The vinylic polymerization of norbornene and its copolymerization with norbornene carboxylic acid methyl esters were investigated. Norbornene was polymerized by us using di-μ-chloro-bis-(6-methoxybicyclo[2.2.1]hept-2-ene-endo-5σ,2π)-palladium(II) as catalyst. The polymerization time can be decreased by a factor of 100000 by activation of the catalyst with methylaluminoxane (MAO). With this palladium catalyst activated by MAO, 140 t of norbornene can be polymerized per mol palladium per h. This catalyst system was much more active than [Pd(CH3CN)4](BF4)2 ( I ). The polymerization of norbornene by (6-methoxybicyclo[2.2.1]hept-2-ene-endo-5σ,2π)-palladium(II) tetrafluoroborate was also possible but it was not as fast as the polymerization by Pd catalysts activated with MAO. We were also able to obtain copolymers of norbornene and 5-norbornene-2-carboxylic acid methyl ester (exo/endo = 1/4 or 2/3) containing between 15 and 20 mol-% ester units. The copolymerization of norbornene and 2-methyl-5-norbornene-2-carboxylic acid methyl ester (exo/endo = 7/3) was faster than the copolymerization mentioned before. In contrast the homopolymerization of 2-methyl-5-norbornene-2-carboxylic acid methyl ester was 10 times slower than that of 5-norbornene-2-carboxylic acid methyl ester (exo/endo = 1/4). 相似文献
Cycloaliphatic polyolefins with functional groups were prepared by the Pd(II)-catalyzed addition polymerization of norbornene derivatives. Homo- and copolymers containing repeating units based on bicyclo[2.2.1] hept-5-en-2-ylmethyl decanoate (endo/exo-ratio = 80/20), bicyclo[2.2.1]hept-5-ene-2-carboxylic acid methyl ester (exo/endo = 80/20), bicyclo[2.2.1]hept-5-ene-2-methanol (endo/exo = 80/20), and bicyclo[2.2.1]hept-5-ene-2-carboxylic acid (100% endo) were prepared in 49–99% yields with {(η3-allyl)Pd(BF4)} and {(η3-allyl)Pd(SbF6)} as catalysts. The catalyst containing the hexafluoroantimonate ion was slightly more active than the tetrafluoroborate based Pd-complex. 相似文献
The reaction of [(domppp) Pd (OAc)2] [domppp = 1,3‐bis (di‐o‐methoxyphenylphosphino)propane] and imidazolium‐functionalized carboxylic acids containing various anions (Br?, PF6?, SbF6? and BF4?) resulted in the formation of nano‐sized Pd (II) aggregates under template‐free conditions. The rate of formation of aggregates can be modulated by changing the anion, affecting the rate of polymerization of CO and olefins without fouling. Herein, we describe the analysis of Pd (II) catalysts by dynamic light scattering, atomic force microscopy, X‐ray photoelectron spectroscopy and X‐ray crystallography, and co‐ and terpolymerization results including the catalytic activity, and bulk density and molecular weight of polymers. 相似文献
The reactions of norbornene polymerization were catalyzed by Pd(CH3CN)4(BF4)2 ( 1 ), AIBN ( 2 ), and [{(2,6‐C6H3(iPr)2)N=C(Me)}2Pd(Me)(CH3CN)][BF4] ( 3 ) without using methylalumoxane (MAO). These poly(norbornene)s are readily soluble in organic solvents such as toluene, dichloromethane and tetrahydrofuran. According to the NMR data, the end group of PNA resulting from the AIBN process is found from THF. The PNT resulting from the catalyst ( 1 ) shows bi‐models of GPC bands (Mn= 4236 and 66317), two glass transition temperatures (Tg = 72.7 and 201.5 °C), as well as two decomposition temperatures (Td = 337 and 460 °C). 相似文献
Novel moisture and air stable, cationic palladium(II) amine complexes (1–4) of the general type [Pd(N∩N)(X)2](BF4)2, [N∩N=1,2-bis(N-indolinyl)ethane (BIE) 1, 3; 1,2-bis(N-1,2,3,4-tetrahydroquinolinyl)ethane (BTQE) 2, 4; X=NCCH3, H2O] were found to catalyze the polymerization reaction of bicyclo[2.2.1]hept-2-ene at room temperature. The amorphous polymer products consist of 2,3-linked norbornene units; no indications for ring opened species could be observed. The polymerization activity of the diaqua-complexes 3, 4 is superior compared to their acetonitrile analogues due to a facile activation by a Wacker-type reaction. The cationic Pd(II)-compounds are inactive towards homo- and copolymerization reactions of polar monomers, like acrylates or carbon monoxide. However, addition of methylacrylate resulted in polynorbornene products with increased molecular weight and narrow molecular weight distributions. 相似文献
An X-ray diffraction analysis is carried out for the complex [Pd(Acac)(PPh3)2]BF4 (I), which is a precursor of the active complexes of styrene dimerization and norbornene additive polymerization in the system
[(Acac)Pd(PPh3)2]BF4-BF3 · OEt2. In complex I the palladium atom is coordinated by two oxygen atoms of the acetylacetonate ligand and two phosphorus atoms of the triphenylphosphine
ligands at the vertices of the distorted square. 相似文献
Polyolefin elastomers ( POEs ) and cyclic olefin copolymers ( COCs ) are high-performance polyolefin materials of wide interest. It is crucial to develop low-cost and high-performance transition metal catalysts to prepare these polyolefin materials. In this contribution, we designed and synthesized a series of bidentate pyridyl-amido hafnium catalysts and used them in ethylene polymerization and copolymerization with comonomers including 1-octene and norbornene. These catalysts exhibited high activities of up to 16.3×106 g mol−1 h−1 and produced polyethylene with a high molecular weight of up to 24.5×104 g mol−1 in ethylene polymerization at 150 °C. More importantly, these catalysts produced ethylene/1-octene copolymers with incorporation of up to 13.7 mol % and molecular weight of up to 72.7×104 g mol−1, and prepared ethylene/norbornene copolymers with incorporation of up to 50.3 mol %, along with glass transition temperature of up to 184.3 °C and molecular weight of up to 187.6×104 g mol−1. The ease of synthesis, high versatility and great copolymerization properties of these hafnium catalysts make them highly attractive for future studies. 相似文献
Acetylacetonate palladium(II) complexes bearing pyridinyl imine ligands [Pd(acac)(L)]BF4 were synthesized via nitrile displacement in [Pd(acac)(MeCN)2]BF4 by the bidentate ligands L of type 2-C5H4N–CH=N–(CH2)nOMe or 2-C5H4N–CH=N–Ar. The structures of complexes were analyzed by X-ray diffractometry, NMR, and DFT. The complexes catalyze hydroamination of phenylacetylene with aniline to give the Markovnikov imine product as well as polymerization of norbornene. 相似文献
A series of nickel(II) complexes bearing two nonsymmetric bidentate β-ketoiminato chelate ligands have been prepared, and the structures of complexes [(2,6-Me2C6H3)NC(CH3)C(H)C(Ph)O]2Ni (4a) and [(2,6-Me2C6H3)NC(CH3)C(H)C(CF3)O]2Ni (4c) have been confirmed by X-ray crystallographic analysis. These nickel(II) complexes were investigated as catalysts for the vinylic polymerization of norbornene. Using modified methylaluminoxane (MMAO) as a cocatalyst, these complexes display very high activities and produce high molecular weight polymers. Catalytic activity of up to 1.16 × 104 kg/molNi · h and the viscosity-average molecular weight of polymer of up to 870 kg/mol were observed. Catalyst activity, polymer yield, and polymer molecular weight could be controlled over a wide range by the variation of the reaction parameters such as Al/Ni molar ratio, norbornene/catalyst molar ratio, monomer concentration, polymerization reaction temperature and time. 相似文献
The selective cationic polymerization of isobutylene(IB)initiated by a BF3·cyclohexanol(CL)complex was carried out from the mixed C4 fraction feed containing the 4C saturated and unsaturated hydrocarbons at-20℃.The effects of CL concentration,BF3 concentration,solvent for preparing BF3·CL complex and polymerization time on the chemical structure of end groups,number-average molecular weight(Mn)and molecular weight distribution(MWD,Mw/Mn)of the resulting polymers were investigated.The experimental results indicate that the BF3·CL complex initiating system exhibited an extremely high selectivity toward the cationic polymerization of IB in the mixed C4 fraction feed and low molecular weight(Mn=900-3600)polyisobutylenes(PIBs)with large proportion of exo-double bond end groups were obtained.The exo-double bond content in PIB chain ends increased by increasing CL concentration or by decreasing solvent polarity in initiating system,BF3 concentration and polymerization time.The Mn and MWD of the resulting PIBs were dependent on the concentrations of CL and BF3.Highly reactive PIBs with around 90 mol%of exo-double bonds were successfully synthesized by the selective polymerization of IB from the mixed C4 fraction feed,providing a potentially practical process for its simplicity and low costs. 相似文献
In bulk polymerization and copolymerization of trioxane with ethylene oxide, it has been shown that p-chlorophenyldiazonium hexafluorophosphate is a superior catalyst as compared to boron trifluoride dibutyl etherate (BF3 · Bu2O). Polymers and copolymers of significantly higher molecular weight have been obtained. The higher molecular weight has been attributed primarily to less inherent chain transfer during propagation, which in turn can be attributed to the superior gegenion PF6?. The polymerization proceeds via a clear period followed by sudden solidification. Faster polymerization and higher molecular weight polymers have been observed for homopolymerization than for copolymerization. The polymer yield obtained after solidification is determined by both rate of polymerization and rate of crystallization of polymers. These rates, in turn, are dependent on the catalyst concentration. The molecular weight is determined both by polymer yield and extent of inherent chain transfer. In the range of monomer to catalyst mole ration [M]/[C] = (0.5–20) × 104 investigated, it has been found that in the higher range, the polymer yield is independent of the catalyst concentration and the extent of inherent chain transfer is inversely proportional to the half power of catalyst concentration: [M]/[C] = (0.5–8) × 104 for homopolymerization and (0.5–3) × 104 for copolymerization with 4.2 mole % ethylene oxide. In the lower range, the yield decreases with catalyst concentration and the extent of inherent chain transfer is inversely proportional to higher power of catalyst concentration. The dependence of molecular weight of polymers on catalyst concentration has been shown to be a complex one. The molecular weight goes through a maximum as the catalyst concentration is decreased. The maximum molecular weights have been obtained at [M]/[C] ≈ 8 × 104 for homopolymerization and ~3 × 104 for copolymerization with 4.2 mole % ethylene oxide. Prior to reaching maximum the molecular weight is inversely proportional to the half power of catalyst concentration indicating it is primarily controlled by inherent chain transfer. Upon further decrease of catalyst, molecular weight decreases as a result of both a decrease in polymer yield and an increase in inherent chain transfer. In copolymerization of trioxane and ethylene oxide, it has been ascertained that methylene chloride exhibits a favorable solvating effect. Although higher inherent chain transfer takes place in copolymerization than in homopolymerization, the extent of chain transfer is independent of ethylene oxide concentration. The difference in polymer yield and molecular weight a t different ethylene oxide concentrations is attributed primarily to the difference in kp/kt ratio. It also has been demonstrated that end capping of polymer chains can be accomplished by the use of a chain transfer agent—methylal. 相似文献
A series of dicationic PdII-acetonitrile complexes containing bi- and tridentate nitrogen and bidentate phosphine ligands (some of which are chiral) has been prepared as their BF4 salts. The molecular structures for two of these, [Pd(CH3CN)2(bipy)] (BF4)2 ( 4 ) and [Pd(CH3CN)((pybox)(i-Pr))] (BF4)2((S,S)-pybox(i-Pr) = 2,6-bis[(S)-4′-isopropyloxazolin-2′-yl]pyridine, 5 ) have been determined by X-ray diffraction. All of these complexes are shown to be effective homogeneous catalysts for the aldol-type condensation of the isonitrile, methyl isocyanoacetate, with benzaldehyde. Two isonitrile complexes, [Pd(2,2′-bipyridyl)(CNCH2COOCH3)2] (BF4)2 and [Pd((S,S)-pybox(i-Pr))(CNCH2COOCH3)] (BF4)2, have also been prepared. 相似文献