniline catalyst, the reaction conditions can be both pH- and redox-neutral. A broad range of functional groups are thus tolerated. Whereas the rhodium catalysts are effective for the formation of five-membered rings, a ruthenium-based system that affords the six-membered ring products was also developed.

  8. Methods of making organic compounds by metathesis

    DOEpatents

    Abraham, Timothy W.; Kaido, Hiroki; Lee, Choon Woo; Pederson, Richard L.; Schrodi, Yann; Tupy, Michael John

    2015-09-01

    Described are methods of making organic compounds by metathesis chemistry. The methods of the invention are particularly useful for making industrially-important organic compounds beginning with starting compositions derived from renewable feedstocks, such as natural oils. The methods make use of a cross-metathesis step with an olefin compound to produce functionalized alkene intermediates having a pre-determined double bond position. Once isolated, the functionalized alkene intermediate can be self-metathesized or cross-metathesized (e.g., with a second functionalized alkene) to produce the desired organic compound or a precursor thereto. The method may be used to make bifunctional organic compounds, such as diacids, diesters, dicarboxylate salts, acid/esters, acid/amines, acid/alcohols, acid/aldehydes, acid/ketones, acid/halides, acid/nitriles, ester/amines, ester/alcohols, ester/aldehydes, ester/ketones, ester/halides, ester/nitriles, and the like.

  9. Controlled Ring-Opening Metathesis Polymerization by Molybdenum and Tungsten Alkylidene Complexes

    DTIC Science & Technology

    1988-07-29

    weights and low polydispersities (as low as 1.03) consistent with a living catalyst system employing 50, 100, 200, and 400 eq of monomer. The reactions are...secondary metathesis of polymer chains Bulky alkoxide ligands Wittig-like reaction Ring-opening metathesis polymerization (ROMP) Feast monomer Cyclic...olefins Retro Diels-Alder reaction Norbornene (NBE) Low temperature column chromatography Endo-,endo-5,6-dicarbomethoxynorbornene Discrete, soluble

  10. Hexacoordinate Ru-based olefin metathesis catalysts with pH-responsive N-heterocyclic carbene (NHC) and N-donor ligands for ROMP reactions in non-aqueous, aqueous and emulsion conditions

    PubMed Central

    Balof, Shawna L; Nix, K Owen; Olliff, Matthew S; Roessler, Sarah E; Saha, Arpita; Müller, Kevin B; Behrens, Ulrich; Valente, Edward J

    2015-01-01

    Summary Three new ruthenium alkylidene complexes (PCy3)Cl2(H2ITap)Ru=CHSPh (9), (DMAP)2Cl2(H2ITap)Ru=CHPh (11) and (DMAP)2Cl2(H2ITap)Ru=CHSPh (12) have been synthesized bearing the pH-responsive H2ITap ligand (H2ITap = 1,3-bis(2’,6’-dimethyl-4’-dimethylaminophenyl)-4,5-dihydroimidazol-2-ylidene). Catalysts 11 and 12 are additionally ligated by two pH-responsive DMAP ligands. The crystal structure was solved for complex 12 by X-ray diffraction. In organic, neutral solution, the catalysts are capable of performing standard ring-opening metathesis polymerization (ROMP) and ring closing metathesis (RCM) reactions with standard substrates. The ROMP with complex 11 is accelerated in the presence of two equiv of H3PO4, but is reduced as soon as the acid amount increased. The metathesis of phenylthiomethylidene catalysts 9 and 12 is sluggish at room temperature, but their ROMP can be dramatically accelerated at 60 °C. Complexes 11 and 12 are soluble in aqueous acid. They display the ability to perform RCM of diallylmalonic acid (DAMA), however, their conversions are very low amounting only to few turnovers before decomposition. However, both catalysts exhibit outstanding performance in the ROMP of dicyclopentadiene (DCPD) and mixtures of DCPD with cyclooctene (COE) in acidic aqueous microemulsion. With loadings as low as 180 ppm, the catalysts afforded mostly quantitative conversions of these monomers while maintaining the size and shape of the droplets throughout the polymerization process. Furthermore, the coagulate content for all experiments stayed <2%. This represents an unprecedented efficiency in emulsion ROMP based on hydrophilic ruthenium alkylidene complexes. PMID:26664616

  11. Olefin hydration

    SciTech Connect

    Butt, M.H.D.; Waller, F.J.

    1993-08-03

    An improved process for the hydration of olefins to alcohols is described wherein the improvement comprises contacting said olefins with the catalytic composition comprising a perfluorinated ion-exchange polymer containing sulfonic acid groups supported on an inert carrier wherein said carrier comprises calcined shot coke with a mean pore diameter of about 1,000 Angstroms in the presence of water at a temperature of from about 180 C to about 250 C.

  12. Unconventional olefin processes

    SciTech Connect

    Hu, Y.C.

    1983-05-01

    The conversion of syngas into olefins is based on the Fischer-Tropsch technology. The FT modified process for olefins includes: upgraded liquids for olefins and aromatics, and catcracking of methanol. Because of the number of catalysts for olefins, data is not yet possible. Economic projections suggest that methanol cracking for olefins will be feasible in 1990. Olefin demand will grow, and C/sub 1/ chemistry research will increase, so that some unconventional olefin processes can be commercialized by then.

  13. Bidirectional cross metathesis and ring-closing metathesis/ring opening of a C 2-symmetric building block: a strategy for the synthesis of decanolide natural products

    PubMed Central

    Kunz, Oliver

    2013-01-01

    Summary Starting from the conveniently available ex-chiral pool building block (R,R)-hexa-1,5-diene-3,4-diol, the ten-membered ring lactones stagonolide E and curvulide A were synthesized using a bidirectional olefin-metathesis functionalization of the terminal double bonds. Key steps are (i) a site-selective cross metathesis, (ii) a highly diastereoselective extended tethered RCM to furnish a (Z,E)-configured dienyl carboxylic acid and (iii) a Ru–lipase-catalyzed dynamic kinetic resolution to establish the desired configuration at C9. Ring closure was accomplished by macrolactonization. Curvulide A was synthesized from stagonolide E through Sharpless epoxidation. PMID:24367418

  14. Absence of the Thorpe–Ingold Effect by gem-Diphenyl Groups in Ring-Closing Enyne Metathesis

    PubMed Central

    Kim, Yi Jin; Grimm, Jonathan B.; Lee, Daesung

    2007-01-01

    In tandem ring-closing metathesis of alkynyl silaketals containing two different tethered olefins, the gem-dimethyl group showed the expected Thorpe-Ingold effect, thereby giving good level of group selectivity. Unexpectedly, however, the corresponding gem-diphenyl group did not show any Thorpe-Ingold effect for the ring closure reaction. PMID:18046462

  15. Stereoselective Access to Z- and E-Macrocycles by Ruthenium- Catalyzed Z-Selective Ring-Closing Metathesis and Ethenolysis

    PubMed Central

    Marx, Vanessa M.; Herbert, Myles B.; Keitz, Benjamin K.; Grubbs, Robert H.

    2013-01-01

    The first report of Z-selective macrocyclizations using a ruthenium-based metathesis catalyst is described. Selectivity for Z-macrocycles is consistently high for a diverse set of substrates with a variety of functional groups and ring sizes. The same catalyst was also employed for the Z-selective ethenolysis of a mixture of E and Z macrocycles, providing the pure E-isomer. Notably, only an atmospheric pressure of ethylene was required. These methodologies were successfully applied to the construction of several olfactory macrocycles, as well as the formal total synthesis of the cytotoxic alkaloid motuporamine C. PMID:23244210

  16. Cross metathesis for the synthesis of novel C-sialosides.

    PubMed

    Meinke, Sebastian; Thiem, Joachim

    2008-07-21

    Cross metathesis of both anomers of C-allyl sialoside (3alpha/3beta) with styrene catalyzed by the second generation Grubbs or Hoveyda-Grubbs catalysts gave the corresponding aryl derivatives (4alpha/4beta) in virtually quantitative yields. The products were hydrogenated to model compounds 5alpha/5beta. Similarly, reaction of the alpha-anomer 3alpha with galactose derivative 8 gave the olefin-linked disaccharide mimetic 9. Following hydrogenation and deprotection, the ethylene-bridged Neu5Acalpha(2-->6)Gal analogue 11 could be obtained.

  17. Prosodically Driven Metathesis in Mutsun

    ERIC Educational Resources Information Center

    Butler, Lynnika

    2013-01-01

    Among the many ways in which sounds alternate in the world's languages, changes in the order of sounds (metathesis) are relatively rare. Mutsun, a Southern Costanoan language of California which was documented extensively before the death of its last speaker in 1930, displays three patterns of synchronic consonant-vowel (CV) metathesis. Two of…

  18. Expanding the scope of metathesis: a survey of polyfunctional, single-site supported tungsten systems for hydrocarbon valorization.

    PubMed

    Popoff, Nicolas; Mazoyer, Etienne; Pelletier, Jérémie; Gauvin, Régis M; Taoufik, Mostafa

    2013-12-07

    Olefin metathesis is increasingly incorporated in polyfunctional industrial processes. The classical WO3/SiO2 olefin metathesis catalyst is combined to other catalysts in order to afford higher added-value chemicals. However, the combination of several reactions, not only in a single reactor, but also stemming from a single, multifunctional surface species is a desirable improvement regarding process issues. Well-defined surface organometallic tungsten species can be designed to implement targeted functionalities (carbene, hydride, alkyl, …). By tuning the metal's coordination sphere, it is possible to combine metathesis with several reactions, such as (de)hydrogenation, dimerization or isomerization. Novel, unconventional reactions for the production and upgrading of alkanes and alkenes have thus been uncovered. The reactivity of this library of supported catalysts is discussed based on the type of mediated transformations: monofunctional (alkene and alkyne metathesis), bifunctional (1-butene or 2-butenes to propylene), trifunctional (ethylene to propylene, alkane metathesis, …). Mechanistic considerations will be discussed to put these results in a wider perspective for future developments.

  19. Olefin Metathesis in Peptidomimetics, Dynamic Combinatorial Chemistry, and Molecular Imprinting

    DTIC Science & Technology

    2006-08-01

    inhibitor against an enzyme found in bacteria .26 Scheme 2-3. Retrosynthethic analysis of 2-6...potential HIV protease inhibitors by grafting pharmacophoric groups on a azasugar scaffold (Figure 1-4),46 but a rather lengthy synthetic scheme starting...macrocyclic lactams is shown in Scheme 2- 2, in which Pei et al. discovered that 15-17 membered rings provided the best inhibitor properties against an

  20. Metathesis depolymerizable surfactants

    DOEpatents

    Jamison, Gregory M.; Wheeler, David R.; Loy, Douglas A.; Simmons, Blake A.; Long, Timothy M.; McElhanon, James R.; Rahimian, Kamyar; Staiger, Chad L.

    2008-04-15

    A class of surfactant molecules whose structure includes regularly spaced unsaturation in the tail group and thus, can be readily decomposed by ring-closing metathesis, and particularly by the action of a transition metal catalyst, to form small molecule products. These small molecules are designed to have increased volatility and/or enhanced solubility as compared to the original surfactant molecule and are thus easily removed by solvent extraction or vacuum extraction at low temperature. By producing easily removable decomposition products, the surfactant molecules become particularly desirable as template structures for preparing meso- and microstructural materials with tailored properties.

  1. Facile synthesis of brush poly(phosphoamidate)s via one-pot tandem ring-opening metathesis polymerization and atom transfer radical polymerization.

    PubMed

    Ding, Liang; Qiu, Jun; Wei, Jun; Zhu, Zhenshu

    2014-09-01

    Poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA)-based brush poly(phosphoamidate)s are successfully synthesized by a combination of ring-opening metathesis polymerization (ROMP) and atom transfer radical polymerization (ATRP) following either a commutative two-step procedure or a straightforward one-pot process using Grubbs ruthenium-based catalysts for tandem catalysis. Compared with the traditional polymerization method, combining ROMP and ATRP in a one-pot process allows the preparation of brush copolymers characterized by a relatively moderate molecular weight distribution and quantitative conversion of monomer. Moreover, the surface morphologies and aggregation behaviors of these polymers are studied by AFM and TEM measurements.

  2. New ruthenium-based protocol for cleavage of terminal olefins to primary alcohols: improved synthesis of a bicyclic nucleoside.

    PubMed

    Sharma, Pawan K; Nielsen, Poul

    2004-08-20

    A new protocol for the oxidative cleavage of terminal alkenes to give exclusively primary alcohols in high yields is introduced. The protocol is based on RuO4-mediated dihydroxylation, NaIO4-mediated diol cleavage, and NaBH4-mediated reduction, but the introduction of a reducing step before the diol cleavage removes the formation of byproducts and improves the yield significantly. The new protocol has been developed and used for the improved preparation of a [3.2.0]bicycloarabinonucleoside with important potential in antisense and antigene technology.

  3. Catalytic living ring-opening metathesis polymerization

    NASA Astrophysics Data System (ADS)

    Nagarkar, Amit A.; Kilbinger, Andreas F. M.

    2015-09-01

    In living ring-opening metathesis polymerization (ROMP), a transition-metal-carbene complex polymerizes ring-strained olefins with very good control of the molecular weight of the resulting polymers. Because one molecule of the initiator is required for each polymer chain, however, this type of polymerization is expensive for widespread use. We have now designed a chain-transfer agent (CTA) capable of reducing the required amount of metal complex while still maintaining full control over the living polymerization process. This new method introduces a degenerative transfer process to ROMP. We demonstrate that substituted cyclohexene rings are good CTAs, and thereby preserve the ‘living’ character of the polymerization using catalytic quantities of the metal complex. The resulting polymers show characteristics of a living polymerization, namely narrow molecular-weight distribution, controlled molecular weights and block copolymer formation. This new technique provides access to well-defined polymers for industrial, biomedical and academic use at a fraction of the current costs and significantly reduced levels of residual ruthenium catalyst.

  4. Acyclic diene metathesis with a monomer from renewable resources: control of molecular weight and one-step preparation of block copolymers.

    PubMed

    Rybak, Anastasiya; Meier, Michael A R

    2008-01-01

    The preparation of a long-chain aliphatic alpha,omega-diene from plant oil derivatives and its subsequent polymerization through acyclic diene metathesis (ADMET) is described. The ADMET bulk polymerization of the thus-obtained monomer, undecyl undecenoate, was investigated and optimized by applying ruthenium-based metathesis catalysts from Grubbs and Hoveyda-Grubbs, leading to high-molecular-weight polyesters. Moreover, by applying different amounts of methyl 10-undecenoate as a chain stopper in this ADMET step growth polymerization, the molecular weight of the resulting polyester could be tuned in a range from approximately 10 to 45 kDa. Finally, the application of a poly(ethylene glycol) methyl ether acrylate as the chain stopper led to the preparation of ABA triblock copolymers in a one-step, one-pot procedure.

  5. Tandem Z-selective cross metathesis – dihydroxylation for the synthesis of anti-1,2-diols**

    PubMed Central

    Dornan, Peter K.; Wickens, Zachary K.

    2015-01-01

    A stereoselective synthesis of anti-1,2-diols has been developed using a multitasking Ru-catalyst in an assisted tandem catalysis protocol. A cyclometalated ruthenium complex catalyzes first a Z-selective cross metathesis of two terminal olefins followed by a stereospecific dihydroxylation. Both steps are catalyzed by Ru, as the Ru-complex is converted to a dihydroxylation catalyst upon addition of NaIO4. A variety of olefins are transformed into valuable highly functionalized and stereodefined molecules. Mechanistic experiments are performed to probe the nature of the oxidation step and catalyst inhibition pathways. These experiments point the way to more broadly applicable tandem catalytic transformations. PMID:25914354

  6. Tandem cross enyne metathesis (CEYM)–intramolecular Diels–Alder reaction (IMDAR). An easy entry to linear bicyclic scaffolds

    PubMed Central

    Miró, Javier; Sánchez-Roselló, María; Sanz, Álvaro; Rabasa, Fernando

    2015-01-01

    Summary A new tandem cross enyne metathesis (CEYM)–intramolecular Diels–Alder reaction (IMDAR) has been carried out. It involves conjugated ketones, esters or amides bearing a remote olefin and aromatic alkynes as the starting materials. The overall process enables the preparation of a small family of linear bicyclic scaffolds in a very simple manner with moderate to good levels of diastereoselectivity. This methodology constitutes one of the few examples that employ olefins differently than ethylene in tandem CEYM–IMDAR protocols. PMID:26425205

  7. Single-Molecule Visualization of Living Polymerization

    DTIC Science & Technology

    2014-02-18

    siloxane bond†. Langmuir 24, 1343-1349 (2007). 4 M. Scholl, S. Ding, C. W. Lee & R. H. Grubbs. Synthesis and activity of a new generation of ruthenium ...Vougioukalakis & G. R. H. Ruthenium -based heterocyclic carbene-coordinated olefin metathesis catalysts. Chem Rev 110 (2010). 6 T. Lionnet, J. F. Allemand...2012). 10 X. Bantreil & S. P. Nolan. Synthesis of n-heterocyclic carbene ligands and derived ruthenium olefin metathesis catalysts. Nat Protoc 6, 69

  8. Alkene metathesis: the search for better catalysts.

    PubMed

    Deshmukh, Prashant H; Blechert, Siegfried

    2007-06-28

    Alkene metathesis catalyst development has made significant progress over recent years. Research in metathesis catalyst design has endeavoured to tackle three key issues: those of (i) catalyst efficiency and activity, (ii) substrate scope and selectivity--particularly stereoselective metathesis reactions--and (iii) the minimization of metal impurities and catalyst recycling. This article describes a brief history of metathesis catalyst development, followed by a survey of more recent research, with a particular emphasis on ruthenium catalysts.

  9. Relay cross metathesis reactions of vinylphosphonates.

    PubMed

    Malla, Raj K; Ridenour, Jeremy N; Spilling, Christopher D

    2014-01-01

    Dimethyl (β-substituted) vinylphosphonates do not readily undergo cross metathesis reactions with Grubbs catalyst and terminal alkenes. However, the corresponding mono- or diallyl vinylphosphonate esters undergo facile cross metathesis reactions. The improved reactivity is attributed to a relay step in the cross metathesis reaction mechanism.

  10. Synthesis of Catenane Structures via Ring-Closing Metathesis.

    PubMed

    Weck, Marcus; Mohr, Bernhard; Sauvage, Jean-Pierre; Grubbs, Robert H.

    1999-07-23

    This study presents a detailed description of a synthetic strategy to obtain catenane architectures through ring-closing metathesis. The approach is based on phenanthroline-based ligands containing terminal olefinic units that were designed to coordinate in a tetrahedral arrangement around a copper atom. Treatment of the assembled copper complexes with ruthenium catalyst 1 resulted in [2]catenates in high yields of 88-92%. Demetalation produced the corresponding [2]catenand in nearly quantitative yields. Hydrogenation of the catenates with Crabtree's catalyst and subsequent demetalation yielded fully saturated catenands. The presently described procedure makes [2]catenanes very accessible since the synthetic route consists of six steps (Schemes 2 and 4) from commercially available 1,10-phenanthroline, the overall yield being 51%.

  11. Cascade Metathesis Reactions for the Synthesis of Taxane and Isotaxane Derivatives

    PubMed Central

    Ma, Cong; Letort, Aurélien; Aouzal, Rémi; Wilkes, Antonia; Maiti, Gourhari; Farrugia, Louis J.; Ricard, Louis

    2016-01-01

    Abstract Tricyclic isotaxane and taxane derivatives have been synthesized by a very efficient cascade ring‐closing dienyne metathesis (RCDEYM) reaction, which formed the A and B rings in one operation. When the alkyne is present at C13 (with no neighboring gem‐dimethyl group), the RCEDYM reaction leads to 14,15‐isotaxanes 16 a,b and 18 b with the gem‐dimethyl group on the A ring. If the alkyne is at the C11 position (and thus flanked by a gem‐dimethyl group), RCEDYM reaction only proceeds in the presence of a trisubstituted olefin at C13, which disfavors the competing diene ring‐closing metathesis reaction, to give the tricyclic core of Taxol 44. PMID:27062670

  12. Structural basis and anticancer properties of ruthenium-based drug complexed with human serum albumin.

    PubMed

    Zhang, Yao; Ho, Andy; Yue, Jiping; Kong, Linlin; Zhou, Zuping; Wu, Xiaoyang; Yang, Feng; Liang, Hong

    2014-10-30

    Ruthenium-based anticancer complexes have become increasingly popular for study over the last two decades. Although ruthenium complexes are currently being investigated in clinical trials, there are still some difficulties with their delivery and associated side effects. Human serum albumin (HSA)-based delivery systems are promising for improving anticancer drug targeting and reducing negative side effects. However, there have been few studies regarding the HSA delivery system for metal-based anticancer compounds and no mention of its structural mechanism. Therefore, we studied the structure and anticancer properties of the ruthenium-based compound [RuCl5(ind)](2-) in complex with HSA. The structure revealed that [RuCl5(ind)](2-) has two binding sites in HSA. In the IB subdomain, [RuCl5(ind)](2-) binds to a new sub-site by coordinating with His-146. In the IIA subdomain, ruthenium (III) of [RuCl5(ind)](2-) binds to the hydrophobic cavity and forms coordination bonds by replacing chlorine atoms with the His-242 and Lys-199 residues of HSA. Interestingly, [RuCl5(ind)](2-), together with HSA, can enhance cytotoxicity by two to five times in cancer cells but has no effect on normal cells in vitro. Compared with unbound drug, the HSA-[RuCl5(ind)](2-) complex promotes MGC-803 cell apoptosis and also has a stronger capacity for cell cycle arrest at the G2 phase in MGC-803. In conclusion, this study will guide the rational design and development of ruthenium-containing or ruthenium-centered drugs and an HSA delivery system for ruthenium-based drugs.

  13. A ruthenium-based biomimetic hydrogen cluster for efficient photocatalytic hydrogen generation from formic acid.

    PubMed

    Chang, Chin-Hao; Chen, Mei-Hua; Du, Wan-Shan; Gliniak, Jacek; Lin, Jia-Hoa; Wu, Hsin-Hua; Chan, Hsin-Fang; Yu, Jen-Shiang K; Wu, Tung-Kung

    2015-04-20

    A ruthenium-based biomimetic hydrogen cluster, [Ru2 (CO)6 (μ-SCH2 CH2 CH2 S)] (1), has been synthesized and, in the presence of the P ligand tri(o-tolyl)phosphine, demonstrated efficient photocatalytic hydrogen generation from formic acid decomposition. Turnover frequencies (TOFs) of 5500 h(-1) and turnover numbers (TONs) over 24 700 were obtained with less than 50 ppm of the catalyst, thus representing the highest TOFs for ruthenium complexes as well as the best efficiency for photocatalytic hydrogen production from formic acid. Moreover, 1 showed high stability with no significant degradation of the photocatalyst observed after prolonged photoirradiation at 90 °C.

  14. A ring closing metathesis strategy for carbapyranosides of xylose and arabinose.

    PubMed

    Mattis, Clayton E; Mootoo, David R

    2016-06-24

    The synthesis of β-carba-xylo and arabino pyranosides of cholestanol is described. The synthetic strategy, which is analogous to the Postema approach to C-glycosides, centers on the ring closing metathesis of an enol ether-alkene precursor to give a cyclic enol ether that is elaborated to a carba-pyranoside via hydroboration-oxidation on the olefin. The method, which is attractive for its modularity and stereoselectivity, may find wider applications to carba-hexopyranosides and other complex cycloalkyl ether frameworks.

  15. A ring closing metathesis strategy for carbapyranosides of xylose and arabinose.

    PubMed

    Mattis, Clayton E; Mootoo, David R

    2016-04-29

    The synthesis of β-carba-xylo and arabino pyranosides of cholestanol is described. The synthetic strategy, which is analogous to the Postema approach to C-glycosides, centers on the ring closing metathesis of an enol ether-alkene precursor to give a cyclic enol ether that is elaborated to a carba-pyranoside via hydroboration-oxidation on the olefin. The method, which is attractive for its modularity and stereoselectivity, may find wider applications to carba-hexopyranosides and other complex cycloalkyl ether frameworks.

  16. Kinetically E-selective macrocyclic ring-closing metathesis.

    PubMed

    Shen, Xiao; Nguyen, Thach T; Koh, Ming Joo; Xu, Dongmin; Speed, Alexander W H; Schrock, Richard R; Hoveyda, Amir H

    2017-01-19

    Macrocyclic compounds are central to the development of new drugs, but preparing them can be challenging because of the energy barrier that must be surmounted in order to bring together and fuse the two ends of an acyclic precursor such as an alkene (also known as an olefin). To this end, the catalytic process known as ring-closing metathesis (RCM) has allowed access to countless biologically active macrocyclic organic molecules, even for large-scale production. Stereoselectivity is often critical in such cases: the potency of a macrocyclic compound can depend on the stereochemistry of its alkene; alternatively, one isomer of the compound can be subjected to stereoselective modification (such as dihydroxylation). Kinetically controlled Z-selective RCM reactions have been reported, but the only available metathesis approach for accessing macrocyclic E-olefins entails selective removal of the Z-component of a stereoisomeric mixture by ethenolysis, sacrificing substantial quantities of material if E/Z ratios are near unity. Use of ethylene can also cause adventitious olefin isomerization-a particularly serious problem when the E-alkene is energetically less favoured. Here, we show that dienes containing an E-alkenyl-B(pinacolato) group, widely used in catalytic cross-coupling, possess the requisite electronic and steric attributes to allow them to be converted stereoselectively to E-macrocyclic alkenes. The reaction is promoted by a molybdenum monoaryloxide pyrrolide complex and affords products at a yield of up to 73 per cent and an E/Z ratio greater than 98/2. We highlight the utility of the approach by preparing recifeiolide (a 12-membered-ring antibiotic) and pacritinib (an 18-membered-ring enzyme inhibitor), the Z-isomer of which is less potent than the E-isomer. Notably, the 18-membered-ring moiety of pacritinib-a potent anti-cancer agent that is in advanced clinical trials for treating lymphoma and myelofibrosis-was prepared by RCM carried out at a substrate

  17. Kinetically E-selective macrocyclic ring-closing metathesis

    NASA Astrophysics Data System (ADS)

    Shen, Xiao; Nguyen, Thach T.; Koh, Ming Joo; Xu, Dongmin; Speed, Alexander W. H.; Schrock, Richard R.; Hoveyda, Amir H.

    2017-01-01

    Macrocyclic compounds are central to the development of new drugs, but preparing them can be challenging because of the energy barrier that must be surmounted in order to bring together and fuse the two ends of an acyclic precursor such as an alkene (also known as an olefin). To this end, the catalytic process known as ring-closing metathesis (RCM) has allowed access to countless biologically active macrocyclic organic molecules, even for large-scale production. Stereoselectivity is often critical in such cases: the potency of a macrocyclic compound can depend on the stereochemistry of its alkene; alternatively, one isomer of the compound can be subjected to stereoselective modification (such as dihydroxylation). Kinetically controlled Z-selective RCM reactions have been reported, but the only available metathesis approach for accessing macrocyclic E-olefins entails selective removal of the Z-component of a stereoisomeric mixture by ethenolysis, sacrificing substantial quantities of material if E/Z ratios are near unity. Use of ethylene can also cause adventitious olefin isomerization—a particularly serious problem when the E-alkene is energetically less favoured. Here, we show that dienes containing an E-alkenyl–B(pinacolato) group, widely used in catalytic cross-coupling, possess the requisite electronic and steric attributes to allow them to be converted stereoselectively to E-macrocyclic alkenes. The reaction is promoted by a molybdenum monoaryloxide pyrrolide complex and affords products at a yield of up to 73 per cent and an E/Z ratio greater than 98/2. We highlight the utility of the approach by preparing recifeiolide (a 12-membered-ring antibiotic) and pacritinib (an 18-membered-ring enzyme inhibitor), the Z-isomer of which is less potent than the E-isomer. Notably, the 18-membered-ring moiety of pacritinib—a potent anti-cancer agent that is in advanced clinical trials for treating lymphoma and myelofibrosis—was prepared by RCM carried out at a

  18. Selective olefin recovery

    SciTech Connect

    1996-07-01

    This report presents the results of the outstanding studies on olefin product purities, pyridine recovery, and absorber offgas utilization. Other reports issued since the May 2 technical review meeting in Grangemouth evaluated the impact of the new VLE data on the solution stripping operation and the olefin loadings in the lean and rich solutions. This report completes the bulk of Stone & Webster`s engineering development of the absorber/stripper process for Phase I. The final feasibility study report (to be issued in August) will present an updated design and economics.

  19. Living olefin polymerization processes

    DOEpatents

    Schrock, R.R.; Baumann, R.

    1999-03-30

    Processes for the living polymerization of olefin monomers with terminal carbon-carbon double bonds are disclosed. The processes employ initiators that include a metal atom and a ligand having two group 15 atoms and a group 16 atom or three group 15 atoms. The ligand is bonded to the metal atom through two anionic or covalent bonds and a dative bond. The initiators are particularly stable under reaction conditions in the absence of olefin monomer. The processes provide polymers having low polydispersities, especially block copolymers having low polydispersities. It is an additional advantage of these processes that, during block copolymer synthesis, a relatively small amount of homopolymer is formed.

  20. Living olefin polymerization processes

    DOEpatents

    Schrock, Richard R.; Baumann, Robert

    1999-01-01

    Processes for the living polymerization of olefin monomers with terminal carbon-carbon double bonds are disclosed. The processes employ initiators that include a metal atom and a ligand having two group 15 atoms and a group 16 atom or three group 15 atoms. The ligand is bonded to the metal atom through two anionic or covalent bonds and a dative bond. The initiators are particularly stable under reaction conditions in the absence of olefin monomer. The processes provide polymers having low polydispersities, especially block copolymers having low polydispersities. It is an additional advantage of these processes that, during block copolymer synthesis, a relatively small amount of homopolymer is formed.

  1. Living olefin polymerization processes

    DOEpatents

    Schrock, Richard R.; Baumann, Robert

    2003-08-26

    Processes for the living polymerization of olefin monomers with terminal carbon-carbon double bonds are disclosed. The processes employ initiators that include a metal atom and a ligand having two group 15 atoms and a group 16 atom or three group 15 atoms. The ligand is bonded to the metal atom through two anionic or covalent bonds and a dative bond. The initiators are particularly stable under reaction conditions in the absence of olefin monomer. The processes provide polymers having low polydispersities, especially block copolymers having low polydispersities. It is an additional advantage of these processes that, during block copolymer synthesis, a relatively small amount of homopolymer is formed.

  2. Living olefin polymerization processes

    DOEpatents

    Schrock, Richard R.; Bauman, Robert

    2006-11-14

    Processes for the living polymerization of olefin monomers with terminal carbon-carbon double bonds are disclosed. The processes employ initiators that include a metal atom and a ligand having two group 15 atoms and a group 16 atom or three group 15 atoms. The ligand is bonded to the metal atom through two anionic or covalent bonds and a dative bond. The initiators are particularly stable under reaction conditions in the absence of olefin monomer. The processes provide polymers having low polydispersities, especially block copolymers having low polydispersities. It is an additional advantage of these processes that, during block copolymer synthesis, a relatively small amount of homopolymer is formed.

  3. Retrofitting olefin cracking plants

    SciTech Connect

    Sumner, C.; Fernandez-Baujin, J.M.

    1983-12-01

    This article discusses the retrofitting of liquid crackers which produce olefins so that gaseous feedstocks can be used. Naphtha and gas oil are the predominant design feedstocks for producing olefins. The price of gaseous feedstocks such as ethane, propane and butane have become economically more attractive than liquid feedstocks. Existing liquid crackers will be able to produce ethylene at 85% or higher capacity when cracking propane and butane feedstock with only minor changes. Topics considered include revamping for vacuum gas oil (VGO) feedstocks and revamping for liquefied petroleum gas (LPG) feedstocks.

  4. Catalytic σ-Bond Metathesis

    NASA Astrophysics Data System (ADS)

    Reznichenko, Alexander L.; Hultzsch, Kai C.

    This account summarizes information on recently reported applications of organo-rare-earth metal complexes in various catalytic transformations of small molecules. The σ-bond metathesis at d0rare-earth metal centers plays a pivotal role in carbon-carbon and carbon-heteroatom bond forming processes. Relevant mechanistic details are discussed and the focus of the review lies in practical applications of organo-rare-earth metal complexes.

  5. Hydrogen Production from Aqueous Solutions of Urea with Ruthenium-based Catalysts.

    PubMed

    Furukawa, Shinya; Suzuki, Ryohei; Ochi, Kazuyoshi; Yashima, Tatsuaki; Komatsu, Takayuki

    2015-06-22

    An efficient catalytic system for hydrogen production from aqueous solution of urea was developed using ruthenium-based catalysts as an alternative for existing systems based on several H2 carriers. Ru/SiO2 showed the highest H2 yield among various SiO2 -supported transition-metal catalysts. Optimization of the catalyst support revealed that Ru/Al2 O3 exhibited the best catalytic performance, with a minimum amount of CO formed as a by-product (1.8 mol %). A mechanistic study suggested that the reaction proceeds mainly via two steps: urea hydrolysis (H2 NCONH2 +H2 O→2 NH3 +CO2 ) followed by NH3 decomposition (2 NH3 →3 H2 +N2 ).

  6. Direct synthesis of Z-alkenyl halides through catalytic cross-metathesis

    PubMed Central

    Koh, Ming Joo; Nguyen, Thach T.; Zhang, Hanmo; Schrock, Richard R.; Hoveyda, Amir H.

    2016-01-01

    Olefin metathesis has made a significant impact on modern organic chemistry, but important shortcomings remain: for example, the lack of efficient processes that can be used to generate acyclic alkenyl halides. Halo-substituted ruthenium carbene complexes decompose rapidly or deliver low activity and/or minimal stereoselectivity, and our understanding of the corresponding high-oxidation-state systems is very limited. In this manuscript, we show that previously unknown halo-substituted molybdenum alkylidene species are exceptionally reactive and are able to participate in high-yielding olefin metathesis reactions that afford acyclic 1,2-disubstituted Z-alkenyl halides. Transformations are promoted by small amounts of an in situ-generated catalyst with unpurified, commercially available and easy-to-handle liquid 1,2-dihaloethene reagents and proceed to high conversion at ambient temperature within four hours. Many alkenyl chlorides, bromides and fluorides can be obtained in up to 91 percent yield and complete Z selectivity. This method can be used to easily synthesize biologically active compounds and to perform the site- and stereoselective fluorination of other organic compounds. PMID:27008965

  7. Direct synthesis of Z-alkenyl halides through catalytic cross-metathesis

    NASA Astrophysics Data System (ADS)

    Koh, Ming Joo; Nguyen, Thach T.; Zhang, Hanmo; Schrock, Richard R.; Hoveyda, Amir H.

    2016-03-01

    Olefin metathesis has had a large impact on modern organic chemistry, but important shortcomings remain: for example, the lack of efficient processes that can be used to generate acyclic alkenyl halides. Halo-substituted ruthenium carbene complexes decompose rapidly or deliver low activity and/or minimal stereoselectivity, and our understanding of the corresponding high-oxidation-state systems is limited. Here we show that previously unknown halo-substituted molybdenum alkylidene species are exceptionally reactive and are able to participate in high-yielding olefin metathesis reactions that afford acyclic 1,2-disubstituted Z-alkenyl halides. Transformations are promoted by small amounts of a catalyst that is generated in situ and used with unpurified, commercially available and easy-to-handle liquid 1,2-dihaloethene reagents, and proceed to high conversion at ambient temperature within four hours. We obtain many alkenyl chlorides, bromides and fluorides in up to 91 per cent yield and complete Z selectivity. This method can be used to synthesize biologically active compounds readily and to perform site- and stereoselective fluorination of complex organic molecules.

  8. Directed evolution of artificial metalloenzymes for in vivo metathesis.

    PubMed

    Jeschek, Markus; Reuter, Raphael; Heinisch, Tillmann; Trindler, Christian; Klehr, Juliane; Panke, Sven; Ward, Thomas R

    2016-09-29

    The field of biocatalysis has advanced from harnessing natural enzymes to using directed evolution to obtain new biocatalysts with tailor-made functions. Several tools have recently been developed to expand the natural enzymatic repertoire with abiotic reactions. For example, artificial metalloenzymes, which combine the versatile reaction scope of transition metals with the beneficial catalytic features of enzymes, offer an attractive means to engineer new reactions. Three complementary strategies exist: repurposing natural metalloenzymes for abiotic transformations; in silico metalloenzyme (re-)design; and incorporation of abiotic cofactors into proteins. The third strategy offers the opportunity to design a wide variety of artificial metalloenzymes for non-natural reactions. However, many metal cofactors are inhibited by cellular components and therefore require purification of the scaffold protein. This limits the throughput of genetic optimization schemes applied to artificial metalloenzymes and their applicability in vivo to expand natural metabolism. Here we report the compartmentalization and in vivo evolution of an artificial metalloenzyme for olefin metathesis, which represents an archetypal organometallic reaction without equivalent in nature. Building on previous work on an artificial metallohydrolase, we exploit the periplasm of Escherichia coli as a reaction compartment for the 'metathase' because it offers an auspicious environment for artificial metalloenzymes, mainly owing to low concentrations of inhibitors such as glutathione, which has recently been identified as a major inhibitor. This strategy facilitated the assembly of a functional metathase in vivo and its directed evolution with substantially increased throughput compared to conventional approaches that rely on purified protein variants. The evolved metathase compares favourably with commercial catalysts, shows activity for different metathesis substrates and can be further evolved in

  9. Directed evolution of artificial metalloenzymes for in vivo metathesis

    NASA Astrophysics Data System (ADS)

    Jeschek, Markus; Reuter, Raphael; Heinisch, Tillmann; Trindler, Christian; Klehr, Juliane; Panke, Sven; Ward, Thomas R.

    2016-09-01

    The field of biocatalysis has advanced from harnessing natural enzymes to using directed evolution to obtain new biocatalysts with tailor-made functions. Several tools have recently been developed to expand the natural enzymatic repertoire with abiotic reactions. For example, artificial metalloenzymes, which combine the versatile reaction scope of transition metals with the beneficial catalytic features of enzymes, offer an attractive means to engineer new reactions. Three complementary strategies exist: repurposing natural metalloenzymes for abiotic transformations; in silico metalloenzyme (re-)design; and incorporation of abiotic cofactors into proteins. The third strategy offers the opportunity to design a wide variety of artificial metalloenzymes for non-natural reactions. However, many metal cofactors are inhibited by cellular components and therefore require purification of the scaffold protein. This limits the throughput of genetic optimization schemes applied to artificial metalloenzymes and their applicability in vivo to expand natural metabolism. Here we report the compartmentalization and in vivo evolution of an artificial metalloenzyme for olefin metathesis, which represents an archetypal organometallic reaction without equivalent in nature. Building on previous work on an artificial metallohydrolase, we exploit the periplasm of Escherichia coli as a reaction compartment for the ‘metathase’ because it offers an auspicious environment for artificial metalloenzymes, mainly owing to low concentrations of inhibitors such as glutathione, which has recently been identified as a major inhibitor. This strategy facilitated the assembly of a functional metathase in vivo and its directed evolution with substantially increased throughput compared to conventional approaches that rely on purified protein variants. The evolved metathase compares favourably with commercial catalysts, shows activity for different metathesis substrates and can be further evolved in

  10. Metathesis in the generation of low-temperature gas in marine shales

    PubMed Central

    2010-01-01

    The recent report of low-temperature catalytic gas from marine shales took on additional significance with the subsequent disclosure of natural gas and low-temperature gas at or near thermodynamic equilibrium in methane, ethane, and propane. It is important because thermal cracking, the presumed source of natural gas, cannot generate these hydrocarbons at equilibrium nor can it bring them to equilibrium over geologic time. The source of equilibrium and the source of natural gas are either the same (generation under equilibrium control) or closely associated. Here we report the catalytic interconversion of hydrocarbons (metathesis) as the source of equilibrium in experiments with Cretaceous Mowry shale at 100°C. Focus was on two metathetic equilibria: methane, ethane, and propane, reported earlier, Q (K = [(C1)*(C3)]/[(C2)2]), and between these hydrocarbons and n-butane, Q* (K = [(C1)*(n-C4)]/[(C2)*(C3)]), reported here for the first time. Two observations stand out. Initial hydrocarbon products are near equilibrium and have maximum average molecular weights (AMW). Over time, products fall from equilibrium and AMW in concert. It is consistent with metathesis splitting olefin intermediates [Cn] to smaller intermediates (fission) as gas generation creates open catalytic sites ([ ]): [Cn] + [ ] → [Cn-m] + [Cm]. Fission rates increasing exponentially with olefin molecular weight could contribute to these effects. AMW would fall over time, and selective fission of [C3] and [n-C4] would draw Q and Q* from equilibrium. The results support metathesis as the source of thermodynamic equilibrium in natural gas. PMID:20142998

  11. Metathesis in the generation of low-temperature gas in marine shales.

    PubMed

    Mango, Frank D; Jarvie, Daniel M

    2010-01-20

    The recent report of low-temperature catalytic gas from marine shales took on additional significance with the subsequent disclosure of natural gas and low-temperature gas at or near thermodynamic equilibrium in methane, ethane, and propane. It is important because thermal cracking, the presumed source of natural gas, cannot generate these hydrocarbons at equilibrium nor can it bring them to equilibrium over geologic time. The source of equilibrium and the source of natural gas are either the same (generation under equilibrium control) or closely associated. Here we report the catalytic interconversion of hydrocarbons (metathesis) as the source of equilibrium in experiments with Cretaceous Mowry shale at 100 degrees C. Focus was on two metathetic equilibria: methane, ethane, and propane, reported earlier, Q (K = [(C(1))*(C(3))]/[(C(2))(2)]), and between these hydrocarbons and n-butane, Q* (K = [(C(1))*(n-C(4))]/[(C(2))*(C(3))]), reported here for the first time. Two observations stand out. Initial hydrocarbon products are near equilibrium and have maximum average molecular weights (AMW). Over time, products fall from equilibrium and AMW in concert. It is consistent with metathesis splitting olefin intermediates [C(n)] to smaller intermediates (fission) as gas generation creates open catalytic sites ([ ]): [C(n)] + [ ] --> [C(n-m)] + [C(m)]. Fission rates increasing exponentially with olefin molecular weight could contribute to these effects. AMW would fall over time, and selective fission of [C(3)] and [n-C(4)] would draw Q and Q* from equilibrium. The results support metathesis as the source of thermodynamic equilibrium in natural gas.

  12. Candle and candle wax containing metathesis and metathesis-like products

    DOEpatents

    Murphy, Timothy A; Tupy, Michael J; Abraham, Timothy W; Shafer, Andy

    2014-12-16

    A wax comprises a metathesis product and/or a product that resembles, at least in part, a product which may be formed from a metathesis reaction. The wax may be used to form articles for example, candles (container candles, votive candles, and/or a pillar candles), crayons, fire logs or tarts. The wax commonly includes other components in addition to the metathesis product.

  13. Candle and candle wax containing metathesis and metathesis-like products

    DOEpatents

    Murphy, Timothy A; Tupy, Michael J; Abraham, Timothy W; Shafer, Andy

    2014-04-01

    A wax comprises a metathesis product and/or a product that resembles, at least in part, a product which may be formed from a metathesis reaction. The wax may be used to form articles, for example, candles (container candles, votive candles, and/or a pillar candles), crayons, fire logs, or tarts. The wax commonly includes other components in addition to the metathesis product.

  14. Phosphate Tether-Mediated Ring-Closing Metathesis for the Generation of P-Stereogenic, Z-Configured Bicyclo[7.3.1]- and Bicyclo[8.3.1]phosphates.

    PubMed

    Markley, Jana L; Maitra, Soma; Hanson, Paul R

    2016-02-05

    A phosphate tether-mediated ring-closing metathesis (RCM) study to the synthesis of Z-configured, P-stereogenic bicyclo[7.3.1]- and bicyclo[8.3.1]phosphates is reported. Investigations suggest that C3-substitution, olefin substitution, and proximity of the forming olefin to the bridgehead carbon of the bicyclic affect the efficiency and stereochemical outcome of the RCM event. This study demonstrates the utility of phosphate tether-mediated desymmetrization of C2-symmetric, 1,3-anti-diol-containing dienes in the generation of macrocyclic phosphates with potential synthetic and biological utility.

  15. Metathesis transformations of natural products: cross-metathesis of natural rubber and mandarin oil by Ru-alkylidene catalysts.

    PubMed

    Martínez, Araceli; Gutiérrez, Selena; Tlenkopatchev, Mikhail A

    2012-05-18

    This study reports on the degradation of natural rubber (NR) via crossmetathesis with mandarin oil and d-limonene, an abundant compound in essential oils; that were used as chain transfer agents (CTAs) and green solvents. Reactions were performed in the presence of the ruthenium-alkylidene catalysts (PCy₃)₂(Cl)₂Ru=CHPh (I) and (1,3-dimesityl-4,5-dihydroimidazol-2-ylidene) (PCy₃)Cl₂Ru=CHPh (II), respectively. Catalyst II bears an N-heterocyclic carbene ligand (NHC) bounded to the ruthenium atom, which has a strong basic character; therefore it is more active toward trisubstituted olefins in comparison with catalyst I. In both cases, isolated monoterpene-terminated isoprene oligomers were obtained as products of the cross-metathesis degradation of NR. In the presence of catalyst II molecular weight values around M(n) × 10² and yields of 80% were obtained; whereas with catalyst I, the molecular weights of products were about M(n) × 10⁴ with yields ranging 70 to 74%. The composition and yield of NR degradation products were determined by GC/MS (EI) analysis and it was found that the oligomers obtained have primarily one vinyl group and one terpene-monocyclic group at the chain end, with isoprene units A(m) = 2, 3 y 4.

  16. Alkyne metathesis on the rise.

    PubMed

    Fürstner, Alois

    2013-03-04

    The early years of alkyne metathesis were marked by a somewhat ironic state of affairs: the proposed mechanism was swiftly validated and more than one effective catalyst became available shortly after the discovery of this transformation; surprisingly, however, the impact on synthesis remained very limited for a long period of time. Recent advances, however, suggest that this situation is about to change: the remarkable activity, functional-group tolerance, and reliability of the latest generation of catalysts open the door for highly advanced applications. The resulting (cyclo)alkynes are amenable to numerous postmetathetic transformations, which diversify the product portfolio and bring many different structural motifs into reach. Since the catalysts have also evolved from the glovebox to the benchtop, there should be little barrier left for a wider use of this reaction in organic synthesis.

  17. Recent applications of ring-rearrangement metathesis in organic synthesis.

    PubMed

    Kotha, Sambasivarao; Meshram, Milind; Khedkar, Priti; Banerjee, Shaibal; Deodhar, Deepak

    2015-01-01

    Ring-rearrangement metathesis (RRM) involves multiple metathesis processes such as ring-opening metathesis (ROM)/ring-closing metathesis (RCM) in a one-pot operation to generate complex targets. RRM delivers complex frameworks that are difficult to assemble by conventional methods. The noteworthy point about this type of protocol is multi-bond formation and it is an atom economic process. In this review, we have covered literature that appeared during the last seven years (2008-2014).

  18. Recent applications of ring-rearrangement metathesis in organic synthesis

    PubMed Central

    Meshram, Milind; Khedkar, Priti; Banerjee, Shaibal; Deodhar, Deepak

    2015-01-01

    Summary Ring-rearrangement metathesis (RRM) involves multiple metathesis processes such as ring-opening metathesis (ROM)/ring-closing metathesis (RCM) in a one-pot operation to generate complex targets. RRM delivers complex frameworks that are difficult to assemble by conventional methods. The noteworthy point about this type of protocol is multi-bond formation and it is an atom economic process. In this review, we have covered literature that appeared during the last seven years (2008–2014). PMID:26664603

  19. High-value alcohols and higher-oxidation-state compounds by catalytic Z-selective cross-metathesis

    NASA Astrophysics Data System (ADS)

    Koh, Ming Joo; Khan, R. Kashif M.; Torker, Sebastian; Yu, Miao; Mikus, Malte S.; Hoveyda, Amir H.

    2015-01-01

    Olefin metathesis catalysts provide access to molecules that are indispensable to physicians and researchers in the life sciences. A persisting problem, however, is the dearth of chemical transformations that directly generate acyclic Z allylic alcohols, including products that contain a hindered neighbouring substituent or reactive functional units such as a phenol, an aldehyde, or a carboxylic acid. Here we present an electronically modified ruthenium-disulfide catalyst that is effective in generating such high-value compounds by cross-metathesis. The ruthenium complex is prepared from a commercially available precursor and an easily generated air-stable zinc catechothiolate. Transformations typically proceed with 5.0 mole per cent of the complex and an inexpensive reaction partner in 4-8 hours under ambient conditions; products are obtained in up to 80 per cent yield and 98:2 Z:E diastereoselectivity. The use of this catalyst is demonstrated in the synthesis of the naturally occurring anti-tumour agent neopeltolide and in a single-step stereoselective gram-scale conversion of a renewable feedstock (oleic acid) to an anti-fungal agent. In this conversion, the new catalyst promotes cross-metathesis more efficiently than the commonly used dichloro-ruthenium complexes, indicating that its utility may extend beyond Z-selective processes.

  20. Hafnocene-Based Olefin Polymerizations

    NASA Astrophysics Data System (ADS)

    Diesner, T.; Troll, C.; Rieger, B.

    Zirconocenes have been used for a long time in the field of olefin polymerization using MAO as cocatalyst. The equivalent hafnocenes were seldom used due to a lack of productivity while using MAO activation. In the last few years borane and borate activation has come into the focus of research for olefin polymerization. A variety of different hafnocenes were used to investigate the polymerization mechanism and the different cocatalysts.

  1. Stereospecific olefin polymerization catalysts

    DOEpatents

    Bercaw, John E.; Herzog, Timothy A.

    1998-01-01

    A metallocene catalyst system for the polymerization of .alpha.-olefins to yield stereospecific polymers including syndiotactic, and isotactic polymers. The catalyst system includes a metal and a ligand of the formula ##STR1## wherein: R.sup.1, R.sup.2, and R.sup.3 are independently selected from the group consisting of hydrogen, C.sub.1 to C.sub.10 alkyl, 5 to 7 membered cycloalkyl, which in turn may have from 1 to 3 C.sub.1 to C.sub.10 alkyls as a substituent, C.sub.6 to C.sub.15 aryl or arylalkyl in which two adjacent radicals may together stand for cyclic groups having 4 to 15 carbon atoms which in turn may be substituted, or Si(R.sup.8).sub.3 where R.sup.8 is selected from the group consisting of C.sub.1 to C.sub.10 alkyl, C.sub.6 to C.sub.15 aryl or C.sub.3 to C.sub.10 cycloalkyl; R.sup.4 and R.sup.6 are substituents both having van der Waals radii larger than the van der Waals radii of groups R.sup.1 and R.sup.3 ; R.sup.5 is a substituent having a van der Waals radius less than about the van der Waals radius of a methyl group; E.sup.1, E.sup.2 are independently selected from the group consisting of Si(R.sup.9).sub.2, Si(R.sup.9).sub.2 --Si(R.sup.9).sub.2, Ge(R.sup.9).sub.2, Sn(R.sup.9).sub.2, C(R.sup.9).sub.2, C(R.sup.9).sub.2 --C(R.sup.9).sub.2, where R.sup.9 is C.sub.1 to C.sub.10 alkyl, C.sub.6 to C.sub.15 aryl or C.sub.3 to C.sub.10 cycloalkyl; and the ligand may have C.sub.S or C.sub.1 -symmetry. Preferred metals are selected from the group consisting of group III, group IV, group V or lanthanide group elements. The catalysts are used to prepare stereoregular polymers including polypropylene from .alpha.-olefin monomers.

  2. Stereospecific olefin polymerization catalysts

    DOEpatents

    Bercaw, J.E.; Herzog, T.A.

    1998-01-13

    A metallocene catalyst system is described for the polymerization of {alpha}-olefins to yield stereospecific polymers including syndiotactic, and isotactic polymers. The catalyst system includes a metal and a ligand of the formula shown wherein: R{sup 1}, R{sup 2}, and R{sup 3} are independently selected from the group consisting of hydrogen, C{sub 1} to C{sub 10} alkyl, 5 to 7 membered cycloalkyl, which in turn may have from 1 to 3 C{sub 1} to C{sub 10} alkyls as a substituent, C{sub 6} to C{sub 15} aryl or arylalkyl in which two adjacent radicals may together stand for cyclic groups having 4 to 15 carbon atoms which in turn may be substituted, or Si(R{sup 8}){sub 3} where R{sup 8} is selected from the group consisting of C{sub 1} to C{sub 10} alkyl, C{sub 6} to C{sub 15} aryl or C{sub 3} to C{sub 10} cycloalkyl; R{sup 4} and R{sup 6} are substituents both having van der Waals radii larger than the van der Waals radii of groups R{sup 1} and R{sup 3}; R{sup 5} is a substituent having a van der Waals radius less than about the van der Waals radius of a methyl group; E{sup 1}, E{sup 2} are independently selected from the group consisting of Si(R{sup 9}){sub 2}, Si(R{sup 9}){sub 2}--Si(R{sup 9}){sub 2}, Ge(R{sup 9}){sub 2}, Sn(R{sup 9}){sub 2}, C(R{sup 9}){sub 2}, C(R{sup 9}){sub 2}--C(R{sup 9}){sub 2}, where R{sup 9} is C{sub 1} to C{sub 10} alkyl, C{sub 6} to C{sub 15} aryl or C{sub 3} to C{sub 10} cycloalkyl; and the ligand may have C{sub S} or C{sub 1}-symmetry. Preferred metals are selected from the group consisting of group III, group IV, group V or lanthanide group elements. The catalysts are used to prepare stereoregular polymers including polypropylene from {alpha}-olefin monomers.

  3. Bond Energies in Models of the Schrock Metathesis Catalyst

    SciTech Connect

    Vasiliu, Monica; Li, Shenggang; Arduengo, Anthony J.; Dixon, David A.

    2011-06-23

    Heats of formation, adiabatic and diabatic bond dissociation energies (BDEs) of the model Schrock-type metal complexes M(NH)(CRR)(OH)₂ (M = Cr, Mo, W; CRR = CH₂, CHF, CF₂) and MO₂(OH)₂ compounds, and Brønsted acidities and fluoride affinities for the M(NH)(CH₂)(OH) ₂ transition metal complexes are predicted using high level CCSD(T) calculations. The metallacycle intermediates formed by reaction of C₂H4 with M(NH)-(CH₂)(OH)2 and MO₂(OH)₂ are investigated at the same level of theory. Additional corrections were added to the complete basis set limit to obtain near chemical accuracy ((1 kcal/mol). A comparison between adiabatic and diabatic BDEs is made and provides an explanation of trends in the BDEs. Electronegative groups bonded on the carbenic carbon lead to less stable Schrock-type complexes as the adiabatic BDEs ofMdCF₂ andMdCHF bonds are much lower than theMdCH₂ bonds. The Cr compounds have smaller BDEs than theWorMo complexes and should be less stable. Different M(NH)(OH)₂(C₃H₆) and MO(OH)₂(OC₂H4) metallacycle intermediates are investigated, and the lowest-energy metallacycles have a square pyramidal geometry. The results show that consideration of the singlet_triplet splitting in the carbene in the initial catalyst as well as in the metal product formed by the retro [2+2] cycloaddition is a critical component in the design of an effective olefin metathesis catalyst in terms of the parent catalyst and the groups being transferred.

  4. 21 CFR 177.1520 - Olefin polymers.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Olefin polymers. 177.1520 Section 177.1520 Food... FOOD ADDITIVES: POLYMERS Substances for Use as Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1520 Olefin polymers. The olefin polymers listed in paragraph (a) of this section may...

  5. 21 CFR 177.1520 - Olefin polymers.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Olefin polymers. 177.1520 Section 177.1520 Food... HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: POLYMERS Substances for Use as Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1520 Olefin polymers. The olefin...

  6. 21 CFR 177.1520 - Olefin polymers.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Olefin polymers. 177.1520 Section 177.1520 Food... HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: POLYMERS Substances for Use as Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1520 Olefin polymers. The olefin...

  7. 21 CFR 177.1520 - Olefin polymers.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Olefin polymers. 177.1520 Section 177.1520 Food... HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: POLYMERS Substances for Use as Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1520 Olefin polymers. The olefin...

  8. 21 CFR 177.1520 - Olefin polymers.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Olefin polymers. 177.1520 Section 177.1520 Food and... CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: POLYMERS Substances for Use as Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1520 Olefin polymers. The olefin polymers listed in paragraph...

  9. Generation of stoichiometric ethylene and isotopic derivatives and application in transition-metal-catalyzed vinylation and enyne metathesis.

    PubMed

    Min, Geanna K; Bjerglund, Klaus; Kramer, Søren; Gøgsig, Thomas M; Lindhardt, Anders T; Skrydstrup, Troels

    2013-12-16

    Ethylene is one of the most important building blocks in industry for the production of polymers and commodity chemicals. (13)C- and D-isotope-labeled ethylenes are also valuable reagents with applications ranging from polymer-structure determination, reaction-mechanism elucidation to the preparation of more complex isotopically labeled compounds. However, these isotopic derivatives are expensive, and are flammable gases, which are difficult to handle. We have developed a method for the controlled generation of ethylene and its isotopic variants including, for the first time, fully isotopically labeled ethylene, from simple alkene precursors by using Ru catalysis. Applying a two-chamber reactor allows both the synthesis of ethylene and its immediate consumption in a chemical transformation permitting reactions to be performed with only stoichiometric amounts of this two carbon olefin. This was demonstrated in the Ni-catalyzed Heck reaction with aryl triflates and benzyl chlorides, as well as Ru-mediated enyne metathesis.

  10. Production of diesel fuel from light olefins

    SciTech Connect

    Tabak, S.A.; Krambeck, F.J.

    1986-03-01

    Mobile Research and Development Corporation has developed a catalytic process for converting light olefinic compounds to high quality gasoline and distillate. The process has been named Mobil Olefin to Gasoline and Distillate (MOGD) Process. Based on the Mobile zeolite catalyst ZSM-5, light olefins can be shape selectively oligomerized to higher molecular weight iso-olefins. In the gasoline boiling range, these olefins have a high octane number and for the diesel fuel range product a high cetane number and low pour point following hydrogenation. Through normally designed to process propylene or butylene, MOGD is applicable to a wide range of feed streams ranging from ethylene to 400/sup 0/F endpoint olefinic naphtha. The process has been tested using commercially-produced catalyst in refinery scale equipment.

  11. Dechloriation mechanisms of chlorinated olefins.

    PubMed Central

    Van Dyke, R A

    1977-01-01

    The dechlorination of chlorinated hydrocarbons has been examined in detail. The reaction is catalyzed by cytochrome P-450 and occurs optimally in the presence of oxygen although some dechlorination may occur under anaerobic conditions. Halothane has been shown to undergo an oxidative dechlorination and a reductive defluorination. Enzymatic attack of chlorinated olefins and hydrocarbons is not on the carbon--halogen bond. Oxidative dechlorination of hydrocarbons is apparently initiated by an attack on the carbon atom and the halogen is then released from the oxidized carbon. The chlorinated olefins, on the other hand, are not easily dechlorinated enzymatically. The chlorines migrate readily across the double bond, therefore, cyclic chloronium ions must occur as intermediates. It is not clear at this time if epoxides are also intermediates in this conversion. PMID:612436

  12. Make olefins from syn gas

    SciTech Connect

    Rao, V.U.S.; Gormley, R.J.

    1980-11-01

    The medium pore zeolite ZSM-5 can be made within a wide range of values of the ratio SiO/sub 2//Al/sub 2/O/sub 3/. The crystal structures of ZSM-5 and Silicalite appear to be very similar. However, Silicalite has essentially no Al. Hence it appears that Silicalite is the limiting form of ZSM-5 when the Al concentration is vanishingly small. A comparison of the properties of ZSM-5 and Silicalite is shown. Silicalite provides an interesting contrast to ZSM-5 owing to the lack of acidity in the former. In comparing products from catalysts based on ZSM-5 and Silicalite, one can discern reactions which result from the acid function in ZSM-5. Our studies on bifunctional catalysts based on ZSM-5 and Silicalite were performed on zeolites or molecular sieves impregnated with Fe and/or Co. The aim was to convert synthesis gas (CO + H/sub 2/), which can be derived from the gasification of coal, to olefins or gasoline. In the case of the ZSM-based catalyst containing Fe, the transition metal catalyzes the hydrogenation of CO, and the acid function of the zeolite catalyzes the conversion of the oxygenates and olefins in the product to aromatics, resulting in a high octane gasoline product. Recent work from our laboratory has clearly shown that if Silicalite is used instead of ZSM-5 as the support, the production of aromatics is almost completely suppressed, and the product stream is rich in olefins. In the present article, molecular sieve based catalysts that can proide olefins are discussed, and some aspects of gasoline production using zeolite based catalysts as well as the control of shift activity are also being considered. 4 tables.

  13. A water-soluble and retrievable ruthenium-based probe for colorimetric recognition of Hg(II) and Cys

    NASA Astrophysics Data System (ADS)

    Cui, Yali; Hao, Yuanqiang; Zhang, Yintang; Liu, Baoxia; Zhu, Xu; Qu, Peng; Li, Deliang; Xu, Maotian

    2016-08-01

    A new ruthenium-based complex 1 [(bis(4,4‧-dimethylphosphonic-2,2‧-bipyridine) dithiocyanato ruthenium (II))] was developed as a colorimetric probe for the detection of Hg(II) and Cys (Cysteine). The obtained compound 1 can give interconversional color changes upon the alternating addition of Hg(II) and Cys in 100% aqueous solution. The specific coordination between NCS groups with Hg(II) can lead to the formation of 1-Hg2 + complex, which can induce a remarkable spectral changes of probe 1. Afterwards the formed 1-Hg2 + complex can act as effective colorimetric sensor for Cys. Owing to the stronger binding affinity of sulfhydryl group to Hg2 +, Cys can extract Hg2 + from 1-Hg2 + complex resulting in the release of 1 and the revival of absorption profile of the probe 1. By introducing the hydrophilic phosphonic acid groups, the proposed probe exhibited excellent water solubility. The limits of detection (LODs) of the assay for Hg2 + and Cys are calculated to be 15 nM and 200 nM, respectively.

  14. Methods for synthesis of olefins and derivatives

    DOEpatents

    Burk, Mark J.; Pharkya, Priti; Van Dien, Stephen J.; Burgard, Anthony P.; Schilling, Christophe H.

    2016-06-14

    The invention provides a method of producing acrylic acid. The method includes contacting fumaric acid with a sufficient amount of ethylene in the presence of a cross-metathesis transformation catalyst to produce about two moles of acrylic acid per mole of fumaric acid. Also provided is an acrylate ester. The method includes contacting fumarate diester with a sufficient amount of ethylene in the presence of a cross-metathesis transformation catalyst to produce about two moles of acrylate ester per mole of fumarate diester. An integrated process for process for producing acrylic acid or acrylate ester is provided which couples bioproduction of fumaric acid with metathesis transformation. An acrylic acid and an acrylate ester production also is provided.

  15. Alkylation of isobutane with light olefins: Yields of alkylates for different olefins

    SciTech Connect

    Albright, L.F.; Kranz, K.E.; Masters, K.R.

    1993-12-01

    For alkylation of isobutane with C{sub 3}-C{sub 5} olefins using sulfuric acid as the catalyst, the yields of alkylates with different olefins are compared as the operating conditions are changed. The results of recent pilot plant experiments with propylene, C{sub 4} olefins, and C{sub 5} olefins permit such comparisons. The yields expressed as weight of alkylate produced per 100 wt of olefin consumed varied from about 201:100 to 220:100. Weight ratios of the isobutane consumed per olefin consumed vary from about 101:100 to 120:100. differences of yield values are explained by the changes in the overall chemistry. The procedure employed to calculate yields with good accuracy is based on the analysis of the alkylate and the amount of conjunct polymers produced. Based on literature data, yields are also reported for alkylations using HF as the catalyst.

  16. Preparation, stability, and photoreactivity of thiolato ruthenium polypyridyl complexes: Can cysteine derivatives protect ruthenium-based anticancer complexes?

    PubMed

    van Rixel, Vincent H S; Busemann, Anja; Göttle, Adrien J; Bonnet, Sylvestre

    2015-09-01

    Ruthenium polypyridyl complexes may act as light-activatable anticancer prodrugs provided that they are protected by well-coordinated ligands that i) prevent coordination of other biomolecules to the metal center in the dark and ii) can be removed by visible light irradiation. In this paper, the use of monodentate thiol ligands RSH as light-cleavable protecting groups for the ruthenium complex [Ru(tpy)(bpy)(OH2)](PF6)2 ([1](PF6)2; tpy=2,2';6',2″-terpyridine, bpy=2,2'-bypyridine), is investigated. The reaction of [1](2+) with RSH=H2Cys (L-cysteine), H2Acys (N-acetyl-L-cysteine), and HAcysMe (N-acetyl-L-cysteine methyl ester), is studied by UV-visible spectroscopy, NMR spectroscopy, and mass spectrometry. Coordination of the monodentate thiol ligands to the ruthenium complex takes place upon heating to 353 K, but full conversion to the protected complex [Ru(tpy)(bpy)(SR)]PF6 is only possible when a large excess of ligand is used. Isolation and characterization of the two new thiolato complexes [Ru(tpy)(bpy)(κS-HCys)]PF6 ([2]PF6) and [Ru(tpy)(bpy)(κS-HAcys)]PF6 ([3]PF6) is reported. [3]PF6 shows a metal-to-ligand charge-transfer absorption band that is red shifted (λmax=492 nm in water) compared to its methionine analogue [Ru(tpy)(bpy)(κS-HAmet)](Cl)2 ([5](Cl)2, λmax=452 nm; HAmet=N-acetyl-methionine). In the dark the thiolate ligand coordinated to ruthenium is oxidized even by traces of oxygen, which first leads to the sulfenato, sulfinato, and disulfide ruthenium complexes, and finally to the formation of the aqua complex [1](2+). [3]PF6 showed slow photosubstitution of the thiolate ligand by water under blue light irradiation, together with faster photooxidation of the thiolate ligand compared to dark conditions. The use of thiol vs. thioether monodentate ligands is discussed for the protection of anticancer ruthenium-based prodrugs.

  17. Cyclic alkyl amino carbene (CAAC) ruthenium complexes as remarkably active catalysts for ethenolysis

    SciTech Connect

    Marx, Vanessa M.; Sullivan, Alexandra H.; Melaimi, Mohand; Virgil, Scott C.; Keitz, Benjamin K.; Weinberger, David S.; Bertrand, Guy; Grubbs, Robert H.

    2014-12-17

    In this paper, an expanded family of ruthenium-based metathesis catalysts bearing cyclic alkyl amino carbene (CAAC) ligands was prepared. These catalysts exhibited exceptional activity in the ethenolysis of the seed-oil derivative methyl oleate. In many cases, catalyst turnover numbers (TONs) of more than 100,000 were achieved, at a catalyst loading of only 3 ppm. Remarkably, the most active catalyst system was able to achieve a TON of 340 000, at a catalyst loading of only 1 ppm. Finally, this is the first time a series of metathesis catalysts has exhibited such high performance in cross-metathesis reactions employing ethylene gas, with activities sufficient to render ethenolysis applicable to the industrial-scale production of linear α-olefins (LAOs) and other terminal-olefin products.

  18. Cyclic alkyl amino carbene (CAAC) ruthenium complexes as remarkably active catalysts for ethenolysis

    DOE PAGES

    Marx, Vanessa M.; Sullivan, Alexandra H.; Melaimi, Mohand; ...

    2014-12-17

    In this paper, an expanded family of ruthenium-based metathesis catalysts bearing cyclic alkyl amino carbene (CAAC) ligands was prepared. These catalysts exhibited exceptional activity in the ethenolysis of the seed-oil derivative methyl oleate. In many cases, catalyst turnover numbers (TONs) of more than 100,000 were achieved, at a catalyst loading of only 3 ppm. Remarkably, the most active catalyst system was able to achieve a TON of 340 000, at a catalyst loading of only 1 ppm. Finally, this is the first time a series of metathesis catalysts has exhibited such high performance in cross-metathesis reactions employing ethylene gas, withmore » activities sufficient to render ethenolysis applicable to the industrial-scale production of linear α-olefins (LAOs) and other terminal-olefin products.« less

  19. Antiproliferative effects of ruthenium-based nucleolipidic nanoaggregates in human models of breast cancer in vitro: insights into their mode of action

    PubMed Central

    Irace, Carlo; Misso, Gabriella; Capuozzo, Antonella; Piccolo, Marialuisa; Riccardi, Claudia; Luchini, Alessandra; Caraglia, Michele; Paduano, Luigi; Montesarchio, Daniela; Santamaria, Rita

    2017-01-01

    Looking for new metal-based anticancer treatments, in recent years many ruthenium complexes have been proposed as effective and safe potential drugs. In this context we have recently developed a novel approach for the in vivo delivery of Ru(III) complexes, preparing stable ruthenium-based nucleolipidic nanoaggregates endowed with significant antiproliferative activity. Herein we describe the cellular response to our ruthenium-containing formulations in selected models of human breast cancer. By in vitro bioscreens in the context of preclinical studies, we have focused on their ability to inhibit breast cancer cell proliferation by the activation of the intrinsic apoptotic pathway, possibly via mitochondrial perturbations involving Bcl-2 family members and predisposing to programmed cell death. In addition, the most efficient ruthenium-containing cationic nanoaggregates we have hitherto developed are able to elicit both extrinsic and intrinsic apoptosis, as well as autophagy. To limit chemoresistance and counteract uncontrolled proliferation, multiple cell death pathways activation by metal-based chemotherapeutics is a challenging, yet very promising strategy for targeted therapy development in aggressive cancer diseases, such as triple-negative breast cancer with limited treatment options. These outcomes provide valuable, original knowledge on ruthenium-based candidate drugs and new insights for future optimized cancer treatment protocols. PMID:28349991

  20. Selective conversion of bio-oil to light olefins: controlling catalytic cracking for maximum olefins.

    PubMed

    Gong, Feiyan; Yang, Zhi; Hong, Chenggui; Huang, Weiwei; Ning, Shen; Zhang, Zhaoxia; Xu, Yong; Li, Quanxin

    2011-10-01

    Light olefins are the basic building blocks for the petrochemical industry. In this work, selective production of light olefins from catalytic cracking of bio-oil was performed by using the La/HZSM-5 catalyst. With a nearly complete conversion of bio-oil, the maximum yield reached 0.28±0.02 kg olefins/(kg bio-oil), which was close to that from methanol. Addition of La into zeolite efficiently changed the total acid amount of HZSM-5, especially the acid distribution among the strong, medium and weak acid sites. A moderate increase of the number of the medium acid sites effectively enhanced the olefins selectivity and improved the catalyst stability. The comparison between the catalytic cracking and pyrolysis of bio-oil was studied. The mechanism of the conversion of bio-oil to light olefins was also discussed.

  1. 40 CFR 721.10672 - Sodium olefin sulfonate derivative (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Sodium olefin sulfonate derivative... Specific Chemical Substances § 721.10672 Sodium olefin sulfonate derivative (generic). (a) Chemical... as sodium olefin sulfonate derivative (PMNs P-09-447 and P-09-448) are subject to reporting...

  2. Olefins can limit desulfurization of reformer feedstock

    SciTech Connect

    Ali, S.A.; Anabtawi, J.A.

    1995-07-03

    Pilot plant studies have shown that the presence of even very small amounts of olefins may limit the desulfurization of reformer feedstocks to trace levels. Engineers at the Research Institute of King Fahd University of Petroleum and Minerals observed under typical industrial conditions the recombination reaction of olefins with hydrogen sulfide to form mercaptans. The results indicate that the advantage of using highly active (third generation) CoMo hydrotreating catalysts can be masked by these reactions if the olefins are not saturated. The trend in naphtha reforming is to use high-rhenium, bimetallic catalysts that display less resistance to sulfur than do balanced Pt-Re catalysts. Due consideration, therefore, should be given to these undesirable recombination reactions while designing hydrotreaters and selecting hydrodesulfurization (HDS) and reforming catalysts. The paper discusses catalysts and feedstock tests, catalyst activity, temperature effects, space velocity, feedstock effect, catalyst performance, and recommendations.

  3. Olefins from methanol by modified zeolites

    SciTech Connect

    Inui, T.; Takegami, Y.

    1982-11-01

    Compares the effects of modified catalysts (ZSM-34 and ZSM-5 class zeolites) on methanol conversion to olefins (MTO) with regard to olefin selectivity and cost. Presents tables with prices of olefins in the US and Japan; comparison of methanol-cracking with naphtha cracking; methanol conversion data for Type-1, Type-II and reference catalysts; hydrocarbon distribution from MTO processes; and speculative economics for MTO processes of Concept-1 and 2. Diagrams the proposed MTO process scheme. Scanning electron micrographs of the zeolite catalysts are shown. Graphs indicate the change of ethylene prices in the US since 1978 and forecast ethylene prices in several countries. Concludes that the prices of ethylene for both MTO processes examined compare favorably with products of conventional processes.

  4. Iron-catalyzed aminohydroxylation of olefins.

    PubMed

    Williamson, Kevin S; Yoon, Tehshik P

    2010-04-07

    We have discovered that N-sulfonyl oxaziridines react with a broad range of olefins in the presence of iron salts to afford 1,3-oxazolidines. This process provides access to 1,2-aminoalcohols with the opposite sense of regioselectivity produced from the copper-catalyzed oxyamination previously reported by our laboratories. Thus, either regioisomeric form of 1,2-aminoalcohols can easily be obtained from the reaction of oxaziridines with olefins, and the sense of regioselectivity can be controlled by the appropriate choice of inexpensive, nontoxic, first-row transition-metal catalyst.

  5. (Z)-Selective Takai olefination of salicylaldehydes

    PubMed Central

    Galloway, Warren R J D; Sore, Hannah F; Goodman, Jonathan M

    2017-01-01

    The Takai olefination (or Takai reaction) is a method for the conversion of aldehydes to vinyl iodides, and has seen widespread implementation in organic synthesis. The reaction is usually noted for its high (E)-selectivity; however, herein we report the highly (Z)-selective Takai olefination of salicylaldehyde derivatives. Systematic screening of related substrates led to the identification of key factors responsible for this surprising inversion of selectivity, and enabled the development of a modified mechanistic model to rationalise these observations. PMID:28326141

  6. Effects of the ruthenium-based drug NAMI-A on the roles played by TGF-β1 in the metastatic process.

    PubMed

    Brescacin, L; Masi, A; Sava, G; Bergamo, A

    2015-10-01

    The ruthenium-based drug NAMI-A, characterised by its selectivity against solid tumour metastases, promotes TGF-β1-dependent fibrosis and the reduction of the release of MMPs in the primary tumour. The aim of the study was to examine the interaction of NAMI-A with TGF-β1 in the process of metastasis formation. NAMI-A (1) affects the secretion of TGF-β1 in metastatic MDA-MB-231 cells rather than in non-tumorigenic HBL-100 cells, (2) prevails over TGF-β1 with regard to the invasive capacity of the treated cells, and (3) contrasts integrin-dependent migration stimulated by TGF-β1. It, thus, appears that the effects of NAMI-A on cell invasion and migration are best summarised as an interference with TGF-β1 and a reduction of its activity in these events. At a molecular level, the similar activity of NAMI-A and TGF-β1 on RhoA GTPase supports its interaction with cell surface integrins while TGF-β1 can activate it by interaction with its TGFβR receptor. The inhibition of TGF-β1-induced migration of MDA-MB-231 cells by NAMI-A cannot simply be attributed to a modulation of the Smad2 and p38MAPK pathways. In conclusion, the effects of NAMI-A on the biological role of TGF-β1 in cancer metastasis are insufficient to attribute the responsibility for the anti-metastatic activity of the ruthenium-based drug to this target alone.

  7. Neutron activation increases activity of ruthenium-based complexes and induces cell death in glioma cells independent of p53 tumor suppressor gene.

    PubMed

    Montel, Aline Monezi; Dos Santos, Raquel Gouvêa; da Costa, Pryscila Rodrigues; Silveira-Lacerda, Elisângela de Paula; Batista, Alzir Azevedo; Dos Santos, Wagner Gouvêa

    2017-04-01

    Novel metal complexes have received great attention in the last decades due to their potential anticancer activity. Notably, ruthenium-based complexes have emerged as good alternative to the currently used platinum-based drugs for cancer therapy, providing less toxicity and side effects to patients. Glioblastoma is an aggressive and invasive type of brain tumor and despite of advances is the field of neurooncology there is no effective treatment until now. Therefore, we sought to investigate the potential antiproliferative activity of phosphine-ruthenium-based complexes on human glioblastoma cell lines. Due to its octahedral structure as opposed to the square-planar geometry of platinum(II) compounds, ruthenium(II) complexes exhibit different structure-function relationship probably acting through a different mechanism from that of cisplatin beyond their ability to bind DNA. To better improve the pharmacological activity of metal complexes we hypothesized that neutron activation of ruthenium in the complexes would allow to decrease the effective concentration of the compound needed to kill tumor cells. Herein we report on the effect of unmodified and neutron activated phosphine ruthenium II complexes on glioblastoma cell lines carrying wild-type and mutated p53 tumor suppressor gene. Induction of apoptosis/authophagy as well as generation of reactive oxygen species were determined. The phosphine ruthenium II complexes tested were highly active against glioblastoma cell lines inducing cell death both through apoptosis and autophagy in a p53 independent fashion. Neutron activation of ruthenium compounds rendered them more active than their original counterparts suggesting a new strategy to improve the antitumor activity of these compounds.

  8. Synthesis of cyclic sulfones by ring-closing metathesis.

    PubMed

    Yao, Qingwei

    2002-02-07

    A general and highly efficient synthesis of cyclic sulfones based on ring-closing metathesis has been developed. The synthetic utility of the resulting cyclic sulfones was demonstrated by their participation in stereoselective Diels-Alder reactions and transformation to cyclic dienes by the Ramberg-Bäcklund reaction.

  9. Bromination of olefins with HBr and DMSO.

    PubMed

    Karki, Megha; Magolan, Jakob

    2015-04-03

    A simple and inexpensive methodology is reported for the conversion of alkenes to 1,2-dibromo alkanes via oxidative bromination using HBr paired with dimethyl sulfoxide, which serves as the oxidant as well as cosolvent. The substrate scope includes 21 olefins brominated in good to excellent yields. Three of six styrene derivatives yielded bromohydrins under the reaction conditions.

  10. Olefin Recovery from Chemical Industry Waste Streams

    SciTech Connect

    A.R. Da Costa; R. Daniels; A. Jariwala; Z. He; A. Morisato; I. Pinnau; J.G. Wijmans

    2003-11-21

    The objective of this project was to develop a membrane process to separate olefins from paraffins in waste gas streams as an alternative to flaring or distillation. Flaring these streams wastes their chemical feedstock value; distillation is energy and capital cost intensive, particularly for small waste streams.

  11. Polymerization Mechanism of α-Linear Olefin

    NASA Astrophysics Data System (ADS)

    Xing, Wen-guo; Zhang, Chang-qiao; Yu, Ping; Liu, Cheng-bu; Wei, Yun-he

    2010-02-01

    The density functional theory on the level of B3LYP/6-31G was empolyed to study the chain growth mechanism in polymerization process of α-linear olefin in TiCl3/AlEt2Cl catalytic system to synthesize drag reduction agent. Full parameter optimization without symmetry restrictions for reactants, products, the possible transition states, and intermediates was calculated. Vibration frequency was analyzed for all of stagnation points on the potential energy surface at the same theoretical level. The internal reaction coordinate was calculated from the transition states to reactants and products respectively. The results showed as follows: (i) Coordination compounds were formed on the optimum configuration of TiCl3/AlEt2Cl. (ii) The transition states were formed. The energy difference between transition states and the coordination compounds was 40.687 kJ/mol. (iii) Double bond opened and Ti-C(4) bond fractured, and the polymerization was completed. The calculation results also showed that the chain growth mechanism did not essentially change with the increase of carbon atom number of α-linear olefin. From the relationship between polymerization activation energy and carbon atom number of the α-linear olefin, it can be seen that the α-linear olefin monomers with 6-10 carbon atoms had low activation energy and wide range. It was optimum to synthesize drag reduction agent by polymerization.

  12. Process feasibility of DME to olefin conversion

    SciTech Connect

    Tartamella, T.L.; Fullerton, K.L.; Lee, S.; Kulik, C.J.

    1994-12-31

    The production of hydrocarbons via a synthetic route has been extensively studied by Mobil through its methanol based Methanol-to-Gasoline (MTG) process. An alternative approach using dimethyl ether (DME) has been developed by the University of Akron -- UA/EPRI DME-to-Hydrocarbons Process. The process feasibility of the production of hydrocarbons from DME has been illustrated in a bench scale, fluidized bed reactor using ZSM-5 type catalyst. In an effort to satisfy the growing demand for olefins as an intermediate chemical feedstocks a mechanistic/kinetic study was developed. The synthesis of olefins has been studied in packed bed micro-reactor using ZSM-5 catalyst. Experimental work has given details of reaction kinetics and mechanism in the conversion of DME to olefins. DME concentration weight hourly space velocity (WHSV), as well as reactor temperature and pressure were investigated in the study. This work was used as a precursor to the production of olefins/hydrocarbons from DME in a fluidized bed reactor. Product gas analysis was performed using an external GC standard method.

  13. Synthesis of pterostilbene by Julie Olefination

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A simple, stereoselective route for the synthesis of the biologically active compounds trans-pterostilbene and tetramethoxy stilbene from the readily available starting materials 3,5-dimethoxy benzyl alcohol and 4-hydroxy benzaldehyde was developed using Julia olefination as a key reaction....

  14. Light olefins from coal derived syngas

    SciTech Connect

    Sardesai, A.; Tartamella, T.; Lee, S.

    1996-12-31

    Synthesis of methanol from coal-derived synthesis gas is a well established technology, and methanol has been used as a feedstock for the synthesis of gasoline range hydrocarbons and olefins commercially. However, an efficient hydrocarbon synthesis process, based on a single-stage dimethyl ether synthesis from syngas, has been developed at the University of Akron. This UA/EPRI`s DTH (Dimethyl Ether to Hydrocarbons) process has significant advantages over its counterpart methanol conversion process in the areas of heat duties, hydrocarbon selectivities, product yield, and reactor size. Lower olefins are the intermediate products in the conversion of dimethyl ether to aromatic hydrocarbons. C{sub 2}-C{sub 4} olefins can be selectively produced by varying the operating parameters of the process, viz., temperature, pressure, DME concentration in the feed, space time, acidity of the catalyst, etc. The present work focuses on the effect of key process variables on the dimethyl ether conversion to lower olefins in a fixed bed microreactor system over ZSM-5 type zeolite catalyst. Experimental results with respect to gaseous hydrocarbon product yields and selectivities have been examined in this study.

  15. Lewis acid promoted titanium alkylidene formation: off-cycle intermediates relevant to olefin trimerization catalysis.

    PubMed

    Sattler, Aaron; VanderVelde, David G; Labinger, Jay A; Bercaw, John E

    2014-07-30

    Two new precatalysts for ethylene and α-olefin trimerization, (FI)Ti(CH2SiMe3)2Me and (FI)Ti(CH2CMe3)2Me (FI = phenoxy-imine), have been synthesized and structurally characterized by X-ray diffraction. (FI)Ti(CH2SiMe3)2Me can be activated with 1 equiv of B(C6F5)3 at room temperature to give the solvent-separated ion pair [(FI)Ti(CH2SiMe3)2][MeB(C6F5)3], which catalytically trimerizes ethylene or 1-pentene to produce 1-hexene or C15 olefins, respectively. The neopentyl analogue (FI)Ti(CH2CMe3)2Me is unstable toward activation with B(C6F5)3 at room temperature, giving no discernible diamagnetic titanium complexes, but at -30 °C the following can be observed by NMR spectroscopy: (i) formation of the bis-neopentyl cation [(FI)Ti(CH2CMe3)2](+), (ii) α-elimination of neopentane to give the neopentylidene complex [(FI)Ti(═CHCMe3)](+), and (iii) subsequent conversion to the imido-olefin complex [(MeOAr2N═)Ti(OArHC═CHCMe3)](+) via an intramolecular metathesis reaction with the imine fragment of the (FI) ligand. If the reaction is carried out at low temperature in the presence of ethylene, catalytic production of 1-hexene is observed, in addition to the titanacyclobutane complex [(FI)Ti(CH(CMe3)CH2CH2)](+), resulting from addition of ethylene to the neopentylidene [(FI)Ti(═CHCMe3)](+). None of the complexes observed spectroscopically subsequent to [(FI)Ti(CH2CMe3)2](+) is an intermediate or precursor for ethylene trimerization, but notwithstanding these off-cycle pathways, [(FI)Ti(CH2CMe3)2](+) is a precatalyst that undergoes rapid initiation to generate a catalyst for trimerizing ethylene or 1-pentene.

  16. One step formation of propene from ethene or ethanol through metathesis on nickel ion-loaded silica.

    PubMed

    Iwamoto, Masakazu

    2011-09-13

    Increased propene production is presently one of the most significant objectives in petroleum chemistry. Especially the one-step conversion of ethene to propene (ETP reaction, 3C₂H₄ →2C₃H₆) is the most desired process. In our efforts, nickel ion-loaded mesoporous silica could turn a new type of ETP reaction into reality. The one-step conversion of ethene was 68% and the propene selectivity was 48% in a continuous gas-flow system at 673 K and atmospheric pressure. The reactivity of lower olefins and the dependences of the ETP reaction on the contact time and the partial pressure of ethene were consistent with a reaction mechanism involving dimerization of ethene to 1-butene, isomerization of 1-butene to 2-butene, and metathesis of 2-butene and ethene to yield propene. The reaction was then expanded to an ethanol-to-propene reaction on the same catalyst, in which two possible reaction routes are suggested to form ethene from ethanol. The catalysts were characterized mainly by EXAFS and TPR techniques. The local structures of the nickel species active for the ETP reaction were very similar to that of layered nickel silicate, while those on the inert catalysts were the same as that of NiO particles.

  17. A Procedure Identifying a Polyacetylene Initiator of Olefin Metathesis. The Reactivities of Metal-Carbenes Toward Alkenes and Alkynes.

    DTIC Science & Technology

    2014-09-26

    Reproduction in whole or in part is permitted for any purpose of the United States Government This document has been approved for public release and...979, 17, 421. (c) Percec, V.; Rinaldi, P. L. Polym. Bull . (Berlin) 1983, 9, 548; (d) Percec, V. ibid. 1983, 10, 1. (24) Masuda, T.; Takahashi, T...Yamamoto, K.; Higashimura, T. J. Polym. Sci.. Polym. Chem. Ed. 1982, 20, 2603. (25) Percec, V.; Rinaldi, P. L., Polym. Bull . (Berlin) 1983, 9, 582. (26

  18. Self-Assembly of Disorazole C1 through a One-Pot Alkyne Metathesis Homodimerization Strategy**

    PubMed Central

    Ralston, Kevin J; Ramstadius, H Clinton; Brewster, Richard C; Niblock, Helen S; Hulme, Alison N

    2015-01-01

    Alkyne metathesis is increasingly explored as a reliable method to close macrocyclic rings, but there are no prior examples of an alkyne-metathesis-based homodimerization approach to natural products. In this approach to the cytotoxic C2-symmetric marine-derived bis(lactone) disorazole C1, a highly convergent, modular strategy is employed featuring cyclization through an ambitious one-pot alkyne cross-metathesis/ring-closing metathesis self-assembly process. PMID:25926364

  19. A chameleon catalyst for nonheme iron-promoted olefin oxidation.

    PubMed

    Iyer, Shyam R; Javadi, Maedeh Moshref; Feng, Yan; Hyun, Min Young; Oloo, Williamson N; Kim, Cheal; Que, Lawrence

    2014-11-18

    We report the chameleonic reactivity of two nonheme iron catalysts for olefin oxidation with H2O2 that switch from nearly exclusive cis-dihydroxylation of electron-poor olefins to the exclusive epoxidation of electron-rich olefins upon addition of acetic acid. This switching suggests a common precursor to the nucleophilic oxidant proposed to Fe(III)-η(2)-OOH and electrophilic oxidant proposed to Fe(V)(O)(OAc), and reversible coordination of acetic acid as a switching pathway.

  20. Block copolymer adhesion promoters via ring-opening metathesis polymerization

    DOEpatents

    Kent, Michael S.; Saunders, Randall

    1997-01-01

    Coupling agents based on functionalized block copolymers for bonding thermoset polymers to solid materials. These are polymers which possess at least two types of functional groups, one which is able to attach to and react with solid surfaces, and another which can react with a thermoset resin, which are incorporated as pendant groups in monomers distributed in blocks (typically two) along the backbone of the chain. The block copolymers in this invention are synthesized by living ring-opening metathesis polymerization.

  1. Heterobimetallic s-block hydrides by σ-bond metathesis.

    PubMed

    Liptrot, David J; Hill, Michael S; Mahon, Mary F

    2014-08-04

    Reactions between PhSiH3 and alkali-metal diamidoalkylmagnesiates ([M{N(SiMe3)2}2MgBu], M = Li, Na, K) provide either selective alkyl metathesis or the formation of polyhydride aggregates contingent upon the identity of the Group 1 metal. In the case of [M{N(SiMe3)2}2MgBu], this reactivity results in a structurally unprecedented dodecametallic decahydride cluster species.

  2. Conversion of olefins to liquid motor fuels

    DOEpatents

    Rabo, Jule A.; Coughlin, Peter K.

    1988-01-01

    Linear and/or branched claim C.sub.2 to C.sub.12 olefins are converted to hydrocarbon mixtures suitable for use as liquid motor fuels by contact with a catalyst capable of ensuring the production of desirable products with only a relatively minor amount of heavy products boiling beyond the diesel oil range. The catalyst having desirable stability during continuous production operations, comprises a steam stabilized zeolite Y catalyst of hydrophobic character, desirably in aluminum-extracted form. The olefins such as propylene, may be diluted with inerts, such as paraffins or with water, the latter serving to moderate the acidity of the catalyst, or to further moderate the activity of the aluminum-extracted catalyst, so as to increase the effective life of the catalyst.

  3. Photochemical preparation of olefin addition catalysts

    NASA Technical Reports Server (NTRS)

    Gray, Harry B. (Inventor); Rembaum, Alan (Inventor); Gupta, Amitava (Inventor)

    1978-01-01

    Novel polymer supported catalysts are prepared by photo-irradiation of low valent transition metal compounds such as Co.sub.2 (CO).sub.8, Rh.sub.4 (CO).sub.12 or Ru.sub.3 (CO).sub.12 in the presence of solid polymers containing amine ligands such as polyvinyl pyridine. Hydroformylation of olefins to aldehydes at ambient conditions has been demonstrated.

  4. Homogeneous catalysts for stereoregular olefin polymerization

    DOEpatents

    Marks, T.J.; Eisen, M.S.; Giardello, M.A.

    1995-10-03

    The synthesis, and use as precatalysts of chiral organozirconium complexes for olefin polymerization are disclosed, having the structure (C{sub 5}R{prime}{sub 4{minus}x}R*{sub x})A(C{sub 5}R{double_prime}{sub 4{minus}y}R{double_prime}{prime}{sub y})MQ{sub p}, where x and y represent the number of unsubstituted locations on the cyclopentadienyl ring; R{prime}, R{double_prime}, R{double_prime}{prime}, and R* represent substituted and unsubstituted alkyl groups having 1--30 carbon atoms and R* is a chiral ligand; A is a fragment containing a Group 13, 14, 15, or 16 element of the Periodic Table; M is a Group 3, 4, or 5 metal of the Periodic Table; and Q is a hydrocarbyl radical, or halogen radical, with 3{>=}p{>=}0. Related complexes may be prepared by alkylation of the corresponding dichlorides. In the presence of methylalumoxane or triarylborane cocatalysts, these complexes form ``cation-like`` species which are highly active for olefin polymerization. In combination with a Lewis acid cocatalyst, propylene or other {alpha}-olefin polymerization can be effected with very high efficiency and isospecificity. 1 fig.

  5. Homogeneous catalysts for stereoregular olefin polymerization

    DOEpatents

    Marks, T.J.; Eisen, M.S.; Giardello, M.A.

    1994-07-19

    The synthesis, and use as precatalysts of chiral organozirconium complexes for olefin polymerization are disclosed, having the structure (C[sub 5]R[prime][sub 4[minus]x]R*[sub x])-A-(C[sub 5]R[double prime][sub 4[minus]y]R[prime][double prime][sub y])-M-Q[sub p], where x and y represent the number of unsubstituted locations on the cyclopentadienyl ring; R[prime], R[double prime], R[prime][double prime], and R* represent substituted and unsubstituted alkyl groups having 1--30 carbon atoms and R* is a chiral ligand; A is a fragment containing a Group 13, 14, 15, or 16 element of the Periodic Table; M is a Group 3, 4, or 5 metal of the Periodic Table; and Q is a hydrocarbyl radical, or halogen radical, with 3 [<=] p [<=] 0. Related complexes may be prepared by alkylation of the corresponding dichlorides. In the presence of methylalumoxane or triarylborane cocatalysts, these complexes form cation-like'' species which are highly active for olefin polymerization. In combination with a Lewis acid cocatalyst, propylene or other [alpha]-olefin polymerization can be effected with very high efficiency and isospecificity. 1 fig.

  6. Homogeneous catalysts for stereoregular olefin polymerization

    DOEpatents

    Marks, Tobin J.; Eisen, Moris S.; Giardello, Michael A.

    1995-01-01

    The synthesis, and use as precatalysts of chiral organozirconium complexes for olefin polymerization are disclosed, having the structure (C.sub.5 R'.sub.4-x R*.sub.x) A (C.sub.5 R".sub.4-y R"'.sub.y) M Q.sub.p, where x and y represent the number of unsubstituted locations on the cyclopentadienyl ring; R', R", R"', and R* represent substituted and unsubstituted alkyl groups having 1-30 carbon atoms and R* is a chiral ligand; A is a fragment containing a Group 13, 14, 15, or 16 element of the Periodic Table; M is a Group 3, 4, or 5 metal of the Periodic Table; and Q is a hydrocarbyl radical, or halogen radical, with 3.ltoreq.p.ltoreq.o. Related complexes may be prepared by alkylation of the corresponding dichorides. In the presence of methylalumoxane or triarylborane cocatalysts, these complexes form "cation-like" species which are highly active for olefin polymerization. In combination with a Lewis acid cocatalyst, propylene or other .alpha.-olefin polymerization can be effected with very high efficiency and isospecificity.

  7. Homogeneous catalysts for stereoregular olefin polymerization

    DOEpatents

    Marks, Tobin J.; Eisen, Moris S.; Giardello, Michael A.

    1994-01-01

    The synthesis, and use as precatalysts of chiral organozirconium complexes for olefin polymerization are disclosed, having the structure (C.sub.5 R'.sub.4-x R*.sub.x) A (C.sub.5 R".sub.4-y R'".sub.y) M Q.sub.p, where x and y represent the number of unsubstituted locations on the cyclopentadienyl ring; R', R", R'", and R* represent substituted and unsubstituted alkyl groups having 1-30 carbon atoms and R* is a chiral ligand; A is a fragment containing a Group 13, 14, 15, or 16 element of the Periodic Table; M is a Group 3, 4, or 5 metal of the Periodic Table; and Q is a hydrocarbyl radical, or halogen radical, with 3.ltoreq.p.ltoreq.o. Related complexes may be prepared by alkylation of the corresponding dichorides. In the presence of methylalumoxane or triarylborane cocatalysts, these complexes form "cation-like" species which are highly active for olefin polymerization. In combination with a Lewis acid cocatalyst, propylene or other .alpha.-olefin polymerization can be effected with very high efficiency and isospecificity.

  8. Reduction in Syllable Onsets in the Acquisition of Polish: Deletion, Coalescence, Metathesis and Gemination

    ERIC Educational Resources Information Center

    Lukaszewicz, Beata

    2007-01-01

    This paper focuses on four strategies of onset reduction employed by a single child (4;0-4;4) acquiring Polish: deletion, coalescence, metathesis, and gemination. Deletion and coalescence occur in word-initial onsets while metathesis and gemination are restricted to word-medial position. The data, which constitute an intriguing "conspiracy" case…

  9. Cobalt carbonyl catalyzed olefin hydroformylation in supercritical carbon dioxide

    SciTech Connect

    Rathke, J.W.; Klingler, R.J.

    1992-12-31

    A method of olefin hydroformylation is provided wherein an olefin reacts with a carbonyl catalyst and with reaction gases such as hydrogen and carbon monoxide in the presence of a supercritical reaction solvent, such as carbon dioxide. The invention provides higher yields of n-isomer product without the gas-liquid mixing rate limitation seen in conventional Oxo processes using liquid media.

  10. Cobalt carbonyl catalyzed olefin hydroformylation in supercritical carbon dioxide

    DOEpatents

    Rathke, J.W.; Klingler, R.J.

    1993-03-30

    A method of olefin hydroformylation is provided wherein an olefin reacts with a carbonyl catalyst and with reaction gases such as hydrogen and carbon monoxide in the presence of a supercritical reaction solvent, such as carbon dioxide. The invention provides higher yields of n-isomer product without the gas-liquid mixing rate limitation seen in conventional Oxo processes using liquid media.

  11. Cobalt carbonyl catalyzed olefin hydroformylation in supercritical carbon dioxide

    DOEpatents

    Rathke, Jerome W.; Klingler, Robert J.

    1993-01-01

    A method of olefin hydroformylation is provided wherein an olefin reacts with a carbonyl catalyst and with reaction gases such as hydrogen and carbon monoxide in the presence of a supercritical reaction solvent, such as carbon dioxide. The invention provides higher yields of n-isomer product without the gas-liquid mixing rate limitation seen in conventional Oxo processes using liquid media.

  12. Supported organometallic catalysts for hydrogenation and Olefin Polymerization

    DOEpatents

    Marks, Tobin J.; Ahn, Hongsang

    2001-01-01

    Novel heterogeneous catalysts for the which hydrogenation of olefins and arenes with high conversion rates under ambient conditions and the polymerization of olefins have been developed. The catalysts are synthesized from Ziegler-type precatalysts by supporting them on sulfate-modified zirconia.

  13. Practical carbon–carbon bond formation from olefins through nickel-catalyzed reductive olefin hydrocarbonation

    PubMed Central

    Lu, Xi; Xiao, Bin; Zhang, Zhenqi; Gong, Tianjun; Su, Wei; Yi, Jun; Fu, Yao; Liu, Lei

    2016-01-01

    New carbon–carbon bond formation reactions expand our horizon of retrosynthetic analysis for the synthesis of complex organic molecules. Although many methods are now available for the formation of C(sp2)–C(sp3) and C(sp3)–C(sp3) bonds via transition metal-catalyzed cross-coupling of alkyl organometallic reagents, direct use of readily available olefins in a formal fashion of hydrocarbonation to make C(sp2)–C(sp3) and C(sp3)–C(sp3) bonds remains to be developed. Here we report the discovery of a general process for the intermolecular reductive coupling of unactivated olefins with alkyl or aryl electrophiles under the promotion of a simple nickel catalyst system. This new reaction presents a conceptually unique and practical strategy for the construction of C(sp2)–C(sp3) and C(sp3)–C(sp3) bonds without using any organometallic reagent. The reductive olefin hydrocarbonation also exhibits excellent compatibility with varieties of synthetically important functional groups and therefore, provides a straightforward approach for modification of complex organic molecules containing olefin groups. PMID:27033405

  14. Homologation of olefins by methanol over ZSM-5 zeolite

    SciTech Connect

    Behrsing, T.; Mole, T.; Smart, P.; Western, R.J.

    1986-11-01

    /sup 13/C-Labeled methanol has been coreacted with excess C/sub 6/ olefins (2-methylpentene-1 or hexene-1) over the proton form of ZSM-5 zeolite under such conditions (ca. 550 K and a 2-s contact time) so that the C/sub 6/ olefins undergo extensive reaction while the methanol undergoes partial conversion to hydrocarbons. The resulting mixture of olefins was then hydrogenated to facilitate isotopic analysis. The /sup 13/C label was most abundant in the C/sub 7/ products, consistent with the hypothesis that the methanol is converted mainly by the homologation of an olefin to form an olefin with one more methylene group. 13 references.

  15. Fluidized bed pyrolysis to gases containing olefins

    SciTech Connect

    Kuester, J.L.

    1980-01-01

    Recent gasification data are presented for a system designed to produce liquid hydrocarbon fuel from various biomass feedstocks. The factors under investigation were feedstock type, fluidizing gas type, residence time, temperature and catalyst usage. The response was gas phase composition. A fluidized bed system was utilized with a separate regenerator-combustor. An olefin content as high as 39 mole % was achieved. Hydrogen/carbon monoxide ratios were easily manipulated via steam addition over a broad range with an autocatalytic effect apparent for most feedstocks.

  16. Process for reacting alcohols and olefins

    SciTech Connect

    Miller, J.T.; Nevitt, T.D.

    1985-01-29

    A method for producing branched aliphatic hydrocarbons by reacting H/sub 2/ with a C/sub 1/-C/sub 6/ alcohol and/or a C/sub 2/-C/sub 6/ olefin in the presence of a cadmium component and a support which comprises an amorphous refractory inorganic oxide, a pillared smectite or vermiculite clay, a molecular sieve consisting essentially of unexchanged or cation-exchanged chabazite, clinoptilite, zeolite A, zeolite L, zeolite X, zeolite Y, ultrastable zeolite Y, or crystalline borosilicate molecular sieve, or a combination thereof.

  17. Syntheses of Synthetic Hydrocarbons Via Alpha Olefins.

    DTIC Science & Technology

    1981-10-01

    Chem. Educ., 42, 502 (1965). 4. A. Priola, C. Corna , and S. Cesca, Macromolecules, 13, 1110 (1980). 5. R. F . Brown, Organic Chemistry, Wadsworth...AD-A110 380 GULF RESEARCH AND DEVELOPENT Co PITTSBURGH PA F /G T/A 1 SYNTHESES OF SYNTHETIC HYDROCARBONS VIA ALPHA OLEFINS.(U) OCT 81 B L CUPPLES, A...FOR THE COMMANDER F . D. CHERRY, Chief Nonmetallic Materials Division "If your address has changed, if you wish to be removed from our mailing list

  18. Block copolymer adhesion promoters via ring-opening metathesis polymerization

    DOEpatents

    Kent, M.S.; Saunders, R.

    1997-02-18

    Coupling agents are disclosed based on functionalized block copolymers for bonding thermoset polymers to solid materials. These are polymers which possess at least two types of functional groups, one which is able to attach to and react with solid surfaces, and another which can react with a thermoset resin, which are incorporated as pendant groups in monomers distributed in blocks (typically two) along the backbone of the chain. The block copolymers in this invention are synthesized by living ring-opening metathesis polymerization. 18 figs.

  19. Methods for the synthesis of olefins and derivatives

    DOEpatents

    Burk, Mark J; Pharkya, Priti; Van Dien, Stephen J; Burgard, Anthony P; Schilling, Christophe H

    2013-06-04

    The invention provides a method of producing acrylic acid. The method includes contacting fumaric acid with a sufficient amount of ethylene in the presence of a cross-metathesis transformation catalyst to produce about two moles of acrylic acid per mole of fumaric acid. Also provided is an acrylate ester. The method includes contacting fumarate diester with a sufficient amount of ethylene in the presence of a cross-metathesis transformation catalyst to produce about two moles of acrylate ester per mole of fumarate diester. An integrated process for process for producing acrylic acid or acrylate ester is provided which couples bioproduction of fumaric acid with metathesis transformation. An acrylic acid and an acrylate ester production also is provided.

  20. Methods for the synthesis of olefins and derivatives

    DOEpatents

    Burk, Mark J.; Pharkya, Priti; Van Dien, Stephen J.; Burgard, Anthony P.; Schilling, Christophe H.

    2011-09-27

    The invention provides a method of producing acrylic acid. The method includes contacting fumaric acid with a sufficient amount of ethylene in the presence of a cross-metathesis transformation catalyst to produce about two moles of acrylic acid per mole of fumaric acid. Also provided is an acrylate ester. The method includes contacting fumarate diester with a sufficient amount of ethylene in the presence of a cross-metathesis transformation catalyst to produce about two moles of acrylate ester per mole of fumarate diester. An integrated process for process for producing acrylic acid or acrylate ester is provided which couples bioproduction of fumaric acid with metathesis transformation. An acrylic acid and an acrylate ester production also is provided.

  1. Z-Selective Ruthenium Metathesis Catalysts: Comparison of Nitrate and Nitrite X-type Ligands

    PubMed Central

    Pribisko, Melanie A.; Ahmed, Tonia S.; Grubbs, Robert H.

    2014-01-01

    Two new Ru-based metathesis catalysts, 3 and 4, have been synthesized for the purpose of comparing their catalytic properties to those of their cis-selective nitrate analogues, 1 and 2. Although catalysts 3 and 4 exhibited slower initiation rates than 1 and 2, they maintained high cis-selectivity in homodimerization and ring-opening metathesis polymerization reactions. Furthermore, the nitrite catalysts displayed higher cis-selectivity than 2 for ring-opening metathesis polymerizations, and 4 delivered higher yields of polymer. PMID:25484484

  2. Splitting a C-O bond in dialkylethers with bis(1,2,4-tri-t-butylcyclopentadienyl) cerium-hydride does not occur by a sigma-bond metathesis pathway: a combined experimental and DFT computational study

    SciTech Connect

    Werkema, Evan; Yahia, Ahmed; Maron, Laurent; Eisenstein, Odile; Andersen, Richard

    2010-04-06

    Addition of diethylether to [1,2,4(Me3C)3C5H2]2CeH, abbreviated Cp'2CeH, gives Cp'2CeOEt and ethane. Similarly, di-n-propyl- or di-n-butylether gives Cp'2Ce(O-n-Pr) and propane or Cp'2Ce(O-n-Bu) and butane, respectively. Using Cp'2CeD, the propane and butane contain deuterium predominantly in their methyl groups. Mechanisms, formulated on the basis of DFT computational studies, show that the reactions begin by an alpha or beta-CH activation with comparable activation barriers but only the beta-CH activation intermediate evolves into the alkoxide product and an olefin. The olefin then inserts into the Ce-H bond forming the alkyl derivative, Cp'2CeR, that eliminates alkane. The alpha-CH activation intermediate is in equilibrium with the starting reagents, Cp'2CeH and the ether, which accounts for the deuterium label in the methyl groups of the alkane. The one-step sigma-bond metathesis mechanism has a much higher activation barrier than either of the two-step mechanisms.

  3. Synthesis of nanosized silicon particles by a rapid metathesis reaction

    SciTech Connect

    Won, C.W.; Nersisyan, H.H.; Won, H.I.; Lee, H.H.

    2009-11-15

    A solid-state rapid metathesis reaction was performed in a bed of sodium silicofluoride (Na{sub 2}SiF{sub 6}) and sodium azide (NaN{sub 3}) powders diluted with sodium fluoride (NaF), to produce silicon nanoparticles. After a local ignition of Na{sub 2}SiF{sub 6}+4NaN{sub 3}+kNaF mixture (here k is mole number of NaF), the reaction proceeded in a self-sustaining combustion mode developing high temperatures (950-1000 deg. C) on very short time scales (a few seconds). Silicon nanoparticles prepared by the combustion process was easily separated from the salt byproducts by simple washing with distilled water. The structural and morphological studies on the nanoparticles were carried out using X-ray diffractometer (XRD) and field emission scanning electron microscope (FESEM). The mean size of silicon particles calculated from the FESEM image was about 37.75 nm. FESEM analysis also shows that the final purified product contains a noticeable amount of silicon fibers, dendrites and blocks, along with nanoparticles. The mechanism of Si nanostructures formation is discussed and a simple model for interpretation of experimental results is proposed. - Graphical abstract: Silicon nanoparticles 37.75 nm in mean diameter was obtained by rapid metathesis reaction performed in Na{sub 2}SiF{sub 6}+4NaN{sub 3} powder bed diluted with NaF.

  4. Selective Oxidation and Ammoxidation of Olefins by Heterogeneous Catalysis.

    ERIC Educational Resources Information Center

    Grasselli, Robert K.

    1986-01-01

    Shows how the ammoxidation of olefins can be understood in terms of free radicals and surface bound organometallic intermediates. Also illustrates the close intellectual relationships between heterogeneous catalysis and organometallic chemistry. (JN)

  5. Direct observation of OH production from the ozonolysis of olefins

    NASA Astrophysics Data System (ADS)

    Donahue, Neil M.; Kroll, Jesse H.; Anderson, James G.; Demerjian, Kenneth L.

    Ozone olefin reactions may be a significant source of OH in the urban atmosphere, but current evidence for OH production is indirect and contested. We report the first direct observation of OH radicals from the reaction of ozone with a series of olefins (ethene, isoprene, trans-2-butene and 2,3 dimethyl-2-butene) in 4-6 torr of nitrogen. Using LIF to directly observe the steady-state of OH produced by the initial ozone-olefin reaction and subsequently destroyed by the OH-olefin reaction, we are able to establish OH yields broadly consistent with indirect values. The identification of the OH is unequivocal, and there is no indication that it is produced by a secondary process. To support these observations, we present a complete ab-initio potential energy surface for the O3-ethene reaction, extending from the reactants to available products.

  6. Direct catalytic conversion of synthesis gas to lower olefins

    SciTech Connect

    Janardanarao, M. )

    1990-09-01

    Direct conversion of synthesis gas to lower olefins has been considered as a possible solution to meet the growing demand for chemical feedstocks such as ethylene, propylene, and butylenes. This review covers the various catalyst systems and operating conditions that have been used in meeting this objective. Though the product distribution in Fischer--Tropsch synthesis is governed by the existence of an Anderson--Schultz--Flory polymerization model, certain modifications in the catalyst formulations have produced a shift toward lower molecular weight olefins. At the present time, the yields and selectivities of lower olefins are far from optimal, but continued research efforts in this area may lead to the development of stable catalyst systems capable of producing highly desirable distributions of lower olefins.

  7. Unsupported catalysts in the production of olefins

    SciTech Connect

    Kreuter, W.; Wernicke, H.

    1980-07-01

    A description is given of a process for the production of olefins in two stages wherein, in the first stage, a heavy petroleum fraction is hydrogenated essentially in the liquid phase in the presence of hydrogen and a hydrogenation catalyst and, in the second stage, the thus-hydrogenated fraction is subjected to thermal cracking in the vapor phase in the presence of steam, the improvement which comprises employing as the hydrogenation catalyst a support-free catalyst consisting essentially of at least one of Co-Mo, Ni-Mo, Co-Mo sulfide, Ni-Co-Mo sulfide, Ni-Mo sulfide, Ni-Co sulfide, Co-mo oxide, Ni-Co-Mo oxide, Ni-Mo oxide, Ni-Co oxide, Ni-W sulfide, Ni-W oxide, or organometallic complexes of aforementioned metallic mixtures.

  8. Selective conversion of syngas to light olefins.

    PubMed

    Jiao, Feng; Li, Jinjing; Pan, Xiulian; Xiao, Jianping; Li, Haobo; Ma, Hao; Wei, Mingming; Pan, Yang; Zhou, Zhongyue; Li, Mingrun; Miao, Shu; Li, Jian; Zhu, Yifeng; Xiao, Dong; He, Ting; Yang, Junhao; Qi, Fei; Fu, Qiang; Bao, Xinhe

    2016-03-04

    Although considerable progress has been made in direct synthesis gas (syngas) conversion to light olefins (C2(=)-C4(=)) via Fischer-Tropsch synthesis (FTS), the wide product distribution remains a challenge, with a theoretical limit of only 58% for C2-C4 hydrocarbons. We present a process that reaches C2(=)-C4(=) selectivity as high as 80% and C2-C4 94% at carbon monoxide (CO) conversion of 17%. This is enabled by a bifunctional catalyst affording two types of active sites with complementary properties. The partially reduced oxide surface (ZnCrO(x)) activates CO and H2, and C-C coupling is subsequently manipulated within the confined acidic pores of zeolites. No obvious deactivation is observed within 110 hours. Furthermore, this composite catalyst and the process may allow use of coal- and biomass-derived syngas with a low H2/CO ratio.

  9. Olefins and chemical regulation in Europe: REACH.

    PubMed

    Penman, Mike; Banton, Marcy; Erler, Steffen; Moore, Nigel; Semmler, Klaus

    2015-11-05

    REACH (Registration, Evaluation, Authorisation and Restriction of Chemicals) is the European Union's chemical regulation for the management of risk to human health and the environment (European Chemicals Agency, 2006). This regulation entered into force in June 2007 and required manufacturers and importers to register substances produced in annual quantities of 1000 tonnes or more by December 2010, with further deadlines for lower tonnages in 2013 and 2018. Depending on the type of registration, required information included the substance's identification, the hazards of the substance, the potential exposure arising from the manufacture or import, the identified uses of the substance, and the operational conditions and risk management measures applied or recommended to downstream users. Among the content developed to support this information were Derived No-Effect Levels or Derived Minimal Effect Levels (DNELs/DMELs) for human health hazard assessment, Predicted No Effect Concentrations (PNECs) for environmental hazard assessment, and exposure scenarios for exposure and risk assessment. Once registered, substances may undergo evaluation by the European Chemicals Agency (ECHA) or Member State authorities and be subject to requests for additional information or testing as well as additional risk reduction measures. To manage the REACH registration and related activities for the European olefins and aromatics industry, the Lower Olefins and Aromatics REACH Consortium was formed in 2008 with administrative and technical support provided by Penman Consulting. A total of 135 substances are managed by this group including 26 individual chemical registrations (e.g. benzene, 1,3-butadiene) and 13 categories consisting of 5-26 substances. This presentation will describe the content of selected registrations prepared for 2010 in addition to the significant post-2010 activities. Beyond REACH, content of the registrations may also be relevant to other European activities, for

  10. Self‐Assembly of Disorazole C1 through a One‐Pot Alkyne Metathesis Homodimerization Strategy†

    PubMed Central

    Ralston, Kevin J.; Ramstadius, H. Clinton; Brewster, Richard C.; Niblock, Helen S.

    2015-01-01

    Abstract Alkyne metathesis is increasingly explored as a reliable method to close macrocyclic rings, but there are no prior examples of an alkyne‐metathesis‐based homodimerization approach to natural products. In this approach to the cytotoxic C2‐symmetric marine‐derived bis(lactone) disorazole C1, a highly convergent, modular strategy is employed featuring cyclization through an ambitious one‐pot alkyne cross‐metathesis/ring‐closing metathesis self‐assembly process. PMID:27346897

  11. Zwitterionic Group VIII transition metal initiators supported by olefin ligands

    DOEpatents

    Bazan, Guillermo C.; Chen, Yaofeng

    2011-10-25

    A zwitterionic Group VIII transition metal complex containing the simple and relatively small 3-(arylimino)-but-1-en-2-olato ligand that catalyzes the formation of polypropylene and high molecular weight polyethylene. A novel feature of this catalyst is that the active species is stabilized by a chelated olefin adduct. The present invention also provides methods of polymerizing olefin monomers using zwitterionic catalysts, particularly polypropylene and high molecular weight polyethylene.

  12. Kinetics and mechanism of olefin catalytic hydroalumination by organoaluminum compounds

    NASA Astrophysics Data System (ADS)

    Koledina, K. F.; Gubaidullin, I. M.

    2016-05-01

    The complex reaction mechanism of α-olefin catalytic hydroalumination by alkylalanes is investigated via mathematical modeling that involves plotting the kinetic models for the individual reactions that make up a complex system and a separate study of their principles. Kinetic parameters of olefin catalytic hydroalumination are estimated. Activation energies of the possible steps of the schemes of complex reaction mechanisms are compared and possible reaction pathways are determined.

  13. Request for Symposia Support: Advances in Olefin Polymerization Catalysis

    DTIC Science & Technology

    2014-11-24

    architectures. Finally, two talks described the use of some unusual ruthenium catalysts for polyolefin synthesis. Overall, all talks were well received, a range...discovery and innovation. 6. Tobias Friedberger 178 - Ruthenium complexes for olefin insertion polymerization Tobias Friedberger, tfriedbe@uci.edu...polyolefins via direct copolymerization of polar vinyl monomers and non-polar olefins. Ruthenium has been used for a variety of catalytic reactions involving

  14. High-performance vitrimers from commodity thermoplastics through dioxaborolane metathesis.

    PubMed

    Röttger, Max; Domenech, Trystan; van der Weegen, Rob; Breuillac, Antoine; Nicolaÿ, Renaud; Leibler, Ludwik

    2017-04-07

    Windmills, cars, and dental restoration demand polymer materials and composites that are easy to process, assemble, and recycle while exhibiting outstanding mechanical, thermal, and chemical resistance. Vitrimers, which are polymer networks able to shuffle chemical bonds through exchange reactions, could address these demands if they were prepared from existing plastics and processed with fast production rates and current equipment. We report the metathesis of dioxaborolanes, which is rapid and thermally robust, and use it to prepare vitrimers from polymers as different as poly(methyl methacrylate), polystyrene, and high-density polyethylene that, although permanently cross-linked, can be processed multiple times by means of extrusion or injection molding. They show superior chemical resistance and dimensional stability and can be efficiently assembled. The strategy is applicable to polymers with backbones made of carbon-carbon single bonds.

  15. Process and catalyst for carbonylating olefins

    DOEpatents

    Zoeller, Joseph Robert

    1998-06-02

    Disclosed is an improved catalyst system and process for preparing aliphatic carbonyl compounds such as aliphatic carboxylic acids, alkyl esters of aliphatic carboxylic acids and anhydrides of aliphatic carboxylic acids by carbonylating olefins in the presence of a catalyst system comprising (1) a first component selected from at least one Group 6 metal, i.e., chromium, molybdenum, and/or tungsten and (2) a second component selected from at least one of certain halides and tertiary and quaternary compounds of a Group 15 element, i.e., nitrogen, phosphorus and/or arsenic, and (3) as a third component, a polar, aprotic solvent. The process employing the improved catalyst system is carried out under carbonylating conditions of pressure and temperature discussed herein. The process constitutes and improvement over known processes since it can be carried out at moderate carbonylation conditions without the necessity of using an expensive noble metal catalyst, volatile, toxic materials such as nickel tetracarbonyl, formic acid or a formate ester. Further, the addition of a polar, aprotic solvent to the catalyst system significantly increases, or accelerates, the rate at which the carbonylation takes place.

  16. Low severity coal liquefaction promoted by cyclic olefins

    SciTech Connect

    Curtis, C.W.

    1992-01-01

    Low severity coal liquefaction promoted by cyclic olefins offers a means of liquefying coal at low severity conditions. Lower temperature, 350[degrees]C, and lower hydrogen pressure, 500 psi, have been used to perform liquefaction reactions. The presence of the cyclic olefin, hexahydroanthracene, made a substantial difference in the conversion of Illinois No. 6 coal at these low severity conditions. The Researchperformed this quarter was a parametric evaluation of the effect of different parameters on the coal conversion and product distribution from coal. The effect of the parameters on product distribution from hexahydroanthracene was also determined. The work planned for next quarter includes combining the most effective parametric conditions for the low severity reactions and determining their effect. The second part ofthe research performed this quarter involved performing Fourier transform infrared (FTIR) spectroscopy using cyclic olefins. The objective of this study was to determine the feasibility of using FTIR and a heated cell to determine the reaction pathway that occurs in the hydrogen donation reactions from cyclic olefins. The progress made to date includes evaluating the FTIR spectra of cyclic olefins and their expected reaction products. This work is included in this progress report.

  17. 40 CFR 721.5450 - α-Olefin sulfonate, sodium salt.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false α-Olefin sulfonate, sodium salt. 721... Substances § 721.5450 α-Olefin sulfonate, sodium salt. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as α-olefin sulfonate, sodium...

  18. 40 CFR 721.5425 - α-Olefin sulfonate, potassium salts.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false α-Olefin sulfonate, potassium salts... Substances § 721.5425 α-Olefin sulfonate, potassium salts. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as an α-olefin sulfonate, potassium salt...

  19. 40 CFR 721.5425 - α-Olefin sulfonate, potassium salts.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false α-Olefin sulfonate, potassium salts... Substances § 721.5425 α-Olefin sulfonate, potassium salts. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as an α-olefin sulfonate, potassium salt...

  20. 40 CFR 721.5450 - α-Olefin sulfonate, sodium salt.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false α-Olefin sulfonate, sodium salt. 721... Substances § 721.5450 α-Olefin sulfonate, sodium salt. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as α-olefin sulfonate, sodium...

  1. 40 CFR 721.5450 - α-Olefin sulfonate, sodium salt.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false α-Olefin sulfonate, sodium salt. 721... Substances § 721.5450 α-Olefin sulfonate, sodium salt. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as α-olefin sulfonate, sodium...

  2. 40 CFR 721.5450 - α-Olefin sulfonate, sodium salt.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false α-Olefin sulfonate, sodium salt. 721... Substances § 721.5450 α-Olefin sulfonate, sodium salt. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as α-olefin sulfonate, sodium...

  3. 40 CFR 721.5425 - α-Olefin sulfonate, potassium salts.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false α-Olefin sulfonate, potassium salts... Substances § 721.5425 α-Olefin sulfonate, potassium salts. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as an α-olefin sulfonate, potassium salt...

  4. 40 CFR 721.5425 - α-Olefin sulfonate, potassium salts.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false α-Olefin sulfonate, potassium salts... Substances § 721.5425 α-Olefin sulfonate, potassium salts. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as an α-olefin sulfonate, potassium salt...

  5. 40 CFR 721.5450 - α-Olefin sulfonate, sodium salt.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false α-Olefin sulfonate, sodium salt. 721... Substances § 721.5450 α-Olefin sulfonate, sodium salt. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as α-olefin sulfonate, sodium...

  6. 40 CFR 721.5425 - α-Olefin sulfonate, potassium salts.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false α-Olefin sulfonate, potassium salts... Substances § 721.5425 α-Olefin sulfonate, potassium salts. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as an α-olefin sulfonate, potassium salt...

  7. 40 CFR 721.10240 - Olefinic carbocycle, reaction products with alkoxysilane (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Olefinic carbocycle, reaction products... Significant New Uses for Specific Chemical Substances § 721.10240 Olefinic carbocycle, reaction products with... substance identified generically as olefinic carbocycle, reaction products with alkoxysilane (PMN...

  8. 40 CFR 721.10242 - Olefinic carbocycle, reaction products with alkoxysilane, polysulfurized (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Olefinic carbocycle, reaction products... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10242 Olefinic carbocycle, reaction... subject to reporting. (1) The chemical substance identified generically as olefinic carbocycle,...

  9. 40 CFR 721.10242 - Olefinic carbocycle, reaction products with alkoxysilane, polysulfurized (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Olefinic carbocycle, reaction products... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10242 Olefinic carbocycle, reaction... subject to reporting. (1) The chemical substance identified generically as olefinic carbocycle,...

  10. 40 CFR 721.10241 - Olefinic carbocycle, reaction products with alkoxysilane, sulfurized (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Olefinic carbocycle, reaction products... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10241 Olefinic carbocycle, reaction... to reporting. (1) The chemical substance identified generically as olefinic carbocycle,...

  11. 40 CFR 721.10240 - Olefinic carbocycle, reaction products with alkoxysilane (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Olefinic carbocycle, reaction products... Significant New Uses for Specific Chemical Substances § 721.10240 Olefinic carbocycle, reaction products with... substance identified generically as olefinic carbocycle, reaction products with alkoxysilane (PMN...

  12. 40 CFR 721.10242 - Olefinic carbocycle, reaction products with alkoxysilane, polysulfurized (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Olefinic carbocycle, reaction products... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10242 Olefinic carbocycle, reaction... subject to reporting. (1) The chemical substance identified generically as olefinic carbocycle,...

  13. 40 CFR 721.10240 - Olefinic carbocycle, reaction products with alkoxysilane (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Olefinic carbocycle, reaction products... Significant New Uses for Specific Chemical Substances § 721.10240 Olefinic carbocycle, reaction products with... substance identified generically as olefinic carbocycle, reaction products with alkoxysilane (PMN...

  14. 40 CFR 721.10241 - Olefinic carbocycle, reaction products with alkoxysilane, sulfurized (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Olefinic carbocycle, reaction products... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10241 Olefinic carbocycle, reaction... to reporting. (1) The chemical substance identified generically as olefinic carbocycle,...

  15. 40 CFR 721.10241 - Olefinic carbocycle, reaction products with alkoxysilane, sulfurized (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Olefinic carbocycle, reaction products... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10241 Olefinic carbocycle, reaction... to reporting. (1) The chemical substance identified generically as olefinic carbocycle,...

  16. Effect of process conditions on olefin selectivity during conventional and supercritical Fischer-Tropsch synthesis

    SciTech Connect

    Bukur, D.B.; Lang, X.; Akgerman, A.; Feng, Z.

    1997-07-01

    A precipitated iron catalyst (100 Fe/5 Cu/4.2 K/25 SiO{sub 2} on mass basis) was tested in a fixed-bed reactor under a variety of process conditions during conventional Fischer-Tropsch synthesis (FTS) and supercritical Fischer-Tropsch synthesis (SFTS). In both modes of operation it was found that: total olefin content decreases whereas 2-olefin content increases with either increase in conversion or H{sub 2}/CO molar feed ratio. Total olefin and 2-olefin selectivities were essentially independent of reaction temperature. The effect of conversion was more pronounced during conventional FTS. Comparison of olefin selectivities in the two modes of operation reveals that total olefin content is greater while the 2-olefin content is smaller during SFTS. Also, both the decrease in total olefin content and the increase in 2-olefin content with increase in carbon number (i.e., molecular weight of hydrocarbon products) was significantly less pronounced during SFTS in comparison to the conventional FTS. The obtained results suggest that 1-olefins, and to a smaller extent n-paraffins, are the primary products of FTS. Secondary reactions (isomerization, hydrogenation, and readsorption) of high molecular weight {alpha}-olefins occur to a smaller extent during SFTS, due to higher diffusivities and desorption rates of {alpha}-olefins in the supercritical propane than in the liquid-filled catalyst pores (conventional FTS).

  17. DFT study of the 1-octene metathesis reaction mechanism with WCl6/C catalytic system.

    PubMed

    Yüksel, Dilek; Düz, Bülent; Sevin, Fatma

    2008-05-22

    A catalytic system consisting of tungsten carbene generated from WCl(6) and an atomic carbon is investigated theoretically for the metathesis of 1-octene at B3LYP/extended LANL2DZ level of DFT. The ground-state geometries and charge distributions of the structures belonging to the reaction mechanism are located. Energetics for the complete set of reactions, involving the formation of the tungsten carbene precatalyst, Cl(4)WCCl(2), the formation of tungsten methylidene and tungsten heptylidene with this precatalyst, and finally productive and degenerative metathesis steps with these alkylidene species are calculated in terms of total electronic energy and thermal energies. The free-energy (ΔG(298)) surfaces of the structures involved in the related reactions are constructed. In addition, solvent effects on the single point energies of the structures are investigated for two different solvents, namely, cyclohexane and chloroform. The results indicate that the formation of the catalytically active heptylidene is energetically favored in comparison to the formation of methylidene, while the degenerative and productive metathesis steps are competitive. In the catalytic cycle, the formation of ethylene is exothermic, while the formation of 7-tetradecene is endothermic. As expected, solvent effects on the metathesis reactions are minor and solvation does not cause any change in the directions of the overall metathesis reactions.

  18. Adsorptive recovery of olefins from mixtures with paraffins

    SciTech Connect

    Zhuravlev, A.M.; Alekseeva, R.V.; Gerasimenko, E.G.; Alekseev, Yu.A.

    1987-11-01

    The recovery of olefins from mixtures with paraffins by adsorption on synthetic zeolites, aimed at obtaining experimental data for developing a mathematical model, was examined for the purpose of finding a linear olefin source for biodegradable detergents and achieving commensurate reductions in water pollution. Studies were performed under static and dynamic conditions. Test mixtures were prepared from individual hydrocarbons with purities of 98-99.5% by weight. Isotherms of excess sorption and selectivity coefficients for solutions of dodecene mixed with dodecane, octane, cyclohexane, and heptene were determined. Calculations were performed by methods of excess quantities and total content. Data shows the dynamic capacity of the olefins to breakthrough in proportion to their concentration in the original mixture.

  19. Ionic liquids for separation of olefin-paraffin mixtures

    DOEpatents

    Dai, Sheng; Luo, Huimin; Huang, Jing-Fang

    2014-07-15

    The invention is directed to an ionic liquid comprising (i) a cationic portion containing a complex of a silver (I) ion and one or more neutral ligands selected from organoamides, organoamines, olefins, and organonitriles, and (ii) an anionic portion having the chemical formula ##STR00001## wherein m and n are independently 0 or an integer of 1 or above, and p is 0 or 1, provided that when p is 0, the group --N--SO.sub.2--(CF.sub.2).sub.nCF.sub.3 subtended by p is replaced with an oxide atom connected to the shown sulfur atom. The invention is also directed to a method for separating an olefin from an olefin-paraffin mixture by passing the mixture through a layer of the ionic liquid described above.

  20. Ionic liquids for separation of olefin-paraffin mixtures

    DOEpatents

    Dai, Sheng; Luo, Huimin; Huang, Jing-Fang

    2013-09-17

    The invention is directed to an ionic liquid comprising (i) a cationic portion containing a complex of a silver (I) ion and one or more neutral ligands selected from organoamides, organoamines, olefins, and organonitriles, and (ii) an anionic portion having the chemical formula ##STR00001## wherein m and n are independently 0 or an integer of 1 or above, and p is 0 or 1, provided that when p is 0, the group --N--SO.sub.2--(CF.sub.2).sub.nCF.sub.3 subtended by p is replaced with an oxide atom connected to the shown sulfur atom. The invention is also directed to a method for separating an olefin from an olefin-paraffin mixture by passing the mixture through a layer of the ionic liquid described above.

  1. Metal-free transfer hydrogenation of olefins via dehydrocoupling catalysis

    PubMed Central

    Pérez, Manuel; Caputo, Christopher B.; Dobrovetsky, Roman; Stephan, Douglas W.

    2014-01-01

    A major advance in main-group chemistry in recent years has been the emergence of the reactivity of main-group species that mimics that of transition metal complexes. In this report, the Lewis acidic phosphonium salt [(C6F5)3PF][B(C6F5)4] 1 is shown to catalyze the dehydrocoupling of silanes with amines, thiols, phenols, and carboxylic acids to form the Si-E bond (E = N, S, O) with the liberation of H2 (21 examples). This catalysis, when performed in the presence of a series of olefins, yields the concurrent formation of the products of dehydrocoupling and transfer hydrogenation of the olefin (30 examples). This reactivity provides a strategy for metal-free catalysis of olefin hydrogenations. The mechanisms for both catalytic reactions are proposed and supported by experiment and density functional theory calculations. PMID:25002489

  2. Low Severity Coal Liquefaction Promoted by Cyclic Olefins

    SciTech Connect

    Christine W. Curtis

    1998-04-09

    The development of the donor solvent technology for coal liquefaction has drawn a good deal of attention over the last three decades. The search for better hydrogen donors led investigators to a class of compounds known as cyclic olefins. Cyclic olefins are analogues of the conventional hydroaromatic donor species but do not contain aromatic rings. The cyclic olefins are highly reactive compounds which readily release their hydrogen at temperatures of 200 C or higher. Considerable effort has been o expended toward understanding the process of hydrogen donation. Most of this work was conducted in bomb reactors, with product analysis being carried out after the reaction was complete. Efforts directed towards fundamental studies of these reactions in situ are rare. The current work employs a high temperature and high pressure infrared cell to monitor in situ the concentrations of reactants and products during hydrogen release from hydrogen donor compounds.

  3. Catalytic production of olefin block copolymers via chain shuttling polymerization.

    PubMed

    Arriola, Daniel J; Carnahan, Edmund M; Hustad, Phillip D; Kuhlman, Roger L; Wenzel, Timothy T

    2006-05-05

    We report a catalytic system that produces olefin block copolymers with alternating semicrystalline and amorphous segments, achieved by varying the ratio of alpha-olefin to ethylene in the two types of blocks. The system uses a chain shuttling agent to transfer growing chains between two distinct catalysts with different monomer selectivities in a single polymerization reactor. The block copolymers simultaneously have high melting temperatures and low glass transition temperatures, and therefore they maintain excellent elastomeric properties at high temperatures. Furthermore, the materials are effectively produced in economically favorable, continuous polymerization processes.

  4. Design of an etch-resistant cyclic olefin photoresist

    NASA Astrophysics Data System (ADS)

    Allen, Robert D.; Opitz, Juliann; Wallow, Thomas I.; Di Pietro, Richard A.; Hofer, Donald C.; Jayaraman, Saikumar; Hullihan, Karen A.; Rhodes, Larry F.; Goodall, Brian L.; Shick, Robert A.

    1998-06-01

    In the quest for a high performance 193 nm photoresist with robust plasma etching resistance equivalent to or better than the DUV resists of today, we have focused on the use of cyclic olefin polymers. In this paper, we will discuss monomer synthesis, polymerization approaches, polymer properties and early lithographic results of 193 nm photoresists formulated from cyclic olefin polymeric materials made from a metal-catalyzed addition polymerization process. The goal of this work is to produce a 193 nm photoresist with excellent imaging performance and etch resistance exceeding DUV resists, and in fact approaching novolak-based photoresists.

  5. Electrochemical Os-mediated asymmetric dihydroxylation of olefins

    SciTech Connect

    Torii, Sigeru

    1995-12-31

    Recently, the effective chiral ligands for enantioselective dihydroxylation of olefins have intensively been investigated. Among the reported asymmetric dihydroxylation systems, the superiority of a H{sub 2}O/t-BuOH-K{sub 3}Fe(CN){sub 6}/K{sub 2}CO{sub 3} system with chiral ligands, i.e., DHQD and/or DHQ derivatives, has been mentioned. Herein, the authors disclose preliminary studies on the electrochemical Os-catalyzed asymmetric dihyroxylation of olefins with Sharpless` ligands (L*).

  6. Well-defined silica-supported zirconium-imido complexes mediated heterogeneous imine metathesis.

    PubMed

    Hamzaoui, Bilel; Pelletier, Jérémie D A; Abou-Hamad, Edy; Basset, Jean-Marie

    2016-03-28

    Upon prolonged thermal exposure under vacuum, a well-defined single-site surface species [([triple bond, length as m-dash]Si-O-)Zr(NEt2)3] () evolves into an ethylimido complex [([triple bond, length as m-dash]Si-O-)Zr([double bond, length as m-dash]NEt)NEt2] (). Reactions of with an imine substrate result in imido/imine ([double bond, length as m-dash]NRi, R: Et, Ph) exchange (metathesis) with the formation of [([triple bond, length as m-dash]Si-O-)Zr([double bond, length as m-dash]NPh)NEt2] (). Compounds and effectively catalyze imine/imine cross-metathesis and are thus considered as the first heterogeneous catalysts active for imine metathesis.

  7. [Synthetic and mechanistic investigation of olefin polymerization catalyzed by early transition metal compounds

    SciTech Connect

    Bercaw, J.E.

    1993-01-01

    During the second year we continued to prepare and characterize organoyttrium and organoscandium compounds for use as catalysts for polymerizing simple olefins and diolefins. Simple, one-component systems are being pursued, suitable for chain initiation, propagation, and termination studies. This document is divided into: dicarbollide derivatives of scandium as potential catalysts; design, synthesis, and characterization of the first isospecific [alpha] olefin polymerization catalysts; polymerization of [alpha] olefins and 1,5- hexadiene using organoscandium catalysts; and attempted preparations of diastereomeric Nb and Ta olefin/hydride and olefin/alkyl derivatives.

  8. Electrochemistry for biofuel generation: transformation of fatty acids and triglycerides to diesel-like olefin/ether mixtures and olefins.

    PubMed

    dos Santos, Tatiane R; Harnisch, Falk; Nilges, Peter; Schröder, Uwe

    2015-03-01

    Electroorganic synthesis can be exploited for the production of biofuels from fatty acids and triglycerides. With Coulomb efficiencies (CE) of up to 50 %, the electrochemical decarboxylation of fatty acids in methanolic and ethanolic solutions leads to the formation of diesel-like olefin/ether mixtures. Triglycerides can be directly converted in aqueous solutions by using sonoelectrochemistry, with olefins as the main products (with a CE of more than 20 %). The latter reaction, however, is terminated at around 50 % substrate conversion by the produced side-product glycerol. An energy analysis shows that the electrochemical olefin synthesis can be an energetically competitive, sustainable, and--in comparison with established processes--economically feasible alternative for the exploitation of fats and oils for biofuel production.

  9. Synthesis of nanosized silicon particles by a rapid metathesis reaction

    NASA Astrophysics Data System (ADS)

    Won, C. W.; Nersisyan, H. H.; Won, H. I.; Lee, H. H.

    2009-11-01

    A solid-state rapid metathesis reaction was performed in a bed of sodium silicofluoride (Na 2SiF 6) and sodium azide (NaN 3) powders diluted with sodium fluoride (NaF), to produce silicon nanoparticles. After a local ignition of Na 2SiF 6+4NaN 3+ kNaF mixture (here k is mole number of NaF), the reaction proceeded in a self-sustaining combustion mode developing high temperatures (950-1000 °C) on very short time scales (a few seconds). Silicon nanoparticles prepared by the combustion process was easily separated from the salt byproducts by simple washing with distilled water. The structural and morphological studies on the nanoparticles were carried out using X-ray diffractometer (XRD) and field emission scanning electron microscope (FESEM). The mean size of silicon particles calculated from the FESEM image was about 37.75 nm. FESEM analysis also shows that the final purified product contains a noticeable amount of silicon fibers, dendrites and blocks, along with nanoparticles. The mechanism of Si nanostructures formation is discussed and a simple model for interpretation of experimental results is proposed.

  10. Organic and composite aerogels through ring opening metathesis polymerization (ROMP)

    NASA Astrophysics Data System (ADS)

    Mohite, Dhairyashil P.

    Aerogels are open-cell nanoporous materials, unique in terms of low density, low thermal conductivity, low dielectric constants and high acoustic attenuation. Those exceptional properties stem from their complex hierarchical solid framework (agglomerates of porous, fractal secondary nanoparticles), but they also come at a cost: low mechanical strength. This issue has been resolved by crosslinking silica aerogels with organic polymers. The crosslinking polymer has been assumed to form a conformal coating on the surface of the skeletal framework by covalent bridging elementary building blocks. However, "assuming" is not enough: for correlating nanostructure with bulk material properties, it is important to know the exact location of the polymer on the aerogel backbone. For that investigation, we synthesized a new norbornene derivative of triethoxysilane (Si-NAD) that can be attached to skeletal silica nanoparticles. Those norbornene-modified silica aerogels were crosslinked with polynorbornene by ring opening metathesis polymerization (ROMP). The detailed correlation between nanostructure and mechanical strength was probed with a wide array of characterization methods ranging from molecular to bulk through nano. Subsequently, it was reasoned that since the polymer dominates the exceptional mechanical properties of polymer crosslinked aerogels, purely organic aerogels with the same nanostructure and interparticle connectivity should behave similarly. That was explored and confirmed by: (a) synthesis of a difunctional nadimide monomer (bis-NAD), and preparation of robust polyimide aerogels by ROMP of its norbornene end-caps; and, (b) synthesis of dimensionally stable ROMP-derived polydicyclopentadiene aerogels by grafting the nanostructure with polymethylmethacrylate (PMMA) via free radical chemistry.

  11. Effects of vanadium and zinc promotion on the olefin selectivity of iron Fischer-Tropsch catalysts

    SciTech Connect

    Saglam, M.

    1989-02-01

    The aim in most of the studies on Fischer-Tropsch synthesis has been the selective production of olefins, which are the raw materials of petrochemical industry. In this study, the effects of V and Zn addition, separately or together in the form of their oxides, to Fe catalysts obtained through precipitation on the olefin selectivity of the catalysts have been investigated. The experiments have been done in a fixed-bed reactor at different temperatures and pressures with various ratios of H/sub 2//CO. The addition of V separately (catalyst 2) or together with Zn (catalyst 1) has greatly increased the olefin selectivity of Fe catalyst. So the amount of olefin in hydrocarbon fractions has reached over 80%. Besides, the ..cap alpha..-olefin parts in olefin fractions have gone over 90%. But the addition of Zn separately has been less effective on the olefin selectivity of the catalyst.

  12. Paternò-Büchi reaction between furan and heterocyclic aldehydes: oxetane formation vs. metathesis.

    PubMed

    D'Auria, Maurizio; Racioppi, Rocco; Viggiani, Licia

    2010-08-01

    The photochemical reaction of 2-substituted heterocyclic aldehydes with furan gave the corresponding exo oxetane derivatives through the excited triplet state. However, in situ the oxetane derivatives were converted through a metathesis reaction into the corresponding Z,E-butadienyl formate derivatives. On the contrary, 3-substituted heterocyclic aldehydes gave the corresponding exo oxetane derivatives. The effect of 2-substituted heterocyclic ring in order to facilitate the metathesis reaction is explained considering the possible participation of the pi aromatic orbitals in the oxetane C-O bond cleavage.

  13. Tandem enyne metathesis-Diels-Alder reaction for construction of natural product frameworks.

    PubMed

    Rosillo, Marta; Domínguez, Gema; Casarrubios, Luis; Amador, Ulises; Pérez-Castells, Javier

    2004-03-19

    Enynes connected through aromatic rings are used as substrates for metathesis reactions. The reactivity of three ruthenium carbene complexes is compared. The resulting 1,3-dienes are suitable precursors of polycyclic structures via a Diels-Alder process. Some domino RCM-Diels-Alder reactions are performed, suggesting a possible beneficial effect of the ruthenium catalyst in the cycloaddition process. Other examples require Lewis acid cocatalyst. When applied to aromatic ynamines or enamines, a new synthesis of vinylindoles is achieved. Monitorization of several metathesis reactions with NMR shows the different behavior for ruthenium catalysts. New carbenic species are detected in some reactions with an important dependence on the solvent used.

  14. ULTRASOUND-ASSISTED ORGANIC SYNTHESIS: ALCOHOL OXIDATION AND OLEFIN EPOXIDATION

    EPA Science Inventory

    Ultrasound-assisted Organic Synthesis: Alcohol Oxidation and Olefin Epoxidation

    Unnikrishnan R Pillai, Endalkachew Sahle-Demessie , Vasudevan Namboodiri, Quiming Zhao, Juluis Enriquez
    U.S. EPA , 26 W. Martin Luther King Dr. , Cincinnati, OH 45268
    Phone: 513-569-773...

  15. Palladium-Catalyzed 1,1- Aryloxygenation of Terminal Olefins

    PubMed Central

    Satterfield, Andrew D.; Kubota, Asako; Sanford, Melanie S.

    2011-01-01

    This paper describes the 1,1-arylacetoxylation of diverse α-olefins using organostannanes and hypervalent iodine oxidants. The reaction provides a convergent approach for generating a C–C and a C-O bond as well as a new stereocenter in a single catalytic transformation. PMID:21291210

  16. Bio-olefins from unsaturated fatty acids via tandem catalysis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A new catalytic route to bio-olefins from unsaturated fatty acids will be described. At the heart of the process, the catalyst apparently functions in a tandem mode by both dynamically isomerizing the positions of double bonds in an aliphatic chain and, subsequently, decarboxylating specific isomers...

  17. Chiral Ketone and Iminium Catalysts for Olefin Epoxidation

    NASA Astrophysics Data System (ADS)

    Wong, O. Andrea; Shi, Yian

    Organo-catalyzed asymmetric epoxidation has received much attention in the past 30 years and significant progress has been made for various types of olefins. This review will cover the advancement made in the field of chiral ketone and chiral iminium salt-catalyzed epoxidations.

  18. Feedstock-flexible olefins plants can be efficient

    SciTech Connect

    DeHaan, S.

    1983-09-26

    Factors such as relative price, political policies, the world economic recovery, and propylene and other byproduct markets will determine the best future olefin feedstock. The choice of feedstocks will have a significant impact on plant investment by increasing sizes and/or requiring additional processing steps. The European and Japanese olefins industries have traditionally been based on liquid feedstock, naphthas, and gas oils. The U.S. industry's base was nearly totally natural gas derived ethane and LPG until a surge of interest in liquid feedstocks in the 1970s. Today, about one-third of the U.S. ethylene plant capacity is designed to utilize liquid feedstocks. The European and Japanese industries remain predominantly liquid feed based. Summary. While a multi-feed olefins plant is a complex entity, a properly conceived olefins design can provide for a wide range of feedstock flexibility, without significantly compromising overall plant efficiency. The optimization of any such operation is an extremely detailed and difficult problem. Therefore, it warrants the use of the best available digital technology. A sophisticated simulator/optimizer can provide valuable guidance to plant operators. Well trained operators assisted by a reliable closed-loop computer control system and a plant optimizer can greatly enhance plant profitability by maintaining optimum performance and maximum on-stream time.

  19. Sterically shielded diboron-containing metallocene olefin polymerization catalysts

    DOEpatents

    Marks, Tobin J.; Ja, Li; Yang, Xinmin

    1995-09-05

    A non-coordinating anion, preferably containing a sterically shielded diboron hydride, if combined with a cyclopenta-dienyl-substituted metallocene cation component, such as a zirconocene metallocene, is a useful olefin polymerization catalyst component. The anion preferably has the formula ##STR1## where R is branched lower alkyl, such as t-butyl.

  20. Pressure-induced metathesis reaction to sequester Cs.

    PubMed

    Im, Junhyuck; Seoung, Donghoon; Lee, Seung Yeop; Blom, Douglas A; Vogt, Thomas; Kao, Chi-Chang; Lee, Yongjae

    2015-01-06

    We report here a pressure-driven metathesis reaction where Ag-exchanged natrolite (Ag16Al16Si24O80·16H2O, Ag-NAT) is pressurized in an aqueous CsI solution, resulting in the exchange of Ag(+) by Cs(+) in the natrolite framework forming Cs16Al16Si24O80·16H2O (Cs-NAT-I) and, above 0.5 GPa, its high-pressure polymorph (Cs-NAT-II). During the initial cation exchange, the precipitation of AgI occurs. Additional pressure and heat at 2 GPa and 160 °C transforms Cs-NAT-II to a pollucite-related, highly dense, and water-free triclinic phase with nominal composition CsAlSi2O6. At ambient temperature after pressure release, the Cs remains sequestered in a now monoclinic pollucite phase at close to 40 wt % and a favorably low Cs leaching rate under back-exchange conditions. This process thus efficiently combines the pressure-driven separation of Cs and I at ambient temperature with the subsequent sequestration of Cs under moderate pressures and temperatures in its preferred waste form suitable for long-term storage at ambient conditions. The zeolite pollucite CsAlSi2O6·H2O has been identified as a potential host material for nuclear waste remediation of anthropogenic (137)Cs due to its chemical and thermal stability, low leaching rate, and the large amount of Cs it can contain. The new water-free pollucite phase we characterize during our process will not display radiolysis of water during longterm storage while maintaining the Cs content and low leaching rate.

  1. Synthesis of Cycloparaphenyleneacetylene via Alkyne Metathesis: C70 Complexation and Copper-Free Triple Click Reaction.

    PubMed

    Lee, Semin; Chénard, Etienne; Gray, Danielle L; Moore, Jeffrey S

    2016-10-10

    Alkyne metathesis provided an efficient macrocyclization route to a cycloparaphenyleneacetylene derivative in high yield. The cavity size was suitably matched for C70 which was tightly bound in an induced-fit fashion. The strain on the alkynyl bonds enabled a copper-free, three-fold azide-alkyne cycloaddi-tion at 50 °C.

  2. Catalytic enantioselective synthesis of naturally occurring butenolides via hetero-allylic alkylation and ring closing metathesis.

    PubMed

    Mao, Bin; Geurts, Koen; Fañanás-Mastral, Martín; van Zijl, Anthoni W; Fletcher, Stephen P; Minnaard, Adriaan J; Feringa, Ben L

    2011-03-04

    An efficient catalytic asymmetric synthesis of chiral γ-butenolides was developed based on the hetero-allylic asymmetric alkylation (h-AAA) in combination with ring closing metathesis (RCM). The synthetic potential of the h-AAA-RCM protocol was illustrated with the facile synthesis of (-)-whiskey lactone, (-)-cognac lactone, (-)-nephrosteranic acid, and (-)-roccellaric acid.

  3. Ring-Closing Metathesis: An Advanced Guided-Inquiry Experiment for the Organic Laboratory

    ERIC Educational Resources Information Center

    Schepmann, Hala G.; Mynderse, Michelle

    2010-01-01

    The design and implementation of an advanced guided-inquiry experiment for the organic laboratory is described. Grubbs's second-generation catalyst is used to effect the ring-closing metathesis of diethyl diallylmalonate. The reaction is carried out under an inert atmosphere at room temperature and monitored by argentic TLC. The crude reaction is…

  4. Bridgehead vicinal diallylation of norbornene derivatives and extension to propellane derivatives via ring-closing metathesis

    PubMed Central

    Gunta, Rama

    2016-01-01

    Summary Here, we report a simple synthetic strategy to the bridgehead vicinal diallylation of norbornene derivatives. These substrates are useful to generate propellanes via ring-closing metathesis. Single-crystal X-ray diffraction analysis of four compounds led to the realization of configurational correction of earlier reported molecules. PMID:27829894

  5. Synthesis of the Caeliferins, elicitors of plant immune responses: accessing Lipophilic natural products via cross metathesis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We report a cross metathesis- (CM-) based syn-thesis of the caeliferins, a family of sulfooxy fatty acids that elicit plant immune responses. Unexpectedly, detailed NMR-spectroscopic and mass spectrometric analyses of CM reaction mixtures revealed extensive isomerization and homologation of starting...

  6. The Acquisition of Consonant Feature Sequences: Harmony, Metathesis, and Deletion Patterns in Phonological Development

    ERIC Educational Resources Information Center

    Gerlach, Sharon Ruth

    2010-01-01

    This dissertation examines three processes affecting consonants in child speech: harmony (long-distance assimilation) involving major place features as in "coat" [kouk]; long-distance metathesis as in "cup" [p[wedge]k]; and initial consonant deletion as in "fish" [is]. These processes are unattested in adult phonology, leading to proposals for…

  7. Tuning PCP-Ir complexes: the impact of an N-heterocyclic olefin.

    PubMed

    Iglesias, Manuel; Iturmendi, Amaia; Sanz Miguel, Pablo J; Polo, Victor; Pérez-Torrente, Jesús J; Oro, Luis A

    2015-08-11

    A new PCP-type ligand based on an N-heterocyclic olefin (NHO) scaffold has been prepared. The flexibility of this ligand, which is able to adopt facial coordination modes in Ir(I) or meridional in Ir(III) complexes, can be attributed to the dual nature (ylide-olefin) of the NHO scaffold. This results in a rare case of olefin "slippage" that is supported by X-ray crystallography and DFT calculations.

  8. Nickel-Catalyzed Heck-Type Reactions of Benzyl Chlorides and Simple Olefins

    PubMed Central

    Matsubara, Ryosuke; Gutierrez, Alicia C.; Jamison, Timothy F.

    2011-01-01

    Nickel-catalyzed intermolecular benzylation and heterobenzylation of unactivated alkenes to provide functionalized allylbenzene derivatives is described. A wide range of both the benzyl chloride and alkene coupling partners are tolerated. In contrast to analogous palladium-catalyzed variants of this process, all reactions described herein employ electronically unbiased aliphatic olefins (including ethylene), proceed at room temperature and provide 1,1-disubstituted olefins over the more commonly observed 1,2-disubstituted olefins with very high selectivity. PMID:22066899

  9. Rare-earth-catalyzed C-H bond addition of pyridines to olefins.

    PubMed

    Guan, Bing-Tao; Hou, Zhaomin

    2011-11-16

    An efficient and general protocol for the ortho-alkylation of pyridines via C-H addition to olefins has been developed, using cationic half-sandwich rare-earth catalysts, which provides an atom-economical method for the synthesis of alkylated pyridine derivatives. A wide range of pyridine and olefin substrates including α-olefins, styrenes, and conjugated dienes are compatible with the catalysts.

  10. The Ziegler—Natta olefin insertion reaction for cationic metals

    NASA Astrophysics Data System (ADS)

    Jensen, Vidar R.; Siegban, Per E. M.

    1993-09-01

    The catalytic Ziegler—Natta polymerization reaction has been studied for a set of metal cations, in order to identify the role of the positive charge on this process. Geometry optimizations have been performed for the reactant metal—methyl systems, the π-coordinated olefin systems, the transition states for the olefin insertion and finally for the product metal—propyl systems. All valence electrons are correlated. The cations selected for this study are the transition metals Zr + and Ti +, the non-transition metals Be +, Mg +, Al + and finally also Si +. The transition metal cations are found to have very low barriers for the insertion, but the lowest barrier is actually found for Be +. The results are discussed in terms of the ionization energies and the accessibility to valence p and d orbitals. Comparisons are made to previous theoretical work on cationic model systems.

  11. Low severity coal liquefaction promoted by cyclic olefins

    SciTech Connect

    Curtis, C.W.

    1991-01-01

    The objective of this project is to evaluate the efficacy of low severity coal liquefaction in the presence of highly reactive hydrogen donors, cyclic olefins. The work that was performed this quarter involved performing a literature search in which different aspects of low severity coal liquefaction were examined. In addition, two new mater's graduate students learned the fundamental differences between high severity coal liquefaction and low severity coal liquefaction by examining the literature and reading texts on coal liquefaction. The literature review presented for the first quarter's work is a compilation of the material which we have found to data involving low severity coal liquefaction. Additional review of low severity liquefaction literature is being conducted this quarter and will be reported in the next quarterly report. In addition, a summary of the work involving the reactivity of cyclic olefins in the absence and presence of coal will be presented next quarter.

  12. Syngas to olefins via dimethyl ether over zeolite catalysts

    SciTech Connect

    Lee, B.G.; Sardesai, A.; Lee, S.

    1998-12-31

    Coal or natural gas-based syngas can be converted to dimethyl ether (DME) in a dual catalytic, single-stage liquid phase process. The process described here converts dimethyl ether to lower olefins, such as ethylene, propylene, and butenes. Thus, a novel process of producing olefins from syngas via dimethyl ether has been introduced. The process feasibility of dimethyl ether conversion has been evaluated and the range of products of this process has also been identified. The effect of operating parameters and catalyst characteristics on product selectivity has been studied. The superior process advantages as well as its competitive economics quite clearly identify this process to be quite promising when conducted on an industrial scale.

  13. Cyclic olefins as new hydrogen donor compounds for coal liquefaction

    SciTech Connect

    Bedell, M.W.; Curtis, C.W. )

    1990-01-01

    A new set of hydrogen donor compounds, cyclic olefins (CLO), has been evaluated to determine their effectiveness as hydrogen donors to coal. These cyclic olefins are hydroaromatic species which do not contain aromatic rings. The efficacy of these donors has been compared to conventional hydroaromatics. The CLO's under study are 1,4,5,8-tetrahydronaphthalene, also known as isotetralin, and 1,4,5,8,9,10-hexahydroanthracene. In this paper, the thermal and catalytic reactivity of the CLO's under nitrogen and hydrogen at coal liquefaction temperature is discussed. Results for the reactions of the CLO's and their conventional hydroaromatic analogues, e.g. tetralin, 9,10-dihydroanthracene, and octahydroanthracene, with Western Kentucky No. 9 coal are discussed.

  14. Low severity coal liquefaction promoted by cyclic olefins

    SciTech Connect

    Curtis, C.W.

    1991-01-01

    The objective of this project is to evaluate the efficacy of low severity coal liquefaction in the presence of highly reactive hydrogen donors, cyclic olefins. The work that was performed this quarter involved performing a literature search in which different aspects of low severity coal liquefaction were examined. In addition, two new master's graduate students learned the fundamental differences between high severity coal liquefaction and low severity coal liquefaction by examining the literature and reading texts on coal liquefaction. The literature review presented for the first quarter's work is a compilation of the material which we have found to date involving low severity coal liquefaction. Additional review of low severity liquefaction literature is being conducted this quarter and will be reported in the next quarterly report. In addition, a summary of the work involving the reactivity of cyclic olefins in the absence and presence of coal will be presented next quarter.

  15. Process for upgrading olefinic gasoline by etherification wherein asymmetrical dialkyl ethers are produced

    SciTech Connect

    Mizrahi, S.; Sorensen, C.M.; Tabak, S.A.

    1992-01-07

    This patent describes an integrated process for improving the value of an olefin-containing gasoline stream. It includes providing an olefinic gasoline feedstream containing C{sub 3}-C{sub 8} olefins; fractionating the olefinic gasoline feedstream to evolve a first stream enriched in C{sub 3}-C{sub 4} olefins and a second gasoline stream enriched in C{sub 5}-C{sub 8} olefins; converting at least 30% by weight of the C{sub 3}-C{sub 4} olefins contained in the first stream of step (b) in a hydration zone to a hydration zone effluent containing alcohols in an aqueous mixture comprising isopropyl alcohol and sec-butyl alcohol with C{sub 3}- C{sub 4} primary alcohols; fractionating the hydration zone effluent into a recycle stream rich in C{sub 3}-C{sub 4} olefins and a purified hydrate stream containing alcohols in an aqueous mixture comprising isopropyl alcohol and sec-butyl alcohol with C{sub 3}-C{sub 4} primary alcohols; extracting the alcohols from the purified hydrate stream with the olefin-enriched second gasoline stream.

  16. Improved light olefin yield from methyl bromide coupling over modified SAPO-34 molecular sieves.

    PubMed

    Zhang, Aihua; Sun, Shouli; Komon, Zachary J A; Osterwalder, Neil; Gadewar, Sagar; Stoimenov, Peter; Auerbach, Daniel J; Stucky, Galen D; McFarland, Eric W

    2011-02-21

    As an alternative to the partial oxidation of methane to synthesis gas followed by methanol synthesis and the subsequent generation of olefins, we have studied the production of light olefins (ethylene and propylene) from the reaction of methyl bromide over various modified microporous silico-aluminophosphate molecular-sieve catalysts with an emphasis on SAPO-34. Some comparisons of methyl halides and methanol as reaction intermediates in their conversion to olefins are presented. Increasing the ratio of Si/Al and incorporation of Co into the catalyst framework improved the methyl bromide yield of light olefins over that obtained using standard SAPO-34.

  17. Probing the Mechanism of the Double C—H (De)Activation Route of a Ru-Based Olefin Metathesis Catalyst

    NASA Astrophysics Data System (ADS)

    Poater, Albert; Cavallo, Luigi

    A theoretical study of a double C—H activation mechanism that deactivates a family of second generation Ru-based catalysts is presented. DFT calculations are used to rationalize the complex mechanistic pathway from the starting precatalyst to the experimentally characterized decomposition products. In particular, we show that all the intermediates proposed by Grubbs and coworkers are indeed possible intermediates in the deactivation pathway, although the sequence of steps is somewhat different

  18. Homogeneous catalysis with methane. A strategy for the hydromethylation of olefins based on the nondegenerate exchange of alkyl groups and sigma-bond metathesis at scandium.

    PubMed

    Sadow, Aaron D; Tilley, T Don

    2003-07-02

    The scandium alkyl Cp*(2)ScCH(2)CMe(3) (2) was synthesized by the addition of a pentane solution of LiCH(2)CMe(3) to Cp*(2)ScCl at low temperature. Compound 2 reacts with the C-H bonds of hydrocarbons including methane, benzene, and cyclopropane to yield the corresponding hydrocarbyl complex and CMe(4). Kinetic studies revealed that the metalation of methane proceeds exclusively via a second-order pathway described by the rate law: rate = k[2][CH(4)] (k = 4.1(3) x 10(-4) M(-1)s(-1) at 26 degrees C). The primary inter- and intramolecular kinetic isotope effects (k(H)/k(D) = 10.2 (CH(4) vs CD(4)) and k(H)/k(D) = 5.2(1) (CH(2)D(2)), respectively) are consistent with a linear transfer of hydrogen from methane to the neopentyl ligand in the transition state. Activation parameters indicate that the transformation involves a highly ordered transition state (DeltaS++ = -36(1) eu) and a modest enthalpic barrier (DeltaH++ = 11.4(1) kcal/mol). High selectivity toward methane activation suggested the participation of this chemistry in a catalytic hydromethylation, which was observed in the slow, Cp*(2)ScMe-catalyzed addition of methane across the double bond of propene to form isobutane.

  19. Vanadyl cationic complexes as catalysts in olefin oxidation.

    PubMed

    Nunes, Carla D; Vaz, Pedro D; Félix, Vítor; Veiros, Luis F; Moniz, Tânia; Rangel, Maria; Realista, Sara; Mourato, Ana C; Calhorda, Maria José

    2015-03-21

    Three new mononuclear oxovanadium(IV) complexes [VO(acac)(R-BIAN)]Cl (BIAN = 1,2-bis{(R-phenyl)imino}acenaphthene, R = H, 1; CH3, 2; Cl, 3) were prepared and characterized. They promoted the catalytic oxidation of olefins such as cyclohexene, cis-cyclooctene, and styrene with both tbhp (tert-butylhydroperoxide) and H2O2, and of enantiopure olefins (S(-)- and R(+)-pinene, and S(-)- and R(+)-limonene) selectively to their epoxides, with tbhp as the oxidant. The TOFs for styrene epoxidation promoted by complex 3 with H2O2 (290 mol mol(-1)V h(-1)) and for cis-cyclooctene epoxidation by 2 with tbhp (248 mol mol(-1)V h(-1)) are particularly good. Conversions reached 90% for several systems with tbhp, and were lower with H2O2. A preference for the internal C=C bond, rather than the terminal one, was found for limonene. Kinetic data indicate an associative process as the first step of the reaction and complex [VO(acac)(H-BIAN)](+) (1(+)) was isolated in an FTICR cell after adding tbhp to 1. EPR studies provide evidence for the presence of a V(IV) species in solution, until at least 48 hours after the addition of tbhp and cis-cyclooctene, and cyclic voltammetry studies revealed an oxidation potential above 1 V for complex 1. DFT calculations suggest that a [VO(H-BIAN)(MeOO)](+) complex is the likely active V(IV) species in the catalytic cycle from which two competitive mechanisms for the reaction proceed, an outer sphere path with an external attack of the olefin at the coordinated peroxide, and an inner sphere mechanism starting with a complex with the olefin coordinated to vanadium.

  20. Synthesis of polytetrafluoroethylene based olefinic copolymer by gamma radiation grafting

    NASA Astrophysics Data System (ADS)

    Ferreto, H. F. R.; Lima, L. F. C. P.; Parra, D. F.; Zaia, V.; Lugão, A. B.

    2007-12-01

    High speed extrusion of linear low density polyethylene (LLDPE) is limited by processes shortcoming known as 'melt fracture' and 'sharkskin', which are surface defect of the extruded polymer. This defect results in a product with a rough surface that lacks luster and with poor surface properties. The fluoropolymer processing additives are used to eliminate the surface defect by coating the die wall and inducing slip at the coated fluoropolymer surface/LLDPE interface. The aim of this study was to obtain a recycled polytetrafluoroethylene polymer grafted with an olefin that could improve the extrudability of the LLDPE. The copolymer was obtained by irradiating recycled PTFE in an inert atmosphere followed by grafting an olefinic monomer the polymeric matrix (PTFE). After a certain time of contact, the copolymer was heat treated to allow recombination and elimination of the radicals, both in a reactive and/or inert atmosphere. The olefinic monomer used was 1,3-butadiene. The 1,3-butadiene monomer was found to be more effective with respect to grafting. The specimens were studied using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and differential thermogravimetry (DTG). The obtained copolymer (0.2-2.0 wt%) was mixed with LLDPE. The rheological properties of the mixture were determined with a torque rheometer. The results indicated that the developed process rendered a copolymer which when added to LLDPE, improved the extrusion process and eliminated the defect 'melt fracture'.

  1. Integrated process and dual-function catalyst for olefin epoxidation

    DOEpatents

    Zhou, Bing; Rueter, Michael

    2003-01-01

    The invention discloses a dual-functional catalyst composition and an integrated process for production of olefin epoxides including propylene oxide by catalytic reaction of hydrogen peroxide from hydrogen and oxygen with olefin feeds such as propylene. The epoxides and hydrogen peroxide are preferably produced simultaneously in situ. The dual-functional catalyst comprises noble metal crystallites with dimensions on the nanometer scale (on the order of <1 nm to 10 nm), specially dispersed on titanium silicalite substrate particles. The dual functional catalyst catalyzes both the direct reaction of hydrogen and oxygen to generate hydrogen peroxide intermediate on the noble metal catalyst surface and the reaction of the hydrogen peroxide intermediate with the propylene feed to generate propylene oxide product. Combining both these functions in a single catalyst provides a very efficient integrated process operable below the flammability limits of hydrogen and highly selective for the production of hydrogen peroxide to produce olefin oxides such as propylene oxide without formation of undesired co-products.

  2. Low severity coal liquefaction promoted by cyclic olefins

    SciTech Connect

    Curtis, C.W.

    1992-07-27

    Low severity coal liquefaction allows for solubilization of coal with reduced gas make. These lower severity conditions may result in some selective bond rupture. Promotion of coal solubilization through hydrogen transfer using highly active and effective hydrogen donors is the objective of this study. The highly effective donors being tested are cyclic olefins. Representative cyclic olefins are isotetralin, which is 1,4,5,8-tetrahydronaphthalene, and 1,4,5,8,9,10-hexahydroanthracene. These compounds are hydroaromatics without aromatic rings and have been shown to be highly effective donors. The objective of the work performed in this study during this quarter was to evaluate reaction parameters for low severity liquefaction reactions using the cyclic olefin, hexahydroanthracene, and the aromatic, anthracene. These model compounds were reacted under a variety of conditions to evaluate their reactivity without coal. The reactions were performed under both thermal and catalytic conditions. Finely divided catalysts from different molybdenum precursors were used to determine their activity in promoting hydrogenation and hydrogen transfer at low severity conditions. The catalysts used were Molyvan L, sulfurized oxymolybdenum dithiocarbamate, molybdenum naphthenate, and Molyvan 822, organo molybdenum dithiocarbamate.

  3. Observation of different catalytic activity of various 1-olefins during ethylene/1-olefin copolymerization with homogeneous metallocene catalysts.

    PubMed

    Wannaborworn, Mingkwan; Praserthdam, Piyasan; Jongsomjit, Bunjerd

    2011-01-07

    This research aimed to investigate the copolymerization of ethylene and various 1-olefins. The comonomer lengths were varied from 1-hexene (1-C₆) up to 1-octadecene (1-C₁₈) in order to study the effect of comonomer chain length on the activity and properties of the polymer in the metallocene/MAO catalyst system. The results indicated that two distinct cases can be described for the effect of 1-olefin chain length on the activity. Considering the short chain length comonomers, such as 1-hexene, 1-octene and 1-decene, it is obvious that the polymerization activity decreased when the length of comonomer was higher, which is probably due to increased steric hindrance at the catalytic center hindering the insertion of ethylene monomer to the active sites, hence, the polymerization rate decreased. On the contrary, for the longer chain 1-olefins, namely 1-dodecene, 1-tetradecene and 1-octadecene, an increase in the comonomer chain length resulted in better activity due to the opening of the gap aperture between C(p)(centroid)-M-C(p)-(centroid), which forced the coordination site to open more. This effect facilitated the polymerization of the ethylene monomer at the catalytic sites, and thus, the activity increased. The copolymers obtained were further characterized using thermal analysis, X-ray diffraction spectroscopy and ¹³C-NMR techniques. It could be seen that the melting temperature and comonomer distribution were not affected by the 1-olefin chain length. The polymer crystallinity decreased slightly with increasing comonomer chain length. Moreover, all the synthesized polymers were typical LLDPE having random comonomer distribution.

  4. New Applications of Ring-Opening Metathesis Polymerization for Grafting Alkylene Oxide-Based Copolymers

    NASA Astrophysics Data System (ADS)

    Spurcaciu, Bogdan; Buzdugan, Emil; Nicolae, Cristian; Ghioca, Paul; Iancu, Lorena; Dragutan, Valerian; Dragutan, Ileana

    This research tackles the challenges of innovative modification of poly(allyl alkylene oxides) by ROMP to produce new materials. Firstly, binary and ternary copolymers, poly(epichlorohydrin-allyl glycidyl ether) (ECH-AGE) and poly (epichlorohydrin-propylene oxide-allyl glycidyl ether) (ECH-PO-AGE), have been prepared using as initiator a catalytic system consisting of an alkyl aluminium, controlled amounts of water and different compounds (ethers, diols, phosphines, salicylic acid derivatives, organozincs) acting as cocatalysts. Among catalysts explored in these copolymerizations most productive showed to be the systems triisobutylaluminium (TIBA), water and Zn(DIPS)2 or Zn(acac)2. Copolymers which have become thus available were subsequently grafted onto the pendent allylic groups by ROMP with cycloolefins (cyclooctene, norbornene, cyclododecene) involving ruthenium based catalysts.

  5. Nitrene Metathesis and Catalytic Nitrene Transfer Promoted by Niobium Bis(imido) Complexes.

    PubMed

    Kriegel, Benjamin M; Bergman, Robert G; Arnold, John

    2016-01-13

    We report a metathesis reaction in which a nitrene fragment from an isocyanide ligand is exchanged with a nitrene fragment of an imido ligand in a series of niobium bis(imido) complexes. One of these bis(imido) complexes also promotes nitrene transfer to catalytically generate asymmetric dialkylcarbodiimides from azides and isocyanides in a process involving the Nb(V)/Nb(III) redox couple.

  6. Rapid assembly of structurally defined and highly functionalized conjugated dienes via tethered enyne metathesis.

    PubMed

    Yao, Q

    2001-06-28

    [reaction: see text] Conjugated dienes are versatile building blocks in organic synthesis, and the development of new methods for their synthesis remains an important topic in modern synthetic organic chemistry. We describe here an expedient synthesis of highly functionalized conjugated dienes through sequential silicon-tethered ring-closing enyne metathesis mediated by Grubbs' Ru carbene catalysts and Tamao oxidation. Notable attributes of this methodology include short synthetic manipulations and the structural complexity it confers on the resulting diene moiety.

  7. Synthesis by Ring-Closing Metathesis and Cytotoxic Evaluation of Novel Thienylmacrolactones

    PubMed Central

    Krauss, Jürgen; Köbler, Daniela; Miller, Verena; Bracher, Franz

    2012-01-01

    This paper describes the synthesis and biological evaluation of macrolactones containing a thienyl substituent as simple analogues of epothilones. The compounds were prepared in a brief and efficient manner from thiophene-2-carbaldehyde using a ring-closing metathesis with Grubbs I or Grubbs II catalyst as the key step. The target lactones showed only insignificant cytotoxicity, while an intermediate simple thienyl carbinol showed very promising cytotoxicity. PMID:22396902

  8. Redox-Neutral Rh(III)-Catalyzed Olefination of Carboxamides with Trifluoromethyl Allylic Carbonate.

    PubMed

    Park, Jihye; Han, Sangil; Jeon, Mijin; Mishra, Neeraj Kumar; Lee, Seok-Yong; Lee, Jong Suk; Kwak, Jong Hwan; Um, Sung Hee; Kim, In Su

    2016-11-18

    The rhodium(III)-catalyzed olefination of various carboxamides with α-CF3-substituted allylic carbonate is described. This reaction provides direct access to linear CF3-allyl frameworks with complete trans-selectivity. In particular, a rhodium catalyst provided Heck-type γ-CF3-allylation products via the β-O-elimination of rhodacycle intermediate and subsequent olefin migration process.

  9. A unique palladium catalyst for efficient and selective alkoxycarbonylation of olefins with formates.

    PubMed

    Fleischer, Ivana; Jennerjahn, Reiko; Cozzula, Daniela; Jackstell, Ralf; Franke, Robert; Beller, Matthias

    2013-03-01

    Forget about CO! Carbonylations are among the most important homogeneously catalyzed reactions in the chemical industry, but typically require carbon monoxide. Instead, straightforward and efficient alkoxycarbonylations of olefins can proceed with alkyl formates in the presence of a specific palladium catalyst. Aromatic, terminal aliphatic, and internal olefins are carbonylated to give industrially important linear esters at low catalyst loadings.

  10. High-valent iron-mediated cis-hydroxyacetoxylation of olefins.

    PubMed

    Mas-Balleste, Ruben; Fujita, Megumi; Que, Lawrence

    2008-04-14

    Evidence is obtained for the unprecedented cis-1,2-hydroxy-acetoxylation of olefins as minor products of the epoxidation of olefins by H2O2 that is catalyzed by nonheme iron complexes in the presence of acetic acid, providing further support for the previously proposed [(TPA)FeV(O)(OAc)]2+ oxidant.

  11. Beyond ketonization: selective conversion of carboxylic acids to olefins over balanced Lewis acid-base pairs.

    PubMed

    Baylon, Rebecca A L; Sun, Junming; Martin, Kevin J; Venkitasubramanian, Padmesh; Wang, Yong

    2016-04-11

    We report the direct conversion of mixed carboxylic acids to C-C olefins with up to 60 mol% carbon yield through cascade (cross) ketonization, (cross) aldolization and self-deoxygenation reactions. Co-feeding hydrogen provides an additional ketone hydrogenation/dehydration pathway to a wider range of olefins.

  12. STIR: Redox-Switchable Olefin Polymerization Catalysis: Electronically Tunable Ligands for Controlled Polymer Synthesis

    DTIC Science & Technology

    2013-03-28

    REPORT Final Report: STIR: Redox-Switchable Olefin Polymerization Catalysis : Electronically Tunable Ligands for Controlled Polymer Synthesis 14...2211 15. SUBJECT TERMS Catalysis , Redox-Switchable, Polymerization, Polyolefins Brian K. Long University of Tennessee at Knoxville Office of Research...Polymerization Catalysis : Electronically Tunable Ligands for Controlled Polymer Synthesis Report Title ABSTRACT Olefin polymerization catalysts containing

  13. Catalytic Transformation of Bio-oil to Olefins with Molecular Sieve Catalysts

    NASA Astrophysics Data System (ADS)

    Huang, Wei-wei; Gong, Fei-yan; Zhai, Qi; Li, Quan-xin

    2012-08-01

    Catalytic conversion of bio-oil into light olefins was performed by a series of molecular sieve catalysts, including HZSM-5, MCM-41, SAPO-34 and Y-zeolite. Based on the light olefins yield and its carbon selectivity, the production of light olefins decreased in the following order: HZSM-5>SAPO-34>MCM-41> Y-zeolite. The highest olefins yield from bio-oil using HZSM-5 catalyst reached 0.22 kg/kgbio-oil with carbon selectivity of 50.7% and a nearly complete bio-oil conversion. The reaction conditions and catalyst characterization were investigated in detail to reveal the relationship between the catalyst structure and the production of olefins. The comparison between the pyrolysis and catalytic pyrolysis of bio-oil was also performed.

  14. Synthesis of epoxybenzo[d]isothiazole 1,1-dioxides via a reductive-Heck, metathesis-sequestration protocol†‡

    PubMed Central

    Asad, Naeem; Hanson, Paul R.; Long, Toby R.; Rayabarapu, Dinesh K.; Rolfe, Alan

    2011-01-01

    An atom-economical purification protocol, using solution phase processing via ring-opening metathesis polymerization (ROMP) has been developed for the synthesis of tricyclic sultams. This chromatography-free method allows for convenient isolation of reductive-Heck products and reclamation of excess starting material via sequestration involving metathesis catalysts and a catalyst-armed Si-surface. PMID:21727956

  15. Kinetic resolution of planar-chiral 1,2-disubstituted ferrocenes by molybdenum-catalyzed asymmetric intraannular ring-closing metathesis.

    PubMed

    Ogasawara, Masamichi; Arae, Sachie; Watanabe, Susumu; Nakajima, Kiyohiko; Takahashi, Tamotsu

    2013-03-25

    Planar chirality: Ring-closing metathesis of 1,2-diallylmetallocenes afforded the corresponding 4,7-dihydroindenyl species in high yields. The metallocenes are planar chiral with two different allylic substituents, and kinetic resolution of the racemic 1,2-diallylmetallocene derivatives was realized by molybdenum-catalyzed asymmetric ring-closing metathesis with excellent enantioselectivity (see scheme).

  16. Reversible and irreversible processing of biogenic olefins on acidic aerosols

    NASA Astrophysics Data System (ADS)

    Liggio, J.; Li, S.-M.

    2008-04-01

    Recent evidence has suggested that heterogeneous chemistry of oxygenated hydrocarbons, primarily carbonyls, plays a role in the formation of secondary organic aerosol (SOA); however, evidence is emerging that direct uptake of alkenes on acidic aerosols does occur and can contribute to SOA formation. In the present study, significant uptake of monoterpenes, oxygenated monoterpenes and sesquiterpenes to acidic sulfate aerosols is found under various conditions in a reaction chamber. Proton transfer mass spectrometry is used to quantify the organic gases, while an aerosol mass spectrometer is used to quantify the organic mass uptake and obtain structural information for heterogeneous products. Aerosol mass spectra are consistent with several mechanisms including acid catalyzed olefin hydration, cationic polymerization and organic ether formation, while measurable decreases in the sulfate mass on a per particle basis suggest that the formation of organosulfate compounds is also likely. A portion of the heterogeneous reactions appears to be reversible, consistent with reversible olefin hydration reactions. A slow increase in the organic mass after a fast initial uptake is attributed to irreversible reactions, consistent with polymerization and organosulfate formation. Uptake coefficients (γ) were estimated for a fast initial uptake governed by the mass accommodation coefficient (α) and ranged from 1×10-6-2.5×10-2. Uptake coefficients for a subsequent slower reactive uptake ranged from 1×10-7-1×10-4. These processes may potentially lead to a considerable amount of SOA from the various biogenic hydrocarbons under acidic conditions, which can be highly significant for freshly nucleated aerosols, particularly given the large array of atmospheric olefins.

  17. Reversible and irreversible processing of biogenic olefins on acidic aerosols

    NASA Astrophysics Data System (ADS)

    Liggio, J.; Li, S.-M.

    2007-08-01

    Recent evidence has suggested that heterogeneous chemistry of oxygenated hydrocarbons, primarily carbonyls, plays a role in the formation of secondary organic aerosol (SOA); however, evidence is emerging that direct uptake of alkenes on acidic aerosols does occur and can contribute to SOA formation. In the present study, significant uptake of monoterpenes, oxygenated monoterpenes and sesquiterpenes to acidic sulfate aerosols is found under various conditions in a reaction chamber. Proton transfer mass spectrometry is used to quantify the organic gases, while an aerosol mass spectrometer is used to quantify the organic mass uptake and obtain structural information for heterogeneous products. Aerosol mass spectra are consistent with several mechanisms including acid catalyzed olefin hydration, cationic polymerization and organic ester formation, while measurable decreases in the sulfate mass on a per particle basis suggest that the formation of organosulfate compounds is also likely. A portion of the heterogeneous reactions appears to be reversible, consistent with reversible olefin hydration reactions. A slow increase in the organic mass after a fast initial uptake is attributed to irreversible reactions, consistent with polymerization and organosulfate formation. Uptake coefficients (γ) were estimated for a fast initial uptake governed by the mass accommodation coefficient (α) and ranged from 1×10-6-2.5×10-2. Uptake coefficients for a subsequent slower reactive uptake ranged from 1×10-7-1×10-4. These processes are estimated to potentially produce greater than 2.5 μg m-3 of SOA from the various biogenic hydrocarbons under atmospheric conditions, which can be highly significant given the large array of atmospheric olefins.

  18. Transmissive Olefination Route to Putative “Morinol I” Lignans

    PubMed Central

    Yao, Lihua; Pitta, Bhaskar; Ravikumar, P. C.; Purzycki, Matthew; Fleming, Fraser F.

    2012-01-01

    A series of morinol-type lignans were rapidly assembled using a Grignard-based transmissive olefination. In combination with palladium-catalyzed arylations, the strategy provides stereoselective access to (7Z, 7′E), (7E, 7′E), (7E, 7′Z) morinol diastereomers and the (7Z, 8′E) and (7E, 8′E) conjugated analogs. Critical for the E/Z-stereoselectivity is a new, general method for converting alkenenitriles to alkenemethanols that circumvents the enal E/Z isomerization commonly encountered during conventional i-Bu2AlH reduction. PMID:22432777

  19. Catalytic Asymmetric Hydroamination of Unactivated Internal Olefins to Aliphatic Amines

    PubMed Central

    Yang, Yang; Shi, Shi-Liang; Niu, Dawen; Liu, Peng; Buchwald, Stephen L.

    2015-01-01

    Catalytic assembly of enantiopure aliphatic amines from abundant and readily available precursors has long been recognized as a paramount challenge in synthetic chemistry. Herein, we describe a mild and general copper-catalyzed hydroamination that effectively converts unactivated internal olefins, an important yet unexploited class of abundant feedstock chemicals, into highly enantioenriched α-branched amines (≥ 96% enantiomeric excess) featuring two minimally differentiated aliphatic substituents. This method provides a powerful means to access a broad range of advanced, highly functionalized enantioenriched amines of interest in pharmaceutical research and other areas. PMID:26138973

  20. Prilezhaev dihydroxylation of olefins in a continuous flow process.

    PubMed

    van den Broek, Bas A M W; Becker, René; Kössl, Florian; Delville, Mariëlle M E; Nieuwland, Pieter J; Koch, Kaspar; Rutjes, Floris P J T

    2012-02-13

    Epoxidation of both terminal and non-terminal olefins with peroxy acids is a well-established and powerful tool in a wide variety of chemical processes. In an additional step, the epoxide can be readily converted into the corresponding trans-diol. Batch-wise scale-up, however, is often troublesome because of the thermal instability and explosive character of the peroxy acids involved. This article describes the design and semi-automated optimization of a continuous flow process and subsequent scale-up to preparative production volumes in an intrinsically safe manner.

  1. Molecular Simulation of Olefin Oligomer Blend Phase Behavior

    NASA Astrophysics Data System (ADS)

    Chen, Qile; Lodge, Timothy; Siepmann, Ilja; Mrsec Collaboration

    Material properties (e.g. toughness) of polyolefin mixtures are closely tied to their phase behavior that often cannot be accurately predicted by the widely used Flory-Huggins (FH) theory. In this work, configurational-bias Monte Carlo (CBMC) simulations in the Gibbs ensemble were used to compute the phase behavior of oligomeric olefins. The cohesive energy density of pure melts and the free energy of mixing were obtained from these simulations, and the discrepancy between the binary interaction χ parameter from simulation and from the FH theory was quantified. Structural analysis and the calculated excess mixing properties provided some rationale into the interpretation of these results.

  2. Thermoplastic Adhesives based on polyolefin and olefinic copolymers

    NASA Astrophysics Data System (ADS)

    Paul, Rituparna

    2014-03-01

    H.B. Fuller has been a leading global industrial adhesive manufacturer for over 125 years. It is a company with a rich history of consistently delivering adhesive innovations for enhancing product performance in the market place. H.B. Fuller technologies/products find application in several markets including packaging, personal hygiene and nonwovens, durable assembly and electronics. In this presentation, H. B. Fuller's technology innovation journey will be shared with emphasis on groundbreaking technologies/products based on polyolefin and olefin copolymers.

  3. Enantioselective Iodolactonization of Disubstituted Olefinic Acids Using a Bifunctional Catalyst

    PubMed Central

    Fang, Chao; Paull, Daniel H.; Hethcox, J. Caleb; Shugrue, Christopher R.; Martin, Stephen F.

    2012-01-01

    The enantioselective iodolactonizations of a series of diversely-substituted olefinic carboxylic acids are promoted by a BINOL-derived, bifunctional catalyst. Reactions involving 5-alkyl- and 5-aryl-4(Z)-pentenoic acids and 6-alkyl- and 6-aryl-5(Z)-hexenoic acids provide the corresponding γ- and δ-lactones having stereogenic C–I bonds in excellent yields and >97:3 er. Significantly, this represents the first organocatalyst that promotes both bromo- and iodolactonization with high enantioselectivities. The potential of this catalyst to induce kinetic resolutions of racemic unsaturated acids is also demonstrated. PMID:23199100

  4. Separation of Olefin/Paraffin Mixtures with Carrier Facilitated Membrane Final Report

    SciTech Connect

    Merkel, T.C.; Blanc, R.; Zeid, J.; Suwarlim, A.; Firat, B.; Wijmans, H.; Asaro, M.; Greene, M.

    2007-03-12

    This document describes the results of a DOE funded joint effort of Membrane Technology and Research Inc. (MTR), SRI International (SRI), and ABB Lummus (ABB) to develop facilitated transport membranes for olefin/paraffin separations. Currently, olefin/paraffin separation is done by distillation—an extremely energy-intensive process because of the low relative volatilities of olefins and paraffins. If facilitated transport membranes could be successfully commercialized, the potential energy savings achievable with this membrane technology are estimated to be 48 trillion Btu per year by the year 2020. We discovered in this work that silver salt-based facilitated transport membranes are not stable even in the presence of ideal olefin/paraffin mixtures. This decline in membrane performance appears to be caused by a previously unrecognized phenomenon that we have named olefin conditioning. As the name implies, this mechanism of performance degradation becomes operative once a membrane starts permeating olefins. This project is the first study to identify olefin conditioning as a significant factor impacting the performance of facilitated olefin transport membranes. To date, we have not identified an effective strategy to mitigate the impact of olefin conditioning. other than running at low temperatures or with low olefin feed pressures. In our opinion, this issue must be addressed before further development of facilitated olefin transport membranes can proceed. In addition to olefin conditioning, traditional carrier poisoning challenges must also be overcome. Light, hydrogen, hydrogen sulfide, and acetylene exposure adversely affect membrane performance through unwanted reaction with silver ions. Harsh poisoning tests with these species showed useful membrane lifetimes of only one week. These tests demonstrate a need to improve the stability of the olefin complexing agent to develop membranes with lifetimes satisfactory for commercial application. A successful effort

  5. Olefin coordination in copper(I) complexes of bis(2-pyridyl)amine.

    PubMed

    Allen, John J; Barron, Andrew R

    2009-02-07

    Complexes of the type [Cu(H-dpa)(olefin)]BF4 for ethylene (1), propylene (2), 1-butene (3), 1-hexene (4), 1-octene (5), cis-2-octene (6), trans-2-octene (7), cis-3-octene (8), trans-3-octene (9), 2-norbornylene (10), 1,5-cyclooctadiene (11), styrene (12), cis-stilbene (13), trans-stilbene (14), and Ph2C=CH2 (15) have been prepared and characterized by 1H and 13C NMR, FTIR, and TGA. The crystal structures have been determined for compounds 5, 6, 8, and 10-13. With the exception of compound 11, copper atoms in each complex are coordinated to the two pyridine nitrogen atoms and the appropriate olefin; consistent with a pseudo three-coordinate Cu(I) cation. Compound 11 has a second weaker p-interaction resulting in a distorted tetrahedral geometry. Steric hindrance between the olefin and H-dpa manifests as both a twisting of the olefin out of the plane of the H-dpa ligand and a concomitant folding of the H-dpa ligand. The shifts in the nN-H IR spectral band for H-dpa ligand are consistent with the formation of N-H...F hydrogen bonded interactions observed in the crystal structures. The 1H and 13C NMR spectra of [Cu(H-dpa)(olefin)]BF4 exhibit an upfield shift in the olefin signal as compared to free olefin. A comparison of the Dd values for terminal olefins shows that the similarity of binding for H2C=CHR (R = CnH2n+1, n = 1-6) mitigates any preferential complexation of various terminal olefins using the H-dpa ligand. For octenes there is a significant difference in binding between a terminal and internal olefin, but there is little preference between binding for different internal olefins and only a modest difference between the cis and trans isomers of the same olefin. A good correlation exists between the 1HNMRDd values and the TGA data, confirming that the shift of the olefin NMR resonances upon coordination is associated with the binding strength of the complex. Ab initio calculations using four different method/basis set combinations on the structure of [Cu

  6. Morphology of Novel Semicrystalline Ethylene-α-Olefin Block Copolymers

    NASA Astrophysics Data System (ADS)

    Li, Sheng; Register, Richard; Landes, Brian

    2009-03-01

    In semicrystalline block copolymers, the solid-state structure can be set either by block incompatibility or by crystallization of one or more blocks. Depending on the block interaction strength, a wide array of solid-state morphologies may be observed, ranging from spherulitic to confined crystallization within preexisting microphase-separated domains. Dow Chemical has recently developed a novel chain shuttling polymerization process to produce olefin block copolymers with alternating amorphous and semicrystalline chain segments, where each block exhibits the most-probable distribution. We examined the melt and solid-state morphologies of these novel olefin block copolymers, having a high octene content in the amorphous block, using two- dimensional synchrotron small-angle and wide-angle x-ray scattering on specimens oriented by channel die compression. Multiblock and diblock copolymers with near-symmetric compositions showed well-ordered lamellar structures at room temperature with long periods exceeding 100 nm, with little dependence on thermal history, indicating the presence of a mesophase-separated melt which templates crystallization.

  7. Ruthenium-catalyzed intramolecular metathesis of dienes and its application in the synthesis of bridged and spiro azabicycles

    NASA Astrophysics Data System (ADS)

    Kuznetsov, N. Yu; Bubnov, Yu N.

    2015-07-01

    The review presents a historical excursion into catalytic alkene metathesis, covering the problems of history of the discovery of this process, as well as investigations on the properties, structure and reactivity of the most popular ruthenium catalysts for metathesis, mechanism of their action and decomposition. The main part covers studies devoted to the syntheses of bridged azabicyclic and 1-azaspirocyclic compounds comprising the intramolecular metathesis of dienes as the key step. The formation of a bicyclic skeleton of a series of natural bridged (cocaine, ferruginine, calystegines, and anatoxin-a) and spiro (pinnaic acids, halichlorine, hystrionicotoxin, and cephalotaxine) azabicycles, as well as their analogues and compounds with larger rings is demonstrated. The methods for the synthesis of diene precursors and the conditions for final assembling of the bicyclic compounds are considered in detail. The generalization of the literature data allows one to efficiently carry out the mentioned process taking into account the most important features. The bibliography includes 129 references.

  8. Fe-Catalyzed C–C Bond Construction from Olefins via Radicals

    PubMed Central

    2017-01-01

    This Article details the development of the iron-catalyzed conversion of olefins to radicals and their subsequent use in the construction of C–C bonds. Optimization of a reductive diene cyclization led to the development of an intermolecular cross-coupling of electronically-differentiated donor and acceptor olefins. Although the substitution on the donor olefins was initially limited to alkyl and aryl groups, additional efforts culminated in the expansion of the scope of the substitution to various heteroatom-based functionalities, providing a unified olefin reactivity. A vinyl sulfone acceptor olefin was developed, which allowed for the efficient synthesis of sulfone adducts that could be used as branch points for further diversification. Moreover, this reactivity was extended into an olefin-based Minisci reaction to functionalize heterocyclic scaffolds. Finally, mechanistic studies resulted in a more thorough understanding of the reaction, giving rise to the development of a more efficient second-generation set of olefin cross-coupling conditions. PMID:28094980

  9. Mechanism of olefin epoxidation in the presence of a titanium-containing zeolite

    NASA Astrophysics Data System (ADS)

    Danov, S. M.; Krasnov, V. L.; Sulimov, A. V.; Ovcharova, A. V.

    2013-11-01

    The effect of the nature of a solvent on the liquid-phase epoxidation of olefins with an aqueous solution of hydrogen peroxide over a titanium-containing zeolite is studied. Butanol-1, butanol-2, propanol-1, isopropanol, methanol, ethanol, water, acetone, methyl ethyl ketone, isobutanol, and tert-butanol are examined as solvents. A mechanism of olefin epoxidation with hydrogen peroxide in an alcohol medium over a titanium-containing zeolite is proposed. Epoxidation reactions involving hydrogen peroxide and different olefins are studied experimentally.

  10. In vivo and in vitro olefin cyclopropanation catalyzed by heme enzymes

    DOEpatents

    Coelho, Pedro S; Brustad, Eric M; Arnold, Frances H; Wang, Zhan; Lewis, Jared C

    2015-03-31

    The present invention provides methods for catalyzing the conversion of an olefin to any compound containing one or more cyclopropane functional groups using heme enzymes. In certain aspects, the present invention provides a method for producing a cyclopropanation product comprising providing an olefinic substrate, a diazo reagent, and a heme enzyme; and admixing the components in a reaction for a time sufficient to produce a cyclopropanation product. In other aspects, the present invention provides heme enzymes including variants and fragments thereof that are capable of carrying out in vivo and in vitro olefin cyclopropanation reactions. Expression vectors and host cells expressing the heme enzymes are also provided by the present invention.

  11. In vivo and in vitro olefin cyclopropanation catalyzed by heme enzymes

    DOEpatents

    Coelho, Pedro S.; Brustad, Eric M.; Arnold, Frances H.; Wang, Zhan; Lewis, Jared C.

    2016-11-15

    The present invention provides methods for catalyzing the conversion of an olefin to any compound containing one or more cyclopropane functional groups using heme enzymes. In certain aspects, the present invention provides a method for producing a cyclopropanation product comprising providing an olefinic substrate, a diazo reagent, and a heme enzyme; and admixing the components in a reaction for a time sufficient to produce a cyclopropanation product. In other aspects, the present invention provides heme enzymes including variants and fragments thereof that are capable of carrying out in vivo and in vitro olefin cyclopropanation reactions. Expression vectors and host cells expressing the heme enzymes are also provided by the present invention.

  12. Metal-free metathesis reaction of C-chiral allylic sulfilimines with aryl isocyanates: construction of chiral nonracemic allylic isocyanates.

    PubMed

    Grange, Rebecca L; Evans, P Andrew

    2014-08-27

    We report the facile and efficient metal-free metathesis reaction of C-chiral allylic sulfilimines with aryl isocyanates. This process facilitates the room temperature construction of an array of chiral nonracemic allylic isocyanates, which are versatile intermediates for the construction of unsymmetrical ureas, carbamates, thiocarbamates and amides. Furthermore, the sulfilimine/isocyanate metathesis reaction with 4,4'-methylene diphenyl diisocyanate (4,4'-MDI) circumvents harsh reaction conditions and/or hazardous reagents employed with more classical methods for the preparation of this important functional group.

  13. Luminescent hybrid materials of lanthanide β-diketonate and mesoporous host through covalent and ionic bonding with anion metathesis.

    PubMed

    Li, Qiu-Ping; Yan, Bing

    2012-07-28

    Luminescent mesoporous materials were prepared by performing an anion metathesis reaction on ionic liquid modified SBA15, which has imidazolium chloride bridging units. The lanthanide β-diketonate complex anion was successfully anchored onto the SBA15 framework after the anion metathesis reaction. The resulting materials were characterized by FTIR, TEM, TGA, small-angle X-ray powder diffraction (SAXRD) and nitrogen adsorption-desorption isotherms. The photoluminescent properties of these materials were investigated in detail, and the results reveal that these hybrid mesoporous SBA15, prepared through this preparation approach, present favorable photoluminescent behavior such as high luminescent quantum efficiencies and long luminescent lifetimes.

  14. Effective immobilisation of a metathesis catalyst bearing an ammonium-tagged NHC ligand on various solid supports

    PubMed Central

    Białecki, Jacek; Czarnocki, Stefan J; Żukowska, Karolina

    2016-01-01

    Summary An ammonium-tagged ruthenium complex, 8, was deposited on several widely available commercial solid materials such as silica gel, alumina, cotton, filter paper, iron powder or palladium on carbon. The resulting catalysts were tested in toluene or ethyl acetate, and found to afford metathesis products in high yield and with extremely low ruthenium contamination. Depending on the support used, immobilised catalyst 8 shows also additional traits, such as the possibility of being magnetically separated or the use for metathesis and subsequent reduction of the obtained double bond in one pot. PMID:26877803

  15. Synthesis of Cyclic Porphyrin Trimers through Alkyne Metathesis Cyclooligomerization and Their Host–Guest Binding Study

    SciTech Connect

    Yu, Chao; Long, Hai; Jin, Yinghua; Zhang, Wei

    2016-06-17

    Cyclic porphyrin trimers were synthesized through one-step cyclooligomerization via alkyne metathesis from diyne monomers. These macrocycles show interesting host-guest binding interactions with fullerenes, selectively binding C70 (6 x 103 M-1) over C60 and C84 (no binding observed). The fullerene-encapsulated host-guest complex can undergo guest or host exchange in the presence of another guest (2,4,6-tri(4-pyridyl)-1,3,5-triazine) or host (cage COP5) molecule with higher binding affinity.

  16. Rapid Solid-State Metathesis Routes to Nanostructured Silicon-Germainum

    NASA Technical Reports Server (NTRS)

    Kaner, Richard B. (Inventor); Bux, Sabah K. (Inventor); Fleurial, Jean-Pierre (Inventor); Rodriguez, Marc (Inventor)

    2014-01-01

    Methods for producing nanostructured silicon and silicon-germanium via solid state metathesis (SSM). The method of forming nanostructured silicon comprises the steps of combining a stoichiometric mixture of silicon tetraiodide (SiI4) and an alkaline earth metal silicide into a homogeneous powder, and initating the reaction between the silicon tetraiodide (SiI4) with the alkaline earth metal silicide. The method of forming nanostructured silicon-germanium comprises the steps of combining a stoichiometric mixture of silicon tetraiodide (SiI4) and a germanium based precursor into a homogeneous powder, and initiating the reaction between the silicon tetraiodide (SiI4) with the germanium based precursors.

  17. Recent advances in metathesis-derived polymers containing transition metals in the side chain

    PubMed Central

    Demonceau, Albert; Fischer, Helmut

    2015-01-01

    Summary This account critically surveys the field of side-chain transition metal-containing polymers as prepared by controlled living ring-opening metathesis polymerization (ROMP) of the respective metal-incorporating monomers. Ferrocene- and other metallocene-modified polymers, macromolecules including metal-carbonyl complexes, polymers tethering early or late transition metal complexes, etc. are herein discussed. Recent advances in the design and syntheses reported mainly during the last three years are highlighted, with special emphasis on new trends for superior applications of these hybrid materials. PMID:26877797

  18. Exploiting charge-transfer complexation for selective measurement of gas-phase olefins with nanoparticle-coated chemiresistors.

    PubMed

    Rowe, Michael P; Steinecker, William H; Zellers, Edward T

    2007-02-01

    Charge-transfer-mediated olefin-selective sensing by use of chemiresistors (CR) coated with composite films of n-octanethiolate-monolayer-protected gold nanoparticles (C8-MPN) and each of several square-planar PtCl2(olefin)(pyridine) coordination complexes is described. Where the gas-phase olefin analyte differs from that initially coordinated to Pt, olefin substitution occurs and is accompanied by a persistent shift in the composite film resistance. Commensurate changes in film mass are also observed with a similarly coated thickness shear mode resonator. Regeneration is possible by exposure to the initially complexed olefin gas or vapor. If the olefin analyte is the same as that initially coordinated to Pt, then a reversible charge-transfer interaction occurs that is accompanied by a decrease in film resistance (increase in film mass), which recovers spontaneously after removal of the olefin from the atmosphere above the sensor. This behavior differs from that of MPN-coated CRs lacking such Pt complexes, which invariably yield resistance increases upon exposure to nonpolar vapors. Red shifts in the UV-vis absorbance spectra of the PtCl2(olefin)(pyridine) complexes in solution upon addition of free olefin support the hypothesis that Pt-olefin coordination in the composite films creates temporary low-resistance pathways that compete effectively with the concurrent increase in tunneling resistance associated with swelling-induced separation of C8-MPN cores. Structurally analogous non-olefins produce only increases in film resistance. Selective measurement of styrene, ethylene, 1-octene, and 1,3-butadiene is illustrated. Olefin detection limits are reduced as much as 23 000-fold by inclusion of the corresponding Pt complex in the CR interface film. Composite films suffer a gradual loss of selectivity from decomposition of the Pt-olefin complex, apparently facilitated by a Au-Pt charge transfer.

  19. Enantioselective Rh-Catalyzed Hydroacylation of Olefins: From Serendipitous Discovery to Rational Design

    PubMed Central

    Murphy, Stephen K.

    2015-01-01

    Rh-catalysed hydroacylation allows the construction of chiral ketones from olefins and aldehydes. Since James' and Young's serendipitous discovery of the enantioselective 4-pentenal cyclisation, both intra and intermolecular variants have emerged that enable broader applications. PMID:25277153

  20. Organo-Lewis acid as cocatalyst for cationic homogenous metallocene Ziegler-Natta olefin polymerizations

    DOEpatents

    Marks, Tobin J.; Chen, You-Xian

    2000-01-01

    The synthesis of the organo-Lewis acid perfluorobiphenylborane (PBB) and the activation of metallocenes for the formation of a variety of highly active homogeneous Ziegler-Natta metallocene olefin polymerization, copolymerization and ring-opening polymerization catalysts is described.

  1. Extreme ultraviolet (EUV) degradation of poly(olefin sulfone)s: Towards applications as EUV photoresists

    NASA Astrophysics Data System (ADS)

    Lawrie, Kirsten; Blakey, Idriss; Blinco, James; Gronheid, Roel; Jack, Kevin; Pollentier, Ivan; Leeson, Michael J.; Younkin, Todd R.; Whittaker, Andrew K.

    2011-02-01

    Poly(olefin sulfone)s, formed by the reaction of sulfur dioxide (SO 2) and an olefin, are known to be highly susceptible to degradation by radiation and thus have been identified as candidate materials for chain scission-based extreme ultraviolet lithography (EUVL) resist materials. In order to investigate this further, the synthesis and characterisation of two poly(olefin sulfone)s namely poly(1-pentene sulfone) (PPS) and poly(2-methyl-1-pentene sulfone) (PMPS), was achieved and the two materials were evaluated for possible chain scission EUVL resist applications. It was found that both materials possess high sensitivities to EUV photons; however; the rates of outgassing were extremely high. The only observed degradation products were found to be SO 2 and the respective olefin suggesting that depolymerisation takes place under irradiation in a vacuum environment. In addition to depolymerisation, a concurrent conversion of SO 2 moieties to a sulfide phase was observed using XPS.

  2. Ruthenium carbonyl catalyst supported on ceric oxide for preparation of olefins from synthesis gas

    DOEpatents

    Pierantozzi, Ronald

    1985-01-01

    A catalyst comprising a ruthenium carbonyl compound deposited on a cerium oxide-containing support material provides for the selective synthesis of low molecular weight olefinic hydrocarbons from mixtures of hydrogen and carbon monoxide.

  3. Preparation of olefins from synthesis gas using ruthenium supported on ceric oxide

    DOEpatents

    Pierantozzi, Ronald

    1985-01-01

    A catalyst comprising a ruthenium carbonyl compound deposited on a cerium oxide-containing support material provides for the selective synthesis of low molecular weight olefinic hydrocarbons from mixtures of hydrogen and carbon monoxide.

  4. Preparation of olefins from synthesis gas using ruthenium supported on ceric oxide

    DOEpatents

    Pierantozzi, R.

    1985-04-09

    A catalyst comprising a ruthenium carbonyl compound deposited on a cerium oxide-containing support material provides for the selective synthesis of low molecular weight olefinic hydrocarbons from mixtures of hydrogen and carbon monoxide.

  5. Ruthenium carbonyl catalyst supported on ceric oxide for preparation of olefins from synthesis gas

    DOEpatents

    Pierantozzi, R.

    1985-04-02

    A catalyst comprising a ruthenium carbonyl compound deposited on a cerium oxide-containing support material provides for the selective synthesis of low molecular weight olefinic hydrocarbons from mixtures of hydrogen and carbon monoxide.

  6. Supported iron nanoparticles as catalysts for sustainable production of lower olefins.

    PubMed

    Torres Galvis, Hirsa M; Bitter, Johannes H; Khare, Chaitanya B; Ruitenbeek, Matthijs; Dugulan, A Iulian; de Jong, Krijn P

    2012-02-17

    Lower olefins are key building blocks for the manufacture of plastics, cosmetics, and drugs. Traditionally, olefins with two to four carbons are produced by steam cracking of crude oil-derived naphtha, but there is a pressing need for alternative feedstocks and processes in view of supply limitations and of environmental issues. Although the Fischer-Tropsch synthesis has long offered a means to convert coal, biomass, and natural gas into hydrocarbon derivatives through the intermediacy of synthesis gas (a mixture of molecular hydrogen and carbon monoxide), selectivity toward lower olefins tends to be low. We report on the conversion of synthesis gas to C(2) through C(4) olefins with selectivity up to 60 weight percent, using catalysts that constitute iron nanoparticles (promoted by sulfur plus sodium) homogeneously dispersed on weakly interactive α-alumina or carbon nanofiber supports.

  7. Catalyst for converting synthesis gas to light olefins

    DOEpatents

    Rao, V. Udaya S.; Gormley, Robert J.

    1982-01-01

    A catalyst and process for making same useful in the catalytic hydrogenation of carbon monoxide in which a silicalite support substantially free of aluminum is soaked in an aqueous solution of iron and potassium salts wherein the iron and potassium are present in concentrations such that the dried silicalite has iron present in the range of from about 5 to about 25 percent by weight and has potassium present in an amount not less than about 0.2 percent by weight, and thereafter the silicalite is dried and combined with amorphous silica as a binder for pellets, the catalytic pellets are used to convert synthesis gas to C.sub.2 -C.sub.4 olefins.

  8. Catalytic Olefin Hydroamidation Enabled by Proton-Coupled Electron Transfer

    PubMed Central

    2015-01-01

    Here we report a ternary catalyst system for the intramolecular hydroamidation of unactivated olefins using simple N-aryl amide derivatives. Amide activation in these reactions occurs via concerted proton-coupled electron transfer (PCET) mediated by an excited state iridium complex and weak phosphate base to furnish a reactive amidyl radical that readily adds to pendant alkenes. A series of H-atom, electron, and proton transfer events with a thiophenol cocatalyst furnish the product and regenerate the active forms of the photocatalyst and base. Mechanistic studies indicate that the amide substrate can be selectively homolyzed via PCET in the presence of the thiophenol, despite a large difference in bond dissociation free energies between these functional groups. PMID:26439818

  9. On the Melting Behavior of Ethylene/alpha-olefin Copolymers

    NASA Astrophysics Data System (ADS)

    Marand, Herve; Alizadeh, Azar; Subramaniam, Chitra; Richardson, Ley

    1998-03-01

    The melting behavior of ethylene/a-olefin copolymers of well controlled microstructure and narrow molecular weight distribution will be discussed. Specifically, we will report results of investigations of the effect of crystallization temperature and time on the multiple melting behavior of ethylene copolymers of various contents in butene, pentene, hexene and octene comonomers. More importantly, it will be shown that the location of the low endotherm is independent of previous thermal history and initial degree of crystallinity at the beginning of the crystallization/annealing process which leads to that endotherm. The low endotherm is furthermore independent of the copolymer composition as long as the crystallization process leads to a fringed micellar crystal morphology. Implications of these new results and comparison of the effect of the nature of the short chain branches on the evolution of the melting behavior with crystallization time provides new venues to the understanding of the multiple endothermic behavior of semicrystalline polymers in general.

  10. Capturing of the monoterpene olefin limonene produced in Saccharomyces cerevisiae.

    PubMed

    Jongedijk, Esmer; Cankar, Katarina; Ranzijn, Jorn; van der Krol, Sander; Bouwmeester, Harro; Beekwilder, Jules

    2015-01-01

    Monoterpene olefins such as limonene are plant compounds with applications as flavouring and fragrance agents, as solvents and potentially also in polymer and fuel chemistry. We engineered baker's yeast Saccharomyces cerevisiae to express a (-)-limonene synthase from Perilla frutescens and a (+)-limonene synthase from Citrus limon. Both proteins were expressed either with their native plastid targeting signal or in a truncated form in which the plastidial sorting signal was removed. The yeast host strain for expression was AE9 K197G, which expresses a mutant Erg20 enzyme. This enzyme catalyses the formation of geranyl diphosphate, which is the precursor for monoterpenes. Several methods were tested to capture limonene produced by the yeast. Extraction from the culture medium by pentane, or by the addition of CaCl2 followed by solid-phase micro-extraction, did not lead to detectable limonene, indicating that limonene is rapidly lost from the culture medium. Volatile terpenes such as limonene may also be trapped in a dodecane phase added to the medium during fermentation. This method resulted in recovery of 0.028 mg/l (+)-limonene and 0.060 mg/l (-)-limonene in strains using the truncated Citrus and Perilla synthases, respectively. Trapping the headspace during culture of the limonene synthase-expressing strains resulted in higher titres, at 0.12 mg/l (+)-limonene and 0.49 mg/l (-)-limonene. These results show that the volatile properties of the olefins produced require specific methods for efficient recovery of these molecules from biotechnological production systems.

  11. Enantioselective intramolecular aldehyde α-alkylation with simple olefins: direct access to homo-ene products.

    PubMed

    Comito, Robert J; Finelli, Fernanda G; MacMillan, David W C

    2013-06-26

    A highly selective method for the synthesis of asymmetrically substituted carbocycles and heterocycles from unactivated aldehyde-olefin precursors has been achieved via enantioselective SOMO-catalysis. Addition of a catalytically generated enamine radical cation across a pendent olefin serves to establish a general asymmetric strategy toward the production of a wide range of formyl-substituted rings with alkene transposition. Conceptually, this novel mechanism allows direct access to "homo-ene"-type products.

  12. Mechanistic insights into the rhenium-catalyzed alcohol-to-olefin dehydration reaction.

    PubMed

    Korstanje, Ties J; Jastrzebski, Johann T B H; Klein Gebbink, Robertus J M

    2013-09-23

    Rhenium-based complexes are powerful catalysts for the dehydration of various alcohols to the corresponding olefins. Here, we report on both experimental and theoretical (DFT) studies into the mechanism of the rhenium-catalyzed dehydration of alcohols to olefins in general, and the methyltrioxorhenium-catalyzed dehydration of 1-phenylethanol to styrene in particular. The experimental and theoretical studies are in good agreement, both showing the involvement of several proton transfers, and of a carbenium ion intermediate in the catalytic cycle.

  13. Nuclearity and cooperativity effects in binuclear catalysts and cocatalysts for olefin polymerization.

    PubMed

    Li, Hongbo; Marks, Tobin J

    2006-10-17

    A series of bimetallic organo-group 4 "constrained geometry" catalysts and binuclear bisborane and bisborate cocatalysts have been synthesized to probe catalyst center-catalyst center cooperativity effects on olefin enchainment in homogenous olefin polymerization and copolymerization processes. Significant nuclearity effects are found versus mononuclear controls, and the effect can be correlated with metal-metal approach distances and ion pairing effects. Novel polymer structures can be obtained by using such binuclear catalyst/cocatalyst systems.

  14. Transport-enhanced. alpha. -olefin readsorption pathways in Ru-catalyzed hydrocarbon synthesis

    SciTech Connect

    Iglesia, E.; Reyes, S.C.; Madon, R.J. )

    1991-05-01

    Residence time and cofeed studies show that olefins and paraffins are primary products in Ru-catalyzed hydrocarbon synthesis. Olefins readsorb and initiate surface chains that are indistinguishable from those formed directly from CO/H{sub 2} and that continue to grow and ultimately desorb as high molecular weight hydrocarbons. Transport-enchanced {alpha}-olefin readsorption leads to an increase in chain growth probability ({alpha}) and in paraffin content with increasing pore and bed residence time. Deviations from conventional (Flory) polymerization kinetics and the increasing paraffinic content of higher hydrocarbons are quantitatively described by transport effects on the residence time of intermediate olefins, without requiring the presence of several types of chain growth sites. The transport-reaction model combines a description of diffusive and convective transport with a mechanistic kinetic model of olefin readsorption and of CO hydrogenation and chain growth. It quantitatively describes carbon number, site density, pellet size, and space velocity effects on hydrocarbon synthesis rate and product distribution. The model is consistant with the experimentally observed maximum C{sub 5+} selectivities at intermediate values of site density and pellet size. These intermediate values permit extensive readsorption of {alpha}-olefins without significant CO arrival transport limitations.

  15. Enantio- and Diastereodivergent Synthetic Route to Multifarious Cyclitols from D-Xylose via Ring-Closing Metathesis

    PubMed Central

    Luchetti, Giovanni; Ding, Kejia; d'Alarcao, Marc; Kornienko, Alexander

    2009-01-01

    Short stereoselective syntheses of various cyclitols, including the derivatives of conduritol B, conduritol F, myo-inositol and chiro-inositol, have been accomplished. The key steps in the syntheses are a ring-closing metathesis process and a diastereodivergent organometallic addition to a D-xylose-derived alde-hyde. PMID:19802347

  16. Dynamic Covalent Synthesis of Aryleneethynylene Cages through Alkyne Metathesis: Dimer, Tetramer, or Interlocked Complex?

    SciTech Connect

    Wang, Qi; Yu, Chao; Zhang, Chenxi; Long, Hai; Azarnoush, Setareh; Jin, Yinghua; Zhang, Wei

    2016-05-01

    A dynamic covalent approach towards rigid aryleneethynylene covalent organic polyhedrons (COPs) was explored. Our study on the relationship of the COP structures and the geometry of their building blocks reveals that the topology of aryleneethynylene COPs strongly depends on the size of the building blocks. A tetramer (D2h symmetric), dimer, or interlocked complex can be formed from monomers with the same face-to-edge angle but in different sizes. As alkyne metathesis is a self-exchange reaction and non-directional, the cyclooligomerization of multi-alkyne monomers involves both intramolecular cyclization and intermolecular metathesis reaction, resulting in complicated thermodynamic process disturbed by kinetic competition. Although a tetrahedron-shaped tetramer (Td symmetric) has comparable thermodynamic stability to a D2h symmetric tetramer, its formation is kinetically disfavored and was not observed experimentally. Aryleneethynylene COPs consist of purely unsaturated carbon backbones and exhibit large internal cavities, which would have interesting applications in host-guest chemistry and development of porous materials.

  17. Engineering the metathesis and oxidation-reduction reaction in solid state at room temperature for nanosynthesis

    PubMed Central

    Hu, Pengfei; Cao, Yali; Jia, Dianzeng; Li, Qiang; Liu, Ruili

    2014-01-01

    It is a long-standing goal to explore convenient synthesis methodology for functional materials. Recently, several multiple-step approaches have been designed for photocatalysts AgnX@Ag (X = Cl−, PO43−, etc.), mainly containing the ion-exchange (metathesis) reaction followed by photoreduction in solution. But they were obsessed by complicated process, the uncontrollability of composition and larger sizes of Ag particles. Here we show a general solid-state route for the synthesis of AgnX@Ag catalysts with hierarchical structures. Due to strong surface plasmon resonance of silver nanoparticles with broad shape and size, the AgnX@Ag showed high photocatalytic activity in visible region. Especially, the composition of AgnX@Ag composites could be accurately controlled by regulating the feed ratio of (NH2OH)2·H2SO4 to anions, by which the performance were easily optimized. Results demonstrate that the metathesis and oxidation-reduction reactions can be performed in solid state at room temperature for nanosynthesis, greatly reducing the time/energy consumption and pollution. PMID:24614918

  18. Low Temperature Activation of Supported Metathesis Catalysts by Organosilicon Reducing Agents

    PubMed Central

    2016-01-01

    Alkene metathesis is a widely and increasingly used reaction in academia and industry because of its efficiency in terms of atom economy and its wide applicability. This reaction is notably responsible for the production of several million tons of propene annually. Such industrial processes rely on inexpensive silica-supported tungsten oxide catalysts, which operate at high temperatures (>350 °C), in contrast with the mild room temperature reaction conditions typically used with the corresponding molecular alkene metathesis homogeneous catalysts. This large difference in the temperature requirements is generally thought to arise from the difficulty in generating active sites (carbenes or metallacyclobutanes) in the classical metal oxide catalysts and prevents broader applicability, notably with functionalized substrates. We report here a low temperature activation process of well-defined metal oxo surface species using organosilicon reductants, which generate a large amount of active species at only 70 °C (0.6 active sites/W). This high activity at low temperature broadens the scope of these catalysts to functionalized substrates. This activation process can also be applied to classical industrial catalysts. We provide evidence for the formation of a metallacyclopentane intermediate and propose how the active species are formed. PMID:27610418

  19. Metathesis reactions of tris(adamantylimido)methylrhenium and aldehydes and imines

    SciTech Connect

    Wang, W.D.; Espenson, J.H.

    1999-11-22

    The tris(imido)methylrhenium compound CH{sub 3}Re(NAd){sub 3} (Ad = 1-adamantyl) was prepared and characterized. It reacts with aromatic aldehydes ArCHO forming the imines ArCH{double{underscore}bond} NAd. The reaction occurs in three stages, during which CH{sub 3}Re(NAd){sub 2}O and CH{sub 3}Re(NAd)O{sub 2} could be detected. In the third and slowest stage CH{sub 3}ReO{sub 3} (MTO) was formed, eventually in quantitative yield. The second-order rate constant for PhCHO in C{sub 6}D{sub 6} at 298 K is 1.4 x 10{sup {minus}4} L/mol s. Electron-donating substituents at the para-position of ArCHO cause a significant diminution in rate. Treated by the Hammett equation, the reaction constant is {rho} = +0.90. The reactions between CH{sub 3}Re(NAd){sub 3} and linear aliphatic aldehydes occur much faster than do reactions of nonlinear aliphatic or aromatic aldehydes, indicating an important steric effect. Ketones do not react. The imidorhenium complex evidently undergoes a metathesis reaction with the aldehyde. Analogously, CH{sub 3}Re(NAd){sub 3} reacts with imines. Imine-imine metathesis is catalyzed by MTO homogeneously and by MTO supported on Nb{sub 2}O{sub 5}.

  20. Stitched α-helical peptides via bis ring-closing metathesis.

    PubMed

    Hilinski, Gerard J; Kim, Young-Woo; Hong, Jooyeon; Kutchukian, Peter S; Crenshaw, Charisse M; Berkovitch, Shaunna S; Chang, Andrew; Ham, Sihyun; Verdine, Gregory L

    2014-09-03

    Conformationally stabilized α-helical peptides are capable of inhibiting disease-relevant intracellular or extracellular protein-protein interactions in vivo. We have previously reported that the employment of ring-closing metathesis to introduce a single all-hydrocarbon staple along one face of an α-helical peptide greatly increases α-helical content, binding affinity to a target protein, cell penetration through active transport, and resistance to proteolytic degradation. In an effort to improve upon this technology for stabilizing a peptide in a bioactive α-helical conformation, we report the discovery of an efficient and selective bis ring-closing metathesis reaction leading to peptides bearing multiple contiguous staples connected by a central spiro ring junction. Circular dichroism spectroscopy, NMR, and computational analyses have been used to investigate the conformation of these "stitched" peptides, which are shown to exhibit remarkable thermal stabilities. Likewise, trypsin proteolysis assays confirm the achievement of a structural rigidity unmatched by peptides bearing a single staple. Furthermore, fluorescence-activated cell sorting (FACS) and confocal microscopy assays demonstrate that stitched peptides display superior cell penetrating ability compared to their stapled counterparts, suggesting that this technology may be useful not only in the context of enhancing the drug-like properties of α-helical peptides but also in producing potent agents for the intracellular delivery of proteins and oligonucleotides.

  1. Reduction in syllable onsets in the acquisition of Polish: deletion, coalescence, metathesis and gemination.

    PubMed

    łukaszewicz, Beata

    2007-02-01

    This paper focuses on four strategies of onset reduction employed by a single child (4;0-4;4) acquiring Polish: deletion, coalescence, metathesis, and gemination. Deletion and coalescence occur in word-initial onsets while metathesis and gemination are restricted to word-medial position. The data, which constitute an intriguing 'conspiracy' case (Kisseberth, 1970), are analysed within OPTIMALITY THEORY (henceforth, OT; Prince & Smolensky, 1993/2004; McCarthy & Prince, 1995) in which all surface-true 'processes' are motivated through the interaction of ranked and violable constraints. The OT account makes it possible to envisage the four strategies as different surface responses to the undominated *COMPLEXOnset which militates against onset clusters. The choice of a particular strategy as well as its restriction to a particular word position is not random but follows from the interplay between *COMPLEXOnset, sonority-based syllable structure constraints (Margin Hierarchy, CONTACT LAW), context-sensitive markedness constraints (CODA CONDITION, *Nasal-Fricative) and faithfulness constraints. The present study confirms previous sonority-based findings, supplies further evidence for universal sonority mechanisms from word-medial clusters, and points to the coexistence of child-specific and abstract adult-based phonological strategies in the child's system.

  2. An investigation of wall effects in microwave-assisted ring-closing metathesis and cyclotrimerization reactions.

    PubMed

    Dallinger, Doris; Irfan, Muhammed; Suljanovic, Amra; Kappe, C Oliver

    2010-08-06

    Challenging Ru-catalyzed ring-closing metathesis transformations leading to eight-membered-ring systems and Ni- or Co-catalyzed [2+2+2] cyclotrimerizations were evaluated at elevated temperatures applying microwave dielectric heating or conventional thermal heating in order to investigate the role of wall effects. All reactions were conducted in a dedicated reactor setup that allowed accurate internal reaction temperature measurements using fiber-optic probes for both types of heating modes. For ring-closing metathesis best results were achieved using an open vessel-gas sparging protocol in 1,2-dichloroethane at reflux temperature (83 degrees C), while cyclotrimerizations were performed under sealed vessel conditions in toluene between 80 and 160 degrees C. For all studied transformations the results achieved in a single-mode microwave reactor could be reproduced by conventional heating in an oil bath by carefully matching the temperature profiles as close as possible during the entire heating and cooling cycle. In contrast to previous literature reports, no evidence that direct in-core microwave heating can increase catalyst lifetime by minimization or elimination of wall effects was obtained. At the same time, no indication for the involvement of nonthermal microwave effects in these homogeneous transition metal-catalyzed transformations was seen.

  3. Hydrogen bonds between methanol and the light liquid olefins 1-pentene and 1-hexene: from application to fundamental science.

    PubMed

    Zhang, Zhaoxi; Xiao, Tiancun; Al-Megren, Hamid; Aldrees, Saud A; Al-Kinany, Mohammad; Kuznetsov, Vladimir L; Kuznetsov, Maxim L; Edwards, Peter P

    2017-04-04

    We have recently developed a new extraction process for significantly reducing the olefin content in commercial FCC gasoline. To gain insights into the origins of this process, we have investigated the dissolution of the light liquid olefins 1-pentene and 1-hexene in methanol through computer modelling together with NMR spectroscopy. We find two important hydrogen bonding modes for methanol olefin interactions - namely, O-Hπ and C-HO.

  4. Determination of thermodynamic affinities of various polar olefins as hydride, hydrogen atom, and electron acceptors in acetonitrile.

    PubMed

    Cao, Ying; Zhang, Song-Chen; Zhang, Min; Shen, Guang-Bin; Zhu, Xiao-Qing

    2013-07-19

    A series of 69 polar olefins with various typical structures (X) were synthesized and the thermodynamic affinities (defined in terms of the molar enthalpy changes or the standard redox potentials in this work) of the polar olefins obtaining hydride anions, hydrogen atoms, and electrons, the thermodynamic affinities of the radical anions of the polar olefins (X(•-)) obtaining protons and hydrogen atoms, and the thermodynamic affinities of the hydrogen adducts of the polar olefins (XH(•)) obtaining electrons in acetonitrile were determined using titration calorimetry and electrochemical methods. The pure C═C π-bond heterolytic and homolytic dissociation energies of the polar olefins (X) in acetonitrile and the pure C═C π-bond homolytic dissociation energies of the radical anions of the polar olefins (X(•-)) in acetonitrile were estimated. The remote substituent effects on the six thermodynamic affinities of the polar olefins and their related reaction intermediates were examined using the Hammett linear free-energy relationships; the results show that the Hammett linear free-energy relationships all hold in the six chemical and electrochemical processes. The information disclosed in this work could not only supply a gap of the chemical thermodynamics of olefins as one class of very important organic unsaturated compounds but also strongly promote the fast development of the chemistry and applications of olefins.

  5. Design and synthesis of hybrid cyclophanes containing thiophene and indole units via Grignard reaction, Fischer indolization and ring-closing metathesis as key steps

    PubMed Central

    2015-01-01

    Summary We demonstrate a new synthetic strategy to cyclophanes containing thiophene and indole moieties via Grignard addition, Fischer indolization and ring-closing metathesis as key steps. PMID:26425209

  6. The effect of supported MoO(X) structures on the reaction pathways of propene formation in the metathesis of ethylene and 2-butene.

    PubMed

    Hahn, T; Kondratenko, E V; Linke, D

    2014-08-21

    The kind of surface MoOX structures on Al2O3-SiO2 was found to determine propene selectivity in the metathesis of ethylene and 2-butene. Compared to isolated tetrahedral MoOX species, their polymerized octahedral counterparts show significantly lower activity for isomerisation of 2- to 1-butene thus hindering non-selective metathesis of these butenes. In addition, they reveal higher ability to engage ethylene in propene formation.

  7. Cobalt carbide nanoprisms for direct production of lower olefins from syngas.

    PubMed

    Zhong, Liangshu; Yu, Fei; An, Yunlei; Zhao, Yonghui; Sun, Yuhan; Li, Zhengjia; Lin, Tiejun; Lin, Yanjun; Qi, Xingzhen; Dai, Yuanyuan; Gu, Lin; Hu, Jinsong; Jin, Shifeng; Shen, Qun; Wang, Hui

    2016-10-06

    Lower olefins-generally referring to ethylene, propylene and butylene-are basic carbon-based building blocks that are widely used in the chemical industry, and are traditionally produced through thermal or catalytic cracking of a range of hydrocarbon feedstocks, such as naphtha, gas oil, condensates and light alkanes. With the rapid depletion of the limited petroleum reserves that serve as the source of these hydrocarbons, there is an urgent need for processes that can produce lower olefins from alternative feedstocks. The 'Fischer-Tropsch to olefins' (FTO) process has long offered a way of producing lower olefins directly from syngas-a mixture of hydrogen and carbon monoxide that is readily derived from coal, biomass and natural gas. But the hydrocarbons obtained with the FTO process typically follow the so-called Anderson-Schulz-Flory distribution, which is characterized by a maximum C2-C4 hydrocarbon fraction of about 56.7 per cent and an undesired methane fraction of about 29.2 per cent (refs 1, 10, 11, 12). Here we show that, under mild reaction conditions, cobalt carbide quadrangular nanoprisms catalyse the FTO conversion of syngas with high selectivity for the production of lower olefins (constituting around 60.8 per cent of the carbon products), while generating little methane (about 5.0 per cent), with the ratio of desired unsaturated hydrocarbons to less valuable saturated hydrocarbons amongst the C2-C4 products being as high as 30. Detailed catalyst characterization during the initial reaction stage and theoretical calculations indicate that preferentially exposed {101} and {020} facets play a pivotal role during syngas conversion, in that they favour olefin production and inhibit methane formation, and thereby render cobalt carbide nanoprisms a promising new catalyst system for directly converting syngas into lower olefins.

  8. A kinetic, mechanistic, and molecular mechanics investigation of olefin insertion into organoactinide-hydride bonds. Metal, olefin, ancillary ligand, and diastereoselection effects

    SciTech Connect

    Lin, Zerong; Marks, T.J. )

    1990-07-04

    This contribution reports a kinetic/mechanistic/stereochemical/molecular mechanics study of olefin insertion into the actinide-hydrogen bonds of Cp{prime}{sub 2}An(H)(OR) complexes (Cp{prime} = {eta}{sup 5}-(CH{sub 3}){sub 5}C{sub 5}; An = Th, U; R = achiral or chiral alkyl group). For the reaction Cp{prime}{sub 2}An(H)(O-t-Bu) + cyclohexene (An = Th), the rate law is first order in organoactinide and first order in olefin. For Cp{prime}{sub 2}Th(H)(OCH(t-Bu){sub 2}) + 1-hexene, k{sub Th{minus}H}/k{sub Th{minus}D} = 1.3 (2). A molecular mechanics/ molecular graphics analysis suggests that the sterically most favorable direction of olefin approach toward the actinide center is between the U-H and U-O bonds rather than from the side. These results provide additional insight into ancillary ligand effects on the kinetics of organo-f-element-catalyzed olefin hydrogenation.

  9. Development and application of FI catalysts for olefin polymerization: unique catalysis and distinctive polymer formation.

    PubMed

    Makio, Haruyuki; Fujita, Terunori

    2009-10-20

    Catalysts contribute to the efficient production of chemicals and materials in almost all processes in the chemical industry. The polyolefin industry is one prominent example of the importance of catalysts. The discovery of Ziegler-Natta catalysts in the 1950s resulted in the production of high-density polyethylenes (PEs) and isotactic polypropylenes (iPPs). Since then, further catalyst development has led to the production of a new series of polyolefins, including linear low-density PEs, amorphous ethylene/1-butene copolymers, ethylene/propylene/diene elastomers, and syndiotactic PPs (sPPs). Polyolefins are now the most important and the most produced synthetic polymers. This Account describes a family of next-generation olefin polymerization catalysts (FI catalysts) that are currently being used in the commercial production of value-added olefin-based materials. An FI catalyst is a heteroatom-coordinated early transition metal complex that combines a pair of nonsymmetric phenoxy-imine [O(-), N] chelating ligands with a group 4 transition metal. The catalytically active species derived from FI catalysts is highly electrophilic and can assume up to five isomeric structures based on the coordination of the phenoxy-imine ligand. In addition, the accessibility of the ligands of the FI catalysts and their amenability to modification offers an opportunity for the design of diverse catalytic structures. FI catalysts exhibit many unique chemical characteristics: precise control over chain transfers (including highly controlled living ethylene and propylene polymerizations), extremely high selectivity for ethylene, high functional group tolerance, MAO- and borate-free polymerization catalysis, significant morphology polymer formation, controlled multimodal behavior, high incorporation ability for higher alpha-olefins and norbornene, and highly syndiospecific and isospecific polymerizations of both propylene and styrene. These reactions also occur with very high catalyst

  10. The partition behavior of fluorotelomer alcohols and olefins.

    PubMed

    Goss, Kai-Uwe; Bronner, Guido; Harner, Tom; Hertel, Monika; Schmidt, Torsten C

    2006-06-01

    In this paper we present a number of equilibrium partition constants for fluorotelomer alcohols and olefins among them data for air/water and octanol/air partitioning. These data are typically required for environmental fate modeling. Our data deviate substantially from those in the literature. A comprehensive check for consistency and plausibility strongly suggests that the data published here are correct. As a consequence the fluorotelomer alcohols will sorb much more to organic phases and have a smaller tendency to remain in the water phase than expected based on previous data. The presented partition data also allow us to derive descriptors for the various kinds of specific (e.g., H-bonds) and nonspecific (e.g., van der Waals) intermolecular interactions thatthe compounds can undergo. These descriptors can be used in polyparameter linear free energy relationships (pp-LFER) in orderto predict a large variety of other partition coefficients (e.g., air/solvent, solvent/ water) as well as the temperature dependence of their air/ water partitioning. The experimental and theoretical approach that we present here can serve as a general example for what needs to be done in order to ensure high quality physicochemical data for organic pollutants.

  11. (Electro)Mechanical Properties of Olefinic Block Copolymers

    NASA Astrophysics Data System (ADS)

    Spontak, Richard

    2014-03-01

    Conventional styrenic triblock copolymers (SBCs) swollen with a midblock-selective oil have been previously shown to exhibit excellent electromechanical properties as dielectric elastomers. In this class of electroactive polymers, compliant electrodes applied as active areas to opposing surfaces of an elastomer attract each other, and thus compress the elastomer due to the onset of a Maxwell stress, upon application of an external electric field. This isochoric process is accompanied by an increase in lateral area, which yields the electroactuation strain (measuring beyond 300% in SBC systems). Performance parameters such as the Maxwell stress, transverse strain, dielectric breakdown, energy density and electromechanical efficiency are determined directly from the applied electric field and resulting electroactuation strain. In this study, the same principle used to evaluate SBC systems is extended to olefinic block copolymers (OBCs), which can be described as randomly-coupled multiblock copolymers that consist of crystallizable polyethylene hard segments and rubbery poly(ethylene-co-octene) soft segments. Considerations governing the development of a methodology to fabricate electroresponsive OBC systems are first discussed for several OBCs differing in composition and bulk properties. Evidence of electroactuation in selectively-solvated OBC systems is presented and performance metrics measured therefrom are quantitatively compared with dielectric elastomers derived from SBC and related materials.

  12. Chemical imaging of thermoplastic olefin (TPO) surface architecture

    SciTech Connect

    Morris, H.R.; Turner, J.F. II; Munro, B.; Ryntz, R.A.; Treado, P.J.

    1999-04-13

    In the automotive industry, ethylene-propylene rubber (EPR) is mixed with polypropylene (PP) to form a thermoplastic olefin (TPO) for use as car bumpers and fascia. An adhesion promoting primer, chlorinated polyolefin (CPO), is spray coated onto the TPO surface to increase adhesion of the base and clear coat paints to the low surface free energy TPO substrate. The surface morphology of rubber domains within the CPO-coated TPO substrate contributes strongly to the material characteristics, including impact resistance and adhesion properties. However, elastomer-phase analysis is challenging using traditional microanalysis imaging techniques. The authors employ fluorescence and Raman chemical imaging to characterize the TPO architecture in order to better understand the surface properties of coated TPO. Fluorescence imaging makes use of Nile red (NR), a fluorescent solvatochromic dye, solvated in the primer, which is effective in differentiating rubber from polypropylene on the basis of large variations in the fluorescence quantum efficiency. Confocal fluorescence chemical imaging performed on T PO coated with NR-doped CPO shows a thin (2--3 {micro}m) layer of elastomer that has migrated to the TPO surface. Raman chemical imaging is in direct agreement with the fluorescence experiments by measuring the intrinsic vibrational signatures of CPO, EPR, and PP without the need for dyes or stains. Raman contrast is enhanced using cosine correlation analysis, a novel multivariate processing technique that provides chemical contrast on the basis of differences in spectral shape.

  13. Engineering a dirhodium artificial metalloenzyme for selective olefin cyclopropanation

    PubMed Central

    Srivastava, Poonam; Yang, Hao; Ellis-Guardiola, Ken; Lewis, Jared C.

    2015-01-01

    Artificial metalloenzymes (ArMs) formed by incorporating synthetic metal catalysts into protein scaffolds have the potential to impart to chemical reactions selectivity that would be difficult to achieve using metal catalysts alone. In this work, we covalently link an alkyne-substituted dirhodium catalyst to a prolyl oligopeptidase containing a genetically encoded L-4-azidophenylalanine residue to create an ArM that catalyses olefin cyclopropanation. Scaffold mutagenesis is then used to improve the enantioselectivity of this reaction, and cyclopropanation of a range of styrenes and donor–acceptor carbene precursors were accepted. The ArM reduces the formation of byproducts, including those resulting from the reaction of dirhodium–carbene intermediates with water. This shows that an ArM can improve the substrate specificity of a catalyst and, for the first time, the water tolerance of a metal-catalysed reaction. Given the diversity of reactions catalysed by dirhodium complexes, we anticipate that dirhodium ArMs will provide many unique opportunities for selective catalysis. PMID:26206238

  14. Low severity coal liquefaction promoted by cyclic olefins. Quarterly report, October--December 1992

    SciTech Connect

    Curtis, C.W.

    1992-12-31

    Low severity coal liquefaction promoted by cyclic olefins offers a means of liquefying coal at low severity conditions. Lower temperature, 350{degrees}C, and lower hydrogen pressure, 500 psi, have been used to perform liquefaction reactions. The presence of the cyclic olefin, hexahydroanthracene, made a substantial difference in the conversion of Illinois No. 6 coal at these low severity conditions. The Researchperformed this quarter was a parametric evaluation of the effect of different parameters on the coal conversion and product distribution from coal. The effect of the parameters on product distribution from hexahydroanthracene was also determined. The work planned for next quarter includes combining the most effective parametric conditions for the low severity reactions and determining their effect. The second part ofthe research performed this quarter involved performing Fourier transform infrared (FTIR) spectroscopy using cyclic olefins. The objective of this study was to determine the feasibility of using FTIR and a heated cell to determine the reaction pathway that occurs in the hydrogen donation reactions from cyclic olefins. The progress made to date includes evaluating the FTIR spectra of cyclic olefins and their expected reaction products. This work is included in this progress report.

  15. A Strategy for Hydroxide Exclusion in Nanocrystalline Solid-State Metathesis Products

    PubMed Central

    Cheng, Jiaqi; Poduska, Kristin M.

    2013-01-01

    We demonstrate a simple strategy to either prevent or enhance hydroxide incorporation in nanocrystalline solid-state metathesis reaction products prepared in ambient environments. As an example, we show that ZnCO3 (smithsonite) or Zn5(CO3)2(OH)6 (hydrozincite) forms extremely rapidly, in less than two minutes, to form crystalline domains of 11 ± 2 nm and 6 ± 2 nm, respectively. The phase selectivity between these nanocrystalline products is dominated by the alkalinity of the hydrated precursor salts, which may in turn affect the availability of carbon dioxide during the reaction. Thus, unlike traditional aqueous precipitation reactions, our solid-state method offers a way to produce hydroxide-free, nanocrystalline products without active pH control.

  16. Constraining an Irregular Peptide Secondary Structure through Ring‐Closing Alkyne Metathesis

    PubMed Central

    Cromm, Philipp M.; Wallraven, Kerstin; Glas, Adrian; Bier, David; Fürstner, Alois; Ottmann, Christian

    2016-01-01

    Abstract Macrocyclization can be used to constrain peptides in their bioactive conformations, thereby supporting target affinity and bioactivity. In particular, for the targeting of challenging protein–protein interactions, macrocyclic peptides have proven to be very useful. Available approaches focus on the stabilization of α‐helices, which limits their general applicability. Here we report for the first time on the use of ring‐closing alkyne metathesis for the stabilization of an irregular peptide secondary structure. A small library of alkyne‐crosslinked peptides provided a number of derivatives with improved target affinity relative to the linear parent peptide. In addition, we report the crystal structure of the highest‐affinity derivative in a complex with its protein target 14‐3‐3ζ. It can be expected that the alkyne‐based macrocyclization of irregular binding epitopes should give rise to new scaffolds suitable for targeting of currently intractable proteins. PMID:27596722

  17. Photoluminescence study of Tb3+ doped CaCO3 synthesized by solid state metathesis

    NASA Astrophysics Data System (ADS)

    Muke, A. M.; Ugemuge, N. S.; Moharil, S. V.

    2016-05-01

    Conventional solid-state reaction or simple solution precipitation techniques suffer from several limitations, i.e. a high processing temperature, relatively high preparation cost and more time of preparation, highly complicated synthesis, in-stoichiometric compositions and poor crystallinity. Preparation of inorganic phosphors by microwave assisted Solid state metathesis is one of the superior methods of synthesis. Time duration required for synthesis by microwave assisted synthesis is relatively low. The required reaction temperature can be attempted using domestic microwave oven with consumption of relatively low energy. CaCO3 is one of the most abundant biological minerals in nature and has found many important applications in industry, such as pigments, paper makings, plastics, rubbers, and so on.

  18. Low-temperature synthesis of actinide tetraborides by solid-state metathesis reactions

    DOEpatents

    Lupinetti, Anthony J.; Garcia, Eduardo; Abney, Kent D.

    2004-12-14

    The synthesis of actinide tetraborides including uranium tetraboride (UB.sub.4), plutonium tetraboride (PuB.sub.4) and thorium tetraboride (ThB.sub.4) by a solid-state metathesis reaction are demonstrated. The present method significantly lowers the temperature required to .ltoreq.850.degree. C. As an example, when UCl.sub.4 is reacted with an excess of MgB.sub.2, at 850.degree. C., crystalline UB.sub.4 is formed. Powder X-ray diffraction and ICP-AES data support the reduction of UCl.sub.3 as the initial step in the reaction. The UB.sub.4 product is purified by washing water and drying.

  19. Visible-light-promoted chloramination of olefins with N-chlorosulfonamide as both nitrogen and chlorine sources.

    PubMed

    Qin, Qixue; Ren, Daan; Yu, Shouyun

    2015-11-07

    A visible-light-promoted chloramination of olefins is reported. N-Chlorosulfonamides serve as both nitrogen and chlorine sources. These reactions provide a simple, efficient, regioselective, and atom-economical method for the preparation of vicinal haloamine derivatives under mild reaction conditions. A variety of olefins were tolerated, and chloramination products were obtained in good yields.

  20. Production of light olefins by catalytic conversion of lignocellulosic biomass with HZSM-5 zeolite impregnated with 6wt.% lanthanum.

    PubMed

    Huang, Weiwei; Gong, Feiyan; Fan, Minghui; Zhai, Qi; Hong, Chenggui; Li, Quanxin

    2012-10-01

    Catalytic conversion of rice husk, sawdust, sugarcane bagasse, cellulose, hemicellulose and lignin into olefins was performed with HZSM-5 containing 6 wt.% lanthanum. The olefins yields for different feedstocks decreased in the order: cellulose>hemicellulose>sugarcane bagasse>rice husk>sawdust>lignin. Biomass containing higher content of cellulose or hemicellulose produced more olefins than feedstocks with higher content of lignin. Among the biomass types, sugarcane bagasse provided the highest olefin yield of 0.12 kg olefins/(kg dry biomass) and carbon yield of 21.2C-mol%. Temperature, residence time and the catalyst/feed ratio influenced olefin yield and selectivity. While the HZSM-5 zeolite was catalytically active, the incorporation of lanthanum at 2.9, and 6.0 wt.% increased the production of olefins from rice husk by 15.6% and 26.5%, respectively. The conversion of biomass to light olefins potentially provides an alternative and sustainable route for production of the key petrochemicals.

  1. Thermochemical study of 1-acetyl vinyl p-nitrobenzoate: vinyl bond enthalpy in captodative olefins.

    PubMed

    Rojas, Aarón; Valdés-Ordoñez, Alejandro; Martínez-Herrera, Melchor; Torres, Luis Alfonso; Campos, Myriam; Hernández-Obregón, Javier; Herrera, Rafael; Tamariz, Joaquín

    2015-05-21

    Captodative olefins are highly reactive and selective substrates in Diels-Alder and 1,3-dipolar cycloadditions. Seeking an explanation of this fact based on molecular energetics, the thermochemical analysis of 1-acetyl vinyl p-nitrobenzoate, a captodative olefin, has been performed using semi-micro-combustion calorimetry, effusion measurements through a quartz crystal microbalance, and differential scanning calorimetry. The molar standard combustion energy and enthalpy as well as the molar standard formation enthalpy are reported along with sublimation and melting enthalpies. From these data, experimental formation enthalpy of the gas-phase is derived and compared with the theoretical value calculated through the density functional theory procedure. The olefinic bond enthalpy is also computed from experimental data, and the relevance of the results is discussed.

  2. Palladium-Catalyzed Allylic C-H Bond Functionalization of Olefins

    NASA Astrophysics Data System (ADS)

    Liu, Guosheng; Wu, Yichen

    Transition metal-mediated carbon-hydrogen bond cleavage and functionalization is a mechanistically interesting and synthetically attractive process. One of the important cases is the removal of a allylic hydrogen from an olefin by a PdII salt to yield a π-allylpalladium complex, followed by nucleophilic attack to efficient produce allylic derivatives. In contrast to the well-known allylic acetoxylation of cyclohexene, the reaction of open-chain olefins is fairly poor until recent several years. Some palladium catalytic systems have been reported to achieve allylic C-H functionalization, including acetoxylation, amination and alkylation of terminal alkenes. In the most of cases, ligand is crucial to the success of the transformation. This review surveys the recent development of palladium-catalyzed allylic C-H functionalziation of alkenes. These results promise a significant increase in the scope of olefin transformation.

  3. Polymerizations of Acetylenes and Cyclic Olefins Induced by Metal-Carbynes.

    DTIC Science & Technology

    1983-12-09

    of the American Chemical Society II to. KEy WORDS (Centinue en reoreo eide it neoedeary end idwntii& A, Weoek rwmbw) Polymers Metath~esis Polyalkenamer...and the polynorbornenamer produced when the initiator is the metal-carbyne are similar to those of the polymers produced when the initiator is penta...below, they cause acetylenes, to poly- merize, giving soluble, structurally homogeneous polymers in accord with equation 1. And they do this not only to

  4. Singlet biradical{yields}singlet zwitterion optical transition in a twisted olefin

    SciTech Connect

    Piotrowiak, P.; Strati, G.; Smirnov, S.N.; Warman, J.M.; Schuddeboom, W.

    1996-09-18

    We report the first direct observation of the singlet biradical $YLD singlet zwitterion transition in a twisted olefin, biphenanthrenylidene. Biphenanthrenylidene (full name, bi-4H-cyclopenta[def]phenanthren-4-ylidene, abbreviated as BPH) is an analogue of tetraphenylethylene (TPE) and stilbene, both of which are the favorite models of photoisomerization reactions. The investigations have been focusing on the dynamics of the twisting motion of the double bond which leads to decoupling of the two halves of the olefin and results in the formation of the D{sub 2d} 90{degree}-twisted zwitterionic or biradical excited state. 13 refs., 2 figs., 1 tab.

  5. Synthesis of hierarchical SAPO-34 nanocrystals with improved catalytic performance for methanol to olefins

    NASA Astrophysics Data System (ADS)

    Yang, Bin; Zhao, Pengbo; Ma, Jinghong; Li, Ruifeng

    2016-11-01

    SAPO-34 molecular sieve was hydrothermally synthesized by using organosilane phenylaminopropyl-trimethoxysilane (PHAPTMS) as a part of silicon source and tetraethylammonium hydroxide as microporous template at 160 °C. The XRD, SEM and N2 adsorption/desorption characterizations revealed the hierarchical SAPO-34 is a nanocrystal assembly of 50 nm particles prepared in the system. The catalyst showed improved stability and unusual selectivity of propylene and butylene in methanol to olefins reaction by introducing the mesoporous structure and changing the surface acid sites distribution. The yield of light olefins in hydrocarbons was up to 86%, the selectivity of C3= and C4= reached more than 40% and 10%.

  6. Alpha-alkylation of ketones by addition of zinc enamides to unactivated olefins.

    PubMed

    Nakamura, Masaharu; Hatakeyama, Takuji; Nakamura, Eiichi

    2004-09-29

    A zinc enamide generated from the corresponding N-aryl imine undergoes addition to an unactivated olefin, such as ethylene, 1-octene, and isobutylene, to generate an alpha-alkylated gamma-zincioimine intermediate in good to excellent yield. Terminal and gem-disubstituted olefins react with >99% regioselectivity, allowing the C-C bond formation to take place at the more hindered carbon of the double bond. The organozinc intermediate undergoes further C-C bond formation with a carbon electrophile to give, upon hydrolysis of the imine, an alpha-alkylated ketone bearing a variety of functionalized primary, secondary, and tertiary alkyl groups.

  7. Femtosecond Kerr index of cyclic olefin co/polymers for THz nonlinear optics

    NASA Astrophysics Data System (ADS)

    Noskovicova, E.; Lorenc, D.; Slusna, L.; Velic, D.

    2016-10-01

    The second-order nonlinear refractive index n2 (Kerr index) of cyclic olefin copolymer (TOPAS) and cyclic olefin polymers (ZEONEX, ZEONOR) was determined at the wavelength of 800 nm within this work. Bulk samples of ZEONEX, ZEONOR and TOPAS were measured using the single-beam Z-scan technique and the values of their nonlinear refractive index were determined to be approximately 2 × 10-20 m2W-1 for all cases. The obtained values of n2 play a vital role for ultrafast pulse evolution and corresponding phenomena such as nonlinear spectral transformation.

  8. A ferroelectric olefin-copper(I) organometallic polymer with flexible organic ligand (R)-MbVBP

    NASA Astrophysics Data System (ADS)

    Wang, Guo-Xi; Xing, Zheng; Chen, Li-Zhuang; Han, Guang-Fan

    2015-07-01

    Hydrothermal treatment of (R)-2-methyl-1,4-bis(4-vinylbenzyl)piperazine [(R)-MbVBP] and CuCl afforded a novel olefin-copper(I) coordination compound. Introducing the flexible ligand (R)-MbVBP allowed the olefin-copper(I) organometallic compound to crystallize in a polar point group P21. The compound was ferroelectric, and its electric hysteresis loop showed a remnant polarization (Pr) of 0.13-0.32 μC cm-2 and a coercive field (Ec) of 3.5-11 kV cm-1.

  9. Olefin oxidation by zeolite-encapsulated Mn(salen) sup + complexes under ambient conditions

    SciTech Connect

    Bowers, C.; Dutta, P.K. )

    1990-04-01

    Zeolite-encapsulated manganese complex of the salen ligand (N,N{prime}-ethylenebis(salicylideneaminato)) was synthesized, and its catalytic activity toward various olefins was examined. Iodosylbenzene was chosen to be the terminal oxidant. Oxidation products, which included the epoxide, alcohol, and aldehyde, are formed from cyclohexene, styrene, and trans- and cis-stilbene. In comparison with catalysis by Mn(salen){sup +} complexes in solution, encapsulation lowers the rate of reaction considerably, but provides for selective oxidation based on olefin size and ability to penetrate the zeolite cages.

  10. Hydroformylation of olefinic compounds in the presence of a cobalt catalyst and an organic nitrile promoter

    SciTech Connect

    Virnig, M.J.

    1986-09-16

    A process for preparing a formylated olefinic fatty compound is described comprising reacting an olefinic fatty compound having at least 9 carbon atoms with carbon monoxide and hydrogen in the presence of a catalytic amount of a soluble cobalt salt catalyst and a promoter comprised of an organic nitrile selected from the group consisting of cyano-substituted alkanes having from 2 to 44 carbon atoms and cyano-substituted alkanes having from 4 to 22 carbon atoms containing no substituent other than cyano.

  11. Carbalumination of higher alpha-olefins catalyzed by titanium and zirconium complexes

    SciTech Connect

    Dzhemilev, U.M.; Ibragimov, A.G.; Tolstikov, G.A.; Vostrikova, O.S.

    1985-07-20

    The authors report on efforts to find catalysts capable of activating trialkylaluminums for the carbalumination of alpha-olefins in order to develop a highly selective and efficient method for the one-step preparation of higher alkylaluminums which are otherwise difficult to prepare. Experimentation produced a regioselective method for the carbometallation of higher alpha-olefins using Et/sub 3/Al and Et/sub 2/AlCl in the presence of titanium and zirconium complexes, which permits the preparation of higher trialkylakuminums and dialkylaluminum halides in high yield under mild conditions in one step.

  12. Resonant infrared pulsed laser deposition of cyclic olefin copolymer films

    NASA Astrophysics Data System (ADS)

    Singaravelu, S.; Klopf, J. M.; Schriver, K. E.; Park, H. K.; Kelley, M. J.; Haglund, R. F.

    2014-03-01

    Barrier materials on thin-film organic optoelectronic devices inhibit the uptake of water, oxygen, or environmental contaminants, and fabricating them is a major challenge. By definition, these barrier layers must be insoluble, so the usual routes to polymer- or organic-film deposition by spin coating are not problematic. In this paper, we report comparative studies of pulsed laser deposition of cyclic olefin copolymer (COC), an excellent moisture barrier and a model system for a larger class of protective materials that are potentially useful in organic electronic devices, such as organic light-emitting diodes (OLEDs). Thin films of COC were deposited by resonant and nonresonant infrared pulsed laser ablation of solid COC targets, using a free-electron laser tuned to the 3.43 μm C-H stretch of the COC, and a high-intensity nanosecond Q-switched laser operated at 1064 nm. The ablation craters and deposited films were characterized by scanning-electron microscopy, Fourier-transform infrared spectrometry, atomic-force microscopy, high-resolution optical microscopy, and surface profilometry. Thermal-diffusion calculations were performed to determine the temperature rise induced in the film at the C-H resonant wavelength. The results show that resonant infrared pulsed laser deposition (RIR-PLD) is an effective, low-temperature thin-film deposition technique that leads to evaporation and deposition of intact molecules in homogeneous, smooth films. Nonresonant PLD, on the other hand, leads to photothermal damage, degradation of the COC polymers, and to the deposition only of particulates.

  13. [Synthetic and mechanistic investigation of olefin polymerization catalyzed by early transition metal compounds]. Progress report, Second year, 1 April 1992--31 March 1992

    SciTech Connect

    Bercaw, J.E.

    1993-08-01

    During the second year we continued to prepare and characterize organoyttrium and organoscandium compounds for use as catalysts for polymerizing simple olefins and diolefins. Simple, one-component systems are being pursued, suitable for chain initiation, propagation, and termination studies. This document is divided into: dicarbollide derivatives of scandium as potential catalysts; design, synthesis, and characterization of the first isospecific {alpha} olefin polymerization catalysts; polymerization of {alpha} olefins and 1,5- hexadiene using organoscandium catalysts; and attempted preparations of diastereomeric Nb and Ta olefin/hydride and olefin/alkyl derivatives.

  14. Theoretical insights into the mechanism of olefin elimination in the methanol-to-olefin process over HZSM-5, HMOR, HBEA, and HMCM-22 zeolites.

    PubMed

    Wang, Sen; Chen, Yanyan; Wei, Zhihong; Qin, Zhangfeng; Chen, Jialing; Ma, Hong; Dong, Mei; Li, Junfen; Fan, Weibin; Wang, Jianguo

    2014-10-02

    The mechanism of olefin elimination in the process of methanol-to-olefins (MTO) over a series of zeolites like HZSM-5, HMOR, HBEA, and HMCM-22 was investigated by DFT-D calculations, which is a crucial step that controls the MTO product distribution. The results demonstrate that the manners of olefin elimination are related to the pore structure of zeolite catalyst and the interaction between proton transfer reagent (water or methanol) and zeolite acidic framework. The indirect spiro mechanism is preferable to the direct mechanism over HMOR, HBEA, and HMCM-22 zeolites with large pores, as suggested by the energy barrier of rate-determining step and the potential energy surface (PES), but is unfavorable over HZSM-5 with medium-sized pores due to the steric hindrance of spiro intermediates. Over various zeolites, water and methanol perform differently in proton transfer to form the spiro intermediates; over HMOR and HBEA with strong acidity, water is superior to methanol in promoting propene elimination, whereas over HMCM-22 with relatively weaker acidity, methanol is more favorable as a proton transfer reagent.

  15. Selective production of alpha olefins from synthesis gas over ZnO supported Pd-Fe bimetallics

    SciTech Connect

    Gustafson, B.L.; Wehner, P.S.

    1986-01-01

    Olefins are basic raw materials for a wide variety of commercial processes within the chemical industry. A synthesis-gas-based route to low molecular weight ..cap alpha..-olefins would provide the chemical industry with an alternative route to raw materials in the advent of future petroleum shortages or price increases. The catalytic production of ..cap alpha..-olefins from synthesis gas has been the subject of many investigations over the past 50 years. It has been established that, in some systems, olefin selectivity can be enhanced through the addition of various promoters such as K, Mn, Ti, or Zn. Olefin selectivity can also be dependent on process parameters such as temperature, pressure, conversion levels, or feed compositions. Recent reports in the literature indicate that supported Fe-containing bimetallics may also be selective for the production of olefins from synthesis gas. This study reports the use of Pd-FE bimetallics supported on ZnO for the selective production of olefins from synthesis gas.

  16. Chloromethane to olefins over H-SAPO-34: Probing the hydrocarbon pool mechanism

    DOE PAGES

    Fickel, Dustin W.; Sabnis, Kaiwalya D.; Li, Luanyi; ...

    2016-09-09

    In this paper, by means of in situ FTIR and ex situ13C NMR studies, the initial periods of the chloromethane-to-olefins (CTO) reaction over SAPO-34 were probed in order to investigate the activation period of the reaction and to elucidate the formation of the catalyst active site. A methylated benzene species has been observed to form during the initial activation period of the reaction, and a direct positive correlation was constructed between the formation of this species and the catalytic activity. The data thus indicate that these methylated benzene species contribute to the formation of active sites within SAPO-34 for themore » CTO reaction. This is the first known report identifying a direct semi-quantitative correlation between the catalyst activity and growth of a methylated benzene active species, during the activation period of the chloromethane to olefins reaction. Finally, the findings here in correspond well to those reported for the methanol to olefins reaction, suggesting that a similar ‘hydrocarbon pool’ mechanism may be responsible for the formation of light olefins in CTO chemistry as well.« less

  17. A new efficient iron catalyst for olefin epoxidation with hydrogen peroxide.

    PubMed

    Mikhalyova, Elena A; Makhlynets, Olga V; Palluccio, Taryn D; Filatov, Alexander S; Rybak-Akimova, Elena V

    2012-01-18

    A new aminopyridine ligand derived from bipiperidine (the product of full reduction of bipyridine, bipy) coordinates to iron(II) in a cis-α fashion, yielding a new selective catalyst for olefin epoxidation with H(2)O(2) under limiting substrate conditions.

  18. Catalyst-controlled dioxygenation of olefins: an approach to peroxides, alcohols, and ketones.

    PubMed

    Xia, Xiao-Feng; Zhu, Su-Li; Gu, Zhen; Wang, Haijun; Li, Wei; Liu, Xiang; Liang, Yong-Min

    2015-06-05

    An efficient catalytic approach for the synthesis of substituted peroxides, alcohols, and ketones through a catalyst-controlled highly selective dioxygenation of olefins has been demonstrated. The reported methods are mild and practical, can be switched by the selection of different catalytic systems, and employ peroxide as an oxidant and a reagent at room temperature.

  19. Catalytic deoxydehydration of diols to olefins by using a bulky cyclopentadiene-based trioxorhenium catalyst.

    PubMed

    Raju, Suresh; Jastrzebski, Johann T B H; Lutz, Martin; Klein Gebbink, Robertus J M

    2013-09-01

    A bulky cyclopentadienyl (Cp)-based trioxorhenium compound was developed for the catalytic deoxydehydration of vicinal diols to olefins. The 1,2,4-tri(tert-butyl)cyclopentadienyl trioxorhenium (2) catalyst was synthesised in a two-step synthesis procedure. Dirhenium decacarbonyl was converted into 1,2,4-tri(tert-butyl)cyclopentadienyl tricarbonyl rhenium, followed by a biphasic oxidation with H2 O2 . These two new three-legged compounds with a 'piano-stool' configuration were fully characterised, including their single crystal X-ray structures. Deoxydehydration reaction conditions were optimised by using 2 mol % loading of 2 for the conversion of 1,2-octanediol into 1-octene. Different phosphine-based and other, more conventional, reductants were tested in combination with 2. Under optimised conditions, a variety of vicinal diols (aromatic and aliphatic, internal and terminal) were converted into olefins in good to excellent yields, and with minimal olefin isomerisation. A high turnover number of 1400 per Re was achieved for the deoxydehydration of 1,2-octanediol. Furthermore, the biomass-derived polyols (glycerol and erythritol) were converted into their corresponding olefinic products by 2 as the catalyst.

  20. Catalytic properties of iron-based mixed oxides in the oxidation of methanol and olefins

    NASA Astrophysics Data System (ADS)

    Trifirò, F.; Carbucicchio, M.; Villa, P. L.

    1998-12-01

    The selective oxidation of alcohols and olefins is carried out commercially on complex systems based on Fe and Mo or Sb mixed oxides. The role of active phases and of the dopant in the catalysts has been elucidated using several characterization techniques and catalytic data.

  1. Fe-Catalyzed Oxidation Reactions of Olefins, Alkanes, and Alcohols: Involvement of Oxo- and Peroxo Complexes

    NASA Astrophysics Data System (ADS)

    Schröder, Kristin; Junge, Kathrin; Bitterlich, Bianca; Beller, Matthias

    In this review, recent developments of iron-catalyzed oxidations of olefins (epoxidation), alkanes, arenes, and alcohols are summarized. Special focus is given on the ligand systems and the catalytic performance of the iron complexes. In addition, the mechanistic involvement of high-valent iron-oxo species is discussed.

  2. 76 FR 65382 - Regulation of Fuel and Fuel Additives: Alternative Test Method for Olefins in Gasoline

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-21

    ... AGENCY 40 CFR Part 80 RIN 2060-AP17 Regulation of Fuel and Fuel Additives: Alternative Test Method for... alternative test method for olefin content in gasoline. This final rule will provide flexibility to the... environmental benefits achieved from our fuels programs. ] DATES: This rule is effective November 21,...

  3. Catalytic epoxidation activity of keplerate polyoxomolybdate nanoball toward aqueous suspension of olefins under mild aerobic conditions.

    PubMed

    Rezaeifard, Abdolreza; Haddad, Reza; Jafarpour, Maasoumeh; Hakimi, Mohammad

    2013-07-10

    Catalytic efficiency of a sphere-shaped nanosized polyoxomolybdate {Mo132} in the aerobic epoxidation of olefins in water at ambient temperature and pressure in the absence of reducing agent is exploited which resulted good-to-high yields and desired selectivity.

  4. RUTHENIUM-CATALYZED TANDEM OLEFIN MIGRATION-ALDOL AND MANNICH-TYPE REACTIONS IN IONIC LIQUID.

    EPA Science Inventory

    In the presence of a catalytic amount of RuCl2(PPh3)3, a cross-coupling of 3-buten-2-ol with aldehydes and imines was developed via a tandem olefin migration--aldol--Mannich reaction in bmim[PF6]. With In(OAc)3 as a co-catalyst, a-vinylbenzyl alcohol and aldehydes underwent sim...

  5. EXPOXIDATION OF OLEFINS AND α,β-UNSATURATED KEYTONES OVER SONOCHEMICALLY PREPARED HYDROXYAPATITES USING HYDROGEN PEROXIDE

    EPA Science Inventory

    An effective and environmentally friendly protocol for the epoxidation of olefins and α,β-unsaturated ketones in the presence of hydroxyapatite as catalyst using hydrogen peroxide is described. The catalyst is active and reusable for the selective epoxidation of a variety...

  6. Chloromethane to olefins over H-SAPO-34: Probing the hydrocarbon pool mechanism

    SciTech Connect

    Fickel, Dustin W.; Sabnis, Kaiwalya D.; Li, Luanyi; Kulkarni, Neeta; Winter, Lea R.; Yan, Binhang; Chen, Jingguang G.

    2016-09-09

    In this paper, by means of in situ FTIR and ex situ13C NMR studies, the initial periods of the chloromethane-to-olefins (CTO) reaction over SAPO-34 were probed in order to investigate the activation period of the reaction and to elucidate the formation of the catalyst active site. A methylated benzene species has been observed to form during the initial activation period of the reaction, and a direct positive correlation was constructed between the formation of this species and the catalytic activity. The data thus indicate that these methylated benzene species contribute to the formation of active sites within SAPO-34 for the CTO reaction. This is the first known report identifying a direct semi-quantitative correlation between the catalyst activity and growth of a methylated benzene active species, during the activation period of the chloromethane to olefins reaction. Finally, the findings here in correspond well to those reported for the methanol to olefins reaction, suggesting that a similar ‘hydrocarbon pool’ mechanism may be responsible for the formation of light olefins in CTO chemistry as well.

  7. Low severity coal liquefaction promoted by cyclic olefins. Quarterly report, October 1994--December 1994

    SciTech Connect

    Curtis, C.W.

    1995-05-01

    The research performed during the October to December 1994 quarter centered on two areas. The first area involved the writing of a paper based on research performed on this project concerning the mild acidic pretreatment of low rank coals and their liquefaction behavior in the presence of hydrogen donors with different reactivities. The second area that was worked on during the quarter was the high temperature infrared analysis of cyclic olefins. The work is ongoing and is currently involving a considerable amount of equipment and technique development. Cyclic olefins, such as 1,4,5,8-tetrahydronaphthalene (isotetralin) and 1,4,5,8,9,10-hexahydroanthracene (HHA), are highly reactive hydrogen donor compounds that readily donate their hydrogen to coal and model acceptors when heated. Numerous reactions have been performed using these cyclic olefins with high rank and low rank coals as well as with model acceptors. In each case the cyclic olefins have proven themselves to be active donors. Further evaluation of the reactivity of these donors with pretreated low rank coals and at different temperatures is described more fully in this report.

  8. The Production and Recovery of C2-C4 Olefins from Syngas.

    ERIC Educational Resources Information Center

    Murchison, C. B.; And Others

    1986-01-01

    Discusses reacting coal-derived hydrogen and carbon monoxide (syngas) at relatively high selectivity to ethylene, propylene, and butenes over novel catalysts. In addition, data are given which illustrate a unique ethylene removal step which is compatible with operating the olefin synthesis at low conversion. (JN)

  9. Chemistry of Furan Conversion into Aromatics and Olefins over HZSM-5: A Model Biomass Conversion Reaction

    SciTech Connect

    Cheng, Yu-Ting; Huber, George W.

    2011-06-03

    The conversion of furan (a model of cellulosic biomass) over HZSM-5 was investigated in a thermogravimetric analysis–mass spectrometry system, in situ Fourier transform infrared analysis, and in a continuous-flow fixed-bed reactor. Furan adsorbed as oligomers at room temperature with a 1.73 of adsorbed furan/Al ratio. These oligomers were polycyclic aromatic compounds that were converted to CO, CO₂, aromatics, and olefins at temperatures from 400 to 600 °C. Aromatics (e.g., benzene, toluene, and naphthalene), oligomer isomers (e.g., benzofuran, 2,2-methylenebisfuran, and benzodioxane), and heavy oxygenates (C₁₂{sub +} oligomers) were identified as intermediates formed inside HZSM-5 at different reaction temperatures. During furan conversion, graphite-type coke formed on the catalyst surface, which caused the aromatics and olefins formation to deactivate within the first 30 min of time on-stream. We have measured the effects of space velocity and temperature for furan conversion to help us understand the chemistry of biomass conversion inside zeolite catalysts. The major products for furan conversion included CO, CO₂, allene, C₂–C₆ olefins, benzene, toluene, styrene, benzofuran, indene, and naphthalene. The aromatics (benzene and toluene) and olefins (ethylene and propylene) selectivity decreased with increasing space velocity. Unsaturated hydrocarbons such as allene, cyclopentadiene, and aromatics selectivity increased with increasing space velocity. The product distribution was selective to olefins and CO at high temperatures (650 °C) but was selective to aromatics (benzene and toluene) at intermediate temperatures (450–600 °C). At low temperatures (450 °C), benzofuran and coke contributed 60% of the carbon selectivity. Several different reactions were occurring for furan conversion over zeolites. Some important reactions that we have identified in this study include Diels–Alder condensation (e.g., two furans form benzofuran and water

  10. A sterically expanded "constrained geometry catalyst" for highly active olefin polymerization and copolymerization: an unyielding comonomer effect.

    PubMed

    Irwin, Levi J; Reibenspies, Joseph H; Miller, Stephen A

    2004-12-29

    The 14 A octamethyloctahydrodibenzofluorene moiety has been incorporated into a sterically expanded constrained geometry catalyst, Me2Si(eta1-C29H36)(eta1-N-tBu)ZrCl2.OEt2 (1). The solid-state structure suggests that the activated olefin polymerization catalyst is quite spatially accessible, rationalizing its extraordinary reactivity toward alpha-olefins. 1/MAO (MAO = methylaluminoxane) can be more reactive toward alpha-olefins than toward ethylene and exhibit activities that are linearly and continuously proportional to 4-methyl-1-pentene or 1-octene concentration in their copolymerizations with ethylene.

  11. Mechanistic insights on platinum- and palladium-pincer catalyzed coupling and cyclopropanation reactions between olefins.

    PubMed

    Rajeev, Ramanan; Sunoj, Raghavan B

    2012-07-21

    The mechanism of M(II)-PNP-pincer catalyzed reaction between (i) ethene, (ii) trans-butene with 2-methylbut-2-ene, 2,3-dimethylbut-2-ene and tert-butylbutene is examined by using density functional theory methods (where M = Pt or Pd). All key intermediates and transition states involved in the reaction are precisely located on the respective potential energy surfaces using the popular DFT functionals such as mPW1K, M06-2X, and B3LYP in conjunction with the 6-31+G** basis set. The reaction between these olefins can lead to a linear coupling product or a substituted cyclopropane. The energetic comparison between coupling as well as cyclopropanation pathways involving four pairs of olefins for both platinum (1-4) and palladium (5-8) catalyzed reactions is performed. The key events in the lower energy pathway in the mechanistic course involves (i) a C-C bond formation between the metal bound olefin (ethene or trans-butene) and a free olefin, and (ii) two successive [1,2] hydrogen migrations in the ensuing carbocationic intermediates (1c-4c, and 1d-4d), toward the formation of the coupling product. The computed barriers for these steps in the reaction of metal bound ethene to free tert-butylbutene (or other butenes) are found to be much lower than the corresponding steps when trans-butene is bound to the metal pincer. The Gibbs free energy differences between the transition states leading to the coupling product (TS(d-e)) and that responsible for cyclopropanated product (TS(d-g)) are found to be diminishingly closer in the case of the platinum pincer as compared to that in the palladium system. The computed energetics indicate that the coupled product prefers to remain as a metal olefin complex, consistent with the earlier experimental reports.

  12. Final Report: Experimental and Theoretical Studies of Surface Oxametallacycles - Connections to Heterogeneous Olefin Epoxidation

    SciTech Connect

    Mark A. Barteau

    2009-09-15

    This project has aimed at the rational design of catalysts for direct epoxidation of olefins. This chemistry remains one of the most challenging problems in heterogeneous catalysis. Although the epoxidation of ethylene by silver catalysts to form ethylene oxide (EO) has been practiced for decades, little progress has been made in expanding this technology to other products and processes. We have made significant advances through the combination of surface science experiments, Density Functional Theory (DFT) calculations, and catalytic reactor experiments, toward understanding the mechanism of this reaction on silver catalysts, and to the rational improvement of selectivity. The key has been our demonstration of surface oxametallacycle intermediates as the species that control reaction selectivity. This discovery permits the influence of catalyst promoters on selectivity to be probed, and new catalyst formulations to be developed. It also guides the development of new chemistry with potential for direct epoxidation of more complex olefins. During the award period we have focused on 1. the formation and reaction selectivity of complex olefin epoxides on silver surfaces, and 2. the influence of co-adsorbed oxygen atoms on the reactions of surface oxametallacycles on silver, and 3. the computational prediction, synthesis, characterization and experimental evaluation of bimetallic catalysts for ethylene epoxidation. The significance of these research thrusts is as follows. Selective epoxidation of olefins more complex than ethylene requires suppression of not only side reactions available to the olefin such as C-H bond breaking, but it requires formation and selective ring closure of the corresponding oxametallacycle intermediates. The work carried out under this grant has significantly advanced the field of catalyst design from first principles. The combination of computational tools, surface science, and catalytic reactor experiments in a single laboratory has few

  13. Low severity coal liquefaction promoted by cyclic olefins. Quarterly report, July--September, 1994

    SciTech Connect

    Curtis, C.W.

    1994-12-31

    Previous research indicates that the cyclic olefin, 1,4,5,8,9,10-hexahydroanthracene (HHA), is one of the most effective hydrogen donors tested under low severity conditions. A mild acidic pretreatment of the coal prior to liquefaction has proven to be significant in increasing conversion of low rank coals under low severity conditions as well. Coal conversion can also be improved by employing hydrotreating catalysts. In this study, reactions with coal mild acidic pretreatment were performed with cyclic olefins with and without catalysts. These reactions provided the data to prove whether catalysts are effective under low severity conditions. Evaluating the effect of these three factors (mild acidic pretreatment, hydrogen donation by cyclic olefins, and the use of slurry phase catalysts) on the reactivity of low severity coal liquefaction was the basis of this study. By examining the results, it is clear that the combination of all of the most favorable factors produced coal conversions of more than 50%. The effectiveness of HHA was tested by performing reactions without a cyclic olefin which produced substantially lower coal conversion, thus proving how effective hydrogen donation by cyclic olefins is in low severity coal liquefaction. The mild acidic pretreatment demonstrated its effectiveness on increasing the conversion low rank coals. By promoting higher conversion for the lignite than for the subbituminous coal, suggested that the lower the rank is, the better mild acidic pretreatment works. The catalyst MoNaph proved its effectiveness in low severity coal liquefaction, too, although the reactions with the other slurry phase catalysts NiOct was not effective. Also, synergy among the mild acid pretreatment, HHA and MoNaph occurred yielding high coal conversions for both coals.

  14. Cobalt carbide nanoprisms for direct production of lower olefins from syngas

    NASA Astrophysics Data System (ADS)

    Zhong, Liangshu; Yu, Fei; An, Yunlei; Zhao, Yonghui; Sun, Yuhan; Li, Zhengjia; Lin, Tiejun; Lin, Yanjun; Qi, Xingzhen; Dai, Yuanyuan; Gu, Lin; Hu, Jinsong; Jin, Shifeng; Shen, Qun; Wang, Hui

    2016-10-01

    Lower olefins—generally referring to ethylene, propylene and butylene—are basic carbon-based building blocks that are widely used in the chemical industry, and are traditionally produced through thermal or catalytic cracking of a range of hydrocarbon feedstocks, such as naphtha, gas oil, condensates and light alkanes. With the rapid depletion of the limited petroleum reserves that serve as the source of these hydrocarbons, there is an urgent need for processes that can produce lower olefins from alternative feedstocks. The ‘Fischer-Tropsch to olefins’ (FTO) process has long offered a way of producing lower olefins directly from syngas—a mixture of hydrogen and carbon monoxide that is readily derived from coal, biomass and natural gas. But the hydrocarbons obtained with the FTO process typically follow the so-called Anderson-Schulz-Flory distribution, which is characterized by a maximum C2-C4 hydrocarbon fraction of about 56.7 per cent and an undesired methane fraction of about 29.2 per cent (refs 1, 10, 11, 12). Here we show that, under mild reaction conditions, cobalt carbide quadrangular nanoprisms catalyse the FTO conversion of syngas with high selectivity for the production of lower olefins (constituting around 60.8 per cent of the carbon products), while generating little methane (about 5.0 per cent), with the ratio of desired unsaturated hydrocarbons to less valuable saturated hydrocarbons amongst the C2-C4 products being as high as 30. Detailed catalyst characterization during the initial reaction stage and theoretical calculations indicate that preferentially exposed {101} and {020} facets play a pivotal role during syngas conversion, in that they favour olefin production and inhibit methane formation, and thereby render cobalt carbide nanoprisms a promising new catalyst system for directly converting syngas into lower olefins.

  15. Rapid Identification and Quantification of Linear Olefin Isomers by Online Ozonolysis-Single Photon Ionization Time-of-Flight Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Xie, Yuanyuan; Chen, Ping; Hua, Lei; Hou, Keyong; Wang, Yongchao; Wang, Haiyan; Li, Haiyang

    2016-01-01

    The specific locations of the double bonds in linear olefins can facilitate olefin catalytic synthetic reactions to improve the quality of target olefin products. We developed a simple and efficient approach based on single photon ionization time-of-flight mass spectrometry (SPI-TOFMS) combined with online ozonolysis to identify and quantify the linear olefin double bond positional isomers. The online ozonolysis cleaved the olefins at the double bond positions that led to formation of corresponding characteristic aldehydes. The aldehydes were then detected by SPI-TOFMS to achieve unique spectrometric "fingerprints" for each linear olefin to successfully identify the isomeric ones. To accurately quantify the isomeric components in olefin mixtures, an algorithm was proposed to quantify three isomeric olefin mixtures based on characteristic ion intensities and their equivalent ionization coefficients. The relative concentration errors for the olefin components were lower than 2.5% while the total analysis time was less than 2 min. These results demonstrate that the online ozonolysis SPI-TOFMS has the potential for real-time monitoring of catalytic olefin synthetic reactions.

  16. Molybdenum Imido Alkylidene Metathesis Catalysts that Contain Electron Withdrawing Biphenolates or Binaphtholates

    PubMed Central

    Singh, Rojendra; Czekelius, Constantin; Schrock, Richard R.; Müller, Peter; Hoveyda, Amir H.

    2008-01-01

    We have prepared new Mo(NR)(CHCMe2Ph)(diolate) complexes (R = 2,6-i-Pr2C6H3, 2,6-Me2C6H3, 1-Adamantyl, or 2-CF3C6H4) that contain relatively electron-withdrawing binaphtholate (3,3′-bis-(9-anthracenyl), 3,3′-bispentafluorophenyl, or 3,3′-bis(3,5-bis(trifluoromethyl)phenyl) or biphenolate (3,3′-di-tert-butyl-5,5′-bistrifluoromethyl-6,6′-dimethyl-1,1′-biphenyl-2,2′-diolate) ligands. We also have prepared new monomeric Mo(NR)(CHCMe2Ph)(2,5-dimethylpyrrolide)2 complexes and have treated them with biphenols or binaphthols in order to prepare several Mo(NR)(CHCMe2Ph)(diolate) species. In one case the new Mo(NR)(CHCMe2Ph)(diolate) complexes could be prepared only through reaction of a binaphthol [3,3′-bis(pentafluorophenyl)binaphthol] with a bis(2,5-dimethylpyrrolide) complex. The pyrrolide approach can be employed either to isolate catalysts on a preparative scale or to generate catalysts in situ. Several simple preliminary ring-closing metathesis reactions show that the new complexes are catalytically competent. PMID:18953421

  17. Non-aqueous metathesis as a general approach to prepare nanodispersed materials: Case study of scheelites

    NASA Astrophysics Data System (ADS)

    Afanasiev, Pavel

    2015-09-01

    A general approach to the preparation of inorganic nanoparticles is proposed, using metathesis of precursor salts in non-aqueous liquids. Nanoparticles of scheelites AMO4 (A=Ba, Sr, Ca; M=Mo, W), were obtained with a quantitative yield. Precipitations in formamide, N-methylformamide, propylene carbonate, DMSO and polyols often provide narrow particle size distributions. Advantageous morphology was explained by strong ionic association in non-aqueous solvents, leading to slow nucleation and negligible Ostwald ripening. Mean particle size below 10 nm and high specific surface areas were obtained for several Ca(Sr)Mo(W)O4 materials, making them promising for applications as adsorbents or catalysts. Zeta-potential of scheelites in aqueous suspensions showed negative values in a wide range of pH. Systematic study of optical properties demonstrated variation of optical gap in the sequences W>Mo and Ba>Sr>Ca. The observed trends were reproduced by DFT calculations. No quantum confinement effect was observed for small particles, though the surface states induce low-energy features in the optical spectra.

  18. Some limitations of an approach to the assembly of bryostatins by ring-closing metathesis.

    PubMed

    Dumeunier, Raphaël; Gregson, Thomas; MacCormick, Somhairle; Omori, Hiroki; Thomas, Eric J

    2017-03-28

    Preliminary studies into the use of ring-closing metathesis (RCM) in a convergent approach for the total synthesis of bryostatins are described. An ester that would have provided an advanced intermediate for a synthesis of a 20-deoxybryostatin by a RCM was prepared from an unsaturated acid and alcohol corresponding to the C1-C16 and C17-C27 fragments. However, studies of the formation of the C16-C17 double-bond by RCM were not successful and complex mixtures of products were obtained. To provide an insight into factors that may be involved in hindering RCM in this system, a slightly simplified C1-C16 acid and modified C17-C25 alcohols were prepared and their use for the synthesis of analogues of bryostatins was investigated. Although only low yields were obtained, it appeared that macrolides analogous to the bryostatins can be prepared by RCM, using the Grubbs II catalyst, if the precursors lack the two methyl groups at C18. RCM was not observed, however, for substrates in which these methyl groups were present.

  19. Rapid solid-state metathesis route to transition-metal doped titanias

    NASA Astrophysics Data System (ADS)

    Coleman, Nathaniel; Perera, Sujith; Gillan, Edward G.

    2015-12-01

    Rapid solid-state metathesis (SSM) reactions are often short-lived highly exothermic reactions that yield a molten alkali halide salt that aids in product growth and crystallization. SSM reactions may also produce kinetically stabilized structures due to the short (seconds) reaction times. This report describes the investigation of rapid SSM reactions in the synthesis of transition-metal doped titanias (M-TiO2). The dopant targeted compositions were ten mol percent and based on elemental analysis, many of the M-TiO2 samples were close to this targeted level. Based on surface analysis, some samples showed large enrichment in surface dopant content, particularly chromium and manganese doped samples. Due to the highly exothermic nature of these reactions, rutile structured TiO2 was observed in all cases. The M-TiO2 samples are visible colored and show magnetic and optical properties consistent with the dopant in an oxide environment. UV and visible photocatalytic experiments with these visibly colored rutile M-TiO2 powders showed that many of them are strongly absorbent for methylene blue dye and degrade the dye under both UV and visible light illumination. This work may open up SSM reactions as an alternate non-thermodynamic reaction strategy for dopant incorporation into a wide range of oxide and non-oxides.

  20. Rapid solid-state metathesis route to transition-metal doped titanias

    SciTech Connect

    Coleman, Nathaniel; Perera, Sujith; Gillan, Edward G.

    2015-12-15

    Rapid solid-state metathesis (SSM) reactions are often short-lived highly exothermic reactions that yield a molten alkali halide salt that aids in product growth and crystallization. SSM reactions may also produce kinetically stabilized structures due to the short (seconds) reaction times. This report describes the investigation of rapid SSM reactions in the synthesis of transition-metal doped titanias (M–TiO{sub 2}). The dopant targeted compositions were ten mol percent and based on elemental analysis, many of the M–TiO{sub 2} samples were close to this targeted level. Based on surface analysis, some samples showed large enrichment in surface dopant content, particularly chromium and manganese doped samples. Due to the highly exothermic nature of these reactions, rutile structured TiO{sub 2} was observed in all cases. The M–TiO{sub 2} samples are visible colored and show magnetic and optical properties consistent with the dopant in an oxide environment. UV and visible photocatalytic experiments with these visibly colored rutile M–TiO{sub 2} powders showed that many of them are strongly absorbent for methylene blue dye and degrade the dye under both UV and visible light illumination. This work may open up SSM reactions as an alternate non-thermodynamic reaction strategy for dopant incorporation into a wide range of oxide and non-oxides.

  1. A design-of-experiments approach for the optimization and understanding of the cross-metathesis reaction of methyl ricinoleate with methyl acrylate.

    PubMed

    Ho, Thao T T; Jacobs, Tina; Meier, Michael A R

    2009-01-01

    A design-of-experiments approach for the investigation of the cross-metathesis of methyl ricinoleate with methyl acrylate is described. Two second-generation metathesis initiators were studied using different reaction conditions, revealing optimal reaction conditions for each catalyst. Interestingly, the two catalysts showed completely different temperature response profiles. As a result of these investigations, suitable reaction conditions for the sustainable production of two value-added chemical intermediates were derived. Moreover, the design-of-experiments approach provided valuable information for a thorough understanding of catalytic reactions that would be more difficult to obtain by classic approaches.

  2. Nickel-catalyzed enantioselective alkylative coupling of alkynes and aldehydes: synthesis of chiral allylic alcohols with tetrasubstituted olefins.

    PubMed

    Yang, Yun; Zhu, Shou-Fei; Zhou, Chang-Yue; Zhou, Qi-Lin

    2008-10-29

    A highly efficient nickel-catalyzed asymmetric alkylative coupling of alkynes, aldehydes, and dimethylzinc has been realized by using bulky spirobiindane phosphoramidite ligands, affording allylic alcohols with a tetrasubstituted olefin functionality in high yields, high regioselectivities, and excellent enantioselectivities.

  3. Hydroboration/amination of N-trimethylsilyl protected olefinic amines and diolefins: Synthesis of isomerically pure diamines

    SciTech Connect

    Kabalka, G.W.; Zhe Wang )

    1990-01-01

    N-Trimethylsilyl protected olefinic amines and terminal diolefins were hydroborated with dimethylborane and the resulting organoboranes were treated with in situ generated chloramine or chloralkylamines to produce isomerically pure diamines or N-substituted diamines in good yields.

  4. A search for thermal isomerization of olefins to carbenes: Thermal generations of the silicon-nitrogen double bond

    SciTech Connect

    Zhang, Xianping.

    1990-09-21

    The first part of this thesis will search for the thermal isomerization of olefins to carbenes which is predicted to be a high energy process by calculations and has only been observed in a few strained olefins. The possibility of thermal isomerization of simple olefins to carbenes will be explored. Substitution of a silyl group on the double bond of an olefin allows a potential intermediate which has a {beta}-radical to the silyl group during the cis-trans isomerization. The effects of a trimethylsilyl group on this isomerization are the subject of this study. The second part of this thesis will include the generation and chemistry of intermediates containing a silicon-nitrogen double bond. The isomerization of parent silanimine to the aminosilylene was calculated to be a high energy process. New approaches to the silicon-nitrogen double bond will also be presented. 92 refs., 12 figs., 11 tabs.

  5. Conversion of syngas to light olefins over silicalite-1 supported iron and cobalt catalysts: Effects of manganese addition

    SciTech Connect

    Das, D.; Ravichandran, G.; Chakrabarty, D.K.

    1996-10-01

    As the demand for light (C2-C4) olefins, an important raw materials for a number of chemical industries, is ever increasing considerable attention is now being paid to the design of suitable catalysts with high selectivity for small chain olefins. Although Fischer-Tropsch synthesis yields a wide spectrum of products from methane to waxes it is possible to restrict the chain growth to a few carbon atoms by containing the active metal panicles inside the small pores of a suitable support like zeolite. The nature of the zeolite support also has a strong influence on the product selectivity due to secondary reactions. This paper discusses the results of syngas conversion to light olefins over iron and cobalt catalysts supported on silicalite-1. Effect of the addition of manganese which is known to improve the selectivity to light olefins is also discussed.

  6. Mild acidic pretreatment to enhance low severity coal liquefaction promoted by cyclic olefins. Quarterly report, July 1995--September 1995

    SciTech Connect

    Curtis, C.W.

    1996-03-01

    Research continued on low severity coal liquefaction. Research using high temperature infrared of cyclic olefins progressed well during this quarter. Several fluorinated solvents were found that provide a high temperature medium for isotetralin and its aromatic and aliphatic analogues.

  7. Solvothermal Metal Metathesis on a Metal-Organic Framework with Constricted Pores and the Study of Gas Separation.

    PubMed

    Li, Liangjun; Xue, Haitao; Wang, Ying; Zhao, Pinhui; Zhu, Dandan; Jiang, Min; Zhao, Xuebo

    2015-11-18

    Metal-organic frameworks (MOFs) with constricted pores can increase the adsorbate density of gas and facilitate effective CO2 separation from flue gas or natural gas due to their enhanced overlapping of potential fields of the pores. Herein, an MOF with constricted pores, which was formed by narrow channels and blocks of functional groups, was fabricated from the assembly of a methyl-functionalized ligand and Zn(II) centers (termed NPC-7-Zn). Structural analysis of the as-synthesized NPC-7-Zn reveals a series of zigzag pores with pore diameters of ∼0.7 nm, which could be favorable for CO2 traps. For reinforcing the framework stability, a solvothermal metal metathesis on the pristine MOF NPC-7-Zn was performed, and a new Cu(II) MOF (termed NPC-7-Cu) with an identical framework was produced. The influence of the reaction temperatures on the metal metathesis process was investigated. The results show that the constricted pores in NPC-7-Zn can induce kinetic issues that largely slow the metal metathesis process at room temperature. However, this kinetic issue can be solved by applying higher reaction temperatures. The modified MOF NPC-7-Cu exhibits significant improvements in framework stability and thus leads to a permanent porosity for this framework. The constricted pore structure enables enhanced potential fields for these pores, rendering this MOF with high adsorbate densities for CO2 and high adsorption selectivity for a CO2/N2 gas mixture. The adsorption kinetic studies reveal that CH4 has a faster diffusion rate constant than CO2, showing a surface diffusion controlled mechanism for CO2 and CH4 adsorption.

  8. Enantioselective Cyclopropanation of a Wide Variety of Olefins Catalyzed by Ru(II)-Pheox Complexes.

    PubMed

    Chanthamath, Soda; Iwasa, Seiji

    2016-10-18

    The transition-metal-catalyzed asymmetric cyclopropanation of olefins with diazoacetates has become one of the most important methods for the synthesis of optically active cyclopropane derivatives, which are key pharmaceutical building blocks and present in a large number of natural products. To date, significant progress has been made in this area of research, and efficient stereocontrolled synthetic approaches to cyclopropane derivatives have been developed using rhodium, ruthenium, copper, and cobalt catalysts. However, the vast majority of these strategies are limited to electron-rich olefins, such as styrene derivatives, due to the electrophilicity of the metal-carbene intermediates generated from the reaction of the metal with the diazo compound. Recently, the D2-symmetric Co(II)-phophyrin complexes developed by Zhang et al. were shown to be the most efficient catalysts for the asymmetric cyclopropanation of electron-deficient olefins. This catalytic system is mechanistically distinct from the previous rhodium and copper catalytic systems, proceeding via radical intermediates. However, the asymmetric cyclopropanation of vinyl carbamates, allenes, and α,β-unsaturated carbonyl compounds has rarely been reported. Therefore, the development of new powerful catalysts for the asymmetric cyclopropanation of a wide range of olefinic substrates is the next challenge in this field. In this Account, we summarize our recent studies on the Ru(II)-Pheox-catalyzed asymmetric cyclopropanation of various olefins, including vinyl carbamates, allenes, and α,β-unsaturated carbonyl compounds. We demonstrate that the developed catalytic system effectively promotes the asymmetric cyclopropanation of a wide variety of olefins to produce the desired cyclopropane products in high yields with excellent stereocontrol. The use of succinimidyl-, ketone-, and ester-functionalized diazoacetates as carbene sources was found to be crucial for the high stereoselectivity of the

  9. Ruthenium-catalyzed intramolecular [2+2+2] cycloaddition and tandem cross-metathesis of triynes and enediynes.

    PubMed

    Yuan, Wei; Wei, Yin; Shi, Min

    2013-04-01

    [2+2+2] Cycloadditions can be applied to specifically build up derivatives of benzene and cyclohexadiene and, therefore, have attracted much attention. Herein, we present an intramolecular [2+2+2] cycloaddition of triynes catalyzed by the first-generation Grubbs ruthenium complex (Ru gen-1), which can efficiently afford benzene derivatives in good yields under mild conditions. Moreover, we also report on a novel tandem cross-metathesis transformation of intramolecular enediynes also catalyzed by Ru gen-1, which has not been observed previously in related reports. On the basis of deuterium labeling experiments, a possible reaction mechanism is presented.

  10. Sequential aza-Baylis-Hillman/ring closing metathesis/aromatization as a novel route for the synthesis of substituted pyrroles.

    PubMed

    Declerck, Valérie; Ribière, Patrice; Martinez, Jean; Lamaty, Frédéric

    2004-11-26

    A new route to diverse 2-substituted-3-methoxycarbonyl pyrroles has been developed. Diverse SES protected alpha-methylene beta-aminoesters were obtained by a 3-component aza-Baylis-Hillman reaction. Diversity arose from the aryl aldehydes which can be used in this reaction. N-Alkylation with allyl bromide under mild conditions provided the corresponding dienes. These substituted dienes were cyclized by ring closing metathesis at room temperature or under microwave-activation with Grubbs-type II catalyst to yield SES-protected pyrroline intermediates. The final pyrroles were obtained by base-promoted dehydrodesulfinylation/aromatization. The scope of each of these reactions was explored.

  11. One-pot cross-enyne metathesis (CEYM)-Diels-Alder reaction of gem-difluoropropargylic alkynes.

    PubMed

    Fustero, Santos; Bello, Paula; Miró, Javier; Sánchez-Roselló, María; Haufe, Günter; Del Pozo, Carlos

    2013-01-01

    Propargylic difluorides 1 were used as starting substrates in a combination of cross-enyne metathesis and Diels-Alder reactions. Thus, the reaction of 1 with ethylene in the presence of 2(nd) generation Hoveyda-Grubbs catalyst generates a diene moiety which in situ reacts with a wide variety of dienophiles giving rise to a small family of new fluorinated carbo- and heterocyclic derivatives in moderate to good yields. This is a complementary protocol to the one previously described by our research group, which involved the use of 1,7-octadiene as an internal source of ethylene.

  12. Functionalized olefin cross-coupling to construct carbon–carbon bonds

    PubMed Central

    Lo, Julian C.; Gui, Jinghan; Yabe, Yuki; Pan, Chung-Mao; Baran, Phil S.

    2014-01-01

    Carbon–carbon (C–C) bonds form the backbone of many important molecules, including polymers, dyes, and pharmaceutical agents. The development of new methods to create these essential connections in a rapid and practical fashion has been the focus of numerous organic chemists. This endeavor heavily relies on the ability to form C–C bonds in the presence of sensitive functional groups and congested structural environments. Here we report a fundamentally new chemical transformation that allows for the facile construction of highly substituted and uniquely functionalized C–C bonds. Using a simple iron catalyst, an inexpensive silane, and a benign solvent under an ambient atmosphere, heteroatom-substituted olefins are easily merged with electron-deficient olefins to create molecular architectures that were previously difficult or impossible to access. More than sixty examples are presented with a wide array of substrates, demonstrating the unique chemoselectivity and mildness of this simple reaction. PMID:25519131

  13. Titanium compounds as catalysts of higher alpha-olefin-based super-high-molecular polymers synthesis

    NASA Astrophysics Data System (ADS)

    Konovalov, K. B.; Kazaryan, M. A.; Manzhay, V. N.; Vetrova, O. V.

    2016-01-01

    The synthesis of polymers of 10 million or more molecular weight is a difficult task even in a chemical lab. Higher α-olefin-based polymer agents of such kind have found a narrow but quite important niche, the reduction of drag in the turbulent flow of hydrocarbon fluids such as oil and oil-products. In its turn, searching for a catalytic system capable to produce molecules of such a high length and to synthesize polymers of a low molecular-mass distribution is part of a global task of obtaining a high-quality product. In this paper we had observed a number of industrial catalysts with respect to their suitability for higher poly-α- olefins synthesis. A number samples representing copolymers of 1-hexene with 1-decene obtained on a previous generation catalyst, a microsphere titanium chloride catalytic agent had been compared to samples synthesized using a titanium-magnesium catalyst both in solution and in a polymer medium.

  14. High-throughput approaches for the discovery and optimization of new olefin polymerization catalysts.

    PubMed

    Murphy, Vince; Bei, Xiaohong; Boussie, Thomas R; Brümmer, Oliver; Diamond, Gary M; Goh, Christopher; Hall, Keith A; Lapointe, Anne M; Leclerc, Margarete; Longmire, James M; Shoemaker, James A W; Turner, Howard; Weinberg, W Henry

    2002-01-01

    The discovery of new olefin polymerization catalysts is currently a time-intensive trial-and-error process with no guarantee of success. A fully integrated high-throughput screening workflow for the discovery of new catalysts for polyolefin production has been implemented at Symyx Technologies. The workflow includes the design of the metal-ligand libraries using custom-made computer software, automated delivery of metal precursors and ligands into the reactors using a liquid-handling robot, and a rapid primary screen that serves to assess the potential of each metalligand-activator combination as an olefin polymerization catalyst. "Hits" from the primary screen are subjected to secondary screens using a 48-cell parallel polymerization reactor. Individual polymerization reactions are monitored in real time under conditions that provide meaningful information about the performance capabilities of each catalyst. Rapid polymer characterization techniques support the primary and secondary screens. We have discovered many new and interesting catalyst classes using this technology.

  15. Substantially isotactic, linear, alternating copolymers of carbon monoxide and an olefin

    DOEpatents

    Sen, Ayusman; Jiang, Zhaozhong

    1996-01-01

    The compound, [Pd(Me-DUPHOS)(MeCN).sub.2 ](BF.sub.4).sub.2, [Me-DUPHOS: 1,2-bis(2,5-dimethylphospholano)benzene] is an effective catalyst for the highly enantioselective, alternating copolymerization of olefins, such as aliphatic .alpha.-olefins, with carbon monoxide to form optically active, isotactic polymers which can serve as excellent starting materials for the synthesis of other classes of chiral polymers. For example, the complete reduction of a propylene-carbon monoxide copolymer resulted in the formation of a novel, optically active poly(1,4-alcohol). Also, the previously described catalyst is a catalyst for the novel alternating isomerization cooligomerization of 2-butene with carbon monoxide to form optically active, isotactic poly(1,5-ketone)

  16. Substantially isotactic, linear, alternating copolymers of carbon monoxide and an olefin

    DOEpatents

    Sen, A.; Jiang, Z.

    1996-05-28

    The compound, [Pd(Me-DUPHOS)(MeCN){sub 2}](BF{sub 4}){sub 2}, [Me-DUPHOS: 1,2-bis(2,5-dimethylphospholano)benzene] is an effective catalyst for the highly enantioselective, alternating copolymerization of olefins, such as aliphatic {alpha}-olefins, with carbon monoxide to form optically active, isotactic polymers which can serve as excellent starting materials for the synthesis of other classes of chiral polymers. For example, the complete reduction of a propylene-carbon monoxide copolymer resulted in the formation of a novel, optically active poly(1,4-alcohol). Also, the previously described catalyst is a catalyst for the novel alternating isomerization cooligomerization of 2-butene with carbon monoxide to form optically active, isotactic poly(1,5-ketone).

  17. Direct Stereospecific Synthesis of Unprotected N-H/N-Me Aziridines from Olefins

    PubMed Central

    Jat, Jawahar L.; Paudyal, Mahesh P.; Gao, Hongyin; Xu, Qing-Long; Yousufuddin, Muhammed; Devarajan, Deepa; Ess, Daniel H.; Kürti, László; Falck, John R.

    2014-01-01

    Despite the prevalence of the N-H aziridine motif in bioactive natural products and the clear advantages of this unprotected parent structure over N-protected derivatives as a synthetic building block, no practical methods have emerged for direct synthesis of this compound class from unfunctionalized olefins. Here, we present a mild, versatile method for the direct stereospecific conversion of structurally diverse mono-, di-, tri- and tetra-substituted olefins to N-H aziridines using O-(2,4-dinitrophenyl)hydroxylamine (DPH) via homogeneous rhodium catalysis with no external oxidants. This method is operationally simple (i.e., one-pot), scalable and fast at ambient temperature, furnishing N-H aziridines in good-to-excellent yields. Likewise, N-alkyl aziridines are prepared from N-alkylated DPH derivatives. Quantum-mechanical calculations suggest a plausible Rh-nitrene pathway. PMID:24385626

  18. Sustainable solid catalyst alkylation of commercial olefins by regeneration with supercritical isobutane

    SciTech Connect

    Daniel M. Ginosar; David N. Thompson; Kyle C. Burch

    2005-12-01

    Supercritical isobutane regeneration of a USY zeolite alkylation catalyst was examined in a continuous, automated reaction / regeneration system. Two feeds were studied; a synthetic isobutane / 2-butene blend, and a commercial refinery isoparaffin / olefin blend. The refinery blend was minimally treated, containing a variety of light olefins, and contaminants, including butadiene, oxygenates and sulfur, which are well known to cause severe catalyst deactivation. Synthetic feed experiments showed that high levels of butene conversion was maintained for more than 200 hours time on stream, and that product quality and catalyst maintenance was relatively stable over the course of the experiment using a 3 hour reaction / 3 hour regeneration cycle. Catalyst activity maintenance was lower when the commercial feed was employed. High levels of alkene conversion were maintained for 78 hours and 192 hours using a 3 hour reaction / 3 hour regeneration cycle and a 2 hour reaction / 2 hour regeneration cycle, respectively.

  19. Development of group IV molecular catalysts for high temperature ethylene-α-olefin copolymerization reactions.

    PubMed

    Klosin, Jerzy; Fontaine, Philip P; Figueroa, Ruth

    2015-07-21

    This Account describes our research related to the development of molecular catalysts for solution phase olefin polymerization. Specifically, a series of constrained geometry and nonmetallocene (imino-amido-type) complexes were developed for high temperature olefin polymerization reactions. We have discovered many highly active catalysts that are capable of operating at temperatures above 120 °C and producing copolymers with a useful range of molecular weights (from medium to ultrahigh depending on precatalyst identity and polymerization conditions) and α-olefin incorporation capability. Constrained geometry catalysts (CGCs) exhibit very high activities and are capable of producing a variety of copolymers including ethylene-propylene and ethylene-1-octene copolymers at high reactor temperatures. Importantly, CGCs have much higher reactivity toward α-olefins than classical Ziegler-Natta catalysts, thus allowing for the production of copolymers with any desired level of comonomer. In search of catalysts with improved performance, we discovered 3-amino-substituted indenyl-based CGCs that exhibit the highest activity and produce copolymers with the highest molecular weight within this family of catalysts. Phenanthrenyl-based CGCs were found to be outstanding catalysts for the effective production of high styrene content ethylene-styrene copolymers under industrially relevant conditions. In contrast to CGC ligands, imino-amido-type ligands are bidentate and monoionic, leading to the use of trialkyl group IV precatalysts. The thermal instability of imino-amido complexes was addressed by the development of imino-enamido and amidoquinoline complexes, which are not only thermally very robust, but also produce copolymers with higher molecular weights, and exhibit improved α-olefin incorporation. Imido-amido and imino-enamido catalysts undergo facile chain transfer reactions with metal alkyls, as evidenced by a sharp decrease in polymer molecular weight when the

  20. Catalyst-controlled C-O versus C-N allylic functionalization of terminal olefins.

    PubMed

    Strambeanu, Iulia I; White, M Christina

    2013-08-14

    The divergent synthesis of syn-1,2-aminoalcohol or syn-1,2-diamine precursors from a common terminal olefin has been accomplished using a combination of palladium(II) catalysis with Lewis acid cocatalysis. Palladium(II)/bis-sulfoxide catalysis with a silver triflate cocatalyst leads for the first time to anti-2-aminooxazolines (C-O) in good to excellent yields. Simple removal of the bis-sulfoxide ligand from this reaction results in a complete switch in reactivity to afford anti-imidazolidinone products (C-N) in good yields and excellent diastereoselectivities. Mechanistic studies suggest the divergent C-O versus C-N reactivity from a common ambident nucleophile arises due to a switch in mechanism from allylic C-H cleavage/functionalization to olefin isomerization/oxidative amination.

  1. Low severity coal liquefaction promoted by cyclic olefins. Quarterly report, October 1991--December 1991

    SciTech Connect

    Curtis, C.W.

    1991-12-31

    The objective of this project is to evaluate the efficacy of low severity coal liquefaction in the presence of highly reactive hydrogen donors, cyclic olefins. The work that was performed this quarter involved performing a literature search in which different aspects of low severity coal liquefaction were examined. In addition, two new mater`s graduate students learned the fundamental differences between high severity coal liquefaction and low severity coal liquefaction by examining the literature and reading texts on coal liquefaction. The literature review presented for the first quarter`s work is a compilation of the material which we have found to data involving low severity coal liquefaction. Additional review of low severity liquefaction literature is being conducted this quarter and will be reported in the next quarterly report. In addition, a summary of the work involving the reactivity of cyclic olefins in the absence and presence of coal will be presented next quarter.

  2. Low severity coal liquefaction promoted by cyclic olefins. Quarterly report, October 1991--December 1991

    SciTech Connect

    Curtis, C.W.

    1991-12-31

    The objective of this project is to evaluate the efficacy of low severity coal liquefaction in the presence of highly reactive hydrogen donors, cyclic olefins. The work that was performed this quarter involved performing a literature search in which different aspects of low severity coal liquefaction were examined. In addition, two new master`s graduate students learned the fundamental differences between high severity coal liquefaction and low severity coal liquefaction by examining the literature and reading texts on coal liquefaction. The literature review presented for the first quarter`s work is a compilation of the material which we have found to date involving low severity coal liquefaction. Additional review of low severity liquefaction literature is being conducted this quarter and will be reported in the next quarterly report. In addition, a summary of the work involving the reactivity of cyclic olefins in the absence and presence of coal will be presented next quarter.

  3. Low severity coal liquefaction promoted by cyclic olefins. Quarterly technical progress report, April--June 1996

    SciTech Connect

    Curtis, C.W.

    1997-12-31

    The goal of this research is to develop a methodology for analyzing the reactivity of cyclic olefins in situ in a high temperature and high pressure infrared cell. Cyclic olefins, such as 1,4,5,8-tetrahydronaphthalene (isotetralin) and 1,4,5,8,9,10-hexahydroanthracene (HHA), are highly reactive donor compounds that readily donate their hydrogen to coal and model acceptors when heated to temperatures of 200{degrees}C and above. These donors are active donors in the low severity liquefaction of coal at 350{degrees}C as shown in the research performed in this project. The infrared studies are being performed in a high temperature infrared cell that was obtained from AABSPEC. Modifications to that cell have been made and have been reported in previous progress reports.

  4. Functionalized olefin cross-coupling to construct carbon-carbon bonds

    NASA Astrophysics Data System (ADS)

    Lo, Julian C.; Gui, Jinghan; Yabe, Yuki; Pan, Chung-Mao; Baran, Phil S.

    2014-12-01

    Carbon-carbon (C-C) bonds form the backbone of many important molecules, including polymers, dyes and pharmaceutical agents. The development of new methods to create these essential connections in a rapid and practical fashion has been the focus of numerous organic chemists. This endeavour relies heavily on the ability to form C-C bonds in the presence of sensitive functional groups and congested structural environments. Here we report a chemical transformation that allows the facile construction of highly substituted and uniquely functionalized C-C bonds. Using a simple iron catalyst, an inexpensive silane and a benign solvent under ambient atmosphere, heteroatom-substituted olefins are easily reacted with electron-deficient olefins to create molecular architectures that were previously difficult or impossible to access. More than 60 examples are presented with a wide array of substrates, demonstrating the chemoselectivity and mildness of this simple reaction.

  5. Non-aqueous metathesis as a general approach to prepare nanodispersed materials: Case study of scheelites

    SciTech Connect

    Afanasiev, Pavel

    2015-09-15

    A general approach to the preparation of inorganic nanoparticles is proposed, using metathesis of precursor salts in non-aqueous liquids. Nanoparticles of scheelites AMO{sub 4} (A=Ba, Sr, Ca; M=Mo, W), were obtained with a quantitative yield. Precipitations in formamide, N-methylformamide, propylene carbonate, DMSO and polyols often provide narrow particle size distributions. Advantageous morphology was explained by strong ionic association in non-aqueous solvents, leading to slow nucleation and negligible Ostwald ripening. Mean particle size below 10 nm and high specific surface areas were obtained for several Ca(Sr)Mo(W)O{sub 4} materials, making them promising for applications as adsorbents or catalysts. Zeta-potential of scheelites in aqueous suspensions showed negative values in a wide range of pH. Systematic study of optical properties demonstrated variation of optical gap in the sequences W>Mo and Ba>Sr>Ca. The observed trends were reproduced by DFT calculations. No quantum confinement effect was observed for small particles, though the surface states induce low-energy features in the optical spectra. - Graphical abstract: Scheelites AMO{sub 4} (A=Ca, Sr, Ba; M=Mo, W) were prepared in various non-aqueous liquids with high specific surface areas and narrow size distributions. The optical gap of scheelites changes in the series Ca

  6. Controlling Cesium Cation Recognition via Cation Metathesis within and Ion Pair Receptor

    SciTech Connect

    Kim, Sung Kuk; Vargas-Zuniga, Gabriela; Hay, Benjamin; Young, Neil J; Delmau, Laetitia Helene; Lee, Prof. Chang-Hee; Kim, Jong Seung; Lynch, Vincent M.; Sessler, Jonathan L.

    2012-01-01

    Ion pair receptor 3 bearing an anion binding site and multiple cation binding sites has been synthesized and shown to function in a novel binding-release cycle that does not necessarily require displacement to effect release. The receptor forms stable complexes with the test cesium salts, CsCl and CsNO{sub 3}, in solution (10% methanol-d{sub 4} in chloroform-d) as inferred from {sup 1}H NMR spectroscopic analyses. The addition of KClO{sub 4} to these cesium salt complexes leads to a novel type of cation metathesis in which the 'exchanged' cations occupy different binding sites. Specifically, K{sup +} becomes bound at the expense of the Cs{sup +} cation initially present in the complex. Under liquid-liquid conditions, receptor 3 is able to extract CsNO{sub 3} and CsCl from an aqueous D{sub 2}O layer into nitrobenzene-d{sub 5} as inferred from {sup 1}H NMR spectroscopic analyses and radiotracer measurements. The Cs{sup +} cation of the CsNO{sub 3} extracted into the nitrobenzene phase by receptor 3 may be released into the aqueous phase by contacting the loaded nitrobenzene phase with an aqueous KClO{sub 4} solution. Additional exposure of the nitrobenzene layer to chloroform and water gives 3 in its uncomplexed, ion-free form. This allows receptor 3 to be recovered for subsequent use. Support for the underlying complexation chemistry came from single-crystal X-ray diffraction analyses and gas-phase energy-minimization studies.

  7. Iron(II)-catalyzed intramolecular aminohydroxylation of olefins with functionalized hydroxylamines.

    PubMed

    Liu, Guan-Sai; Zhang, Yong-Qiang; Yuan, Yong-An; Xu, Hao

    2013-03-06

    A diastereoselective aminohydroxylation of olefins with a functionalized hydroxylamine is catalyzed by new iron(II) complexes. This efficient intramolecular process readily affords synthetically useful amino alcohols with excellent selectivity (dr up to > 20:1). Asymmetric catalysis with chiral iron(II) complexes and preliminary mechanistic studies reveal an iron nitrenoid is a possible intermediate that can undergo either aminohydroxylation or aziridination, and the selectivity can be controlled by careful selection of counteranion/ligand combinations.

  8. Development of a flow method for the hydroboration/oxidation of olefins.

    PubMed

    Souto, José A; Stockman, Robert A; Ley, Steven V

    2015-04-07

    A method for the continuous preparation of alcohols by hydroboration/oxidation of olefins using flow techniques is described. The process allows the isolation of up to 120 mmol h(-1) of the desired alcohol in a very rapid manner with good functional group tolerance. The flow setup can be modified to perform a continuous extraction of the desired alcohol from the biphasic mixture produced by the reaction.

  9. Hydroalkoxylation of unactivated olefins with carbon radicals and carbocation species as key intermediates.

    PubMed

    Shigehisa, Hiroki; Aoki, Tatsuya; Yamaguchi, Sumiko; Shimizu, Nao; Hiroya, Kou

    2013-07-17

    A unique Markovnikov hydroalkoxylation of unactivated olefins with a cobalt complex, silane, and N-fluoropyridinium salt is reported. Further optimization of reaction conditions yielded high functional group tolerance and versatility of alcoholic solvent employed, including methanol, i-propanol, and t-butanol. Use of trifluorotoluene as a solvent made the use of alcohol in stoichiometric amount possible. Mechanistic insight into this novel catalytic system is also discussed. Experimental results suggest that catalysis involves both carbon radical and carbocation intermediates.

  10. Ruthenium-catalyzed hydroformylation/reduction of olefins to alcohols: extending the scope to internal alkenes.

    PubMed

    Wu, Lipeng; Fleischer, Ivana; Jackstell, Ralf; Profir, Irina; Franke, Robert; Beller, Matthias

    2013-09-25

    In the presence of 2-phosphino-substituted imidazole ligands and Ru3(CO)12 or Ru(methylallyl)2(COD) direct hydroformylation and hydrogenation of alkenes to alcohols takes place. In addition to terminal alkenes, also more challenging internal olefins are converted preferentially to industrially important linear alcohols in high yield (up to 88%) and regioselectivity (n:iso up to 99:1).

  11. Improving olefin tolerance and production in E. coli using native and evolved AcrB.

    PubMed

    Mingardon, Florence; Clement, Camille; Hirano, Kathleen; Nhan, Melissa; Luning, Eric G; Chanal, Angelique; Mukhopadhyay, Aindrila

    2015-05-01

    Microorganisms can be engineered for the production of chemicals utilized in the polymer industry. However many such target compounds inhibit microbial growth and might correspondingly limit production levels. Here, we focus on compounds that are precursors to bioplastics, specifically styrene and representative alpha-olefins; 1-hexene, 1-octene, and 1-nonene. We evaluated the role of the Escherichia coli efflux pump, AcrAB-TolC, in enhancing tolerance towards these olefin compounds. AcrAB-TolC is involved in the tolerance towards all four compounds in E. coli. Both styrene and 1-hexene are highly toxic to E. coli. Styrene is a model plastics precursor with an established route for production in E. coli (McKenna and Nielsen, 2011). Though our data indicates that AcrAB-TolC is important for its optimal production, we observed a strong negative selection against the production of styrene in E. coli. Thus we used 1-hexene as a model compound to implement a directed evolution strategy to further improve the tolerance phenotype towards this alpha-olefin. We focused on optimization of AcrB, the inner membrane domain known to be responsible for substrate binding, and found several mutations (A279T, Q584R, F617L, L822P, F927S, and F1033Y) that resulted in improved tolerance. Several of these mutations could also be combined in a synergistic manner. Our study shows efflux pumps to be an important mechanism in host engineering for olefins, and one that can be further improved using strategies such as directed evolution, to increase tolerance and potentially production.

  12. Frontiers in olefin polymerization: reinventing the world's most common synthetic polymers.

    PubMed

    Hustad, Phillip D

    2009-08-07

    Synthetic polymers are vital to our society, affecting practically every aspect of modern life. The ubiquitous nature of these materials is a result of years of collaboration between basic and applied researchers across many disciplines, resulting in economic routes to materials that meet customer needs. These considerations are exemplified by recent developments in the synthesis of block copolymers from simple olefins. The practical application of creative chemistry has produced materials with a favorable balance of desirable polymer properties and process economics.

  13. High Performance Organic Transistors: Percolating Arrays of Nanotubes Functionalized with an Electron Deficient Olefin

    DTIC Science & Technology

    2011-04-03

    electronics. In the present work, we have extended carbon nanotube functionalization via a 2-2 cycloaddition to electron withdrawing non-fluorinated...have extended carbon nanotube functionalization via a 2-2 cycloaddition to electron withdrawing non-fluorinated olefins as well. Our results show...Moyon et Al. 27 work on cycloaddition of azomenthine suggests preferential functionalization of the semiconducting tubes. In contrast, Kamaras et al

  14. New methods for the synthesis of aromatic fluorine compounds from industrial freons and polyfluorinated olefins

    SciTech Connect

    Nefedov, O.M.; Volchkov, N.V.

    1995-01-10

    The results from investigations into the development and application of a strategy and new methods for the synthesis of aromatic fluorine compounds, using fluorohalogenomethanes and polyfluorinated olefins as initial fluorine-containing substrates or structural units, are summarized. Two general methods for the production of fluoroarenes, involving the synthetic assembly of fluorobenzenoid structures through the cycloaddition of fluorocarbenes and fluoroalkenes to various 1,3-diene substrates and subsequent aromatization of the obtained fluorinated cyclopropane, cyclobutane, or cyclohexene adducts, are examined.

  15. Terminating Platinum-Initiated Cation-Olefin Reactions with Simple Alkenes

    DTIC Science & Technology

    2011-05-05

    an asymmetric cascade cyclization was investigated using the chiral [P2PPt] 2+ com- plex (P2=DTBM-SEGPHOS, P=PMe3) 19. The combina- tion of a chiral ...P2 ligand and an achiral monodentate phosphine has been previously shown to catalyze cyclo- rearrangment reactions with high enantiomeric excess.[27...the chiral initiator efficiently and diastereoselectively activates a single olefin face. In summary, we report the results of a platinum(II

  16. An adaptive self-healing ionic liquid nanocomposite membrane for olefin-paraffin separations.

    PubMed

    Pitsch, Fee; Krull, Florian F; Agel, Friederike; Schulz, Peter; Wasserscheid, Peter; Melin, Thomas; Wessling, Matthias

    2012-08-16

    An adaptive self-healing ionic liquid nanocomposite membrane comprising a multi-layer support structure hosting the ionic salt [Ag](+) [Tf(2) N](-) is used for the separation of the olefin propylene and the paraffin propane. The ionic salt renders liquid like upon complexation with propylene, resulting in facilitated transport of propylene over propane at benchmark-setting selectivity and permeance levels. The contacting with acetylene causes the ionic salt to liquefy without showing evidence of forming explosive silver acetylide.

  17. Improving olefin tolerance and production in E. coli using native and evolved AcrB

    DOE PAGES

    Mingardon, Florence; Clement, Camille; Hirano, Kathleen; ...

    2015-01-20

    Microorganisms can be engineered for the production of chemicals utilized in the polymer industry. However many such target compounds inhibit microbial growth and might correspondingly limit production levels. Here, we focus on compounds that are precursors to bioplastics, specifically styrene and representative alpha-olefins; 1-hexene, 1-octene, and 1-nonene. We evaluated the role of the Escherichia coli efflux pump, AcrAB-TolC, in enhancing tolerance towards these olefin compounds. AcrAB-TolC is involved in the tolerance towards all four compounds in E. coli. Both styrene and 1-hexene are highly toxic to E. coli. Styrene is a model plastics precursor with an established route for productionmore » in E. coli (McKenna and Nielsen, 2011). Though our data indicates that AcrAB-TolC is important for its optimal production, we observed a strong negative selection against the production of styrene in E. coli. Thus we used 1-hexene as a model compound to implement a directed evolution strategy to further improve the tolerance phenotype towards this alpha-olefin. We focused on optimization of AcrB, the inner membrane domain known to be responsible for substrate binding, and found several mutations (A279T, Q584R, F617L, L822P, F927S, and F1033Y) that resulted in improved tolerance. Several of these mutations could also be combined in a synergistic manner. Our study shows efflux pumps to be an important mechanism in host engineering for olefins, and one that can be further improved using strategies such as directed evolution, to increase tolerance and potentially production.« less

  18. Preliminary results in the fast pyrolysis of biomass to lower olefins

    SciTech Connect

    Diebold, J.P.

    1980-08-01

    The pyrolysis of pure cellulose and -80-mesh birch wood flour in a low-residence-time, entrained-flow tubular reactor yielded primarily gaseous products, with virtually no char formation. There were some condensible by-products which were almost entirely water soluble. The gases contained significant amounts of olefinic hydrocarbons such as ethylene. Although the yields of the olefinic hydrocarbons were not as high as previous yields from trash-derived organics, this study demonstrated that cellulose and biomass can be used to produce ethylene and other olefins in better yields than attained in conventional gasifiers. Very little of the char from birch wood pyrolysis had a charcoal appearance in scanning electron microscope photographs; instead, it had a sintered or agglomerated appearance. This implies that the char was formed by a different mechanism than charcoal and involves a liquification step. The attempts to feed lignin powder into the reactor, which resulted in the material sintering, bubbling, and charring at the reactor entrance, suggest that the agglomerated birch char particles may have been agglomerated birch lignin char particles; in fact, the heat of combustion of the char was close to that of lignin on an ash-free basis. A feed system for continuous pyrolysis research should be more reproducible and resistant to mass flow fluctuations than the China Lake pyrolysis steam as it was evolved to make pyrolysis gases for the previous gas purification system check out and demonstration. This study consisted of only a preliminary screening of the pyrolysis of pure cellulose, wood flour, and pure lignin. The pyrolysis of these materials needs to be further characterized. The ability to use relatively large feedstock particles in fast pyrolysis to produce olefins would significantly reduce the cost and process energy requirements of feedstock preparation.

  19. Hydroxyamination of olefins using Br-N-(CO2Me)2.

    PubMed

    Kuszpit, Michael R; Giletto, Matthew B; Jones, Corey L; Bethel, Travis K; Tepe, Jetze J

    2015-02-06

    The hydroxyamination reagent Br-N-(CO2Me)2 underwent Markovnikov addition to various olefins in the presence of catalytic BF3·OEt2 and provides efficient access to aminoalcohols. The reaction provided the trans-1-bromo, 2-N-bis-carbamate adduct stereoisomer in all cases. The resulting adduct underwent cyclization to give an oxazolidinone, which could be readily hydrolyzed to an oxazolidin-2-one or an amino alcohol.

  20. Low severity coal liquefaction promoted by cyclic olefins. Quarterly report, October 1996--December 1996

    SciTech Connect

    Curtis, C.W.

    1997-06-01

    The goal of this research is to develop a methodology for analyzing the reactivity of cyclic olefins in situ in a high temperature and high pressure infrared cell. The reactivities of naphthalene, decalin, tetralin, isotetralin, 1,2-dihydronaphthalene and 1,4-dihydronaphthalene have been studied at 230{degrees}C under ambient pressure and under 500 psig blankets of both nitrogen and hydrogen.

  1. Determination of aromatics and olefins in wide-boiling petroleum fractions

    NASA Technical Reports Server (NTRS)

    Spakowski, A E; Evans, A; Hibbard, R R

    1950-01-01

    A chromatographic method is described herein for the analysis of aromatics and olefins in wide boiling petroleum fractions. The fuel is split into four fractions: nonaromatic, intermediate, pure aromatic, and wash. The analysis, which need be run only on the intermediate cut to determine aromatics in the fuel, is based on specific dispersion. With analysis times of less than 8 hours, accuracies of 1 percent were attained.

  2. Artificial Informational Polymers and Nanomaterials from Ring-Opening Metathesis Polymerization

    NASA Astrophysics Data System (ADS)

    James, Carrie Rae

    Inspired by naturally occurring polymers (DNA, polypeptides, polysaccharides, etc.) that can self-assemble on the nanoscale into complex, information-rich architectures, we have synthesized nucleic acid based polymers using ROMP. These polymers were synthesized using a graft-through strategy, whereby nucleic acids bearing a strained cyclic olefin were directly polymerized. This is the first example of the graft-through polymerization of nucleic acids. Our approach takes advantage of non-charged peptide nucleic acids (PNAs) as elements to incorporate into ROMP polymer backbones. PNA is a synthetic nucleic acid analogue known for its increased affinity and specificity for complementary DNA or RNA. To accomplish the graft-through polymerization of PNA, we conjugated PNA to strained cyclic olefins using solid phase peptide conjugation chemistry. These PNA monomers were then directly polymerized into homo and block copolymers forming brushes, or comb-like arrangements, of information. Block copolymer amphiphiles of these materials, where the PNA brush served as the hydrophilic portion, were capable of self-assembly into spherical nanoparticles (PNA NPs). These PNA NPs were then studied with respect to their ability to hybridize complementary DNA sequences, as well as their ability to undergo cellular internalization. PNA NPs consisting of densely packed brushes of nucleic acids possessed increased thermal stability when mixed with their complementary DNA sequence, indicating a greater DNA binding affinity over their unpolymerized PNA counterparts. In addition, by arranging the PNA into dense brushes at the surface of the nanoparticle, Cy5.5 labeled PNA NPs were able to undergo cellular internalization into HeLa cells without the need for an additional cellular delivery device. Importantly, cellular internalization of PNA has remained a significant challenge in the literature due to the neutrally charged amino-ethyl glycine backbone of PNA. Therefore, this represents a

  3. Elaboration of Sterically Hindered δ-Lactones through Ring-Closing Metathesis: Application to the Synthesis of the C1-C27 Fragment of Hemicalide.

    PubMed

    Lecourt, Camille; Boinapally, Srikanth; Dhambri, Sabrina; Boissonnat, Guillaume; Meyer, Christophe; Cossy, Janine; Sautel, François; Massiot, Georges; Ardisson, Janick; Sorin, Geoffroy; Lannou, Marie-Isabelle

    2016-12-16

    The synthesis of the C1-C27 fragment of hemicalide, a marine metabolite displaying a unique potent antiproliferative activity, has been accomplished. The synthetic approach highlights a remarkably efficient ring-closing metathesis reaction catalyzed by Nolan ruthenium indenylidene complexes to elaborate the highly substituted δ-lactone framework.

  4. Microchannel fabrication on cyclic olefin polymer substrates via 1064 nm Nd:YAG laser ablation

    NASA Astrophysics Data System (ADS)

    McCann, Ronán; Bagga, Komal; Groarke, Robert; Stalcup, Apryll; Vázquez, Mercedes; Brabazon, Dermot

    2016-11-01

    This paper presents a method for fabrication of microchannels on cyclic olefin polymer films that have application in the field of microfluidics and chemical sensing. Continuous microchannels were fabricated on 188-μm-thick cyclic olefin polymer substrates using a picosecond pulsed 1064 nm Nd:YAG laser. The effect of laser fluence on the microchannel morphology and dimensions was analysed via scanning electron microscopy and optical profilometry. Single laser passes were found to produce v-shaped microchannels with depths ranging from 12 μm to 47 μm and widths from 44 μm to 154 μm. The ablation rate during processing was lower than predicted theoretically. Multiple laser passes were applied to examine the ability for finer control over microchannel morphology with channel depths ranging from 22 μm to 77 μm and channel widths from 59 μm to 155 μm. For up to five repeat passes, acceptable reproducibility was found in the produced microchannel morphology. Infrared spectroscopy revealed oxidation and dehydrogenation of the polymer surface following laser ablation. These results were compared to other work conducted on cyclic olefin polymers.

  5. Energy and materials flows in the production of olefins and their derivatives

    SciTech Connect

    Gaines, L.L.; Shen, S.Y.

    1980-08-01

    Production of olefins and their derivatives uses almost 3.5% of the oil and gas consumed annually in the United States. It is estimated that their production requires an input energy of 2 Q, which is 50% of the energy used in the production of all petrochemicals. Substantial amounts of this energy could be recovered through recycling. For example, recycling of a single plastic product, polyester soft drink bottles, could have recovered about 0.014 Q in 1979. (About 1.4 Q is used to produce plastic derivatives of olefins). Petrochemical processes use fuels as feedstocks, as well as for process energy, and a portion of this energy is not foregone and can be recovered through combustion of the products. The energy foregone in the production of ethylene is estimated to be 7800 Btu/lb. The energy foregone in plastics production ranges from 12,100 Btu/lb for the new linear low-density polyethylene to 77,200 Btu/lb for nylon 66, which is about 60% of the total energy input for that product. Further investigation of the following areas could yield both material and energy savings in the olefins industry: (1) recycling of petrochemical products to recover energy in addition to that recoverable through combustion, (2) impact of feedstock substitution on utilization of available national resources, and (3) effective use of the heat embodied in process steam. This steam accounts for a major fraction of the industry's energy input.

  6. Cyclopentadienyl-containing low-valent early transition metal olefin polymerization catalysts

    DOEpatents

    Marks, Tobin J.; Luo, Lubin; Yoon, Sung Cheol

    2003-04-08

    A catalyst system useful to polymerize and co-polymerize polar and non-polar olefin monomers is formed by in situ reduction with a reducing agent of a catalyst precursor comprising {Cp*MRR'.sub.n }.sup.+ {A}.sup.- wherein Cp* is a cyclopentadienyl or substituted cyclopentadienyl moiety; M is an early transition metal; R is a C.sub.1 -C.sub.20 hydrocarbyl; R' are independently selected from hydride, C.sub.1 -C.sub.20 hydrocarbyl, SiR".sub.3, NR".sub.2, OR", SR", GeR".sub.3, and SnR".sub.3 containing groups (R"=C.sub.1 -C.sub.10 hydrocarbyl); n is an integer selected to balance the oxidation state of M; and A is a suitable non-coordinating anionic cocatalyst or precursor. This catalyst system may form stereoregular olefin polymers including syndiotactic polymers of styrene and methylmethacrylate and isotactic copolymers of polar and nonpolar olefin monomers such as methylmethacrylate and styrene.

  7. Cyclopentadienyl-containing low-valent early transition metal olefin polymerization catalysts

    DOEpatents

    Marks, Tobin J.; Luo, Lubin; Yoon, Sung Cheol

    2007-01-09

    A catalyst system useful to polymerize and co-polymerize polar and non-polar olefin monomers is formed by in situ reduction with a reducing agent of a catalyst precursor comprising {Cp*MRR'.sub.n}.sup.+{A}.sup.- wherein Cp* is a cyclopentadienyl or substituted cyclopentadienyl moiety; M is an early transition metal; R is a C.sub.1 C.sub.20 hydrocarbyl; R' are independently selected from hydride, C.sub.1 C.sub.20 hydrocarbyl, SiR''.sub.3, NR''.sub.2, OR'', SR'', GeR''.sub.3, SnR''.sub.3, and C.dbd.C-containing groups (R''=C.sub.1 C.sub.10 hydrocarbyl); n is an integer selected to balance the oxidation state of M; and A is a suitable non-coordinating anionic cocatalyst or precursor. This catalyst system may form stereoregular olefin polymers including syndiotactic polymers of styrene and methylmethacrylate and isotactic copolymers of polar and nonpolar olefin monomers such as methylmethacrylate and styrene.

  8. Cyclopentadienyl-containing low-valent early transition metal olefin polymerization catalysts

    DOEpatents

    Marks, Tobin J.; Luo, Lubin; Yoon, Sung Cheol

    2003-12-30

    A catalyst system useful to polymerize and co-polymerize polar and non-polar olefin monomers is formed by in situ reduction with a reducing agent of a catalyst precursor comprising wherein Cp* is a cyclopentadienyl or substituted cyclopentadienyl moiety; M is an early transition metal; R is a C.sub.1 -C.sub.20 hydrocarbyl; R' are independently selected from hydride, C.sub.1 -C.sub.20 hydrocarbyl, SiR".sub.3, NR".sub.2, OR", SR", GeR".sub.3, SnR".sub.3, and C.dbd.C containing groups (R".dbd.C.sub.1 -C.sub.10 hydrocarbyl); n is an integer selected to balance the oxidation state of M; and A is a suitable non-coordinating anionic cocatalyst or precursor. This catalyst system may form stereoregular olefin polymers including syndiotactic polymers of styrene and methylmethacrylate and isotactic copolymers of polar and nonpolar olefin monomers such as methylmethacrylate and styrene.

  9. Cyclopentadienyl-containing low-valent early transition metal olefin polymerization catalysts

    DOEpatents

    Marks, Tobin J.; Luo, Lubin; Yoon, Sung Cheol

    2006-10-10

    A catalyst system useful to polymerize and co-polymerize polar and non-polar olefin monomers is formed by in situ reduction with a reducing agent of a catalyst precursor comprising {Cp*MRR'.sub.n}.sup.+{A}.sup.- wherein Cp* is a cyclopentadienyl or substituted cyclopentadienyl moiety; M is an early transition metal; R is a C.sub.1 C.sub.20 hydrocarbyl; R' are independently selected from hydride, C.sub.1 C.sub.20 hydrocarbyl, SiR''.sub.3, NR''.sub.2, OR'', SR'', GeR''.sub.3, SnR''.sub.3, and C.dbd.C-containing groups (R''=C.sub.1 C.sub.10 hydrocarbyl); n is an integer selected to balance the oxidation state of M; and A is a suitable non-coordinating anionic cocatalyst or precursor. This catalyst system may form stereoregular olefin polymers including syndiotactic polymers of styrene and methylmethacrylate and isotactic copolymers of polar and nonpolar olefin monomers such as methylmethacrylate and styrene.

  10. Cyclopentadienyl-Containing Low-Valent Early Transition Metal Olefin Polymerization Catalysts

    DOEpatents

    Marks, Tobin J.; Luo, Lubin; Yoon, Sung Cheol

    2004-06-08

    A catalyst system useful to polymerize and co-polymerize polar and non-polar olefin monomers is formed by in situ reduction with a reducing agent of a catalyst precursor comprising {Cp*MRR'.sub.n }.sup.+ {A}.sup.- wherein Cp* is a cyclopentadienyl or substituted cyclopentadienyl moiety; M is an early transition metal; R is a C.sub.1 -C.sub.20 hydrocarbyl; R' are independently selected from hydride, C.sub.1 -C.sub.20 hydrocarbyl, SiR".sub.3, NR".sub.2, OR", SR", GeR".sub.3, SnR".sub.3, and C.dbd.C-containing groups (R"=C.sub.1 -C.sub.10 hydrocarbyl); n is an integer selected to balance the oxidation state of M; and A is a suitable non-coordinating anionic cocatalyst or precursor. This catalyst system may form stereoregular olefin polymers including syndiotactic polymers of styrene and methylmethacrylate and isotactic copolymers of polar and nonpolar olefin monomers such as methylmethacrylate and styrene.

  11. 1-O-vinyl glycosides via Tebbe olefination, their use as chiral auxiliaries and monomers.

    PubMed

    Yuan, Jialong; Lindner, Kristof; Frauenrath, Holger

    2006-07-21

    A series of anomerically pure 1-O-formyl glycosides 1 was prepared and converted into the corresponding 1-O-vinyl glycosides 2 by Tebbe olefination. The unsubstituted vinyl glycosides were obtained as anomerically pure compounds in good yields, and the method of preparation was compatible with the presence of a variety of functional groups. Remarkably, the anomeric formate group was regioselectively converted into the corresponding olefin in the presence of acetate and benzoate protecting groups. With the perspective to use the 1-O-vinyl glycosides as monomers for the preparation of glycosylated poly(vinyl alcohol) derivatives with controlled tacticity, their scope as chiral auxiliaries for a stereodifferentiation in addition reactions to the olefin function was investigated by using the [2+2] cycloaddition to dichloroketene as a model reaction. In particular, vinyl 2,3,4,6-tetra-O-benzoyl-alpha-d-mannopyranoside (2i) exhibited excellent diastereoselectivity. Finally, the 1-O-vinyl glycosides were successfully subjected to radical homopolymerization in bulk or used as electron-rich comonomers in radical copolymerizations with maleic anhydride, yielding alternating, glycosylated poly(vinyl alcohol-alt-maleic anhydride).

  12. Wood-derived olefins by steam cracking of hydrodeoxygenated tall oils.

    PubMed

    Pyl, Steven P; Dijkmans, Thomas; Antonykutty, Jinto M; Reyniers, Marie-Françoise; Harlin, Ali; Van Geem, Kevin M; Marin, Guy B

    2012-12-01

    Tall oil fractions obtained from Norwegian spruce pulping were hydrodeoxygenated (HDO) at pilot scale using a commercial NiMo hydrotreating catalyst. Comprehensive two dimensional gas chromatography (GC×GC) showed that HDO of both tall oil fatty acids (TOFA) and distilled tall oil (DTO) produced highly paraffinic hydrocarbon liquids. The hydrotreated fractions also contained fatty acid methyl esters and norabietane and norabietatriene isomers. Steam cracking of HDO-TOFA in a pilot plant revealed that high light olefin yields can be obtained, with 35.4 wt.% of ethene and 18.2 wt.% of propene at a coil outlet pressure (COP) of 1.7 bara, a dilution of 0.45 kg(steam)/kg(HDO-TOFA) and a coil outlet temperature (COT) of 820 °C. A pilot plant coking experiment indicated that cracking of HDO-TOFA at a COT of 850 °C results in limited fouling in the reactor. Co-cracking of HDO tall oil fractions with a typical fossil-based naphtha showed improved selectivity to desired light olefins, further demonstrating the potential of large scale olefin production from hydrotreated tall oil fractions in conventional crackers.

  13. LDRD final report on new homogeneous catalysts for direct olefin epoxidation (LDRD 52591).

    SciTech Connect

    Goldberg, Karen; Smythe, Nicole A.; Moore, Joshua T.; Stewart, Constantine A.; Kemp, Richard Alan; Miller, James Edward; Kornienko, Alexander (New Mexico Institute of Mining and Technology); Denney, Melanie C. (University of Washington); Cetto, Kara L.

    2006-02-01

    This report summarizes our findings during the study of a novel homogeneous epoxidation catalyst system that uses molecular oxygen as the oxidant, a ''Holy Grail'' in catalysis. While olefins (alkenes) that do not contain allylic hydrogens can be epoxidized directly using heterogeneous catalysts, most olefins cannot, and so a general, atom-efficient route is desired. While most of the work performed on this LDRD has been on pincer complexes of late transition metals, we also scouted out metal/ligand combinations that were significantly different, and unfortunately, less successful. Most of the work reported here deals with phosphorus-ligated Pd hydrides [(PCP)Pd-H]. We have demonstrated that molecular oxygen gas can insert into the Pd-H bond, giving a structurally characterized Pd-OOH species. This species reacts with oxygen acceptors such as olefins to donate an oxygen atom, although in various levels of selectivity, and to generate a [(PCP)Pd-OH] molecule. We discovered that the active [(PCP)Pd-H] active catalyst can be regenerated by addition of either CO or hydrogen. The demonstration of each step of the catalytic cycle is quite significant. Extensions to the pincer-Pd chemistry by attaching a fluorinated tail to the pincer designed to be used in solvents with higher oxygen solubilities are also presented.

  14. Microporous and mesoporous ZSM-5 catalyst for catalytic cracking of C5 raffinate to light olefins.

    PubMed

    Lee, Joongwon; Hong, Ung Gi; Hwang, Sunhwan; Youn, Min Hye; Song, In Kyu

    2014-11-01

    ZSM5 catalysts (PAM(X)-ZSM5) with micropores and mesopores were prepared using polyacrylamide (PAM) as a soft template at different PAM content (X = 0, 0.12, 0.25, 0.53, 0.64, and 0.78 wt%), and they were applied to the production of light olefins (ethylene and propylene) through catalytic cracking of C5 raffinate. The effect of PAM content of PAM(X)-ZSM5 catalysts on the physicochemical properties and catalytic activities was investigated. N2 adsorption-desorption isotherms of PAM(X)-ZSM5 catalysts exhibited a broad hysteresis loop at high relative pressure, indicating the existence of mesopores in the catalysts. It was found that the catalytic performance of PAM(X)-ZSM5 catalysts was closely related to the mesoporosity of the catalysts. Conversion of C5 raffinate and yield for light olefins showed volcano-shaped trends with respect to mesopore/micropore volume ratio of the catalysts. Thus, an optimal PAM content was required to achieve maximum production of light olefins through catalytic cracking of C5 raffinate over microporous and mesoporous PAM(X)-ZSM5 catalysts.

  15. Iron particle size effects for direct production of lower olefins from synthesis gas.

    PubMed

    Torres Galvis, Hirsa M; Bitter, Johannes H; Davidian, Thomas; Ruitenbeek, Matthijs; Dugulan, A Iulian; de Jong, Krijn P

    2012-10-03

    The Fischer-Tropsch synthesis of lower olefins (FTO) is an alternative process for the production of key chemical building blocks from non-petroleum-based sources such as natural gas, coal, or biomass. The influence of the iron carbide particle size of promoted and unpromoted carbon nanofiber supported catalysts on the conversion of synthesis gas has been investigated at 340-350 °C, H(2)/CO = 1, and pressures of 1 and 20 bar. The surface-specific activity (apparent TOF) based on the initial activity of unpromoted catalysts at 1 bar increased 6-8-fold when the average iron carbide size decreased from 7 to 2 nm, while methane and lower olefins selectivity were not affected. The same decrease in particle size for catalysts promoted by Na plus S resulted at 20 bar in a 2-fold increase of the apparent TOF based on initial activity which was mainly caused by a higher yield of methane for the smallest particles. Presumably, methane formation takes place at highly active low coordination sites residing at corners and edges, which are more abundant on small iron carbide particles. Lower olefins are produced at promoted (stepped) terrace sites that are available and active, quite independent of size. These results demonstrate that the iron carbide particle size plays a crucial role in the design of active and selective FTO catalysts.

  16. Low severity coal liquefaction promoted by cyclic olefins. Quarterly report, April--June 1992

    SciTech Connect

    Curtis, C.W.

    1992-07-27

    Low severity coal liquefaction allows for solubilization of coal with reduced gas make. These lower severity conditions may result in some selective bond rupture. Promotion of coal solubilization through hydrogen transfer using highly active and effective hydrogen donors is the objective of this study. The highly effective donors being tested are cyclic olefins. Representative cyclic olefins are isotetralin, which is 1,4,5,8-tetrahydronaphthalene, and 1,4,5,8,9,10-hexahydroanthracene. These compounds are hydroaromatics without aromatic rings and have been shown to be highly effective donors. The objective of the work performed in this study during this quarter was to evaluate reaction parameters for low severity liquefaction reactions using the cyclic olefin, hexahydroanthracene, and the aromatic, anthracene. These model compounds were reacted under a variety of conditions to evaluate their reactivity without coal. The reactions were performed under both thermal and catalytic conditions. Finely divided catalysts from different molybdenum precursors were used to determine their activity in promoting hydrogenation and hydrogen transfer at low severity conditions. The catalysts used were Molyvan L, sulfurized oxymolybdenum dithiocarbamate, molybdenum naphthenate, and Molyvan 822, organo molybdenum dithiocarbamate.

  17. Low severity coal liquefaction promoted by cyclic olefins. Quarterly report, January--March 1995

    SciTech Connect

    Curtis, C.W.

    1995-09-01

    The research performed during the quarter, January to March 1995, focused on two areas. The first area involved completing the writing of a manuscript based on research performed on this project concerning the mild acidic pretreatment of low rank coals and their liquefaction behavior in the presence of hydrogen donors with different reactivities. The manuscript was submitted for review to Energy and Fuels. A second manuscript was begun which discussed the research involving the hydrogen donation at low severity condition by hexahydroanthracene. The catalytic enhancement of hydrogen transfer by cyclic olefins was also examined. The data from this research was reexamined; it was decided that before writing the paper than the data should be reanalyzed. Therefore, this quarter was spent taking the raw data and reanalyzing the data, putting the solvent fractionation data on a solvent-free basis. The recalculated data and the calculational method is given as Part 1 in this report. The second area that was worked on this quarter was the high temperature infrared analysis of cyclic olefins. The work is ongoing and is currently involving a considerable amount of equipment and technique development. Part 2 is the discussion on the high temperature infrared analysis of cyclic olefins.

  18. Development of a General, Sequential, Ring Closing Metathesis/Intramolecular Cross-Coupling Reaction for the Synthesis of Polyunsaturated Macrolactones

    PubMed Central

    Denmark, Scott E.; Muhuhi, Joseck M.

    2010-01-01

    A general strategy for the construction of macrocyclic lactones containing conjugated Z,Z-1,3-diene subunits has been is described. The centerpiece of the strategy is a sequential ring-closing metathesis that forms an unsaturated siloxane ring followed by an intramolecular cross-coupling reaction with a pendant alkenyl iodide. A highly modular assembly of the various precursors allowed the preparation of unsaturated macrolactones containing 11-, 12-, 13- and 14-membered rings. Although the ring closing metathesis process proceeded uneventfully, the intramolecular cross-coupling required extensive optimization of palladium source, solvent, fluoride source and particularly fluoride hydration level. Under the optimal conditions (including syringe pump high dilution), the macrolactones were produced in 53-78% yield as single stereoisomers. A benzo fused 12-membered ring macrolactone containing an E,Z-1,3-diene unit was also prepared by the same general strategy. The E-2-styryl iodide was prepared by a novel Heck reaction of an aryl nonaflate with vinyltrimethylsilane followed by iododesilylation with ICl. PMID:20666473

  19. Multinuclear group 4 catalysis: olefin polymerization pathways modified by strong metal-metal cooperative effects.

    PubMed

    McInnis, Jennifer P; Delferro, Massimiliano; Marks, Tobin J

    2014-08-19

    Polyolefins are produced today catalytically on a vast scale, and the manufactured polymers find use in everything from artificial limbs and food/medical packaging to automotive and electrical components and lubricants. Although polyolefin monomers are typically cheap (e.g., ethylene, propylene, α-olefins), the resulting polymer properties can be dramatically tuned by the particular polymerization catalyst employed, and reflect a rich interplay of macromolecular chemistry, materials science, and physics. For example, linear low-density polyethylene (LLDPE), produced by copolymerization of ethylene with linear α-olefin comonomers such as 1-butene, 1-hexene, or 1-octene, has small but significant levels of short alkyl branches (C2, C4, C6) along the polyethylene backbone, and is an important technology material due to outstanding rheological and mechanical properties. In 2013, the total world polyolefin production was approximately 211 million metric tons, of which about 11% was LLDPE. Historically, polyolefins were produced using ill-defined but highly active heterogeneous catalysts composed of supported groups 4 or 6 species (usually halides) activated by aluminum alkyls. In 1963, Karl Ziegler and Giulio Natta received the Nobel Prize for these discoveries. Beginning in the late 1980s, a new generation of group 4 molecule-based homogeneous olefin polymerization catalysts emerged from discoveries by Walter Kaminsky, a team led by James Stevens at The Dow Chemical Company, this Laboratory at Northwestern University, and a host of talented groups in Germany, Italy, Japan, the United Kingdom, and the United States. These new "single-site" catalysts and their activating cocatalysts were far better defined and more rationally tunable in terms of structure, mechanism, thermodynamics, and catalyst activity and selectivity than ever before possible. An explosion of research advances led to new catalysts, cocatalysts, deeper mechanistic understanding of both the

  20. Emissions and ambient air monitoring trends of lower olefins across Texas from 2002 to 2012.

    PubMed

    Myers, Jessica L; Phillips, Tracie; Grant, Roberta L

    2015-11-05

    Texas has the largest ambient air monitoring network in the country with approximately 83 monitoring sites that measure ambient air concentrations of volatile organic compounds (VOCs). The lower olefins, including 1,3-butadiene, ethylene, isoprene, and propylene, are a group of VOCs that can be measured in both 24h/every sixth-day canister samples and continuous 1-h Automated Gas Chromatography (AutoGC) samples. Based on 2012 Toxics Release Inventory data, the total reported industrial air emissions in Texas for these olefins, as compared to total national reported air emissions, were 79% for 1,3-butadiene, 62% for ethylene, 76% for isoprene, and 54% for propylene, illustrating that Texas industries are some of the major emitters for these olefins. The purpose of this study was to look at the patterns of annual average air monitoring data from 2002 to 2012 using Texas Commission on Environmental Quality (TCEQ) data for these four lower olefins. It should be emphasized that monitors may not be located close to or downwind of the highest emitters of these lower olefins. In addition, air monitors only provide a snapshot in time of air concentrations for their respective locations, and may not be able to discriminate emissions between specific sources. In 2012, the highest annual average air concentration for 1,3-butadiene was 1.28 ppb by volume (ppbv), which was measured at the Port Neches monitoring site in Region 10-Beaumont. For ethylene, the highest 2012 annual average air concentration was 5.77 ppbv, which was measured at the Dona Park monitoring site in TCEQ Region 14-Corpus Christi. Although reported industrial emissions of isoprene are predominantly from the Houston and Beaumont regions, trees are natural emitters of isoprene, and the highest ambient air concentrations tend to be from regions with large areas of coniferous and hardwood forests. This was observed with TCEQ Region 5-Tyler, which had the two highest isoprene annual average air concentrations for

  1. Catalytic pyrolysis of model compounds and waste cooking oil for production of light olefins over La/ZSM-5 catalysts

    NASA Astrophysics Data System (ADS)

    Li, F. W.; Ding, S. L.; Li, L.; Gao, C.; Zhong, Z.; Wang, S. X.; Li, Z. X.

    2016-08-01

    Waste cooking oil (WCO) and its model compounds (oleic acid and methyl laurate) are catalytically pyrolyzed in a fixed-bed reactor over La modified ZSM-5 catalysts (La/ZSM-5) aiming for production of C2-C4 light olefins. The LaO content in catalysts was set at 0, 2, 6, 10 and 14 wt%. The gas and liquid products are analyzed. The La/ZSM-5 catalyst with 6% LaO showed higher selectivity to light olefins when WCO and methyl laurate were pyrolyzed, and olefin content was 26% for WCO and 21% for methyl laurate. The catalyst with 10% LaO showed high selectivity to light olefins (28.5%) when oleic acid was pyrolyzed. The liquid products from WCO and model compounds mainly contain esters and aromatic hydrocarbons. More esters were observed in liquid products from methyl laurate and WCO pyrolysis, indicating that it is more difficult to pyrolyze esters and WCO than oleic acid. The coked catalysts were analyzed by temperature-programmed oxidation. The result shows that graphite is the main component of coke. The conversion of WCO to light olefins potentially provides an alternative and sustainable route for production of the key petrochemicals.

  2. Alkane production by the marine cyanobacterium Synechococcus sp. NKBG15041c possessing the α-olefin biosynthesis pathway.

    PubMed

    Yoshino, Tomoko; Liang, Yue; Arai, Daichi; Maeda, Yoshiaki; Honda, Toru; Muto, Masaki; Kakunaka, Natsumi; Tanaka, Tsuyoshi

    2015-02-01

    The production of alkanes in a marine cyanobacterium possessing the α-olefin biosynthesis pathway was achieved by introducing an exogenous alkane biosynthesis pathway. Cyanobacterial hydrocarbons are synthesized via two separate pathways: the acyl-acyl carrier protein (ACP) reductase/aldehyde-deformylating oxygenase (AAR/ADO) pathway for the alkane biosynthesis and the α-olefin synthase (OLS) pathway for the α-olefin biosynthesis. Coexistence of these pathways has not yet been reported. In this study, the marine cyanobacterium Synechococcus sp. NKBG15041c was shown to produce α-olefins similar to those of Synechococcus sp. PCC7002 via the α-olefin biosynthesis pathway. The production of heptadecane in Synechococcus sp. NKBG15041c was achieved by expressing the AAR/ADO pathway genes from Synechococcus elongatus PCC 7942. The production yields of heptadecane in Synechococcus sp. NKBG15041c varied with the expression level of the aar and ado genes. The maximal yield of heptadecane was 4.2 ± 1.2 μg/g of dried cell weight in the transformant carrying a homologous promoter. Our results also suggested that the effective activation of ADO may be more important for the enhancement of alkane production by cyanobacteria.

  3. Metal-free oxidative olefination of primary amines with benzylic C-H bonds through direct deamination and C-H bond activation.

    PubMed

    Gong, Liang; Xing, Li-Juan; Xu, Tong; Zhu, Xue-Ping; Zhou, Wen; Kang, Ning; Wang, Bin

    2014-09-14

    An oxidative olefination reaction between aliphatic primary amines and benzylic sp(3) C-H bonds has been achieved using N-bromosuccinimide as catalyst and tert-butyl hydroperoxide as oxidant. The olefination proceeds under mild metal-free conditions through direct deamination and benzylic C-H bond activation, and provides easy access to biologically active 2-styrylquinolines with (E)-configuration.

  4. A novel efficient method for the synthesis of substituted olefins; cross coupling of two different alcohols using NaHSO4/SiO2.

    PubMed

    Aoyama, Tadashi; Koda, Shuichi; Takeyoshi, Yuka; Ito, Tetsuhiro; Takido, Toshio; Kodomari, Mitsuo

    2013-07-28

    Simple and efficient cross coupling of alcohols was developed in the presence of NaHSO4/SiO2 to give the corresponding substituted olefins. Direct coupling of alcohols and alkenes was also achieved to give substituted olefins. NaHSO4/SiO2 could be recycled 7 times without loss of catalytic activity.

  5. Does crystal or gel matter to stereochemistry of a reaction? Silver complexation-promoted solid-state [2+2] reaction of an unsymmetrical olefin.

    PubMed

    Samai, Suman; Ghosh, Prabir; Biradha, Kumar

    2013-05-14

    Head-to-tail and head-to-head [2+2] photodimerization of an unsymmetrical olefin containing benzimidazole and pyridyl groups was achieved by irradiating Ag(I) complexed olefin in crystalline state and gel state, respectively, in stereoselective manner. The [2+2] reaction indicates that the molecular arrangement in a gel is different from that of a xerogel.

  6. Exposing the hidden complexity of stoichiometric and catalytic metathesis reactions by elucidation of Mg-Zn hybrids

    PubMed Central

    Hevia, Eva; Chua, Jonathan Z.; García-Álvarez, Pablo; Kennedy, Alan R.; McCall, Matthew D.

    2010-01-01

    Studying seemingly simple metathesis reactions between ZnCl2 and tBuMgCl has, surprisingly, revealed a much more complex chemistry involving mixed magnesium-zinc compounds that could be regarded as Mg-Zn hybrids. Thus, the reaction of equimolar amounts of ZnCl2 and tBuMgCl reveals the formation of the unprecedented mixed Mg-Zn complex [(THF)4Mg(μ-Cl)2Zn(tBu)(Cl)] (1), as a result of the co-complexation of the two anticipated exchange products of the metathesis. This magnesium zincate adopts a contacted ion-pair structure, closely related to Knochel’s pioneering “Turbo” Grignard reagents. Furthermore, a second coproduct identified in this reaction is the solvent-separated mixed magnesium-zinc chloride complex [{Mg(THF)6}2+{Zn2Cl6}2-] (3) that critically diminishes the amount of ZnCl2 available for the intended metathesis reaction to take place. In another surprising result, when the reaction is carried out by using an excess of 3 M equivalents of the Grignard reagent (closer to the catalytic conditions employed by synthetic chemists), solvent-separated magnesium trialkyl zincate [{Mg2Cl3(THF)6}+{Zn(tBu)3}-] (4) is obtained that can be viewed as a model for the active species involved in the increasingly important organic transformations of Grignard reagents catalysed by ZnCl2. Furthermore, preliminary reactivity studies reveal that complex 4 can be used as an effective new reagent for direct Zn-I exchange reactions that allow the preparation and structural identification of the magnesium tris(aryl) zincate [{Mg2Cl3(THF)6}+{Zn(p-Tol)3}-] (5) that represents the first example of complete 3-fold activation of a zincate in a Zn-I exchange reaction which, in turn, can efficiently be used as a precursor for Negishi cross-coupling reactions. PMID:20212145

  7. Kinetic resolution of racemic α-olefins with ansa-zirconocene polymerization catalysts: Enantiomorphic site vs. chain end control

    PubMed Central

    Byers, Jeffery A.; Bercaw, John E.

    2006-01-01

    Copolymerization of racemic α-olefins with ethylene and propylene was carried out in the presence of enantiopure C1-symmetric ansa metallocene, {1,2-(SiMe2)2(η5-C5H-3,5-(CHMe2)2)(η5-C5H3)}ZrCl2 to probe the effect of the polymer chain end on enantioselection for the R- or S-α-olefin during the kinetic resolution by polymerization catalysis. Copolymerizations with ethylene revealed that the polymer chain end is an important factor in the enantioselection of the reaction and that for homopolymerization, chain end control generally works cooperatively with enantiomorphic site control. Results from propylene copolymerizations suggested that chain end control arising from a methyl group at the β carbon along the main chain can drastically affect selectivity, but its importance as a stereo-directing element depends on the identity of the olefin. PMID:17032768

  8. Synthesis gas and olefins from the catalytic autothermal reforming of volatile and non-volatile liquids

    NASA Astrophysics Data System (ADS)

    Dreyer, Bradon Justin

    2007-12-01

    The research presented in this thesis develops an understanding of a clean energy process technology, catalytic partial oxidation (CPO). CPO is a process in which a carbon containing fuel, such as a hydrocarbon, is passed over a noble metal catalyst (e.g. rhodium and platinum) to efficiently generate synthesis gas (H2 and CO) and olefins (e.g. ethylene and propylene) in millisecond contact times. Chapter 1 introduces CPO and compares this technology with conventional methods for synthesis gas and olefin production. CPO has several advantages over the traditional synthesis gas and olefin production methods. One advantage includes autothermal operation, requiring no external heat input from furnaces or heat exchangers. Autothermal operation allows these reactors to be built compactly. The short contact-times associated with CPO further enable for high throughput in relatively small reactor systems, and more compact reactors typically translate to faster response times if transient operation is required. Nobel metal based CPO catalysts are also resistant to deactivation, resulting in less catalyst replacement, regeneration, and maintenance, and an increase in operating efficiency. An overview of the many applications of the chemicals produced from CPO is also presented in Chapter 1. The chemicals produced are crucial in generating valuable chemical intermediates that are eventually incorporated in consumer products, medical devices, building structures, and fertilizers. Additionally, H2 can be used as a source of energy in mobile fuel applications. Fuel cells convert H2 and O2 into electricity and water at higher efficiencies than thermal engine generators. Due to the difficulties in H2 storage, these more efficient energy generators are dependent on hydrogen obtained from synthesis gas production in compact, portable fuel reformers, such as CPO reactors. Furthermore, H2 and CO can be used in reducing environmentally harmful emissions. Particularly, the implementation

  9. Glycosyl-Templated Chiral Helix Stapling of Ethynylpyridine Oligomers by Alkene Metathesis between Inter-Pitch Side Chains.

    PubMed

    Abe, Hajime; Kayamori, Fumihiro; Inouye, Masahiko

    2015-06-22

    Ethynylpyridine polymers and oligomers consisting of 4-substituted pyridine rings linked by acetylene bonds at the 2- and 6-positions have been investigated. Ethynylpyridine oligomers covalently linked with a glycosyl chiral template form chiral helical complexes by intramolecular hydrogen bonding, in which the chirality of the template is translated to the helix. With a view to fixation of the chiral architecture, D/L-galactosyl- and D/L-mannosyl-linked ethynylpyridine oligomers have been developed with 4-(3-butenyloxy)pyridine units having alkene side chains. The helical structures are successfully stapled by alkene metathesis of the side chains. Subsequent removal of the chiral templates by acidolysis produces template-free stapled oligomers. The chiral, template-free, stapled oligomers show chiral helicity, which is resistant to polar solvents and heating.

  10. Cyclic olefin homopolymer-based microfluidics for protein crystallization and in situ X-ray diffraction

    SciTech Connect

    Emamzadah, Soheila; Petty, Tom J.; De Almeida, Victor; Nishimura, Taisuke; Joly, Jacques; Ferrer, Jean-Luc; Halazonetis, Thanos D.

    2009-09-01

    A cyclic olefin homopolymer-based microfluidics system has been established for protein crystallization and in situ X-ray diffraction. Microfluidics is a promising technology for the rapid identification of protein crystallization conditions. However, most of the existing systems utilize silicone elastomers as the chip material which, despite its many benefits, is highly permeable to water vapour. This limits the time available for protein crystallization to less than a week. Here, the use of a cyclic olefin homopolymer-based microfluidics system for protein crystallization and in situ X-ray diffraction is described. Liquid handling in this system is performed in 2 mm thin transparent cards which contain 500 chambers, each with a volume of 320 nl. Microbatch, vapour-diffusion and free-interface diffusion protocols for protein crystallization were implemented and crystals were obtained of a number of proteins, including chicken lysozyme, bovine trypsin, a human p53 protein containing both the DNA-binding and oligomerization domains bound to DNA and a functionally important domain of Arabidopsis Morpheus’ molecule 1 (MOM1). The latter two polypeptides have not been crystallized previously. For X-ray diffraction analysis, either the cards were opened to allow mounting of the crystals on loops or the crystals were exposed to X-rays in situ. For lysozyme, an entire X-ray diffraction data set at 1.5 Å resolution was collected without removing the crystal from the card. Thus, cyclic olefin homopolymer-based microfluidics systems have the potential to further automate protein crystallization and structural genomics efforts.

  11. Dinickel Bisphenoxyiminato Complexes for the Polymerization of Ethylene and α-Olefins

    PubMed Central

    Radlauer, Madalyn; Day, Michael W.; Agapie, Theodor

    2012-01-01

    Dinuclear nickelphenoxyiminato olefin polymerization catalysts based on rigid p-terphenyl frameworks are reported. Permethylation of the central arene of the terphenyl unit and oxygen substitution of the peripheral rings ortho to the aryl-aryl linkages blocks rotation around these linkages allowing atropisomers of the ligand to be isolated. The corresponding syn and anti dinickel complexes (25-s and 25-a) were synthesized and characterized by single crystal X-ray diffraction. These frameworks limit the relative movement of the metal centers restricting the metal-metal distance. Kinetics studies of isomerization of a ligand precursor (7-a) allowed the calculation of the activation parameters for the isomerization process (ΔH‡ = 28.0 ± 0.4 kcal×mol−1 and ΔS‡ = −12.3 ± 0.4 cal×mol−1×K−1). The reported nickel complexes are active for ethylene polymerization [TOF up to 3700 (mol C2H4)×(mol Ni)−1×h−1] and ethylene/α-olefin copolymerization. Only methyl branches are observed in the polymerization of ethylene, while α-olefins are incorporated without apparent chain walking. These catalysts are active in the presence of polar additives and in neat tetrahydrofuran. The syn and anti isomers differ in polymerization activity and polymer degree of branching and molecular weight. For comparison, a series of mononuclear nickel complexes (26, 27-s, 27-a, 28, 30) was prepared and studied. The effects of structure and catalyst nuclearity on reactivity are discussed. PMID:22711966

  12. Low severity coal liquefaction promoted by cyclic olefins. Quarterly report, January--March 1993

    SciTech Connect

    Curtis, C.W.

    1993-07-01

    The combination of some of these methods could further improve low severity conversion. It seems logical that a combination of a proven pretreatment technique with a good dissolution catalyst or a good hydrogen donor would increase reactivity. The importance of surface chemistry with yield and nature of reactions shown in early research indicates the physical importance of pretreatment. Swelling of the coal with an organic solvent improves the contact. This good contact is also important to slowing retrogressive reactions. The best conversions come when the initial products of liquefaction are preserved. In addition to the physical importance of pretreatment, there is a chemical advantage. Shams saw not only the effect of minimization of organic oxygen coupling reactions, but with his process there also seemed to be a demineralization. The minerals removed the catalysts for retrogressive reactions. The chemistry of liquefaction is still not well understood. Stansberry`s attempt to determine whether catalysts liberate species or just further decomposition was largely inconclusive. There was improvement in conversion so the catalysts seemingly assisted in bond breakage. These good catalytic effects were also seen in the work involving coprocessing. The most compelling factor in each of these procedures, is the ability of the coal to receive the hydrogen that it needs to be liquefied. Bedell and Curtis (1991) found that cyclic olefins gave their hydrogen up much more readily than did hydroaromatics. The coal conversion was a significantly improved. The combination of retrogressive reaction suppression and good hydrogen donability should provide for good coal conversion. It was this reasoning that influenced the decision to investigate a combination of the HCl/methanol pretreatment and the usage of cyclic olefins as hydrogen donors. The increased reactivity of the pretreated coal should enhance the effect of the hydrogen donability of the cyclic olefins.

  13. Low severity coal liquefaction promoted by cyclic olefins. Quarterly report, October 1995--December 1995

    SciTech Connect

    Curtis, C.W.

    1995-12-31

    The goal of this research is to develop a methodology for analyzing the reactivity of cyclic olefins in situ in a high temperature and high pressure infrared cell. Cyclic olefins, such as 1,4,5,8-tetrahydronaphthalene (isotetralin) and 1,4,5,8,9,10-hexahydroanthracene (HHA), are highly reactive donor compounds that readily donate their hydrogen to coal and model acceptors when heated to temperatures of 200{degrees}C and above. These donors are active donors in the low severity liquefaction of coal at 350{degrees}C as shown in the research performed in this project. The infrared studies are being performed in a high temperature infrared cell that was obtained from AABSPEC. Modifications to that cell have been made and have been reported in previous progress reports. During this last quarter the useful temperature range of the high temperature infrared cell was extended to 230{degrees}C through the use of a high-boiling perfluorocarbon solvent. The solvent used was an Air Products and Chemicals Company proprietary product trade named Multifluor APF-240. Solubilities of aromatics and cyclic olefins were quite low in APF-240, usually less than 0.1 wt% at room temperature, but were found to be a strong function of temperature, increasing markedly when the mixtures were heated to 65{degrees}C. Spectra have been obtained of n-hexadecane and naphthalene at temperatures of 65, 100, 125, 150, 175, 200 and 230{degrees}C. This demonstration of the safe operation of the high temperature IR cell and the acquisition of spectra at elevated temperatures paves the way for kinetic studies of the hydrogen donor capability of isotetralin. A perfluoroether has been obtained from Dupont which should extend the useful temperature range of the high temperature IR cell to 350{degrees}C.

  14. Enantioselective Hydroaminomethylation of Olefins Enabled by Rh/Brønsted Acid Relay Catalysis.

    PubMed

    Meng, Jing; Li, Xing-Han; Han, Zhi-Yong

    2017-03-03

    Herein, by employing a rhodium catalyst with a commercial ligand and a phosphoric acid catalyst, highly chemo-, regio-, and enantioselective hydroaminomethylation of olefins is realized through a relay catalytic hydroformylation/dynamic kinetic reductive amination process. The method features mild conditions (1 bar of syngas, room temperature in most cases), high yields (up to 99%), and high enantioselectivities (up to >99.5:0.5 er). Besides styrenes, acrylamides also provided the products with high yields and enantioselectivities. Aliphatic alkenes and vinyl esters are also applicable for the current method, albeit lower yields and enantioselectivities were obtained.

  15. A Serine-Substituted P450 Catalyzes Highly Efficient Carbene Transfer to Olefins In Vivo

    PubMed Central

    Coelho, Pedro S.; Wang, Z. Jane; Ener, Maraia E.; Baril, Stefanie A.; Kannan, Arvind A.; Arnold, Frances H.; Brustad, Eric M.

    2013-01-01

    Genetically encoded catalysts for non-natural chemical reactions will open new routes to sustainable production of chemicals. We designed a unique serine-heme ligated cytochrome “P411” that catalyzes efficient and selective carbene transfers from diazoesters to olefins in intact Escherichia coli cells. The mutation C400S in cytochrome P450BM3 gives a signature ferrous-CO Soret peak at 411 nm, abolishes monooxygenation activity, raises the resting state FeIII/II reduction potential, and significantly improves NAD(P)H-driven cyclopropanation activity. PMID:23792734

  16. Pd(II)-catalyzed ortho- or meta-C-H olefination of phenol derivatives.

    PubMed

    Dai, Hui-Xiong; Li, Gang; Zhang, Xing-Guo; Stepan, Antonia F; Yu, Jin-Quan

    2013-05-22

    A combination of weakly coordinating auxiliaries and ligand acceleration allows for the development of both ortho- and meta-selective C-H olefination of phenol derivatives. These reactions demonstrate the feasibility of directing C-H functionalizations when functional groups are distal to target C-H bonds. The meta-C-H functionalization of electron-rich phenol derivatives is unprecedented and orthogonal to previous electrophilic substitution of phenols in terms of regioselectivity. These methods are also applied to functionalize α-phenoxyacetic acids, a fibrate class of drug scaffolds.

  17. Wittig Reaction: Domino Olefination and Stereoselectivity DFT Study. Synthesis of the Miharamycins' Bicyclic Sugar Moiety.

    PubMed

    Cachatra, Vasco; Almeida, Andreia; Sardinha, João; Lucas, Susana D; Gomes, Ana; Vaz, Pedro D; Florêncio, M Helena; Nunes, Rafael; Vila-Viçosa, Diogo; Calhorda, Maria José; Rauter, Amélia P

    2015-11-20

    2-O-Acyl protected-d-ribo-3-uloses reacted with [(ethoxycarbonyl)methylene]triphenylphosphorane in acetonitrile to afford regio- and stereoselectively 2-(Z)-alkenes in 10-60 min under microwave irradiation. This domino reaction is proposed to proceed via tautomerization of 3-ulose to enol, acyl migration, tautomerization to the 3-O-acyl-2-ulose, and Wittig reaction. Alternatively, in chloroform, regioselective 3-olefination of 2-O-pivaloyl-3-uloses gave (E)-alkenes, key precursors for the miharamycins' bicyclic sugar moiety.

  18. Synthesis and characterization of new magnetically recoverable molybdenum nanocatalyst for epoxidation of olefins

    NASA Astrophysics Data System (ADS)

    Masteri-Farahani, M.; Kashef, Z.

    2012-04-01

    New heterogeneous molybdenum catalyst was prepared through covalent attachment of a Schiff base ligand on the surface of silica coated magnetite nanoparticles via aminopropyl spacer and subsequent complexation with MoO2(acac)2. The prepared nanocatalyst was characterized with Fourier transform infrared spectroscopy, X-ray diffraction, scanning and transmission electron microscopies and vibrating sample magnetometry. Catalytic epoxidation of some olefins and allylic alcohols by prepared nanocatalyst using tert-butyl hydroperoxide and cumene hydroperoxide as oxidants was achieved with good activities and selectivities.

  19. Catalytical Photocyclization of Arylamines with a-Olefins in the Synthesis of 2-Alkylquinoline

    ERIC Educational Resources Information Center

    Makhmutov, Aynur; Usmanov, Salavat; Mustafin, Ahat

    2016-01-01

    The article deals with the results of investigation of the process of catalytical photocyclization of aniline and aniline hydrochloride with a-olefins (hexene-1, heptene-1 and octene-1). The following compounds of d- and f-metals are tested as probable catalysts: CuSO4•5H2O, EuCl3•6H2O, PrCl3•6H2O, TbCl3•6H2O, La2O3, MnO2, NiSO4•6H2O, NiCl2•6H2O,…

  20. How the Proximal Pocket May Influence the Enantiospecificities of Chloroperoxidase-Catalyzed Epoxidations of Olefins

    PubMed Central

    Morozov, Alexander N.; Chatfield, David C.

    2016-01-01

    Chloroperoxidase-catalyzed enantiospecific epoxidations of olefins are of significant biotechnological interest. Typical enantiomeric excesses are in the range of 66%–97% and translate into free energy differences on the order of 1 kcal/mol. These differences are generally attributed to the effect of the distal pocket. In this paper, we show that the influence of the proximal pocket on the electron transfer mechanism in the rate-limiting event may be just as significant for a quantitatively accurate account of the experimentally-measured enantiospecificities. PMID:27517911

  1. Coal-water slurry viscosity reduction using olefin/maleic acid salt copolymers

    SciTech Connect

    Matt, J.; Ferrara, J.M.

    1984-04-10

    An improved coal-water slurry of the type comprising at least 45% by weight of finely divided coal particles and a dispersing agent, said slurry being characterized as having a Brookfield viscosity at 60 rpm of less than 4,000 centipoise, the improvement which comprises adjusting the pH of said slurry to at least 6 and using as the dispersing agent, a water-soluble salt of an olefin/maleic acid copolymer having a molecular weight within the range of about between 3,000-50,000.

  2. A serine-substituted P450 catalyzes highly efficient carbene transfer to olefins in vivo.

    PubMed

    Coelho, Pedro S; Wang, Z Jane; Ener, Maraia E; Baril, Stefanie A; Kannan, Arvind; Arnold, Frances H; Brustad, Eric M

    2013-08-01

    Whole-cell catalysts for non-natural chemical reactions will open new routes to sustainable production of chemicals. We designed a cytochrome 'P411' with unique serine-heme ligation that catalyzes efficient and selective olefin cyclopropanation in intact Escherichia coli cells. The mutation C400S in cytochrome P450(BM3) gives a signature ferrous CO Soret peak at 411 nm, abolishes monooxygenation activity, raises the resting-state Fe(III)-to-Fe(II) reduction potential and substantially improves NAD(P)H-driven activity.

  3. Biological Evaluation of Ferrocenyl Olefins: Cancer Cell Growth Inhibition, ROS Production, and Apoptosis Activity.

    PubMed

    Sun, Aijing; Lin, Junsheng; Pi, Chao; Xu, Ruian; Cui, Xiuling

    2016-03-01

    The antiproliferative effects of various ferrocenyl olefins were evaluated against the cell lines MCF-7 (human breast cancer cells), DLD-1 (human colon adenocarcinoma cells), HUVEC (human umbilical vein endothelial cells), and A549 (human lung carcinoma cells), using the MTT test. IC50 values were determined. Compounds 8, 9, 11, and 12 with high antiproliferative activity were tested for their reactive oxygen species (ROS) production, and cell cycle analysis was performed on A549 cells. The results show that these compounds might perform their antiproliferative activity through inducing ROS generation, apoptosis induction, and cell cycle arrest.

  4. Synthesis of Chiral, Enantiopure Allylic Amines by the Julia Olefination of α-Amino Esters.

    PubMed

    Benedetti, Fabio; Berti, Federico; Fanfoni, Lidia; Garbo, Michele; Regini, Giorgia; Felluga, Fulvia

    2016-06-21

    The four-step conversion of a series of N-Boc-protected l-amino acid methyl esters into enantiopure N-Boc allylamines by a modified Julia olefination is described. Key steps include the reaction of a lithiated phenylalkylsulfone with amino esters, giving chiral β-ketosulfones, and the reductive elimination of related α-acetoxysulfones. The overall transformation takes place under mild conditions, with good yields, and without loss of stereochemical integrity, being in this respect superior to the conventional Julia reaction of α-amino aldehydes.

  5. A new approach to ferrocene derived alkenes via copper-catalyzed olefination

    PubMed Central

    Muzalevskiy, Vasily M; Shastin, Aleksei V; Demidovich, Alexandra D; Shikhaliev, Namiq G; Magerramov, Abel M; Khrustalev, Victor N; Rakhimov, Rustem D; Vatsadze, Sergey Z

    2015-01-01

    Summary A new approach to ferrocenyl haloalkenes and bis-alkenes was elaborated. The key procedure involves copper catalyzed olefination of N-unsubstituted hydrazones, obtained from ferrocene-containing carbonyl compounds and hydrazine, with polyhaloalkanes. The procedure is simple, cheap and could be applied for the utilization of environmentally harmful polyhalocarbons. The cyclic voltammetry study of the representative examples of the synthesized ferrocenyl alkenes shows the strong dependence of the cathodic behavior on the amount of vinyl groups: while for the monoalkene containing molecules no reduction is seen, the divinyl products are reduced in several steps. PMID:26664627

  6. Transition-metal-catalyzed carbonylation reactions of olefins and alkynes: a personal account.

    PubMed

    Wu, Xiao-Feng; Fang, Xianjie; Wu, Lipeng; Jackstell, Ralf; Neumann, Helfried; Beller, Matthias

    2014-04-15

    Carbon monoxide was discovered and identified in the 18th century. Since the first applications in industry 80 years ago, academic and industrial laboratories have broadly explored CO's use in chemical reactions. Today organic chemists routinely employ CO in organic chemistry to synthesize all kinds of carbonyl compounds. Despite all these achievements and a century of carbonylation catalysis, many important research questions and challenges remain. Notably, apart from academic developments, industry applies carbonylation reactions with CO on bulk scale. In fact, today the largest applications of homogeneous catalysis (regarding scale) are carbonylation reactions, especially hydroformylations. In addition, the vast majority of acetic acid is produced via carbonylation of methanol (Monsanto or Cativa process). The carbonylation of olefins/alkynes with nucleophiles, such as alcohols and amines, represent another important type of such reactions. In this Account, we discuss our work on various carbonylations of unsaturated compounds and related reactions. Rhodium-catalyzed isomerization and hydroformylation reactions of internal olefins provide straightforward access to higher value aldehydes. Catalytic hydroaminomethylations offer an ideal way to synthesize substituted amines and even heterocycles directly. More recently, our group has also developed so-called alternative metal catalysts based on iridium, ruthenium, and iron. What about the future of carbonylation reactions? CO is already one of the most versatile C1 building blocks for organic synthesis and is widely used in industry. However, because of CO's high toxicity and gaseous nature, organic chemists are often reluctant to apply carbonylations more frequently. In addition, new regulations have recently made the transportation of carbon monoxide more difficult. Hence, researchers will need to develop and more frequently use practical and benign CO-generating reagents. Apart from formates, alcohols, and metal

  7. A highly effective cobalt catalyst for olefin aziridination with azides: hydrogen bonding guided catalyst design.

    PubMed

    Ruppel, Joshua V; Jones, Jess E; Huff, Chelsea A; Kamble, Rajesh M; Chen, Ying; Zhang, X Peter

    2008-05-15

    [Co(P1)], which was designed on the basis of potential hydrogen-bonding interactions in the metal-nitrene intermediate, is a highly active aziridination catalyst with azides. [Co(P1)] can effectively aziridinate various aromatic olefins with arylsulfonyl azides under mild conditions, forming sulfonylated aziridines in excellent yields. The Co-based system enjoys several attributes associated with the relatively low cost of cobalt and the wide accessibility of arylsulfonyl azides. Furthermore, it generates stable dinitrogen as the only byproduct.

  8. Comparison of Topas cyclic olefin copolymers to BK7 glass in night vision goggle objectives

    NASA Astrophysics Data System (ADS)

    Stevens, James S.

    2004-09-01

    The objective of this study was to determine the suitability of Topas cyclic olefin copolymers (COC) as an optical plastic for use in military-grade night vision goggle (NVG) lens objectives. Test objective lenses that could include either a Topas COC window element or BK7 glass window element were manufactured. The test objectives were evaluated for low light resolution, MTF, off-axis veiling glare, and on-axis stray light. Additionally, the spectral transmittance of the individual windows elements was measured. This paper compares the evaluation results of test objectives containing Topas COC with test objectives containing BK7 glass.

  9. Desulfurization of coal. Final report. [Flotation followed by olefin and vinyl monomer treatment

    SciTech Connect

    Dichter, M.; Sanduja, M.

    1980-10-01

    Ohio coal, like many other types of coal, has a high sulfur as well as ash content. We at PRCA, through a series of steps involving the treatment of coal with an olefin-catalyst and/or catalyzed oxidizing system, have established the following: (1) Crushing and pulverizing of coal to a size of 150 to 200 mesh is an important factor in the process of desulfurization, as this allows improvement of the efficiency of flotation and chemical desulfurization. (2) Flotation results in a significant reduction of sulfur and ash content of the coal and reduces the amount of water absorbed on the pulverized coal when petroleum fractions are introduced into the flotation process. Coal containing 4.3% and 2.7% sulfur have been desulfurized to 2.8% to 3.0% and 1.5% to 1.9%, respectively. The ash content has been reduced after flotation from 10.7% to 6.5% of the Pittsburgh No. 8 coal and from 16.5% to 10.5% of a coal provided by Consolidation Coal Co. (3) Chemical treatment with olefins and monomers allows complete removal of the rest of the pyritic sulfur and part of the organic sulfur. The higher molecular weight olefins give better results and an introduction of some maleic anhydride monomer helps to get a higher reduction of the sulfur in the coal. The presence of an alkaline medium (NaOH or Na/sub 2/CO/sub 3/) enhances the sulfur removal efficiency. (4) Elevated temperatures and pressures allows reduction of the time of reaction to obtain lower sulfur content coal. However, the pressure in the range of 100 to 200 psi allows achievement of an optimum desulfurization of treated coal. Even 25 to 30 psi has shown satisfactory results in the same time. (5) The results of desulfurization by a monomer (olefin) treatment are given. Further work on the desulfurization of the Ohio coals is recommended in a small scale pilot plant on a continuous basis. This pilot plant will represent an approximation of a real plant which will allow the necessary insight needed for scale up.

  10. Effects of Process Parameters on Replication Accuracy of Microinjection Molded Cyclic Olefins Copolymers Parts

    NASA Astrophysics Data System (ADS)

    Lin, Hsuan-Liang; Chen, Chun-Sheng; Lee, Ruey-Tsung; Chen, Shia-Chung; Chien, Rean-Der; Jeng, Ming-Chang; Hwang, Jiun-Ren

    2013-04-01

    In this study, the effects of various processing parameters of microinjection molding on the replication accuracy of the micro featured fluidic platform used for DNA/RNA tests are investigated. LIGA-like processes were utilized to prepare a silicon-based SU-8 photoresist, followed by electroforming to make a Ni-Co-based stamp. A cyclic olefin copolymer (COC) was used as the injection molding material. The molding parameters associated with the replication accuracy of micro channel parts were investigated. It was found that for microinjection molded devices, the replication accuracies of the imprint width and depth increase with increasing of mold temperature, melt temperature, injection velocity, and packing pressure.

  11. Nickel-Catalyzed Insertion of Alkynes and Electron-Deficient Olefins into Unactivated sp(3) C-H Bonds.

    PubMed

    Maity, Soham; Agasti, Soumitra; Earsad, Arif Mahammad; Hazra, Avijit; Maiti, Debabrata

    2015-08-03

    Insertion of unsaturated systems such as alkynes and olefins into unactivated sp(3) C-H bonds remains an unexplored problem. We herein address this issue by successfully incorporating a wide variety of functionalized alkynes and electron-deficient olefins into the unactivated sp(3) C-H bond of pivalic acid derivatives with excellent syn- and linear- selectivity. A strongly chelating 8-aminoquinoline directing group proved beneficial for these insertion reactions, while an air-stable and inexpensive Ni(II) salt has been employed as the active catalyst.

  12. Rhodium fluorapatite catalyst for the synthesis of trisubstituted olefins via cross coupling of Baylis-Hillman adducts and arylboronic acids.

    PubMed

    Kantam, M Lakshmi; Kumar, K B Shiva; Sreedhar, B

    2008-01-04

    Treatment of fluorapatite (prepared by incorporating basic species F(-) in apatite in situ by coprecipitation) with an aqueous solution of RhCl(3) resulted in rhodium-exchanged fluorapatite catalyst (RhFAP), which successfully promoted cross coupling of Baylis-Hillman adducts with arylboronic acids to yield trisubstituted olefins. A variety of arylboronic acids and Baylis-Hillman adducts were converted to the corresponding trisubstituted olefins, demonstrating the versatility of the reaction. The reaction is highly stereoselective. RhFAP was recovered quantitatively by simple filtration and reused with almost consistent activity.

  13. Isolation of Pure Disubstituted E Olefins through Mo-Catalyzed Z-Selective Ethenolysis of Stereoisomeric Mixtures

    PubMed Central

    Marinescu, Smaranda C.; Levine, Daniel S.; Zhao, Yu; Schrock, Richard R.; Hoveyda, Amir H.

    2011-01-01

    MonoAryloxide-Pyrrolide (MAP) complexes of molybdenum are employed for the selective ethenolysis of 1,2-disubstituted Z olefins in the presence of the corresponding E olefins. Reactions are performed in the presence of 0.02−3.0 mol % catalyst at 22 °C under 20 atm of ethylene. We demonstrate that the Z isomer of an easily accessible E:Z mixture can be destroyed through ethenolysis and the E alkene thereby isolated readily in high yield and exceptional stereoisomeric purity. PMID:21718001

  14. High-throughput evaluation of olefin copolymer composition by means of attenuated total reflection Fourier tranform infrared spectroscopy.

    PubMed

    Tuchbreiter, A; Marquardt, J; Zimmermann, J; Walter, P; Mülhaupt, R; Kappler, B; Faller, D; Roths, T; Honerkamp, J

    2001-01-01

    As a consequence of developing fully automated reactors for organic and organometallic synthesis and polymerizations combined with rapid on-line analysis, databases, and data mining, the analysis of polymers with respect to composition and properties has been speeded up. High-throughput evaluation of olefin copolymers requires fast measurements and high accuracy without tedious sample preparation such as pressing KBr pellets. This has been achieved by using attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR spectroscopy) in conjunction with multivariate calibration in order to determine the composition of olefin copolymers such as ethene/propene, ethene/1-hexene and ethene/1-octene copolymers.

  15. Development of a ruthenium/phosphite catalyst system for domino hydroformylation-reduction of olefins with carbon dioxide.

    PubMed

    Liu, Qiang; Wu, Lipeng; Fleischer, Ivana; Selent, Detlef; Franke, Robert; Jackstell, Ralf; Beller, Matthias

    2014-06-02

    An efficient domino ruthenium-catalyzed reverse water-gas-shift (RWGS)-hydroformylation-reduction reaction of olefins to alcohols is reported. Key to success is the use of specific bulky phosphite ligands and triruthenium dodecacarbonyl as the catalyst. Compared to the known ruthenium/chloride system, the new catalyst allows for a more efficient hydrohydroxymethylation of terminal and internal olefins with carbon dioxide at lower temperature. Unwanted hydrogenation of the substrate is prevented. Preliminary mechanism investigations uncovered the homogeneous nature of the active catalyst and the influence of the ligand and additive in individual steps of the reaction sequence.

  16. Z-Selective Olefin Synthesis via Iron-Catalyzed Reductive Coupling of Alkyl Halides with Terminal Arylalkynes

    PubMed Central

    2015-01-01

    Selective catalytic synthesis of Z-olefins has been challenging. Here we describe a method to produce 1,2-disubstituted olefins in high Z selectivity via reductive cross-coupling of alkyl halides with terminal arylalkynes. The method employs inexpensive and nontoxic catalyst (iron(II) bromide) and reductant (zinc). The substrate scope encompasses primary, secondary, and tertiary alkyl halides, and the reaction tolerates a large number of functional groups. The utility of the method is demonstrated in the synthesis of several pharmaceutically relevant molecules. Mechanistic study suggests that the reaction proceeds through an iron-catalyzed anti-selective carbozincation pathway. PMID:25831473

  17. Synthesis of Side Chain Liquid Crystal Polymers by Living Ring Opening Metathesis Polymerization. 4. Synthesis of Amorphous and Side Chain Liquid Crystal AB Block Copolymers

    DTIC Science & Technology

    1992-05-01

    Metathesis Polymerization. 4. Synthesis of C N00014-89-JI542 Amorphous and Side Chain Liquid Crystal AB Block Copolym rs 6. AUTHOR(S) Zen Komiya, Coleen ...Liquid Crystal AB Block Copolymers by Zen Komiya, Coleen Pugh: and Richard R. Schrock* Submitted to Macromolecules F r fCarnegie Mellon University...Amorphous and Side Chain Liquid Crystal AB Block Copolymers by Zen Komiya, Coleen Pught, and Richard R. Schrock* Contribution from Department of Chemistry 6

  18. Phosphate Tether-Mediated Ring-Closing Metathesis for the Generation of Medium to Large, P-Stereogenic Bicyclo[n.3.1]phosphates.

    PubMed

    Maitra, Soma; Markley, Jana L; Chegondi, Rambabu; Hanson, Paul R

    2015-09-02

    A phosphate tether-mediated ring-closing metathesis study towards the synthesis of P-stereogenic bicyclo[6.3.1]-, bicyclo[7.3.1]-, and bicyclo[8.3.1]phosphates is reported. This study demonstrates expanded utility of phosphate tether-mediated desymmetrization of C2-symmetric, 1,3-anti-diol dienes in generating complex medium to large, P-stereogenic bicyclo[n.3.1]phosphates..

  19. Cross metathesis with hydroxamate and benzamide BOC-protected alkenes to access HDAC inhibitors and their biological evaluation highlighted intrinsic activity of BOC-protected dihydroxamates.

    PubMed

    Zwick, Vincent; Nurisso, Alessandra; Simões-Pires, Claudia; Bouchet, Samuel; Martinet, Nadine; Lehotzky, Attila; Ovadi, Judit; Cuendet, Muriel; Blanquart, Christophe; Bertrand, Philippe

    2016-01-01

    Conditions for the metathesis of alkenes in the convergent synthesis of HDAC inhibitors have been improved by continuous catalyst flow injection in the reaction media. Intermediate and target compounds obtained were tested for their ability to induce HDAC inhibition and tubulin acetylation, revealing the key role of the tert-butyloxycarbonyl (BOC) group for more HDAC6 selectivity. Molecular modelling added rationale for this BOC effect.

  20. Coke formation and carbon atom economy of methanol-to-olefins reaction.

    PubMed

    Wei, Yingxu; Yuan, Cuiyu; Li, Jinzhe; Xu, Shutao; Zhou, You; Chen, Jingrun; Wang, Quanyi; Xu, Lei; Qi, Yue; Zhang, Qing; Liu, Zhongmin

    2012-05-01

    The methanol-to-olefins (MTO) process is becoming the most important non-petrochemical route for the production of light olefins from coal or natural gas. Maximizing the generation of the target products, ethene and propene, and minimizing the production of byproducts and coke, are major considerations in the efficient utilization of the carbon resource of methanol. In the present work, the heterogeneous catalytic conversion of methanol was evaluated by performing simultaneous measurements of the volatile products generated in the gas phase and the confined coke deposition in the catalyst phase. Real-time and complete reaction profiles were plotted to allow the comparison of carbon atom economy of methanol conversion over the catalyst SAPO-34 at varied reaction temperatures. The difference in carbon atom economy was closely related with the coke formation in the SAPO-34 catalyst. The confined coke compounds were determined. A new type of confined organics was found, and these accounted for the quick deactivation and low carbon atom economy under low-reaction-temperature conditions. Based on the carbon atom economy evaluation and coke species determination, optimized operating conditions for the MTO process are suggested; these conditions guarantee high conversion efficiency of methanol.