Showing papers on "Ring-opening metathesis polymerisation published in 1997"
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01 Jan 1997
TL;DR: The metal carbene/metallacyclobutane mechanism has been studied extensively in the literature as mentioned in this paper, with a focus on the use of a ring-opening metathesis.
Abstract: Preface. Abbreviations. Introduction: The Olefin Metathesis Reaction. Brief History. The Metal Carbene Mechanism. Equilibria and Stereoselectivity. Survey of Catalyst Systems: Group IV. Group V. GroupVI. Group VII. Group VIII. Photochemically Activated Catalysts. The Metal Carbene/Metallacyclobutane Mechanism: Evidence from Cross-Metathesis Reactions. Evidence from the Stereochemistry of Metathesis of Internal Olefins. Evidence from Ring-Opening Metathesis Polymerization (ROMP). Evidence from the reactions of Well-Defined Metal Carbene Complexes. Evidence from the Reactions of Metallacyclobutane Complexes. Evidence of Initiating Species in Systems with Non-Carbene Catalysts. Theoretical Treatments. Related Reactions: [2+2] Reactions Between Compounds Containing Multiple Bonds. Relationship to Ziegler-Natta Polymerization. Involvement of Three-Membered Ring Compounds in Metathesis Reactions. Ethene and Terminal Alkenes: Ethene. Propene. But-1-ene and its Derivatives. Pent-1-ene and its Derivatives. Hex-1-ene and its Derivatives. Higher Acyclic Terminal Alkenes. Acyclic Disubstituted and Trisubstituted Ethenes. Cis/trans Isomerization. Pent-2-ene and 4-Substituted Derivatives. Hex-2-ene and 4-Methylhex-2-ene.Hept-2-ene and Hept-3-ene. Higher Acyclic Internal Olefins. Stereoselectivity in the Metathesis of Acyclic Olefins. 1,1-Disubstituted Olefins. Trisubstituted Ethenes. Acyclic Functionalized Alkenes: Esters. Other Carbonyl-Containing Compounds. Ethers. Amines. Nitriles. Chlorides and Bromides. Sulfides and Sulfonates. Silancs and Germanes. Phospanes. Acyclic Dienes: Double Bonds Linked only by C Atoms. Double Bonds Linked by C and Si, Ge orSn Atoms. Double Bonds Linked by C and N Atoms. Double Bonds Linked by C, Si, and O Atoms. Divinylferrocene. Some Further Applications in Organic Synthesis. Copolymers by Metathesis Condensation. Cross-Metathesis Between Acyclic Compounds: Ethene.Propene. Butenes. Pentenes. Hexenes. Higher Olefins. Functionalized Olefins. Acetylenes: Metathesis Reactions Involving Total Cleavage of the C=C bond. Metathesis Reactions Involving Cleavage of Two of the thress C=C Bonds. Metathesis Reactions of Enynes and Dienynes. Other Metathesis Routes to Polyacetylenes. Ring-Opening Metathesis Polymerization: General Aspects: Thermodynamic Aspects. Efficiency of Initiation. The Use of Chain-Transfer Agents. Molecular Weight Distributions. Polymer Micostructure. Monocyclic Alkenes and Polyenes: Four-Membered Rings. Five-Membered Rings. Six-Membered Rings. Seven-Membered Rings. Eight-Membered Rings. Nine-Membered Rings. Ten-Membered Rings. Twelve-Membered and Other Rings. Polycyclic Alkenes: Monomers Containing a Fused Cyclobutene Ring. Monomers Containing a Fused Cyclopentene Ring and One Double Bond. Monomers Containing a Fused Cyclopentene Ring and More than One Double Bond. Bicyclo[2.2.1] Compounds Containing Heteroatoms in the Ring System. Other Bicyclic Compounds. Copolymers of Cycloalkenes: Direct Metathesis Copolymerization. Cyclic Co-Oligomers. Block Copolymers by Sequential Addition of Monomers to Living Systems. Block Copolymers by Modification of Homopolymers. Comb and GraftCopolymers. Copolymers by ROMP in Conjunction with Radical Reactions. Cross-Metathesis Between Cyclic and Acyclic Olefins: End-Groups and Telomers. Dependence of Molecular Weight on [M 2]/[M 1]. Kinetic Data. Degradation of UnsaturatedPolymers by Metathesis: Degradation by Intramolecular Metathesis. Applications of the Olefin Metathesis Reaction: The Phillips Triolefin Process. The Neohexene Process. The Shell Higher Olefins Process. Other Multistage Processes Involving Metathesis. The Isoamylene Process. (Circle around alpha and omega) ((-Diolefins. trans-Poly(1-Pentenylene). trans-Poly(1-octenylene). Polymers of Norhornene. Polymers of Norbornene Derivatives. Miscellaneous. Bibliography. Subject Index.
841 citations
TL;DR: Olefin metathesis as discussed by the authors is a metal-catalyzed exchange of alkylidene moieties between alkenes, which can induce both cleavage and formation of CC double bonds.
Abstract: Transition metal catalyzed CC bond formations belong to the most important reactions in organic synthesis. One particularly interesting reaction is olefin metathesis, a metal-catalyzed exchange of alkylidene moieties between alkenes. Olefin metathesis can induce both cleavage and formation of CC double bonds. Special functional groups are not necessary. Although this reaction—which can be catalyzed by numerous transition metals—is used in industry, its potential in organic synthesis was not recognized for many years. The recent abrupt end to this Sleeping-Beauty slumber has several reasons. Novel catalysts can effect the conversion of highly fictionalized and sterically demanding olefins under mild reaction conditions and in high yields. Improved understanding of substrate–catalyst interaction has greatly contributed to the recent establishment of olefin metathesis as a synthetic method. In addition to the preparation of polymers with fine-tuned characteristics, the metathesis today also provides new routes to compounds of low molecular weight. The highly developed ring-closing metathesis has been proven to be key step in the synthesis of a growing number of natural products. At the same time interesting applications can be envisioned for newly developed variants of bimolecular metathesis. Improvements in the selective cross-metathesis of acyclic olefins as well as promising attempts to include alkynes as viable substrates provide for a vivid development of the metathesis chemistry.
745 citations
TL;DR: Several ruthenium-based olefin metathesis catalysts of the formula (PR3)2X2RuCHCHCPh2 have been synthesized, and relative catalyst activities were determined by monitoring the ring-closing met athesis of the acyclic diene diethyl diallylmalonate as discussed by the authors.
Abstract: Several ruthenium-based olefin metathesis catalysts of the formula (PR3)2X2RuCHCHCPh2 have been synthesized, and relative catalyst activities were determined by monitoring the ring-closing metathesis of the acyclic diene diethyl diallylmalonate. The following order of increasing activity was determined: X = I < Br < Cl and PR3 = PPh3 ≪ PiPr2Ph < PCy2Ph < PiPr3 < PCy3. Additional studies were conducted with the catalyst (PCy3)2Cl2RuCH2 to probe the mechanism of olefin metathesis by this class of catalysts. The data support a scheme in which there are two competing pathways: the dominant one in which a phosphine dissociates from the ruthenium center and a minor one in which both phosphines remain bound. Higher catalyst activites could be achieved by the addition of CuCl to the reaction.
631 citations
TL;DR: In this article, the effects of arene and phosphine ligands and of the solvent on polynorbornene and polyoctenamer molecular weight distributions and microstructures were investigated.
Abstract: Highly active catalyst systems for the ring-opening metathesis polymerization (ROMP) of strained (norbornene) and low-strain (cyclooctene) olefins are readily prepared from RuCl2(arene)(PR3) precursors (directly available by addition of a phosphine to the stable [(arene)RuCl2]2 dimers) after activation with (trimethylsilyl)diazomethane. Durene or p-cymene as arene ligands, together with a sterically demanding basic phosphine (typically tricyclohexylphosphine), promoted the formation of the most active polymerization catalysts. The effects of arene and phosphine ligands and of the solvent on polynorbornene and polyoctenamer molecular weight distributions and microstructures were investigated. The excellent functional group compatibility of the catalyst system was illustrated by the synthesis of a variety of polyoctenamers bearing epoxide, acid, ether, ester, acetal, and bromine functionalities. The polymers were isolated in quite good yields. The striking positional influence of the functional group on the...
181 citations
TL;DR: In this paper, it is shown that amphiphilic branched structures of hitherto unreported topologies can be prepared by living ring-opening metathesis polymerization (ROMP) of miscellaneous macromonomers, provided the latter polymers carry an end-standing norbornene unsaturation.
Abstract: In this study the possibilities offered by “living” ring-opening metathesis polymerization (ROMP) are exploited to engineer novel macromolecular architectures. It is indeed shown that amphiphilic branched structures of hitherto unreported topologies can be prepared by ROMP of miscellaneous macromonomers, provided the latter polymers carry an end-standing norbornene unsaturation. Janus-type architectures are, for instance, accessible by sequential ROMP of polystyrene (PS) and poly(ethylene oxide) (PEO) macromonomers; other original branched structures, whose topology makes them particularly attractive for applications such as unimolecular micelles or associative thickeners, can be obtained through homopolymerization of macromonomers based on PS-b-PEO diblock copolymers.
170 citations
TL;DR: In this paper, the polymerization of cyclooctadiene (COD) in the presence of an allylic difunctionalized chain transfer agent (1) by a ruthenium metathesis catalyst (Ru) was accomplished.
Abstract: The polymerization of cyclooctadiene (COD) in the presence of an allylic difunctionalized chain transfer agent (1) by a ruthenium metathesis catalyst (Ru) was accomplished. Deprotection of the resulting acetate end-functionalized polybutadiene was performed, leading to commercially important 1,4-hydroxytelechelic polybutadiene (HTPBD) with number average functionalities close to 2.0. The polymerizations were performed at high monomer concentrations or in the absence of solvent, and the robust nature of Ru allowed the use of high monomer to catalyst ratios (∼0.01 mol % Ru relative to total olefin). Investigation of the metathesis of olefin alcohols with Ru showed that side reactions may complicate the use of these compounds as chain transfer agents in metathesis polymerizations. The kinetics of this Ru-catalyzed ring-opening metathesis polymerization with added chain transfer agent was also investigated.
166 citations
149 citations
TL;DR: A general method of transformation of living ring-opening metathesis polymerization (ROMP) into controlled/living atom transfer radical polymerization for the preparation of block copolymers is reported in this article.
Abstract: A general method of transformation of living ring-opening metathesis polymerization (ROMP) into controlled/“living” atom transfer radical polymerization (ATRP) is reported for the preparation of block copolymers. For example, the macroinitiators PNB−C6H4−CH2Br (Mn = 30 520, Mw/Mn = 1.09) or PDCPD−C6H4−CH2Br (Mn = 12 100, Mw/Mn = 1.24) were prepared by ROMP of norbornene (NB) or dicyclopentadiene (DCPD) and subsequent Wittig-like reactions with p-(bromomethyl)benzaldehyde. These compounds were used as efficient macroinitiators for homogeneous controlled/“living” ATRP to prepare block copolymers with styrene (St), PNB-b-PSt (Mn = 110 400, Mw/Mn = 1.06) and PDCPD-b-PSt (Mn = 20 100, Mw/Mn = 1.37), and methyl acrylate (MA), PNB-b-PMA (Mn = 85 100, Mw/Mn = 1.07) and PDCPD-b-PMA (Mn = 25 300, Mw/Mn = 1.47).
141 citations
140 citations
TL;DR: The use of various enantiopure amino acid-derived diolefins as substrates for the ring closing olefin metathesis reaction (RCM) has been investigated as mentioned in this paper.
125 citations
TL;DR: In this paper, a process for the production of chemical products by means of a metathesis reaction of olefins in the presence of homogeneous or heterogeneous reactive metal catalysts (I) in a reaction medium consisting of compressed carbon dioxide is claimed.
Abstract: A process for the production of chemical products by means of a metathesis reaction of olefins in the presence of homogeneous or heterogeneous metathesis reactive metal catalysts (I) in a reaction medium consisting of compressed carbon dioxide is claimed.
TL;DR: The vinylene-bridged ansa-ferrocene complex was synthesized by the McMurry coupling of 1,1' -ferrocenedicarbaldehyde as discussed by the authors.
TL;DR: In this article, nearly monodisperse CdSe nanoclusters, surface-passivated with a layer of trio-ctylphosphine and trio-cycled phosphine oxide, have been sequestered within phosphine-containing domains in a diblock copolymer.
Abstract: Nearly monodisperse CdSe nanoclusters, surface-passivated with a layer of trioctylphosphine and trioctylphosphine oxide, have been sequestered within phosphine-containing domains in a diblock copolymer. A convergent approach to fabrication of these composites was adopted via independent synthesis of nanoclusters and polymer. Diblock copolymers of phosphine- or phosphine oxide-functionalized monomers and methyltetracyclododecene (MTD) were prepared by ring opening metathesis polymerization using Mo alkylidene initiators. Nanoclusters were prepared by pyrolysis of CdMe2 and SeP(octyl)3 in the presence of P(octyl)3 and OP(octyl)3. An immediate and sustained increase in electronic passivation is found for nanoclusters incorporated into octylphosphine-containing polymers. In contrast, nanoclusters in pure hydrocarbon or phosphine oxide-containing polymers rapidly lose passivation. Films of nanoclusters in a phosphine-containing polymer matrix were static cast from dilute solution. Under suitable conditions, th...
TL;DR: In this article, the synthesis and living ring-opening metathesis polymerization (ROMP) of substituted cyclobutenes were investigated with the functional group tolerant initiators (PCy3)2Cl2RuCHCHCPh2 (1) and (PCY3) 2Cl 2RuCHPh (2).
Abstract: The synthesis and living ring-opening metathesis polymerization (ROMP) of substituted cyclobutenes were investigated with the functional group tolerant initiators (PCy3)2Cl2RuCHCHCPh2 (1) and (PCy3)2Cl2RuCHPh (2). Synthetic methodology was developed for the synthesis of a wide variety of 3-functionalized cyclobutenes containing ether, ester, alcohol, amine, amide, and carboxylic acid substituents. Coordination of these functional groups to the propagating carbene was observed, resulting in the formation of a chelated propagating species with concomitant loss of one phosphine ligand from the metal center. Studies aimed at understanding this chelation and its effect on the polymerization were undertaken. On the basis of these results, the synthesis of a series of functionalized cyclobutenes was accomplished which minimized this chelation and allowed for living polymerizations. A new class of functionalized poly(butadiene)s were synthesized and their thermal properties analyzed by thermogravimetric analysis ...
TL;DR: In this article, the synthesis of the monomer exo,exo-5,6-bis, containing two tapered monodendrons and its living ring-opening metathesis polymerization initiated with RuCl2(CHPh)(PCy3)2 is discussed.
Abstract: The synthesis of the monomer exo,exo-5,6-bis[[[(3,4,5-tris((4-(dodecyl-1-oxy)benzyl)oxy)]benzyl)oxy]carbonyl]-7-oxabicyclo[2.2.1]hept-2-ene (4), containing two tapered monodendrons and its living ring-opening metathesis polymerization initiated with RuCl2(CHPh)(PCy3)2 are discussed. Oligomers and polymers with narrow molecular weight distribution (Mw/Mn = 1.06−1.29) and degrees of polymerization (DP) from 6 to 120, which correspond to Mn from 12 600 to 252 800, were synthesized and characterized. The monomer (4) and the corresponding polymers (5) self-assemble into disklike and cylindrical shapes which produce an enantiotropic hexagonal columnar (Φh) liquid crystalline (LC) phase. The analysis of the Φh phase of the monomer, oligomers, and polymers as a function of the DP reveals four regions and mechanisms for the generation of the Φh phase, i.e., below the DP which forms a disklike molecule, below the DP which corresponds to the maximum length of a disklike molecule (DP = 26), up to the DP which corresp...
TL;DR: In this paper, the ring-closing metathesis of silyl ether connected dienes using molybdenum and ruthenium alkylidene catalysts is described.
TL;DR: In this paper, the effect of backbone rigidity on mesomorphism was investigated by differential scanning calorimetry (DSC) and powder diffraction X-ray scattering.
Abstract: Discotic liquid crystalline polymers bearing alkoxy-substituted triphenylene moieties in the side-chain were synthesized by ring-opening metathesis polymerization using a well-defined ruthenium initiator. To elucidate the effect of backbone flexibility on the mesomorphism, norbornene and cyclobutene monomers containing triphenylene moieties were synthesized, which yielded the relatively rigid poly(norbornene)s and the more flexible poly(butadiene)s, respectively, after polymerization. To further increase the backbone flexibility, the poly(butadiene)s were hydrogenated using Crabtree's catalyst to yield triphenylene-substituted poly(butane)s. The mesomorphic behavior of the polymers has been investigated by differential scanning calorimetry (DSC) and powder diffraction X-ray scattering (wide angle X-ray scattering, WAXS). All polymers bearing a 2,3,6,7,19-pentakis(decyloxy)triphenylene-based mesogenic unit exhibit enantiotropic discotic hexagonal mesophases, while the pentoxy analogues do not display liquid crystalline behavior. No effect of backbone rigidity on the mesomorphism could be detected.
TL;DR: In this paper, a ring-opening-metathesis suspension polymerization of 1,4,4a,5,8,8a-hexahydro was used for the modular, molecular design of stationary phases, and the resulting crosslinked polymers were investigated in terms of influence of the polymerization sequence as well as of the stoichiometries I/II and II/III on swelling behavior, surface area, capacity, accessability of the functional groups, and their possible use in SPE, respectively.
Abstract: Ring-opening-metathesis polymerization (ROMP) was used for the modular, molecular design of stationary phases. New materials for solid-phase extraction (SPE) as well as for air and water clean-up have been prepared by ring-opening-metathesis suspension polymerization of 1,4,4a,5,8,8a-hexahydro-1,4,5,8-exo,endo-dimethanonaphthalene (I) and its copolymerization with the functional monomer endo,endo[2.2.1]bicyclohept-2-ene-5,6-dicarboxylic anhydride (II), using the well-defined Schrock catalyst Mo(N-2,6-i-Pr2-C6H3)CHCMe2Ph(OCMe(CF3)2)2 (III). The resulting cross-linked polymers have been investigated in terms of influence of the polymerization sequence as well as of the stoichiometries I/II and II/III on swelling behavior, surface area, capacity, accessability of the functional groups, and their possible use in SPE, respectively. In order to obtain further information about the new resins, the microstructure of poly(II) was determined by NMR techniques. Investigations revealed that it represents an all cis, ...
01 Jan 1997
TL;DR: In this article, the effect of ring size on polymerizability and the formation of cyclic oligomers was discussed, and the boundary between polymerizabilty and non-polymerizability was defined for ring-opening metathesis polymerization.
Abstract: This chapter discusses general aspects of the group of metathesis reactions, such as the effect of ring size on polymerizability, the formation of cyclic oligomers, living systems, molecular weight distributions, and stereochemistry For addition polymerization processes of any kind, of which ring-opening metathesis polymerization (ROMP) is a particular case, the boundary between polymerizabilty and nonpolymerizabilty, corresponding to ∆G negative and positive respectively, is very distinct Metal carbene complexes used as initiators (I) are not always fully consumed before the monomer (M) has been completely polymerized This can happen when the propagation rate constant kp is somewhat greater than the initiation rate constant ki In nonliving systems, the initiating species may be generated over a period of time, and the termination reactions are generally not well defined In some cases, there will also be backbiting reactions leading to the formation of cyclic oligomers
TL;DR: The effect of backbone flexibility on the mesomorphic behavior of side-chain liquid crystalline polymers synthesized by ring-opening metathesis polymerization was investigated in this paper.
Abstract: The effect of backbone flexibility on the mesomorphic behavior of side-chain liquid crystalline polymers synthesized by ring-opening metathesis polymerization was investigated The synthesis of norbornene and cyclobutene monomers containing a p-nitrostilbene moiety as the mesogenic group and polymerization of these monomers to produce side-chain liquid crystalline polymers with low polydispersities and defined molecular weights was accomplished The relatively rigid poly(norbornene)s displayed enantiotropic nematic mesomorphism with glass transitions from 44 to 64 °C and isotropization temperatures between 108 and 121 °C, whereas the more flexible poly(butadiene)s showed enantiotropic smectic A mesomorphism with glass transition temperatures from 14 to 31 °C and isotropization temperatures between 74 and 111 °C A diblock copolymer containing a 1:1 mixture of the poly(norbornene) and poly(butadiene) also exhibited a smectic A mesophase, clearly demonstrating the dominance of the poly(butadiene) backbone
TL;DR: In this article, a ring-opening metathesis polymerization (ROMP) was used to synthesize poly(1,4-phenylenevinylenes) (PPVs) by aromatizing the cyclohexadiene rings using 2,3-dichloro-5,6-dicyano-1, 4-benzoquinone (DDQ).
Abstract: 2,3-Dicarboxybicyclo[2.2.2]octa-2,5,7-triene (barrelene) monomers (4a,b) were synthesized by a novel route and then polymerized by ring-opening metathesis polymerization (ROMP). Complete initiation of the ROMP initiator (5) and living polymerization of monomer 4b were achieved by tuning the activity of 5 with hexafluoro-tert-butanol (HFB) and tetrahydrofuran (THF). The precursor polymers (6a,b) were readily converted to diester-substituted poly(1,4-phenylenevinylenes) (PPVs) (7a,b) by aromatizing the cyclohexadiene rings using 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ). The resulting PPVs were highly luminescent, and polymer 7b, bearing tert-butyl groups on its esters, was soluble in methylene chloride and chloroform. We found that partially oxidizing 6b so that only 80% of the polymer units are aromatized increases both the solubility and photoluminescence quantum yield of 7b. Deprotection of polymer 7b by acid-catalyzed thermolysis of the tert-butyl groups followed by treatment with aqueous base pr...
TL;DR: The ring-closing diene metathesis of siloxytriene 3 surprisingly afforded siloxyricycle 9 in which the newly formed ring is one carbon unit smaller than expected.
TL;DR: In this paper, aqueous ring-opening metathesis polymerization was used to generate non-natural carbohydrate-bearing polymers for the investigation of multivalent carbohydrate-protein interactions.
Abstract: Non-natural carbohydrate-bearing polymers are emerging as important materials for the investigation of multivalent carbohydrate-protein interactions In the present study, neoglycopolymers were generated via aqueous ring-opening metathesis polymerizations A procedure employing a ruthenium catalyst, preformed by treating a small quantity of the monomer with RuCl 3 , reduced metal contamination in the products To examine the effect of sugar residue density on polymer function, materials bearing one or two sugar ligands per repeat unit were synthesized These polymers were tested for their ability to inhibit the erythrocyte agglutinating activity of the carbohydrate-binding protein, concanavalin A The polymers with lower sugar density were found to be more potent inhibitors than polymers with higher density, a result that can be rationalized by analysis of the protein and polymer structures
TL;DR: In this article, the rate dependence on substrate conformation has been studied for catalytic cyclisation/cleavage of tetrapeptide-derived macrocycles from a solid support.
TL;DR: A new carbazole-functionalized norbornene derivative, 5-[methylbis(N-carbazolyl)silyl]-2-norbornene, was polymerized via living ring-opening metathesis polymerization (ROMP) with RuCl2(CHPh)(PCy3)2...
Abstract: A new carbazole-functionalized norbornene derivative, 5-[methylbis(N-carbazolyl)silyl]-2-norbornene, was polymerized via living ring-opening metathesis polymerization (ROMP) with RuCl2(CHPh)(PCy3)2...
TL;DR: In this article, the synthesis of macromonomers via the reaction of living polystyrene capped with propylene oxide with bicyclo[2.2.1]hept-5-ene-2,3-trans-dicarbonyl chloride and living ROMP of the macromers using well defined Schrock molybdenum initiator to produce well-characterised graft copolymers is described.
Abstract: The synthesis of macromonomers via the reaction of living polystyrene capped with propylene oxide with bicyclo[2.2.1]hept-5-ene-2,3-trans-dicarbonyl chloride and living ROMP of the macromonomers using well-defined Schrock molybdenum initiator to produce well-characterised graft copolymers is described. The scaling up of the ROMP of the macromonomers of different molecular weights revealed the presence of an experimental limit to the length of polynorbornene backbone chain and to the length of the polystyrene graft. It is found that as the length of polystyrene graft in the macromonomer is increased the length of polynorbornene backbone chain in the graft copolymer is decreased an observation ascribed due to steric hindrance. The ROMP of macromonomers of different molecular weight has been shown to be living allowing the synthesis of tapered and block copolymers.
TL;DR: Thymine functionalised poly(norbornene)s are synthesised via living ring-opening metathesis polymerisation using the ruthenium initiator.
TL;DR: In this article, the authors used the olefin metathesis reaction to join and combinatorially randomize the length of a linking tether in a C2-symmetric library.