Showing papers on "Norbornene published in 1999"
TL;DR: In this paper, the aziridination of cis-stilbene and cis-β-methylstyrene by [RuVI(Por)(NTs)2] is nonstereospecific with a partial loss of the alkene stereochemistry.
Abstract: Bis(tosylimido)ruthenium(VI) porphyrins, [RuVI(Por)(NTs)2] (Por = TPP, TTP, 4-Cl-TPP, 4-MeO-TPP, OEP), were prepared in 60−74% yields by treatment of [RuII(Por)(CO)(MeOH)] with (N-(p-tolylsulfonyl)imino)phenyliodinane (PhINTs) in dichloromethane. In dichloromethane containing pyrazole, they reacted with alkenes or alkanes to give tosylamidoruthenium(IV) porphyrins, [RuIV(Por)(NHTs)(pz)], in about 75% yields. The reactions of [RuVI(TPP)(NTs)2] and [RuVI(OEP)(NTs)2] with styrene, para-substituted styrenes, norbornene, cyclooctene, and β-methylstyrene afforded the corresponding N-tosylaziridines in 66−85% yields. The aziridination of cis-stilbene and cis-β-methylstyrene by [RuVI(Por)(NTs)2] is nonstereospecific with a partial loss of the alkene stereochemistry. Kinetic studies on the reactions between [RuVI(TPP)(NTs)2] and 16 alkenes (cyclooctene, norbornene, 2,3-dimethyl-2-butene, styrene, para-substituted styrenes, α- and β-methylstyrene, and α- and β-deuteriostyrene) gave the second-order rate constants (...
264 citations
TL;DR: The rhodium bis-olefin complex [C5Me5Rh(C2H3SiMe3)2], 1, has been shown to be a catalyst for the selective addition of olefins to the ortho position of aromatic ketones as discussed by the authors.
Abstract: The rhodium bis-olefin complex [C5Me5Rh(C2H3SiMe3)2], 1, has been shown to be a catalyst for the selective addition of olefins to the ortho position of aromatic ketones. The addition of vinyltrimethylsilane to benzophenone was studied by NMR spectroscopy, which indicated that 1 was the catalyst resting state for this process. This reaction was applied to a series of olefins (allyltrimethylsilane, 1-pentene, norbornene, 2,2‘-dimethyl-3-butene, cyclopentene, and vinyl ethyl ether) and aromatic ketones (benzophenone, 4,4‘-dimethoxybenzophenone, 3,3‘-bis(trifluoromethyl)benzophenone, dibenzosuberone, acetophenone, p-chloroacetophenone, and p-(trifluoromethyl)acetophenone). The dependence of the turnover frequency on substrate concentration was investigated. In the presence of excess ketone the formation of a benzophenone complex, 5, [(C5Me5Rh)2-η4-η4-C6H5C(O)Ph] was observed after consumption of olefin. Active catalyst is regenerated upon addition of olefin to 5. On the basis of kinetic experiments and labeli...
175 citations
TL;DR: In this paper, the reaction temperature of CpA catalysts was determined at 40 °C for a copolymerization of poly(ethylene-co-norbornene) copolymers with a variety of α-olefins.
Abstract: Group 4 ansa-cyclopentadienylamido (CpA) complexes [Me2Si(Cp‘)(NR)]MCl2 (R = alkyl, M = Ti, Zr) efficiently copolymerize ethylene with a variety of α-olefins. Ethylene/norbornene copolymerization reactivity ratios were determined at 40 °C for CpA catalysts [Me2Si(Cp‘)(NtBu)]TiCl2 (Cp‘ = Me4Cp, 2,4-Me2Cp, 3-tBuCp, Ind), and the resulting values are low (r1 = 2.0−5.1, r2 → 0), suggesting a tendency toward alternating comonomer insertion at high norbornene/ethylene feed ratios. As reaction temperature is increased and norbornene concentration is decreased, productivity increases and norbornene incorporation decreases. No more than 46 mol % norbornene is incorporated into the copolymer using these CpA catalysts even at low feed ratios (E/N ≥ 0.02), and norbornene homopolymerizations with [Me2Si(Me4Cp)(NtBu)]TiCl2 proceed to very low conversion (<1%). 13C NMR spectroscopy of CpA-derived poly(ethylene-co-norbornene)s shows the copolymers contain virtually no consecutive norbornene sequences, and the microstruct...
171 citations
TL;DR: A trans configuration and phosphane dissociation are not necessarily necessary for catalytic activity in Grubbs-type ruthenium carbene complexes as mentioned in this paper, as shown by the fact that the chelate ligand tBu2PCH2PtBu2 (dtbpm) is an active catalyst for the ring opening metathesis polymerization of norbornene and cyclopentene.
Abstract: Atrans configuration and phosphane dissociation are not necessarily prerequisites for catalytic activity in Grubbs-type ruthenium carbene complexes [(PR3)2Cl2RuCR1R2]. This is shown by the fact that the complex [(η2-dtbpm)Cl2Ru=CH−CHCMe2] (1), in which the chelate ligand tBu2PCH2PtBu2 (dtbpm) enforces a cis geometry and disfavors phosphane dissociation, is an active catalyst for the ring opening metathesis polymerization (ROMP) of norbornene [Eq. (a)] and cyclopentene.
134 citations
TL;DR: In this article, a yellow-orange toluene solution of [Rh(Cl)(COD)]2 to a colorless CF3C6F11 solution of P(CH2CH2Rf6)3 (Rf 6 = (CF2)5CF3)3) was added to a green-orange CF3c6f11 solution to give analytically pure 1 (94%), which is insoluble in most organic solvents.
Abstract: Addition of a yellow-orange toluene solution of [Rh(Cl)(COD)]2 to a colorless CF3C6F11 solution of P(CH2CH2Rf6)3 (Rf6 = (CF2)5CF3)3) gives a colorless toluene solution of COD and an orange CF3C6F11 solution of ClRh[P(CH2CH2Rf6)3]3 (1). Evaporation of CF3C6F11 gives analytically pure 1 (94%), which is insoluble in most organic solvents and stable to 300 °C. Alkenes, catecholborane, and CF3C6F11 solutions of 1 (950:950:1 mol ratio for norbornene) are stirred for 1−24 h at 40 °C (heterogeneous conditions). The resulting alkylboranes are extracted with benzene (2×; turnover number (TON) 854 (90%) for norbornene), toluene, or THF, and the catalyst solution is reused (TON 2409 for three cycles). Subsequent reactions with H2O2/NaOH give alcohols, which are isolated in 92−77% yields (11 examples). Longer reaction times afford TON values higher than 10 000 (<0.1 mol % 1). Analogous reactions of alkynes yield alkenylboranes (89−88%). Pinacolborane additions are also catalyzed. A higher homologue of 1, ClRh[P(CH2CH2...
128 citations
TL;DR: The cationic ruthenium−alkylidene complex was found to catalyze both hydrovinylation and cycloaddition reactions of alkynes and alkenes as discussed by the authors.
125 citations
TL;DR: In this paper, the first use of a d0 metal complex with non-Cp ligands in the catalytic hydrosilylation of olefins was presented.
112 citations
TL;DR: In this paper, a high molecular weight vinyl-type polynorbornene was obtained in high yields with a highly active nickel-based phosphoraneiminato complex in the presence of methylaluminoxane.
Abstract: High molecular weight vinyl-type polynorbornene was obtained in high yields with a highly active nickel-based phosphoraneiminato complex in the presence of methylaluminoxane. This polynorbornene is soluble at room temperature in chlorobenzene and shows no indication of crystallinity in the solid state. Catalyst activity, polymer yield, and polymer molecular weight can be controlled over a wide range by variation of reaction parameters.
100 citations
TL;DR: In this article, the combination of N-heterocyclic carbenes and coordinatively labile ligands (phosphanes or chloro-bridged transition metals) on the ruthenium center proves not only successful regarding catalytic performance but also promising with respect to polymer properties.
94 citations
TL;DR: In this paper, a rotationalisomeric state treatment of ethylene−norbornene copolymers has been used for the purpose of establishing a correlation between conformation and 13C NMR chemical shifts of this copolymer.
Abstract: A rotational-isomeric-state treatment of ethylene−norbornene copolymers has been worked out for the purpose of establishing a correlation between conformation and 13C NMR chemical shifts of this ne...
91 citations
TL;DR: In this article, the microstructure of ethene/norbornene copolymers produced by metallocene/methylaluminoxane catalysts is investigated by 13C NMR spectroscopy.
Abstract: The microstructure of ethene/norbornene copolymers produced by metallocene/methylaluminoxane catalysts is investigated by 13C NMR spectroscopy. The microstructure of alternating copolymers is assigned on the pentad level by comparison of the pentad distribution in 13C NMR spectra with the calculated distribution according to the alternating mechanism. Norbornene block structures produced with different catalysts are compared, and norbornene diblock structures are assigned. Triad distributions for the alternating copolymers and diad distributions for copolymers containing diblocks were obtained.
TL;DR: The ground-state and potential energy surfaces of norbornene and isomeric C_7H_(10) species were mapped using CASSCF theory and the 6-31G^* basis set.
Abstract: The ground-state and ^1(ππ^*)-state potential energy surfaces of norbornene and isomeric C_7H_(10) species were mapped using CASSCF theory and the 6-31G^* basis set and compared with the results of femtosecond experiments on norbornene retro Diels−Alder reactions. Computations explored stepwise and concerted retro Diels−Alder pathways, [1,3]-sigmatropic shifts, and [1,2]-sigmatropic shifts originating from the ^1(ππ^*)-state or ground-state surfaces. Extremely efficient decay occurs from the excited state to the ground state via two different conical intersections (surface crossings). The first of these crossing points is accessed by one-bond cleavage of C1−C6 (or C4−C5). Several possible subsequent ground-state reaction paths have been identified: (a) ring-closure to form norbornene; (b) ring-closure to form bicyclo[3.2.0]hept-2-ene ([1,3]-sigmatropic shift); (c) formation of a metastable 1,3-biradical which closes to form tricyclo[3.2.1.0^(3,7)]heptane ([1,2]-sigmatropic shift); and (d) collapse of a gauche-in biradical to a vibrationally excited cyclopentadiene and ethylene, or norbornene. Excited-state one-bond cleavage of C4−C7 (or C1−C7) leads to the second conical intersection. Possible ground-state reaction pathways from this structure lead to the formation of bicyclo[4.1.0]hept-2-ene ([1,3]-sigmatropic shift product) or to a second 1,3-biradical leading to tricyclo[3.2.1.0^(3,7)]heptane ([1,2]-sigmatropic shift product). The vibrationally excited cyclopentadiene is the 220 fs lifetime species of mass 66 amu, consistent with the retro Diels−Alder reaction observed in the femtosecond laser experiments. It is proposed that biradicaloids formed after decay through the conical intersections are the 94 amu species, with an average lifetime of about 160 fs.
TL;DR: In this article, the copper(I) ethylene complex (But2P(NSiMe3)2-κ2N) and its norbornene analogue have been synthesized and characterized and their solid state structures determined.
TL;DR: In this paper, the preparation of a polymer-supported ruthenium alkylidene metathesis catalyst is described, which is used to initiate a ring-opening metathesizing polymerization of norbornene derivatives onto a polymer support to prepare novel highloading resins for use in combinatorial chemistry.
TL;DR: The potential energy surfaces for the thermal reactions of bicyclo[3.2.0] and norbornene have been explored with density functional theory at the Becke3LYP/6-31G* level.
Abstract: The potential energy surfaces for the thermal reactions of bicyclo[3.2.0]hept-2-ene and norbornene have been explored with density functional theory at the Becke3LYP/6-31G* level. Both concerted and diradical pathways for the retro-Diels−Alder reaction of norbornene have been examined, and the activation parameters and 13C primary kinetic isotope effects predicted for the concerted pathway are in excellent agreement with experimental data. The concerted mechanism is favored over the lowest energy stepwise diradical route by 12.4 kcal/mol. For the orbital symmetry-allowed suprafacial-inversion (si) pathway of the [1,3] sigmatropic rearrangement of bicyclo[3.2.0]hept-2-ene to form norbornene, a mechanism involving a transition state which leads to a broad diradical plateau on the potential energy surface is predicted. Implications of these surfaces, which differ substantially from those obtained by semiempirical calculations, are also discussed.
Patent•
02 Mar 1999TL;DR: In this article, a method of making polymer blends using series reactors and a metallocene catalyst was proposed, which relates to making blends of EP copolymers in which the blend components differ in any of the following characteristics: 1) composition, 2) molecular weight, and 3) crystallinity.
Abstract: This invention relates to a method of making polymer blends using series reactors and a metallocene catalyst. Monomers used by the invention are ethylene, a higher alpha-olefin (propylene most preferred), and optionally, a non-conjugated diene (ethylidene norbornene, i.e., ENB, most preferred). More specifically, this invention relates to making blends of EP (ethylene-propylene) copolymers in which the blend components differ in any of the following characteristics: 1) composition, 2) molecular weight, and 3) crystallinity. We use the terminology EP copolymer to also include terpolymers that contain varying amounts of non-conjugated diene. Such terpolymers are commonly known as EPDM.
Book•
01 Jan 1999
TL;DR: In this paper, Ziegler-Natta et al. presented a simulation of a Heterogeneous Titanium-based catalysts for Oligomeric Methylaluminoxanes (MAO) in Olefin Polymerization.
Abstract: 1. Heterogeneous Ziegler-Natta Catalysis.- Polyethylene: Polymer with Future.- Polypropylene: 44 Years Young! The Challenge for the 21st Century.- Characterization of PP Prepared with the Latest Metallocene and MgCl2-supported TiCl4 Catalyst Systems.- An Absolute Test of Rival Theories for MWDs in Heterogeneous Polymerization-MWDs during Quasi-Living Polymerization.- Olefin Polymerization with Novel Type of Ziegler Catalysts.- Kinetics and Mechanism of Ethylene Polymerization and Copolymerization Reactions with Heterogeneous Titanium-Based Ziegler-Natta Catalysts.- New Insight into Propene Polymerization Promoted by Heterogeneous Ziegler-Natta Catalysts.- Energy Distribution of Active Sites in Heterogeneous Ziegler-Natta Catalysts. Method of Study of Active Site Non-uniformity.- Ziegler-Natta and Metallocene Polymerisation of Olefins with Heterogeneous Catalysts.- 2. Homogeneous Catalysis, Synthesis and Polymerization.- Formation, Structure and Mechanism of Oligomeric Methylaluminoxanes(MAO).- The Activation of Metal-Fluorine Bonds in Compounds of Group 4 by Aluminum Alkyls.- A DFT Quantum-chemical Study of the Structures and Reactive Sites of Polymethylalumoxane.- In situ FTIR Spectroscopy Shows no Evidence of Reaction between MAO and TMA.- Alumoxanes alternative to MAO: Synthesis and characterization.- Expanding the Scope of Metallocene Catalysis: Beyond Indenyl and Fluorenyl Derivatives.- New C1-Symmetric Metallocenes for the Polymerization of Olefins.- New Catalyst Concepts for the Polymerization of Ethylene with Metallocenes.- Synthesis of Novel Complex with Bridged Bis(indenyl)Ligand and its Polymerization Behavior of Propylene.- Linked Amido-Cyclopentadienyl Complexes of Group 3 and 4 Metals: The First "Post-Metallocenes".- Late Transition Metal Catalysts for Olefin Polymerization.- 3. Homogeneous Catalysis, Mechanism of Polymerization.- Chain Growth in Zirconocene-catalyzed Olefin Polymerization -DFT Studies on Possible Reaction Paths and the Influence of a Second Olefin Ligand.- Syndiotactic and Isotactic Specific Metallocene Catalysts with Hapto-flexible Cyclopentadienyl-Fluorenyl Ligand.- Current Vitality of Ziegler's Monumental Discovery of Zirconium Catalysis in Olefin Polymerization: Metallocene and Nonmetallocene Catalysts via Reductive Dimerization.- Kinetic Features of Living Polymerization of Propene with the [t-BuNSiMe2Flu]TiMe2/B(C6F5)3 Catalyst.- Quantitative Structure-Activity Relationships for Unbridged Zirconocene Catalysts During Ethene Polymerization.- Coexistence of two Active Species in the Polymerization of 1-Hexene Catalyzed with Zirconocene/MAO Catalysts.- In-depth Investigation of Unsaturated Chain-end Groups: A Tool for Understanding Hydrogen Activation Mechanism in Zirconocene Catalysed Propene Polymerization.- 4. Supported Metallocene Catalysts.- Supported Metallocene Catalysts for Propene Polymerization.- Influence of the Particle Size of Silica Support on the Kinetics and the Resulting Polymer Properties at the Polypropylene Polymerization with Heterogeneous Metallocene Catalysts Part I: Experimental Studies and Kinetic Analysis.- Influence of the Particle Size of Silica Support on the Kinetics and the Resulting Polymer Properties at the Polypropylene Polymerization with Heterogeneous Metallocene Catalysts Part II: Development of a Model as well as a Mathematical Simulation.- Supported Metallocene Catalysts in Olefin Polymerization: Toward High Performances.- Zeolite Supported Metallocene Catalysts: Effect of Support Structure and Surface Groups on the Polymerization Process.- Preparation of Novel Supported Metallocene and their Olefin Polymerization Capabilities.- Development of Supported Single-site Catalysts and Produced Polyethylene.- Ethylene Polymerization with the Heterogeneous Single Site CpIndZrCl2 Catalyst.- The Impact of the Cocatalyst on the Polymerisation Behaviour of Supported Metallocenes.- Heterogenised MAO-free Metallocene Catalysts.- A New Supported Zirconocene Catalyst for Ethylene Polymerization.- 5. Polystyrene and Copolymers.- Syndiospecific Polymerization of Styrene.- Monocyclopentadienyl Titanium Catalyst.- The Effects of the Bridge Structure and the Ligand System of Zirconocene Catalysts on the Copolymerization of Styrene and Ethylene.- Branched Polyethenes Prepared via Olefin Copolymerization and Migratory Insertion.- Metallocene Catalyzed Alternating Copolymerization of Olefins.- Copolymer Microstructures of Ethylene Norbornene Copolymers Prepared with Homogeneous Metallocene Based Catalysts.- Studies on Properties of Metallocene Catalysed Copolymers of Ethylene and Linear, Non-conjugated Dienes.- Ethylene/?-Olefin Copolymerization with Dimethylsilyl-bis-(2-methyl-4-phenyl-indenyl)zirconium dichloride and Methylaluminoxane: Influences on Polymerization Activity and Molecular Weight.- 6. Functional Polyolefins and Polydienes.- The Role of the Cyclopentadienyl Ligand in Catalysts for 1,3-Diene Polymerization.- Catalytic Reaction Mechanisms and Structure-Reactivity Relationships in the Stereospecific Butadiene Polymerization.- Styrene and Conjugated Dienes Polymerization with Half Sandwich Titanocene Catalysts.- Half-Vanadocene Catalyst for Butadiene Polymerization.- Chemical Functionalization of Polypropylene with a V-based Living Polymerization Catalyst.- Copolymerization of Ethylene/?-Hydroxy ?-Olefins.- Stereospecific Polymerization of Methacrylates with Dimethylsilylene-bridged Zirconocene Catalysts.- Development of Catalytic Systems based on Lanthanoid Complexes for Olefin Polymerization.- 7. Polymer Characterization and Processes.- Initial 2,1-Insertions in Metallocene Polymerizations of Polypropylene.- Olefin Polymerization with DuPont's VersipolTM Catalyst System.- Features of Cyclopentadienyl Metal Catalysts for Ethylene Copolymerization in Gas and Liquid Phase.- How to Avoid Gas-Liquid Mass Transfer Limitations During Polymerization of Olefins.- Ternary Metallocene Based Catalysts in High Temperature, High Pressure Polymerization.- Advanced in the Use of Stopped-flow Techniques for Olefin Polymerization.- Contributors.
TL;DR: In this article, an efficient route to sulfonation and epoxidation of the double bonds in a polynorbornene backbone has been found that do not interfere with side chain functional groups of interest for making light-emitting devices.
Abstract: Efficient routes to sulfonation and epoxidation of the double bonds in a polynorbornene backbone have been found that do not interfere with side chain functional groups of interest for making light-emitting devices. Substituted norbornene monomers were prepared with ether or thioether linkages, which were stable to sulfonation. Oligomers (25mers or 50mers) of homo- and copolymers containing diphenylanthracene (for blue-light emission), oxadiazole (for electron transport), and p-triphenylene (for hole transport) side chains were prepared via ring-opening metathesis polymerization (ROMP) of the corresponding norbornene monomers. Sulfonation of the polynorbornene backbone yielded a polyanionic material that was suitable for creating films via sequential adsorption with the polycation, poly(allylamine HCl) (PAH). Devices with an indium tin oxide (ITO) anode and an aluminum cathode were constructed. A two-layer device comprised of a layer of diphenylanthracene/oxadiazole copolymer and a layer of p-triphenylene...
TL;DR: In this paper, a ring-opening metathesis with formation of graft copolymers and polymacromonomers has been used to synthesize poly(e-caprolactone) (PCL) macromers with norbornene and polymerizable derivatives.
Abstract: Poly(e-caprolactone) (PCL) macromonomers capped by a polymerizable norbornene end-group have been synthesized and (co)polymerized by ring-opening metathesis with formation of graft copolymers and polymacromonomers. α-Norbornenyl PCL macromonomers have been synthesized by ring opening polymerization (ROP) of e-caprolactone (eCL) initiated by 2-diethylaluminoxymethyl-5-norbornene. Copolymerization of these PCL macromonomers with norbornene and polymerizable derivatives has been catalyzed by the [RuCl2(p-cymene)]2 PCy3/(trimethylsilyl)diazomethane complex yielding a series of poly(norbornene)-graft-poly(e-caprolactone) copolymers. These new graft copolymers have been characterized by a set of analytical methods, i.e., SEC, 1H-NMR, FTIR, DSC, and TGA. Furthermore, PCL macromonomers have been polymerized into high molecular weight comb chains of narrow molecular weight distribution (Mw/Mn = 1.10) within high yields (90%). © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2447–2455, 1999
TL;DR: New reaction conditions and stereochemical control elements for heterodimerization between ethylene (or propylene) and functionalized vinyl arenes are highlighted in this article, where an enantioselective version of the hydrovinylation reaction uses [{(allyl)NiBr}2], a noncoordinating counter anion, (bis-CF3−C6H3)4B−, and a hemilabile ligand such as MOP.
Abstract: New reaction conditions and stereochemical control elements for heterodimerization between ethylene (or propylene) and functionalized vinyl arenes are highlighted (see equation). For example, an enantioselective version of the hydrovinylation reaction uses [{(allyl)NiBr}2], a noncoordinating counter anion, (bis-CF3−C6H3)4B−, and a hemilabile ligand such as MOP. Other applications include intramolecular cyclization of 1,6-dienes and heterodimerization of norbornene and ethylene.
TL;DR: In this article, a ring opening metathesis polymerization (ROMP) of norbomene was achieved using a new Ru(ID-vinylidene complex as catalyst precursor.
TL;DR: In this paper, the homogeneous catalytic hydroformylation of 20 alkenes was studied, starting with Rh4(CO)12 as catalyst precursor in n-hexane as solvent, using high-pressure in-situ infrared spectroscopy as the analytical tool.
TL;DR: In this article, the authors show that cyclization of cyclopentane derivatives is induced by zinc and acid or by BuSnH4, depending on the relative intensity of the 19 F NMR spectrum with relative intensities of 3:2.
TL;DR: In this article, copolymerization of ethylene with endo-dicyclopentadiene (DCP) was performed by using Cp2ZrCl2 (Cp = Cyclopentadienyl), Et(Ind) 2ZrCL2 (Ind = Indenyl), and Ph2C(Cp)(Flu)Zrcl2 (Flu = Fluorenyl) combined with MAO as cocatalyst.
Abstract: Copolymerizations of ethylene with endo-dicyclopentadiene (DCP) were performed by using Cp2ZrCl2 (Cp = Cyclopentadienyl), Et(Ind)2ZrCl2 (Ind = Indenyl), and Ph2C(Cp)(Flu)ZrCl2 (Flu = Fluorenyl) combined with MAO as cocatalyst. Among these three metallocenes, Et(Ind)2ZrCl2 showed the highest catalyst performance for the copolymerization. From 1H-NMR analysis, it was found that DCP was copolymerized through enchainment of norbornene rings. The copolymer was then epoxidated by reacting with m-chloroperbenzoic acid. 13C-NMR spectrum of the resulting copolymer indicated the quantitative conversion of olefinic to epoxy groups. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 103–108, 1999
Patent•
08 Dec 1999
TL;DR: In this paper, a catalyst system and a process for the bulk addition polymerization or of polycyclic olefins, such as norbornene, methylnorbornene and ethylnorbornenes, was presented.
Abstract: A catalyst system and a process for the bulk addition polymerization or of polycyclic olefins, such as norbornene, methylnorbornene, ethylnorbornene, butylnorbornene or hexylnorbornene, 1,2,3,4,4a,5,8,8a-octahydro-1,4:5,8-dimethanonapthalene, 5,5′-(1,2-ethanediyl)bisbicyclo[2.2.1]hept-2-ene, and 1,4,4a,4b,5,8,8a,8b-octahydro-1,4:5,8-dimethanobiphenylene are disclosed. The catalyst includes an organonickel or organopalladium transition metal procatalyst and an activator compound. Polymerization can be carried out in a reaction injection molding process to yield thermoplastic and thermoset molded polymeric articles possessing high glass transition temperatures.
TL;DR: In this article, the resonances of the norbornene C 5/6 and the ethene carbon atoms, which overlap extensively in the 13 C NMR spectrum, were differentiated and assigned by comparing the 13C NMR spectra of the copolymers obtained from monomers having 13 C at natural abundance with those prepared from feedstocks containing 13 C 1 -enriched ethenes or 13 C 5 /6 -enhanced norbornenes.
Abstract: Ethene and norbornene were copolymerized using metallocene catalysts that produce copolymers having isolated norbornene units or microblocks with a maximum of two norbornene units. The resonances of the norbornene C 5/6 and the ethene carbon atoms, which overlap extensively in the 13 C NMR spectrum, were differentiated and assigned by comparing the 13 C NMR spectra of the copolymers obtained from monomers having 13 C at natural abundance with those prepared from feedstocks containing 13 C 1 -enriched ethene or 13 C 5/6 -enriched norbornene. The NMR analysis revealed that the chemical shifts of the norbornene C 5/6 carbon atoms are triad sensitive and those of the ethene carbon atoms are pentad sensitive. 13 C NMR analysis of copolymers containing isolated norbornene units in various proportions allowed the resonances of the norbornene C 5/6 and the ethene carbon atoms to be assigned to the respective triads and pentads. The complete triad distributions of these copolymers determined in this way were used to calculate the copolymerization parameters for a representative metallocene catalyst.
TL;DR: The dinuclear complex Cp*2Os2Br4 (Cp* = pentamethylcyclopentadienyl) and related mono(pentamethylcycledienyl)-osmium compounds are catalysts for the ring-opening metathesis polymerization (ROMP).
TL;DR: In this article, 11 polyoxoanion-supported transition metal acetonitrile compositions have been synthesized in 1:1, 1:2, and even a few 1:3 Mn+ to polyoxoinion ratios; these precatalysts were then tested for their catalytic efficacy for norbornene and cyclohexene oxygenation using [PhIO]n as the oxidant.
Abstract: Eleven new polyoxoanion-supported transition metal acetonitrile compositions have been synthesized in 1:1, 1:2, and even a few 1:3 Mn+ to polyoxoanion ratios; these new precatalysts were then tested for their catalytic efficacy for norbornene and cyclohexene oxygenation using [PhIO]n as the oxidant. The catalytic results identify {(CH3CN)xMn2+/P2W15Nb3O629-} (1) and {2(CH3CN)xMn2+/P2W15Nb3O629-} (2) as the best precatalysts within this new subclass of polyoxoanion-supported catalysts. The results reveal a modest ca. 14-fold rate increase for either 1 or 2 in norbornene or cyclohexene epoxidation compared to the polyoxoanion-free [MnII(CH3CN)4](BF4)2 solvate, kinetic results which require the presence of the P2W15Nb3O629- polyoxoanion in the rate-determining step of the active catalyst. Catalyst reisolation, then IR, UV−visible, and ion-exchange resin studies (and in comparison to authentic 2 that has not undergone catalysis) provide compelling evidence that 2 is, in fact, the true catalyst. Also compared ...
TL;DR: The tetrathioperrhenate anion, ReS4- (1), is shown to form adducts with a variety of alkenes as discussed by the authors, including norbornene and norbornadiene.
Abstract: The tetrathioperrhenate anion, ReS4- (1), is shown to form adducts with a variety of alkenes. The alkene adducts form reversibly, and those of norbornene and norbornadiene were isolated. For norbor...
TL;DR: The long-term stability and solution characterization of these polymers are dramatically influenced by ligand-exchange reactions within the boronate moiety, as demonstrated in the ROMP polymerization of norbornene monomers with borons both in exo and endo positions.
Abstract: Molybdenum and ruthenium catalysis has been used to synthesize main-chain boronate ADMET polymers under bulk conditions; however, the long-term stability and solution characterization of these polymers are dramatically influenced by ligand-exchange reactions within the boronate moiety. Placing the boronate pendent to the main chain obviates this phenomenon as demonstrated in the ROMP polymerization of norbornene monomers with boronates both in exo and endo positions. The stereochemistry of the monomer influences both the rate of polymerization and the microstructure of the resulting polymer; these effects are more pronounced in the case of ruthenium catalysis. The thermal stability of these polymers also is dependent upon monomer stereochemistry.