共查询到20条相似文献,搜索用时 15 毫秒
1.
Youngchan Jang Dai Seung Choi Shin Han 《Journal of polymer science. Part A, Polymer chemistry》2004,42(5):1164-1173
The activation of a metal alkyl‐free Ni‐based catalyst with B(C6F5)3 was investigated in the polymerization of 1,3‐butadiene. A catalyst of bis(1,5‐cyclooctadiene)nickel (Ni(COD)2)/B(C6F5)3 was found to have high catalytic activity and 1,4‐cis stereoregularity. The catalyst was also found to provide polybutadiene having a molecular weight (Mw) of up to 117,000, even in the absence of AlR3 and MAO. Variations in the mol ratio of B(C6F5)3 to Ni affected catalytic activity, 1,4‐cis stereoregularity, and the Mw of polybutadiene, while the molecular weight distribution (MWD) of polybutadiene showed little correlation with the mol ratio of B(C6F5)3 to Ni. The use of other borane compounds such as B(C6H5)3, BEt3, and BF3 etherate in place of B(C6F5)3 clearly showed the two main functions of B(C6F5)3 in the present catalyst. The high Lewis acidity of B(C6F5)3 enabled it to activate catalytic complexes, thus inducing the polymerization. The steric bulkiness of B(C6F5)3 suppressed chain transfer reactions, contributing to the production of polybutadiene with a high Mw. Kinetic studies showed that the catalyst had an induction period, possibly due to the time needed for the formation of catalytic complexes starting from Ni(COD)2. A plot of ?ln (1?X), where X is the fractional conversion, as a function of time resulted in a linear relationship, showing that the present catalyst system followed first‐order kinetics with respect to monomer concentration. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1164–1173, 2004 相似文献
2.
Alexei V. Radchenko Sergei V. Kostjuk Irina V. Vasilenko François Ganachaud Fyodor N. Kaputsky Yohann Guillaneuf 《Journal of polymer science. Part A, Polymer chemistry》2008,46(20):6928-6939
A kinetic study of the living cationic polymerization of p‐methoxystyrene using 1‐(4‐methoxyphenyl)ethanol ( 1 )/B(C6F5)3 initiating system in a mixture of CH3CN with CH2Cl2 1:1 (v/v) at room temperature was carried out utilizing a wide variety of conditions. The polymerization proceeded in a living fashion even in the presence of a large amount of water ([H2O]/[B(C6F5)3] ratio up to 20) to afford polymers whose Mn increased in direct proportion to monomer conversion with fairly narrow MWDs (Mw/Mn ≤ 1.3). The investigation revealed that the rate of polymerization was first‐order in B(C6F5)3 concentration, while a negative order in H2O concentration close to ?2 was obtained. It was also found that the rate of polymerization decreased with lowering temperature, which could be attributed to a decreased concentration in free Lewis acid, the true coinitiator of polymerization. A mechanistic scheme to explain the kinetic behavior of living p‐methoxystyrene polymerization is proposed, which has been validated by PREDICI simulation on multiple‐data curves obtained by 1H NMR in situ polymerization experiment. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6928–6939, 2008 相似文献
3.
The activity of the transition metal complex, such as Ni(2-ethyl hexanoate)2 (1), Co(2-ethyl hexanoate)2 (2), TiCl4 (3), or CpTiCl3 (4) (Cp = cyclopentadiene), in combination with MAO (methylaluminoxane), was investigated in the polymerization of norbornene. The Ni(II) complex 1 with MAO showed moderate activity to give 20.8 kgpolymer/molNi h, while the other three complexes 2-4 with MAO just showed trivial activity. Effects of the Lewis acids on the activation of the catalyst of 1/MAO were examined. The employment of B(C6F5)3 with 1/MAO significantly enhanced the activity to give up to around 133 kgpolymer/molNi h. The use of other borane compounds, such as B(C6H5)3 and BEt3, or the stronger electron acceptor BF3 · OBu2, with 1/MAO in place of B(C6F5)3 clearly showed the main functions of B(C6F5)3. The high Lewis acidity of B(C6F5)3 enabled it to develop matured active complexes, thus enhancing the activity. Several Ni(II) complexes were employed to determine whether their activity was comparable to that of complex 1 in norbornene polymerization. The study of the 1H and 13C NMR spectra of the polynorbornene produced with 1/B(C6F5)3/MAO showed that the initiation of addition polymerization occurred through the insertion of the exo face of the norbornene into the active complex. Effects of the variation in the polymerization variables, such as the levels of B(C6F5)3 and MAO, temperature, and solvent, on the polymerization were discussed. 相似文献
4.
It has been shown that tris(pentafluorophenyl)bismuth arylates polyfluorinated electrophilic compounds in the presence of cesium fluoride.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 171–172, January, 1994. 相似文献
5.
Alexander D. Dilman Dmitry E. Arkhipov Valentine P. Ananikov Vladimir A. Tartakovsky 《Journal of organometallic chemistry》2005,690(16):3680-3689
A general method for the synthesis of carbon-centered tris(pentafluorophenyl)silyl derivatives (RSi(C6F5)3) by reaction of trichlorosilanes (RSiCl3) with pentafluorophenylmagnesium bromide was described. The crystal structures of obtained compounds were studied by X-ray diffraction analysis (7 structures). The peculiarities of crystal packing were analyzed by means of DFT calculations. 相似文献
6.
Alexander D. Dilman Vitalij V. Levin Pavel A. Belyakov Mikhail Yu. Antipin 《Journal of organometallic chemistry》2008,693(6):1005-1019
A detailed analysis of monodentate and bidentate complexation of tris(pentafluorophenyl)silyl (TPFS) derivatives with neutral Lewis bases was performed. The NMR spectroscopy and X-ray diffraction analysis (11 structures) were the key methods to characterize tetra- or pentacoordinate silicon compounds, whereas the peculiarities of crystal packing were analyzed by means of DFT calculations. The interaction of TPFS-X (X = F, Cl, OTf) with strong Lewis bases (HMPA, N-methylpyrrolidinone) may afford three different species: neutral pentacoordinate TPFS(X)-L, cationic tetracoordinate TPFS-L+ X−, and cationic pentacoordinate TPFS-(L)+2X−, representatives of each type were characterized by X-ray diffraction. A variety of complexes with bidentate complexation, featuring the trigonal bipyramidal geometry with apical C6F5-group was prepared and structurally characterized. The extent of Si-Capical bond elongation depends on the donating ability of the coordinating ligand, with the longest Si-C bond of 1.981(1) Å observed for six-membered complex of TPFS-ether of N-(2-hydroxybenzoyl)pyrrolidine. 相似文献
7.
Jose Ramos Jacqueline Forcada 《Journal of polymer science. Part A, Polymer chemistry》2003,41(15):2322-2334
The objective of this work was to analyze the effects of the concentration and type of cationic surfactant on the kinetic features (instantaneous and overall conversions) and colloidal characteristics [mean particle diameter, particle size distribution (PSD), and surface charge density] in the semicontinuous seeded cationic emulsion polymerization of styrene. 2,2′‐Azobis(N,N′‐dimethyleneisobutyramidine)dihydrochloride was used as an initiator. The surfactants were dodecyltrimethylammonium bromide (DTAB) and hexadecyltrimethylammonium bromide (HDTAB). So that the evolution of some polymeric and colloidal characteristics of the synthesized latices could be followed, the overall and instantaneous conversions were defined and determined gravimetrically. The PSDs and average particle diameters were determined by transmission electron microscopy and photon correlation spectroscopy. The surface charge density was determined by conductimetric titration. The evolution of the instantaneous conversions, the total number of particles, and the PSDs of the different reactions were related to the nucleation, growth, and coagulation processes taking place in the semicontinuous seeded emulsion polymerizations. The PSDs obtained from the reactions carried out with the emulsifier DTAB, at a concentration equal to its critical micelle concentration (cmc) and at a concentration twice its cmc, presented more and smaller particles than those obtained by the addition of HDTAB to the polymerization recipe. At lower emulsifier concentrations equal to half of the cmc, the system had lower colloidal stability with DTAB. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2322–2334, 2003 相似文献
8.
Electronic property and molecule design for luminescent metal complexes of tris(8-hydroxyquinoline) gallium 总被引:1,自引:0,他引:1
By means of ab initio HF and DFT B3LYP methods, the structure of Gaq3 (q = 8-hydroxyquinoline) was optimized. The frontier molecular orbital characteristics and energy levels of Gaq3 have been analyzed systematically in order to study the electronic transition mechanism in Gaq3. Three derivatives of Gaq3 and their polymers were designed and the possibilities that they were employed as luminescent materials were discussed. The regularities and characteristic of energy bands of Gaq3 and its derivatives were also investigated. The results show that the electronic π-π* transitions in Gaq3 are localized on the quinolate ligands. The emission of Gaq3 is due to the electron transitions from a phenoxide donor to a pyridyl acceptor. Two possible electron transfer pathways are presented, one by carbon atoms, and the other via metal cation Ga3 . The derivatives of Gaq3 may possess high luminescence efficiency. 相似文献
9.
Liangjiu Bai Lifen Zhang Jian Zhu Zhenping Cheng Xiulin Zhu 《Journal of polymer science. Part A, Polymer chemistry》2009,47(8):2002-2008
A commercially available tris(3,6‐dioxaheptyl)amine (TDA‐1) was used as a novel ligand for activator generated by electron transfer atom transfer radical polymerization (AGET ATRP) of styrene in bulk or solution mediated by iron(III) catalyst in the presence of a limited amount of air. FeCl3 · 6H2O and (1‐bromoethyl)benzene (PEBr) were used as the catalyst and initiator, respectively; and environmentally benign ascorbic acid (VC) was used as the reducing agent. The polymerizations show the features of “living”/controlled free‐radical polymerizations and well‐defined polystyrenes with molecular weight Mn = 2400–36,500 g/mol and narrow polydispersity (Mw/Mn = 1.11–1.29) were obtained. The “living” feature of the obtained polymer was further confirmed by a chain‐extension experiment. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2002–2008, 2009 相似文献
10.
Dioxygen Reactivity with a Ferrocene–Lewis Acid Pairing: Reduction to a Boron Peroxide in the Presence of Tris(pentafluorophenyl)borane 下载免费PDF全文
Justin T. Henthorn Prof. Theodor Agapie 《Angewandte Chemie (International ed. in English)》2014,53(47):12893-12896
Ferrocenes, which are typically air‐stable outer‐sphere single‐electron transfer reagents, were found to react with dioxygen in the presence of B(C6F5)3, a Lewis acid unreactive to O2, to generate bis(borane) peroxide. Although several Group 13 peroxides have been reported, boron‐supported peroxides are rare, with no structurally characterized examples of the BO2B moiety. The synthesis of a bis(borane)‐supported peroxide anion and its structural and electrochemical characterization are described. 相似文献
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Alexander N. Frolov Sergei V. Kostjuk Irina V. Vasilenko Fyodor N. Kaputsky 《Journal of polymer science. Part A, Polymer chemistry》2010,48(17):3736-3743
The controlled cationic polymerization of styrene using CumOH/AlCl3OBu2/Py initiating system in a mixture CH2Cl2/n‐hexane 60/40 v/v at ?40 and ?60 °C is reported. The number‐average molecular weights of the obtained polystyrenes increased with increasing monomer conversion (up to Mn = 85,000 g mol?1) although experimental values of Mn were higher than the theoretical ones at the beginning of the reaction that was ascribed to slow exchange between reversible‐terminated and propagating species. The molecular weight distribution became narrower through the reaction and leveled of at the value of Mw/Mn = 1.8–2.0. A kinetic investigation revealed that the rate of polymerization was first‐order in AlCl3OBu2 concentration meaning that monomeric counteranion (AlCl3OH? or AlCl) involved in the initiation and propagation steps of the reaction. It was also found that the rate of polymerization decreased with lowering temperature, which could be attributed to a decrease in concentration of free Lewis acid (AlCl3), the true coinitiator of polymerization, because of an increase in the tightness of its complex with dibutyl ether. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3736–3743, 2010 相似文献
14.
Masanao Kawabe Masahide Murata 《Journal of polymer science. Part A, Polymer chemistry》2001,39(21):3692-3706
The polymerizations of styrene and 4‐methylstyrene (4MS) with a half‐metallocene type catalytic system composed of (trimethyl)pentamethylcyclopentadienyltitanium (Cp*TiMe3), trioctylaluminum (AlOct3), and tris(pentafluorophenyl)borane [B(C6F5)3] were investigated at ?25 °C. The addition of AlOct3 as a third component of the catalytic system is effective both to promote the syndiospecific polymerization and to inhibit the nonstereospecific polymerization at the low‐temperature region. The use of AlOct3 was also effective to eliminate the chain transfer reaction to alkylaluminum. The number‐average molecular weights (Mn's) of poly(4MS) or polystyrene increased proportionally with increasing monomer conversion. The molecular weight distribution (MWD) of polymer stayed narrow [Mw/Mn = ~ 1.1 for poly(4MS) and Mw/Mn = ~ 1.5 for polystyrene]. It was thus concluded that the polymerizations of the styrenic monomers with Cp*TiMe3/B(C6F5)3/AlOct3 catalytic system proceeded under living fashion at ?25 °C. The living random copolymerization behaviors of styrene and 4MS were also confirmed. The 13C NMR analysis clarified that each of the homopolymers and random copolymers obtained in this work had highly syndiotactic structure. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3692–3706, 2001 相似文献
15.
Water-tolerant catalyst systems have been investigated for the cationic oligomerization of technical-grade p-methylstyrene and indene, for the production of industrially relevant aromatic resins. Systems based on 1-p-tolylethanol and 1-indanol (ROH) as initiators, in association with Cu(OTf)2, Bi(OTf)3 (OTf = triflate) and B(C6F5)3 as co-initiators/catalysts, show interesting productivities at 60 °C under air, with as low as 0.2-1.0 mol% catalyst loading. Most of the reactions are not controlled in terms of molecular weights of the products, except for indene oligomerization by the borane catalyst where experimental Mn values match well the theoretical values, as determined by the amount of added initiator over a 5-fold range (with 2-10 mol% vs. monomer). The ROH/tris(pentafluorophenyl)borane system offers the best compromise in terms of productivity and control over the molecular weights of the oligomers, which can be manipulated by the amount of initiator and reaction temperature. 相似文献
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Yusuf Yagci Selcuk Denizligil 《Journal of polymer science. Part A, Polymer chemistry》1995,33(9):1461-1464
The cationic polymerization of cyclohexene oxide (CHO), n-butyl vinylether (BVE), N-vinylcarbazole (NVC), and 4-vinyl cyclohexenedioxide (4-VCHD) is initiated upon UV irradiation (Λinc. = 350 nm) of dichloromethane solution containing N-ethoxy-2-methyl-pyridinium hexafluorophosphate (EMP+PF6) and o-phthaldehyde. A feasible initiation mechanism involves formation of biradical by intramolecular hydrogen abstraction of triplet o-phthaldehyde. Oxidation of these radicals by EMP+ ions yields protons capable of initiating the cationic polymerization. © 1995 John Wiley & Sons, Inc. 相似文献
18.
Motomasa Yonezumi Shokyoku Kanaoka Sadahito Aoshima 《Journal of polymer science. Part A, Polymer chemistry》2008,46(13):4495-4504
Cationic polymerization of 2,3‐dihydrofuran (DHF) and its derivatives was examined using base‐stabilized initiating systems with various Lewis acids. Living cationic polymerization of DHF was achieved using Et1.5AlCl1.5 in toluene in the presence of THF at 0 °C, whereas it has been reported that only less controlled reactions occurred at 0 °C. Monomer‐addition experiments of DHF and the block copolymerization with isobutyl vinyl ether demonstrated the livingness of the DHF polymerization: the number–average molecular weight of the polymers shifted higher with low polydispersity as the polymerization proceeded after the monomer addition. Furthermore, this base‐stabilized cationic polymerization system allowed living polymerization of ethyl 1‐propenyl ether and 4,5‐dihydro‐2‐methylfuran at ?30 and ?78 °C, respectively. In the polymerization of 2,3‐benzofuran, the long‐lived growing species were produced at ?78 °C. The obtained polymers have higher glass transition temperatures compared to poly(acyclic alkyl vinyl ether)s. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4495–4504, 2008 相似文献
19.
Natesan Thirupathi Dino Amoroso Andrew Bell John D. Protasiewicz 《Journal of polymer science. Part A, Polymer chemistry》2009,47(1):103-110
The catalytic efficacy of trans‐[(R3P)2Pd(O2CR′)(LB)][B(C6F5)4] ( 1 ) (LB = Lewis base) and [(R3P)2Pd(κ2‐O,O‐O2CR′)][B(C6F5)4] ( 2 ) for mass polymerization of 5‐n‐butyl‐2‐norbornene (Butyl‐NB) was investigated. The nature of PR3 and LB in 1 and 2 are the most critical components influencing catalytic activity/latency for the mass polymerization of Butyl‐NB. Further, it was shown that 1 is in general more latent than 2 in mass polymerization of Butyl‐NB. 5‐n‐Decyl‐2‐norbornene (Decyl‐NB) was subjected to solution polymerization in toluene at 63(±3) °C in the presence of several of the aforementioned palladium complexes as catalysts and the polymers obtained were characterized by gel permeation chromatography. Cationic trans‐[(R3P)2PdMe(MeCN)][B(C6F5)4] [R = Cy ( 3a ), and iPr ( 3b )] and trans‐[(R3P)2PdH (MeCN)][B(C6F5)4] [R = Cy ( 4a ), and iPr ( 4b )], possible products from thermolysis of trans‐[(R3P)2Pd(O2CMe)(MeCN)][B(C6F5)4] [R = Cy ( 1a ) and iPr ( 1g )], as well as trans‐[(R3P)2Pd(η3‐C3H5)][B(C6F5)4] [R = Cy ( 5a ), and iPr ( 5b )], were also examined as catalysts for solution polymerization of Decyl‐NB. A maximum activity of 5360 kg/(molPd h) of 2a was achieved at a Decyl‐NB/Pd: 26,700 ratio which is slightly better than that achieved with 5a [activity: 5030 kg/(molPd h)] but far less compared with 4a [activity: 6110 kg/(molPd h)]. Polydispersity values indicate a single highly homogeneous character of the active catalyst species. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 103–110, 2009 相似文献
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Hyun-Ju Lee Jun-Won Baek Yeong-Hyun Seo Hong-Cheol Lee Sun-Mi Jeong Junseong Lee Chong-Gu Lee Bun-Yeoul Lee 《Molecules (Basel, Switzerland)》2021,26(9)
Homogeneous olefin polymerization catalysts are activated in situ with a co-catalyst ([PhN(Me)2-H]+[B(C6F5)4]− or [Ph3C]+[B(C6F5)4]−) in bulk polymerization media. These co-catalysts are insoluble in hydrocarbon solvents, requiring excess co-catalyst (>3 eq.). Feeding the activated species as a solution in an aliphatic hydrocarbon solvent may be advantageous over the in situ activation method. In this study, highly pure and soluble ammonium tetrakis(pentafluorophenyl)borates ([Me(C18H37)2N-H]+[B(C6F5)4]− and [(C18H37)2NH2]+[B(C6F5)4]−) containing neither water nor Cl− salt impurities were prepared easily via the acid–base reaction of [PhN(Me)2-H]+[B(C6F5)4]− and the corresponding amine. Using the prepared ammonium salts, the activation reactions of commercial-process-relevant metallocene (rac-[ethylenebis(tetrahydroindenyl)]Zr(Me)2 (1-ZrMe2), [Ph2C(Cp)(3,6-tBu2Flu)]Hf(Me)2 (3-HfMe2), [Ph2C(Cp)(2,7-tBu2Flu)]Hf(Me)2 (4-HfMe2)) and half-metallocene complexes ([(η5-Me4C5)Si(Me)2(κ-NtBu)]Ti(Me)2 (5-TiMe2), [(η5-Me4C5)(C9H9(κ-N))]Ti(Me)2 (6-TiMe2), and [(η5-Me3C7H1S)(C10H11(κ-N))]Ti(Me)2 (7-TiMe2)) were monitored in C6D12 with 1H NMR spectroscopy. Stable [L-M(Me)(NMe(C18H37)2)]+[B(C6F5)4]− species were cleanly generated from 1-ZrMe2, 3-HfMe2, and 4-HfMe2, while the species types generated from 5-TiMe2, 6-TiMe2, and 7-TiMe2 were unstable for subsequent transformation to other species (presumably, [L-Ti(CH2N(C18H37)2)]+[B(C6F5)4]−-type species). [L-TiCl(N(H)(C18H37)2)]+[B(C6F5)4]−-type species were also prepared from 5-TiCl(Me) and 6-TiCl(Me), which were newly prepared in this study. The prepared [L-M(Me)(NMe(C18H37)2)]+[B(C6F5)4]−-, [L-Ti(CH2N(C18H37)2)]+[B(C6F5)4]−-, and [L-TiCl(N(H)(C18H37)2)]+[B(C6F5)4]−-type species, which are soluble and stable in aliphatic hydrocarbon solvents, were highly active in ethylene/1-octene copolymerization performed in aliphatic hydrocarbon solvents. 相似文献