Showing papers on "Norbornene published in 2008"
TL;DR: This Account reports the methodology, based on the cooperative action of Pd and norbornene, that achieves selective aryl-aryl coupling through C-halide and C-H activation, and obtained the key metallacycle able to selectively direct the reactions by replacing nor Bornene with an aryL-bonded aminocarbonyl group.
Abstract: Catalytic methods are important tools for the synthesis of C−C bonds under mild and ambient conditions. Palladium chemistry predominates in this area because it offers the opportunity to form several different types of bonds in one pot. Palladium can also tolerate a variety of functional groups. Among the many investigations of catalytic aryl−aryl couplings, the most successful technique has been the Suzuki reaction, which uses an arylboronic acid to attack an aryl−Pd bond. This Account reports our methodology, based on the cooperative action of Pd and norbornene, that achieves selective aryl−aryl coupling through C−halide and C−H activation. We are primarily interested in Pd-catalyzed sequential reactions. These reactions combine palladium as an inorganic catalyst and a strained olefin such as norbornene as an organic catalyst and can lead to biphenyl derivatives. While the palladium facilitates C−C bond formation through C−halide and C−H activation, the norbornene contributes to the construction of a pa...
430 citations
TL;DR: Mechanistic studies show that addition of aniline-d2 occurs in a syn fashion and suggest that the catalytic cycle comprises oxidative addition ofAniline to form a bis-anilide hydride complex, followed by migratory insertion of olefin and reductive elimination of product in a series of steps involving iridium complexes containing ancillary bisphosphine and arylamide ligands.
Abstract: A set of catalytic, intermolecular hydroaminations of strained bicyclic olefins and dienes are reported that occur in both high yield and high enantioselectivity. These reactions occur with a catalyst generated from [Ir(cyclooctene)Cl]2, sterically hindered and electron-rich derivatives of the Segphos and BIPHEP family of ligands, and a soluble base. This system catalyzes the addition of various anilines to norbornene, norbornadiene, and other bicyclic olefins. The products from addition of p-anisidine can be transformed to BOC-protected norbornylamine and to substituted cyclopentanes in nearly enantiopure form. Mechanistic studies show that addition of aniline-d2 occurs in a syn fashion and suggest that the catalytic cycle comprises oxidative addition of aniline to form a bis-anilide hydride complex, followed by migratory insertion of olefin and reductive elimination of product in a series of steps involving iridium complexes containing ancillary bisphosphine and arylamide ligands.
162 citations
TL;DR: The resulting positron-emitting nanoparticles are to be used as in vivo molecular imaging agents for use in tumor imaging.
Abstract: Nanoparticles containing fluorine-18 were prepared from block co-polymers made by ring-opening metathesis polymerization (ROMP). Using the fast initiating ruthenium metathesis catalyst (H2IMes)(pyr)2(Cl)2RuCHPh, narrow polydispersity, amphiphilic block copolymers were prepared from a cinnamoyl-containing, hydrophobic norbornene monomer and a mesylate-terminated, PEG-containing hydrophilic norbornene monomer. Self-assembly into micelles and subsequent crosslinking of the micelle cores by light-activated dimerization of the cinnamoyl groups yielded stable nanoparticles. Incorporation of fluorine-18 was achieved by nucleophilic displacement of the mesylates with the radioactive fluoride ion with 31% incorporation of radioactivity. The resulting positron-emitting nanoparticles are to be used as in vivo molecular imaging agents in tumor imaging.
130 citations
TL;DR: Quantitative energy-resolved collision-induced dissociation cross-sections by tandem ESI-MS provide absolute thermochemical data for phosphine binding energies in first- and second-generation ruthenium metathesis catalysts of 33.4 and 36.9 kcal/mol, respectively.
Abstract: Quantitative energy-resolved collision-induced dissociation cross-sections by tandem ESI-MS provide absolute thermochemical data for phosphine binding energies in first- and second-generation ruthenium metathesis catalysts of 33.4 and 36.9 kcal/mol, respectively. Furthermore a study of the ring-closing metathesis in the second-generation system to liberate norbornene by forming the 14-electron reactive intermediate from the intramolecular π-complex gives an estimate of the olefin binding energy to the 14-electron complex of around 18 kcal/mol, assuming a loose transition state. The results reported here are in remarkably good agreement with the latest DFT calculations using the M06-L functional.
128 citations
TL;DR: Cationic Ir complex catalyzed the addition of ortho-C-H bonds in aryl ketones to alkynes, which gave alkenylated products in good to high yield as discussed by the authors.
124 citations
TL;DR: An alternative system for the synthesis of alternating copolymers based on Grubbs-type initiators containing an unsymmetrical, chiral N-heterocyclic carbene (NHC) ligand is reported on.
Abstract: Reports on alternating copolymers prepared by metathesis copolymerization of two different monomers are relatively rare. In 2005, Chen et al. reported on the mechanismbased design of a ROMP (ring-opening metathesis polymerization) catalyst for sequence-selective copolymerization. Here, we report on an alternative system for the synthesis of alternating copolymers based on Grubbs-type initiators containing an unsymmetrical, chiral N-heterocyclic carbene (NHC) ligand. As part of our on ongoing research on ruthenium metathesis catalysts with saturated unsymmetrical NHC ligands initiator 1 was prepared from [RuCl2(PCy3)2(CHPh)] and 1-mesityl-3-((1’R)-1-phenylethyl)-4,5-dihydroimidazolium tetrafluoroborate in 90% yield. This initiator was used for the copolymerization of norbornene (NBE) and cyclooctene (COE) using a stoichiometry of 1/NBE/COE of 1:2000:100000. Reactions kinetics recorded for this copolymerization in CH2Cl2 revealed that NBE was consumed in less than 15 min. Terminating the copolymerization after 60 min in fact provided an almost perfectly alternating copolymer of NBE and COE. Unfortunately, the polymer was only partially soluble in standard solvents such as CHCl3. However, the soluble fraction showed a unimodal molecular weight distribution (PDI= 2.19), andMn = 40400 gmol 1 was found. Longer reaction times led to the formation of substantial amounts of a poly(COE) homopolymer block attached to the alternating copolymer. This homopolymer block is easily identified by NMR spectroscopy. The C NMR spectrum of the alternating copolymer (97% alternating units, d = 128–136 ppm) is shown in Figure 1. Hardly any signals for poly(NBE) or poly(COE) can be detected. The signals for the alternating copolymer are observed around d = 135.0 and 128.5 ppm. The first set of signals around d = 135.0 ppm is assigned to the C=C CH2 carbon atoms and consists of eight different signals at d = 135.28, 135.26, 135.14, 135.00, 134.98, 134.95, 134.83, and 134.80 ppm, which we attribute, without specific assignment, to the ccc, tcc, ctc, cct, ttc, tct, ctt, and ttt triads. The fact that all eight signals display roughly the same intensity is indicative for a cis content of about 50% and is in accordance with the H NMR spectrum, which shows signals of the cis and trans double bonds in a 1:1 ratio at d = 5.36 and 5.28 ppm, respectively. Such a high cis content is rather unusual for polymers prepared by Grubbs-type initiators; most display a cis/trans ratio of roughly 25:75. The less well-resolved signals around 128.5 ppm are assigned to the C=C CH2 carbon atoms and correspond to the same triads. DSC measurements of the alternating copolymer revealed a single glass transition at Tg = 50.9 8C (Dcp = 0.32 Jg )), which is in between the glass transition temperatures of poly(COE) ( 78 8C, 50% trans) and various poly(NBE)s (40–64 8C). We next turned our attention to the initiation efficiency of 1. Second-generation Grubbs-type initiators having one NHC and one phosphine ligand are known to display rather poor initiation efficiencies as a result of unfavorable ratios of the rate constants of initiation and polymerization (ki and kp, respectively). H NMR experiments carried out with 1 and either of the two monomers, that is, NBE or COE, in a 1:5 ratio in fact revealed poor initiation efficiencies of less than 1 and 3.8%, respectively. We therefore prepared the monopyridine adduct of 1, [RuCl2(Py)(1-mesityl-3-((1’R)-1-phenylethyl)-4,5-dihydroimidazolin-2-ylidene)(CHPh)] (2), in analogy to the known complex [RuCl2(Py)2(IMesH2)(CHPh)] (IMesH2 = 1,3-dimesitylimidazolidin-2-ylidene), by reaction of 1 with excess pyridine (Scheme 1). Owing to the high solubility of 2 in conventional organic solvents, purification by recrystallization was not possible. Instead, a Cu-loaded polymer-bound triphenylphosphine was used to remove the released PCy3 and isolate 2 in a pure form. The fact that only one pyridine ligand is capable of coordination to the catalyst is indicative for the significant steric demand of the NHC ligand [17] and is relevant to mechanistic considerations (vide infra). To our great delight, catalyst 2 displayed significantly improved initiation efficiencies for NBE and COE—values of Figure 1. C NMR spectrum of poly(NBE-alt-COE)n prepared with initiator 1.
115 citations
TL;DR: A new family of ruthenium-based olefin metathesis catalysts bearing a series of thiazole-2-ylidene ligands has been prepared, and theosphine-free catalysts of this family are more stable than their phosphine-containing counterparts, exhibiting pseudo-first-order kinetics in the ring-closing of diethyldiallyl malonate.
Abstract: A new family of ruthenium-based olefin metathesis catalysts bearing a series of thiazole-2-ylidene ligands has been prepared. These complexes are readily accessible in one step from commercially available (PCy_3)_2Cl_2Ru CHPh or (PCy_3)Cl_2Ru CH(o-iPrO−Ph) and have been fully characterized. The X-ray crystal structures of four of these complexes are disclosed. In the solid state, the aryl substituents of the thiazole-2-ylidene ligands are located above the empty coordination site of the ruthenium center. Despite the decreased steric bulk of their ligands, all of the complexes reported herein efficiently promote benchmark olefin metathesis reactions such as the ring-closing of diethyldiallyl and diethylallylmethallyl malonate and the ring-opening metathesis polymerization of 1,5-cyclooctadiene and norbornene, as well as the cross metathesis of allyl benzene with cis-1,4-diacetoxy-2-butene and the macrocyclic ring-closing of a 14-membered lactone. The phosphine-free catalysts of this family are more stable than their phosphine-containing counterparts, exhibiting pseudo-first-order kinetics in the ring-closing of diethyldiallyl malonate. Upon removing the steric bulk from the ortho positions of the N-aryl group of the thiazole-2-ylidene ligands, the phosphine-free catalysts lose stability, but when the substituents become too bulky the resulting catalysts show prolonged induction periods. Among five thiazole-2-ylidene ligands examined, 3-(2,4,6-trimethylphenyl)- and 3-(2,6-diethylphenyl)-4,5-dimethylthiazol-2-ylidene afforded the most efficient and stable catalysts. In the cross metathesis reaction of allyl benzene with cis-1,4-diacetoxy-2-butene increasing the steric bulk at the ortho positions of the N-aryl substituents results in catalysts that are more Z-selective.
114 citations
TL;DR: In this paper, the synthesis and characterization of novel bimetallic, neutrally charged dinickel 2,7-diimino-1,8-dioxynaphthalene polymerization catalysts is reported.
103 citations
TL;DR: Mechanistic studies do not favor an olefin coordination mechanism but are instead consistent with a mechanism involving sulfonamide coordination and generation of an acidic proton that is transferred to the norbornene.
Abstract: Hydroaminations of norbornene with arylsulfonamides and weakly basic anilines were achieved using electrophilic Pt(II) bis(triflate) complexes of the type L2Pt(OTf)2 (L2 = tBu2bpy, tBuC6H4N═C(CH3)C(CH3)═NC6H4tBu, (C6H5)2PCH2CH2P(C6H5)2, (C6F5)2PCH2CH2P(C6F5)2, S-BINAP). Pseudo-first-order kinetics reveal little to no dependence of the reaction rate on the ancillary ligand. Mechanistic studies do not favor an olefin coordination mechanism but are instead consistent with a mechanism involving sulfonamide coordination and generation of an acidic proton that is transferred to the norbornene. It is postulated that the resulting norbornyl cation is then attacked by free sulfonamide, and loss of proton from this adduct completes the hydroamination. The platinum−sulfonamide complex readily undergoes deprotonation to give a μ-amido platinum-bridged dimer that was isolated from the reaction solution. These studies also involve use of Me3SiPh and Me3SnPh as non-nucleophilic proton traps. Cleavage of the Ph−E bonds w...
101 citations
TL;DR: In this article, the authors reported a facile strategy for the preparation of a novel well-defined brush copolymer with two different grafts distributed on the same unit along the backbone via combination of three controlled polymerization methods, including ring-opening polymerization (ROP), ring opening metathesis polymerization, and atom transfer radical polymerization.
Abstract: This work reports a facile strategy for the preparation of a novel well-defined brush copolymer with two different grafts distributed on the same unit along the backbone via combination of three controlled polymerization methods, ring-opening polymerization (ROP), ring-opening metathesis polymerization (ROMP), and atom transfer radical polymerization (ATRP) based on the synthesis of the heterotrifunctional inimer, 2-hydroxymethyl-3-(2-bromoisobutyryloxymethyl)-5-norbornene (NBE-OH/Br). ROP of e-caprolactone initiated by NBE-OH/Br was carried out to generate macroinimer, norbornene-graft-poly(e-caprolactone)/Br (NBE-g- PCL/Br). The grafting-through strategy was then employed to construct the polymer backbone, poly(norbornene)-graft-poly(e-caprolactone)/Br (PNBE-g-PCL/Br) via ROMP of the norbornene-terminated macroinimer NBE-g-PCL/Br. Finally, the grafting-from route was used for the synthesis of amphiphilic grafted brush copolymer, poly(norbornene)-graft-poly(e-caprolactone)/poly(2-(dimethylamino)ethyl met...
97 citations
TL;DR: A series of nickel(II) hydride complexes supported by amido diphosphine ligands, including symmetrical [N(o-C6H4PR2)2]− ([R-PNP]−; R = Ph, iPr, Cy) and unsymmetrical [n(o]-C 6H4PPh2)(o-c6H 4PiPr2)]− ([Ph-PNPs-iPr]−], have been prepared for the investigation of olefin insertion chemistry as discussed by the authors.
TL;DR: In this article, four new sulfur-containing monomers consisting of cyclic dithiocarbonate, norbornene, and (meth)acrylate units were synthesized to develop high refractive index polymers with high Abbe's numbers.
Abstract: Four new sulfur-containing monomers consisting of cyclic dithiocarbonate, norbornene, and (meth)acrylate units were synthesized to develop high refractive index polymers with high Abbe’s numbers fo...
TL;DR: The C-H bond of a terminal alkyne adds to a carbon-carbon double bond of 1,3-dienes, styrenes, and norbornene at room temperature in the presence of a nickel catalyst to give branched hydroalkynylation products in good yields.
Abstract: The C−H bond of a terminal alkyne adds to a carbon−carbon double bond of 1,3-dienes, styrenes, and norbornene at room temperature in the presence of a nickel catalyst in regio- and stereoselective manners. Reaction of triisopropylsilylacetylene with 1-substituted 1,3-butadiene derivatives afforded hydroalkynylation products via introduction of a hydrogen atom and a triisopropylsilylethynyl group to 4- and 3-positions of the dienes, respectively. Likewise, 1-triisopropylsiloxy-1,3-butadiene, 1,3-pentadiene, 1-cyclohexen-1-yl-1,3-butadiene, and 1,3-cyclohexadiene underwent the hydroalkynylation reaction, giving the corresponding 1,4-enyne derivatives in good yields at room temperature. Reaction of p-substituted styrene with triisopropylsilylacetylene also proceeded in the presence of the nickel catalyst, giving the branched hydroalkynylation products in good yields. Norbornene gave a exo-addition product in good yield under the same reaction conditions.
TL;DR: Internal olefins, cis-cyclooctene and norbornene, react with (dpms)PtII(OH)(ethene) in water to produce PtII oxetanes or hydroxo olefin complexes that undergo direct C(sp3)−O reductive elimination of ole Finish oxides in various solvents and in the solid-state that is unprecedented for PtIV.
Abstract: Internal olefins, cis-cyclooctene and norbornene, react with (dpms)PtII(OH)(ethene) in water to produce PtII oxetanes (norbornene) or hydroxo olefin complexes (cis-cyclooctene); both produce anionic PtII oxetanes in basic solutions; their subsequent aerobic oxidation cleanly furnishes corresponding PtIV oxetanes that undergo direct C(sp3)−O reductive elimination of olefin oxides in various solvents and in the solid-state that is unprecedented for PtIV.
TL;DR: In this paper, a simple one-pot procedure for the catalytic preparation of the biologically interesting class of carbazoles was proposed. But this procedure is based on the combined catalysis of palladium and norbornene starting from o-substituted iodoarenes and N-sulfonylated or N-acetylated o-bromoanilines.
Abstract: The present paper offers a synthetically simple one-pot procedure for the catalytic preparation of the biologically interesting class of carbazoles. The new procedure is based on the combined catalysis of palladium and norbornene starting from o-substituted iodoarenes and N-sulfonylated or N-acetylated o-bromoanilines. A well-known member of this class, carbazomycin A, has been successfully prepared.
TL;DR: In this article, five vanadium(III) complexes have been synthesized and characterized, in the presence of ethyl trichloroacetate (ETA) as a promoter, which are highly active precatalysts for ethylene polymerization and produce high molecular weight and linear polymers.
Abstract: Five novel vanadium(III) complexes [PhN = C(R-2)CHC(R-1)O]VCl2(THF)(2) (4a: R-1 = Ph, R-2 = CF3; 4b: R-1 =t-Bu, R-2 = CF3; 4c: R-1 = CF3, R-2 = CH3; 4d: R-1 = Ph, R-2 = CH3; 4e: R-1 = Ph, R-2 = H) have been synthesized and characterized. On activation with Et2AlCl, all the complexes, in the presence of ethyl trichloroacetate (ETA) as a promoter, are highly active precatalysts for ethylene polymerization, and produce high molecular weight and linear polymers. Catalyst activities more than 16.8 kg PE/mmolv h bar and weight-average molecular weights higher than 173 kg/ mol were observed under mild conditions.
TL;DR: In this article, a poly(norbornene) with pendant imidazolium moieties and three different counter anions, i.e. poly[exo,endo-5-norbornenes-2-yl-carboxyethyl-3-ethylimidazolishexafluorophosphate] bis(trifluoromethylsulfonyl)imide, poly(exo-5)-norbornenene-2.
Abstract: Poly(norbornene)s with pendant imidazolium moieties and three different counter anions, i.e. poly[exo,endo-5-norbornene-2-yl-carboxyethyl-3-ethylimidazolium bis(trifluoromethylsulfonyl)imide], poly(exo,endo-5-norbornene-2-yl-carboxyethyl-3-ethylimidazolium tetrafluoroborate), and poly(exo,endo-5-norbornene-2-yl-carboxyethyl-3-ethylimidazolium hexafluorophosphate) were prepared via ROMP using ionic liquids as the reaction medium. The ionic polymers possessed M w in the range 8.1-44 x 10 3 and ionic conductivity up to 1.13 x 10 -5 and 1.44 x 10 -4 S cm -1 at 20 and 50°C, respectively. The solubility of the new polymeric ionic liquids, their thermal stability and their glass transition temperatures were investigated in detail. Ionic conductivities were found to depend on the nature of the counter-anion and on the polymers' glass transition temperature rather than its molecular weight.
TL;DR: In this paper, the authors studied the hydrogenation of dicyclopentadiene (DCPD) over nickel alloy catalyst SRNA-4 and showed that the reaction is a consecutive process with two hydrogenated intermediates.
TL;DR: In this article, a vanadium−alkylidene complex, V(CHSiMe3)(NAr)(O-2,6-iPr2C6H3)(PMe3)x (3, x = 0.89), has been isolated when the C6D6 solution containing 2b was heated at 80 °C in the presence of PMe3 (5.0 equiv).
TL;DR: In this paper, the organochalcogen ligands derived from 3-methylimidazole-2-thione/selone groups mbit (2a), mbis (2b), ebit(2c), and ebis (2d) were synthesized and characterized.
Abstract: The organochalcogen ligands (S, Se) derived from 3-methylimidazole-2-thione/selone groups mbit (2a), mbis (2b), ebit (2c), and ebis (2d) [mbit = 1,1′-methylenebis(1,3-dihydro-3-methyl-2H-imidazole-2-thione), mbis = 1,1′-methylenebis(1,3-dihydro-3-methyl-2H-imidazole-2-selone), ebit = 1,1′-(1,2-ethanediyl)bis(1,3-dihydro-3-methyl-1H-imidazole-2-thione), ebis = 1,1′-(1,2-ethanediyl)bis(1,3-dihydro-3-methyl-1H-imidazole-2-selone)] were synthesized and characterized. Mononuclear NiII complexes NiBr2mbit (3a), NiBr2mbis (3b), NiBr2ebit (3c), and NiBr2ebis (3d) were obtained by the reactions of Ni(PPh3)2Br2 with 2a, 2b, 2c, and 2d, respectively. However, when the corresponding ligands 2a, 2b, 2c, and 2d were treated with CoCl2 in thf solution CoII 1D coordination polymers (CoCl2mbit)n (4a), (CoCl2mbis)n (4b), (CoCl2ebit)n (4c), and (CoCl2ebis)n (4d) were obtained. All compounds were fully characterized by IR spectroscopy and elemental analysis. The crystal structures of 2c, 3a, 3b, 3c, 4a, 4b, and 4c were determined by X-ray crystallography. The local geometry around the nickel atom in complexes 3a–c was distorted tetrahedron with coordinated S(Se) and two Br atoms, and the organochalcogen ligands form an eight- or a nine-membered ring with the nickel atom included. The cobalt atom coordination polymers 4a and 4b coexist as left-handed and right-handed helical chains, but 4c formed a zigzag chain with a CH3CN solvent molecule taken up in the channel structure. After activation with methylaluminoxane (MAO), the nickel complexes exhibited high activities for addition polymerization of norbornene (1.42 × 108 g PNBmol–1 Nih–1 for 3a). The effects of the Al/Ni ratio, reaction temperature, and reaction time to norbornene polymerization were also investigated.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
TL;DR: In this paper, a ring-opening metathesis using a ruthenium−carbene catalyst was used to synthesize and polymerize poly(1)−poly(3) polymers.
Abstract: TEMPO-containing norbornene monomers 1−8 (TEMPO = 2,2,6,6-tetramethylpiperidine-1-oxy) were synthesized and polymerized via ring-opening metathesis using a ruthenium−carbene catalyst. The TEMPO moiety did not inhibit the polymerization, and the monomers gave corresponding polymers in good to high yields. Poly(2) and poly(3) were soluble in common solvents and possessed high molecular weight, while other polymers were insoluble. The resulting polymers were thermally stable up to ca. 240 °C according to TGA measurements in air. In the case of poly(1)−poly(3), the charge/discharge capacities of the polymer-based cells were largely dependent on the spatial arrangement of the two TEMPO moieties on each repeating unit. Quite interestingly, the capacity of the poly(2)-based cell reached its theoretical value (109 A h/kg), and a large capacity (>90 A h/kg) was retained even at high current densities up to 6 A/g, indicating the possibility of very fast charging (within 1 min). The cells utilizing the present polym...
TL;DR: In this paper, a facile reaction of o-alkylated aryl iodides, o-bromoarenesulfonylanilines and activated olefins in the presence of palladium and norbornene as catalysts is presented.
Abstract: Selectively substituted phenanthridine derivatives are obtained by a facile reaction of o-alkylated aryl iodides, o-bromoarenesulfonylanilines and activated olefins in the presence of palladium and norbornene as catalysts. The reaction takes place under mild conditions to give the products in satisfactory yields using readily available starting materials.
TL;DR: Ni(II) and Pd(II)-X complexes based on N-((1H-pyrrol-2-yl)methylene)-2-(diphenylphosphino)benzenamine were synthesized and characterized X-ray diffraction studies on complexes 1, 2, and 4 revealed that N, N, P, and halogen atoms coordinated to metal, with distorted square planar geometries in all cases as mentioned in this paper.
TL;DR: In this paper, Picolyl, pyridine, and methyl functionalized N-heterocyclic carbene iridium complexes [Cp∗Ir(C^N)Cl]Cl (4, C^N = 3-Methyl-1-picolyimidazol-2-ylidene), [cp ∗IrClCl2]Cl(5, C-N = 1,3-dimethylimidazolate-2]-Cl(6, L = 1.3dimethylamidazoline-
TL;DR: In this paper, the synthesis of novel tetracyclic fused pyrroles from 1-(2-iodophenyl)-1H-pyrrole and various bromoalkyl-aryl alkynes via a palladium(0)-catalyzed and norbornene-mediated threefold domino reaction is reported.
TL;DR: In this article, the authors measured the transport parameters of poly(trimethylsilyl norbornene) (PTMSN) using gas chromatographic and mass spectrometric methods for different gases (H 2, He, O 2, N 2, CO 2, CH 4, C 2 H 6, C 3 H 8 and n -C 4 H 10 ).
TL;DR: In this article, the synthesis of poly(ethylene oxide) macromonomers with a norbornene and oxanorbornene end group was presented, which were polymerized to comb-polymers by ring-opening metathesis polymerization (ROMP) using Grubbs' Catalyst G3 to produce water soluble polymers with polydispersities between 1.04 and 1.30.
Abstract: The synthesis of three different poly(ethylene oxide) macromonomers with a norbornene and oxanorbornene end group is presented. The macromonomers were polymerized to comb-polymers by ring-opening metathesis polymerization (ROMP) using Grubbs' Catalyst G3 to produce water soluble polymers with polydispersities between 1.04 and 1.30 and molecular weights between 14,000 and 50,000 g/mol. Characterization by static and dynamic light scattering reveals that the comb-polymers with norbornene backbone are molecularly disperse in aqueous solution, while the oxanorbornene-backbone polymers form small water-soluble aggregates.
TL;DR: In this paper, a commercial norbornyl-functionalized linseed oil, blended with a bicyclic norbornene-based crosslinking agent, undergoes ring-opening metathesis polymerization with the 1st generation Grubbs' catalyst to form a biorenewable polymer network.
Abstract: A commercial norbornyl-functionalized linseed oil, blended with a bicyclic norbornene-based crosslinking agent (at loadings ranging from 0 to 50 wt %) undergoes ring-opening metathesis polymerization with the 1st generation Grubbs' catalyst to form a biorenewable polymer network. Comonomers are characterized, the thermal and mechanical properties of the cured systems are investigated by dynamic mechanical analysis, and thermal decomposition is evaluated by thermogravimetric analysis. The resin is shown to consist of a modified linseed oil and small oligomers of cyclopentadiene. Broad tan δ peaks suggest inhomogeneous phase morphologies, which result in complex crosslinking behaviors. The thermal stability of the polymers increases with increasing crosslinker content.
TL;DR: In this paper, ring-opening metathesis polymerization (ROMP) was used to synthesize novel norbornene based polycarboxy-based polysulfobetaines using the third generation Grubbs’ catalyst (G3) as the initiator.
Abstract: Ring-opening metathesis polymerization (ROMP) was used to synthesize novel norbornene based polycarboxy- (d-Poly 3a and d-Poly 3b) and polysulfobetaines (Poly 3c) using the third generation Grubbs’ catalyst (G3) as the initiator. Hydrophobicity of the polycarboxybetaines was varied by changing the bridging group of the norbornene backbone. A protective group approach was utilized to prevent any possible retardation in the polymerization due to interactions of the carboxylate functionality with the catalyst and to provide ease of characterization. The tert-butyl ester protected precursor polymers (Poly 3a and Poly 3b) were deprotected under acidic conditions to yield the corresponding polycarboxybetaines with very narrow polydispersity indices, ranging from 1.03 to 1.15. This method allowed excellent control over the molecular weight distributions compared to the direct polymerization approach. When molecular weight was plotted against the theoretical degree of polymerization (DP), linear relationships wer...