Showing papers on "Norbornene published in 1994"
160 citations
TL;DR: A great number of symmetric and chiral zirconocenes have been synthesized to give totally different structures of isotactic, syndiotactic, stereoblock, or isoblock polymers as mentioned in this paper.
131 citations
126 citations
TL;DR: In this article, two fluorine-containing glassy polynorbornenes were synthesized, and their properties (permeability (P), diffusion (D), and solubility (S) coefficients, sorption isotherms, and lifetime positron annihilation spectra) were studied.
Abstract: Two fluorine-containing glassy polynorbornenes were synthesized, and their properties (permeability (P), diffusion (D), and solubility (S) coefficients, sorption isotherms, and lifetime positron annihilation spectra) were studied. Both polymers, poly(5,5-difluoro-6,6-bis(trifluoromethyl)norbornene) (PFMNB) and poly(5,5,6-trifluoro-6-(heptafluoropropoxy)norbornenel (POFPNB), were demonstrated to be highly permeable materials having Pvalues much larger than the Pvalue of nonsubstituted polynorbornene. Positron annihilation analysis and density measurements showed that these polymers have high free volumes. However, the reasons for the high permeabilities of these two materials were different. The permeability of PFMNB (Tg = 169 "C) is related to its very high solubility coefficients while that of POFPNB (Tg = 77 "C) appears to be caused by both its diffusion and solubility coefficients. Sorption isotherms have the form expected for materials behaving according to the dual-mode sorption model. The parameters for this model were determined by a least squares analysis of the isotherms. It was shown that the Henry's law solubility coefficient ko is enhanced in these fluorine-containing polymers compared to other polynorbornenes. On the other hand, the Langmuir capacity parameter C'H, which characterizes the nonequilibrium state of a polymer, also correlates with the Tgvalues of these norbornene polymers. Hence, both equilibrium and nonequilibrium factors appear to be responsible for the enhanced solubility and permeability seen for these fluorine-containing norbornene polymers.
84 citations
83 citations
TL;DR: In this article, the authors measured the kinetics of extrusion of ethylene, 2-butene, and bicyclo[2.2]oct-2-ene from Cp * Re(O)(OCH(R)CH-(R)O) (Cp * =η-C 5 (CH 3 ) 5 ) and showed that strain in the double bond has a large effect on the enthalpy of activation for alkene oxidation but little or no effect on activation for alkenene extrusion.
Abstract: The kinetics of extrusion of ethylene, 2-butene, and bicyclo[2.2.2]oct-2-ene from Cp * Re(O)(OCH(R)CH-(R)O) (Cp * =η-C 5 (CH 3 ) 5 ) are measured, as are the kinetics of oxidation of norbornene, norbornadiene, and trans-cyclooctene by Cp * ReO 3 . Activation parameters calculated from the data show that strain in the double bond has a large effect on the enthalpy of activation for alkene oxidation but little or no effect on the enthalpy of activation for alkene extrusion. Entropies of activation for alkene extrusion are less than zero. A secondary deuterium isotope effect of 1.3 at 99.5 o C is measured for extrusion of ethylene-d 4 . Taken together, this data is inconsistent with a concerted mechanism for interaction of alkenes with Cp * ReO 3 but consistent with a stepwise mechanism with a metallaoxetane intermediate
75 citations
TL;DR: In this article, the synthesis and X-ray structure determination of the novel complex, Cp2Ti(Ph2SiH2)(PMe3), 4 is reported, which is best described as being a hybrid between a titanium(IV) (silyl) hydride complex and a titanium (II) silane complex Complex 4 reacts reversibly with N2 to form the bridging dinitrogen complex 5 and, in the presence of norbornene, 4 catalytically dimerizes Ph 2SiH 2 in quantitative yield Silane complex, Titanium
Abstract: : The synthesis and X-ray structure determination of the novel complex, Cp2Ti(Ph2SiH2)(PMe3), 4 is reported The spectroscopic and structural data indicate that 4 is best described as being a hybrid between a titanium(IV) (silyl)hydride complex and a titanium(II) silane complex Complex 4 reacts reversibly with N2 to form the bridging dinitrogen complex 5 and, in the presence of norbornene, 4 catalytically dimerizes Ph2SiH2 in quantitative yield Silane complex, Titanium
73 citations
TL;DR: In this paper, the condensation of aniline, toluidines or diphenylamine with norbornene tetrahydrofuran is promoted by a system generated from Li n Bu, ArNH 2 and [(PEt 3 ) 2 RhCl 2 ].
71 citations
69 citations
TL;DR: In this paper, a four-component domino coupling reaction was studied under palladium-catalysis, and the structures of two such products 4a and 4e were proved by X-ray crystal structure analysis.
67 citations
TL;DR: In this article, the authors described the preparation of polystyrene macromonomers containing a norbornene unit and their living ring opening metathesis polymerization (ROMP) to produce comb graft copolymers.
TL;DR: In this article, the mechanism of Ziegler-Natta catalysis with metallocenes has been investigated and a large range of new polymers with narrow molecular weight distribution and different microstructures can be produced with these single-site catalysts.
Abstract: Metallocenes have gained widespread interest as catalysts for olefin polymerization due to their high activity and versatility. A large range of new polymers with narrow molecular weight distribution and different microstructures can be produced with these “single-site” catalysts. These highly active catalysts which are able to produce 40 tonnes of polyethylene per gram zirconium per hour are even capable of incorporating remarkable amounts of sterically demanding olefins and dienes in copolymerization with ethylene. Isotactic, syndiotactic, stereoblock and isoblock polyolefins are accessible by variation of the metallocene ligands. Similarly, the isotacticity and molecular weight of the generated polyolefins are influenced by the ligand structure. By heterogenization of the metallocene on metal powder or silica polymers with substantially higher molecular weight, higher melting points and other new properties may be attained. Cyclic olefins like cyclopentene, norbornene or dimethanooctahydronaphthalene polymerize without ring-opening to yield highly melting and poorly soluble polymers. By separation of the racemic catalyst into enantiomers, optically active alkanes and alkenes are accessi-ble. Trimers are obtained with ee of 95%. These results provide new insights into the mechanism of Ziegler-Natta catalysis.
TL;DR: The living ring-opening metathesis polymerization (ROMP) of cyclobutene has been used to synthesize near monodispersed linear polyethylene as discussed by the authors.
Abstract: Near monodispersed linear polyethylene can be synthesized y hydrogenation of polybutadiene
prepared by the living ring-opening metathesis polymerization (ROMP) of cyclobutene. The polyethylene
is highly crystalline, as determined by powder X-ray diffraction, and defect free, as shown by spectroscopic
data. Living polycyclobutene can also react with anthracene dialdehyde to give a labeled polymer and with
norbornene to produce a block copolymer.
Patent•
15 Nov 1994TL;DR: In this paper, the chain transfer agent is inserted at the terminal end of the polymer chain and the addition polymers are prepared from a single or multicomponent catalyst system including a Group VIII metal ion source.
Abstract: Addition polymers derived from norbornene-functional monomers are terminated with an olefinic moiety derived from a chain transfer agent selected from a compound having a terminal olefinic double bond between adjacent carbon atoms, excluding styrenes, vinyl ethers, and conjugated dienes and at least one of said carbon atoms has two hydrogen atoms attached thereto. The addition polymers of this invention are prepared from a single or multicomponent catalyst system including a Group VIII metal ion source. The catalyst systems are unique in that they catalyze the insertion of the chain transfer agent exclusively at a terminal end of the polymer chain.
TL;DR: In this paper, it was shown that the aqueous ROMP with these catalysts is not a living polymerization, since molecular weights are almost independent of the polymerization time and of the monomer to catalyst ratio.
Patent•
27 Jan 1994
TL;DR: A fiber-reinforced cycloolefin polymer material comprises 1 to 99% by weight of reinforcing fibers, in particular glass fibers, and 99 to 1% of a cycloo-lefin copolymer which is built up from a polycyclo-olefin which is derived from norbornene, for example tetracyclododecene, and at least one olefin which was chosen from monocycloolefins having 4 to 12 C atoms (VII) and/or the group of acyclic olefs VIII ##STR
Abstract: A fiber-reinforced cycloolefin polymer material comprises 1 to 99% by weight of reinforcing fibers, in particular glass fibers, and 99 to 1% by weight of a cycloolefin copolymer which is built up from a) at least one (polycyclo)olefin which is derived from norbornene, for example tetracyclododecene, and b) at least one olefin which is chosen from monocycloolefins having 4 to 12 C atoms (VII) and/or the group of acyclic olefins VIII ##STR1## in which R 9 , R 10 , R 11 and R 12 are identical or different and are a hydrogen atom or a C 1 -C 8 -alkyl radical. VII is preferably ethylene. The monomer units of the (polycyclo)olefin in the cycloolefin copolymer molecule are in each case separated by monomer units of the cyclic olefins VII and/or of the acyclic olefins of the formula VIII.
TL;DR: In this article, homochiral norbornene monomers derived from amino acids undergo ring-opening metathesis polymerisation with [Mo(CHCMe2Ph)(NC6H3Pri2-2,6)(OBut)2] to give narrow molecular mass distributions.
Abstract: Homochiral norbornene monomers derived from amino acids undergo ring-opening metathesis polymerisation with [Mo(CHCMe2Ph)(NC6H3Pri2-2,6)(OBut)2] to give homochiral polymers with narrow molecular mass distributions.
TL;DR: In this paper, a catalytic asymmetric hydroalkenylation of norbornene (bicyclo[2.2.1]hept-2-ene) can be performed in 93% e.g. using 1-methyl-2-(ethoxycarbonyl)ethenyl triflate 5 as alkenylation agent and Pd{(R)-binap}2 as chiral catalyst.
Abstract: Catalytic asymmetric hydroalkenylation of norbornene (bicyclo[2.2.1]hept-2-ene) can be performed in 93% e.e. using 1-methyl-2-(ethoxycarbonyl)ethenyl triflate 5 as alkenylation agent and Pd{(R)-binap}2 as chiral catalyst.
TL;DR: Alkyne-dicobalthexacarbonyl complexes are readily prepared by the reduction of cobalt bromide by Zn in the presence of alkynes in THF while bubbling carbon monoxide under ambient conditions as discussed by the authors.
TL;DR: In this paper, a mixture of 2:1 coupling products was obtained in the presence of Pd(OAc)2, K2CO3, and nBu4NBr in DMF.
Abstract: (E)-β-Bromostyrene [(E)-2] reacts with norbornene (1a) or dicyclopentadiene (1b) in the presence of Pd(OAc)2, K2CO3, and nBu4NBr in DMF to yield a mixture of the 2:1 coupling products 4 and 5, while (Z)-β-bromostyrene [(Z)-2] gives exclusively 5. Under analogous conditions, (Z)-3-iodoacrylic acid (6) reacts with norbornene (1a) to give the diene 11 with an exo, exo-2,3-disubstituted norbornane skeleton.
TL;DR: Several homochiral hydroxylated norbornene derivatives have been synthesized from D-mannitol as mentioned in this paper, which are real or potential precursors in the synthesis of carbocyclic nucleosides and related products.
Abstract: Several homochiral hydroxylated norbornene derivatives have been synthesized from D-mannitol. Stereocontrolled Diels-Alder cycloadditions and stereospecific hydroxylations are key processes for the creation of the stereogenic centers in the target molecules. These compounds are real or potential precursors in the synthesis of carbocyclic nucleosides and related products.
TL;DR: In this article, the ring-opening metathesis polymerization of norbornene and 5,5-dimethylnorbornene has been studied with a range of tungsten(VI) ring opening procatalysts containing chelating diolate ligands.
TL;DR: In this paper, a ring-opening metathesis polymerization (ROMP) was applied to poly[norborn-5-ene-2,3-diyl bis(S-methyl xanthate) (polyl) to obtain complete trans connection of the repeating units, whereas the oxa analogue is not as stereoregular.
Abstract: exo,exo-Norborn-5-ene-2,3-diyl bis(S-methyl dithiocarbonate) (1) and exo,exo-norborn-5-ene-2,3-diyl bis(methyl carbonate) (2) were polymerized by ring-opening metathesis polymerization (ROMP) using Mo(CH-t-Bu)(NAr)(O-t-Bu) 2 . Depending on the bulkiness of the substituents, a higher stereoregularity of the polymer was achieved. Spectroscopic data (IR, NMR) of poly[norborn-5-ene-2,3-diyl bis(S-methyl xanthate) (polyl) show a complete trans connection of the repeating units, whereas the oxa analogue is not as stereoregular. Thermal properties of poly(1) offer interesting possibilities for application as a precursor polymer to poly(cyclopentadienylenevinylene)
TL;DR: In this paper, a one-step synthesis of disubstituted brendane derivatives is described starting from commercially available vinyl norbornene by the Wacker-type oxidation with PdCl2/CuCl2 or Pdcl2/cuCln/O2 (n=1,2), in addition to the formation of a new carbon carbon bond two different nucleophilic groups are incorporated with complete chemio-, regio-and high (>90%) stereoselectivity.
TL;DR: The self-metathesis of functionalized olefins with two unconjugated carbon-carbon bonds takes place with high yields and selectivity with homogeneous catalysts as mentioned in this paper.
TL;DR: In this article, the relation between structural parameters and reactivity in ring-opening metathesis polymerization of cyclo-olefins was studied from a kinetic point of view.
Abstract: Concerning the study on the relation between structural parameters and reactivity in ring-opening metathesis polymerization of cyclo-olefins, the “living” polymerization of norbornene initiated by Schrock's-type complexes was considered as a reference and studied from the kinetic point of view. First kinetic orders with respect to both monomer and active species allow the values of absolute rate constants of propagation to be determined. The thermodynamic parameters obtained from kinetic experiments performed at different temperatures seem to indicate that monomer coordination and metallacycle formation are rate-determining steps in the process studied. © 1994 John Wiley & Sons, Inc.
TL;DR: In this article, the binuclear amide complexes of Ru(III) are described and the catalytic activity of the complexes, which are highly soluble in water, is examined by carrying out the epoxidations of norbornene, cis-cyclooctene and trans-4-octene to give the respective oxides in the presence of the oxidant iodosylbenzene.