共查询到20条相似文献,搜索用时 15 毫秒
1.
A. S. Brar Sukhdeep Kaur 《Journal of polymer science. Part A, Polymer chemistry》2005,43(23):5906-5922
With CuBr/tetramethylguanidino‐tris(2‐aminoethyl)amine (TMG3‐TREN) as the catalyst, the atom transfer radical polymerization (ATRP) of methyl methacrylate, n‐butyl acrylate, styrene, and acrylonitrile was conducted. The catalyst concentration of 0.5 equiv with respect to the initiator was enough to prepare well‐defined poly(methyl methacrylate) in bulk from methyl methacrylate monomer. For ATRP of n‐butyl acrylate, the catalyst behaved in a manner similar to that reported for CuBr/tris[2‐(dimethylamino)ethyl]amine. A minimum of 0.05 equiv of the catalyst with respect to the initiator was required to synthesize the homopolymer of the desired molecular weight and low polydispersity at the ambient temperature. In the case of styrene, ATRP with this catalyst occurred only when a 1:1 catalyst/initiator ratio was used in the presence of Cu(0) in ethylene carbonate. The polymerization of acrylonitrile with CuBr/TMG3‐TREN was conducted successfully with a catalyst concentration of 50% with respect to the initiator in ethylene carbonate. End‐group analysis for the determination of the high degree of functionality of the homopolymers synthesized by the new catalyst was determined by NMR spectroscopy. The isotactic parameter calculated for each system indicated that the homopolymers were predominantly syndiotactic, signifying that the tacticity remained the same, as already reported for ATRP. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5906–5922, 2005 相似文献
2.
Jorge Cervantes Guillermo Gonzlez‐Alatorre Diane Rohack Keith H. Pannell 《应用有机金属化学》2000,14(3):146-151
Product distribution and kinetic studies on the hydrosilylation of phenylacetylene by Ph3SiH, Ph2MeSiH, PhMe2SiH and Et3SiH were performed using bis‐[1,2‐diphenylphosphinoethane]norbornadienerhodium(I) hexafluorophosphate, 1, as catalyst. Pre‐equilibration of the catalyst with the acetylene produced hydrosilylations, pre‐equilibration with the silane did not. The catalyst showed a pronounced selectivity for cis‐addition to form β‐products, t‐PhCHCHSiR3, unlike most hydrosilylation catalysts. The kinetic studies showed a hydrosilylation reaction that is zero order with respect to both acetylene and the silane, with a dependency upon catalyst concentration. The kobs value is directly influenced by the substituents on the silane: k(PhMe2SiH) > k (Et3SiH > k (Ph2MeSiH) > k (Ph3SiH). Intercalation of the catalyst in hectorite was not useful, since either no reaction occurred in non‐polar solvents, or extraction of the catalyst occurred in polar solvents to produce the same product distributions. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献
3.
Oxygenation of sulfides catalysed by SBA‐15‐immobilized molybdenum(VI) complex of a bis(phenol) diamine ligand using aqueous hydrogen peroxide as a green oxidant
下载免费PDF全文
![点击此处可从《应用有机金属化学》网站下载免费的PDF全文](/ch/ext_images/free.gif)
A highly efficient and reusable molybdenum‐based catalyst has been synthesized by covalent grafting of a bis(phenol) diamine ligand, namely 2‐(((2‐bromoethyl)(2‐((3,5‐di‐tert‐butyl‐2‐hydroxybenzyl)amino)ethyl)amino)methyl)‐4,6‐di‐tert‐butylphenol, onto functionalized ordered mesoporous silica (SBA‐15) followed by complexation with MoO2(acac)2. The resulting organic–inorganic hybrid material was found to be a highly effective catalyst for oxygenation of various sulfides to their corresponding sulfoxides or sulfones. The catalyst was characterized using transmission and scanning electron microscopies, X‐ray photoelectron, Fourier transform infrared and atomic absorption spectroscopies, Brunauer–Emmett–Teller surface area analysis and thermogravimetric analysis. Mild reaction conditions, high selectivity and easy recovery and reusability of the catalyst render the presented protocol very useful for addressing industrial needs and environmental concerns. 相似文献
4.
采用自由配体法将(1S,2S)-DPEN(1,2-diphenyl-1,2-ethylene-diamine)-Ru(TPP)2(TPP=三苯基膦,triphenylphosphine)配合物封装于NaY沸石分子筛超笼中,制备了(1S,2S)-DPEN-Ru(TPP)2/Y主客体材料(1S,2S)-DPEN=1,2-二苯基-1,2-乙二胺).采用等离子体发射光谱ICP、粉末X射线衍射(XRD)、紫外光谱(UV-Vis)、氮吸附等物理化学手段对所制备材料进行了表征.结果表明,(1S,2S)-DPEN-Ru(TPP)2配合物封装于Y型分子筛超笼中保持了原有的物理化学性能;作为苯乙酮不对称加氢催化剂,在优化条件下,苯乙酮的转化率可达100%,(R)-苯乙醇的对映体过量值(ee值)可达61.0%.该催化剂具有良好的稳定性和重复使用性. 相似文献
5.
Yoshikatsu Tsuchiya Kiyoshi Endo 《Journal of polymer science. Part A, Polymer chemistry》2011,49(4):1006-1012
The polymerization of vinyl chloride (VC) with vanadium complex/alkylaluminum catalyst was investigated. In the case of polymerization with vanadium oxytriethoxide (VO(OEt)3), poly(vinyl chloride) was obtained in a good yield. The effect of cocatalyst, solvent, and cocatalyst/precatalyst ratio was observed. The structure of the polymer obtained with VO(OEt)3/i‐Bu3Al catalyst consisted of regular head‐to‐tail sequence and isobutyl chain‐end structure. VO(OEt)3/alkylaluminum catalyst was able to copolymerize VC with styrene, 1‐butene, methyl methacrylate, and methyl acrylate. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
6.
Konstantin V. Deriabin Ekaterina K. Lobanovskaia Sergey O. Kirichenko Marie N. Barshutina Pavel E. Musienko Regina M. Islamova 《应用有机金属化学》2020,34(1):e5300
Self-cross-linkable ferrocenyl-containing polymethylhydrosiloxanes were synthesized. Karstedt's catalyst and cis-[PtCl2(BnCN)2] were examined as cross-linking catalysts at room temperature for the reaction between Si–H groups of the ferrocenyl-containing polymethylhydrosiloxanes. Cis-[PtCl2(BnCN)2] is an effective catalyst that allows cross-linked ferrocenyl-containing silicones (silicone rubbers) to be obtained with no visible mechanical defects (bubbles or cracks) compared with Karstedt's catalyst. The ferrocene content of the ferrocenyl-containing silicone rubbers was found to be approximately 50 wt.% by energy-dispersive X-ray analysis. Compared with cross-linked non-modified polymethylhydrosiloxanes, the ferrocenyl-containing silicone rubbers exhibited improved tensile properties (the tensile strength increased from 0.47 to 0.75 MPa) and a 1.5–2.5 times lower cross-linking degree. The surface resistivity of the ferrocenyl-containing silicone rubbers (50 wt.% ferrocenyl units) was approximately 7 × 109 Ω/□, which was 10,000 times lower than that of pure polymethylhydrosiloxane. The obtained flexible electroactive ferrocenyl-containing silicone rubbers can potentially be applied as coatings for electronic and electrostatic-sensitive devices, interfaces, and sensors. 相似文献
7.
A series of novel heteronuclear Ln(III)-CU(II) complexes with noncyclic polyether-amino acid Schiff base were synthesized.
The general formula is (LnCu2(H2TALY) (NO3)5] (NO3)2·nH2O (Ln= La, Nd, Sm, Gd,n = 4; Ln = Yb, Y,n = 3), where H2TALY = tetraglycol aldehyde bis-lysine Schiff base. It is the first time to report the synthetic method for this new Cu(II)
complexes and Ln(III)-Cu(II) heteronuclear complexes. The complexes were characterized by elemental analysis, IR spectra.
TG-DTA, magnetic susceptibility, and especially by a 500 MHz NMR spectrometer for 2D-COSY NMR. Coordination mechanism and
structures of complexes have been suggested as well. Of particular interest is the potential that the novel complexes obtained
may be used as a catalyst. which prompted us to investigate them. It shows 100% conversion with the viscosity-average molecular
weight 120 000 for the polymerization of methyl methacrylate (MMA) without addition of any cocatalyst. Furthermore, the complexes
with such aliphatic Schiff bases can be used as a good catalyst, which has been confirmed and discussed here. They may be
a new kind of catalyst system with the above speciality.
Project supported by the National Natural Science Foundation of China (Grant No. 29671026) and Natural Science Foundation
of Zhejiang Province (Grant No. 296062) and the Laboratory of MRAMP (Grant No. 971502). 相似文献
8.
Antti Tynys Jan L. Eilertsen Jukka V. Seppälä Erling Rytter 《Journal of polymer science. Part A, Polymer chemistry》2007,45(7):1364-1376
Propylene was polymerized at varying trimethylaluminium (TMA) concentration with a homogeneous binary metallocene catalyst system activated by methylaluminoxane (MAO) in an attempt to better understand interactions between active catalyst sites and to clarify the role of the TMA as a chain shuttling agent. TMA‐free polymerization conditions were obtained by chemical treatment of MAO solution with 2,6‐di‐tert‐butyl‐4‐methylphenol (BHT). A binary catalyst system consisting of catalyst precursors diphenylmethyl(cyclopentadienyl)(9‐fluorenyl)zirconium dichloride ( 1 ) producing high Mw syndiotactic polypropylene and rac‐dimethylsilylbis(4‐tert‐butyl‐2‐methyl‐cyclopentadienyl)zirconium dichloride ( 2 ) producing low Mw isotactic polypropylene was investigated. At the studied polymerization conditions, chain shuttling between the active catalysts caused by TMA was confirmed. The chain shuttling reactions caused changes in catalyst activity, molecular weights, melting behavior, and polymer microstructure. We propose that TMA is capable to transfer a growing polymer chain from catalyst 2 to catalyst 1 , and a stereoblock copolymer is formed. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1364–1376, 2007 相似文献
9.
G. A. Hiremath P. L. Timmanagoudar S. T. Nandibewoor 《Reaction Kinetics and Catalysis Letters》1998,63(2):403-408
Ruthenium(III) catalyzed oxidation of hexacyanoferrate(II) by periodate in alkaline medium is assumed to occurvia substrate-catalyst complex formation followed by the interaction of oxidant and complex in the rate-limiting stage and yield
the products with regeneration of catalyst in the subsequent fast step. The reaction exhibits fractional order in hexacyanoferrate(II)
and first-order unity each in oxidant and catalyst. The reaction constants involved in the mechanism are derived. 相似文献
10.
Shouji Minegishi Muneharu Ito Atsushi Kameyama Tadatomi Nishikubo 《Journal of polymer science. Part A, Polymer chemistry》2000,38(12):2254-2259
The polyaddition of bis(3‐ethyl‐3‐oxetanylmethyl) terephthalate (BEOT) with dichlorodiphenylsilane (CPS) using tetrabutylammonium bromide (TBAB) as a catalyst proceeded under mild reaction conditions to afford a polymer containing silicon atoms in the polymer main chain. A poly(silyl ether) (P‐1) with a high molecular weight (Mn = 53,200) was obtained by the reaction of BEOT with CPS in the presence of 5 mol % of TBAB in toluene at 0 °C for 1 h and then at 50 °C for 24 h. The structure of the resulting polymer was confirmed by IR and 1H NMR spectra. Furthermore, it was proved that the polyaddition of certain bis(oxetane)s with dichlorosilanes proceeds smoothly to give corresponding poly(silyl ether)s with TBAB as the catalyst. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2254–2259, 2000 相似文献
11.
Zhong Hui Li Yong Ming Zhang Min Zhao Xue Lei Zhou Yan Gang Liu 《Journal of polymer science. Part A, Polymer chemistry》2005,43(21):5207-5216
A new catalyst system, CoCl2/tris(2‐(dimethyl amino) ethyl)amine (Me6 TREN), was used to catalyze the polymerization of methyl methacrylate (MMA) successfully through atom transfer radical polymerization mechanism. The control over the polymerization was not ideal, the molecular weight distribution of the resulting polymer (PMMA) was relatively broad (Mw/Mn = 1.63–1.80). To improve its controllability, a small amount of hybrid deactivator (FeBr3/Me6TREN or CuBr2/Me6TREN) was added in the cobalt catalyst system. The results showed that the level of control over the polymerization was significantly improved with the hybrid cobalt–iron (or cobalt–copper) catalyst system; the polydispersity index of the resulting polymer was reduced to a low level (Mw/Mn = 1.15–1.46). Furthermore, with the hybrid cobalt–iron catalyst, the dependence of the propagation rate on the temperature and the copolymerization of methacrylate (MA) with PMMA‐Br as macroinitiator were also investigated. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5207–5216, 2005 相似文献
12.
13.
Antidepressant drug (R)-rolipram was readily prepared on a large scale from isovanilline via a succinct route. The key reaction was carried out using a 1 mol% loading of nickel(II)-bis[(S,S)-N,N′-dibenzylcyclohexane-1,2-diamine]Br2 complex as the catalyst. The ee% could reach to 99%, and the catalyst could be recovered and used in the next reaction cycle with high ee%. 相似文献
14.
Based on (1R,2R)-(+)-(1,2)-DPEN skeleton, a series of primary amine–sulfamide bifunctional catalysts were synthesized, which exhibited excellent catalytic performance in the Michael addition of acetone to β-nitrostyrene. Therefore, a trifunctional heterogeneous catalyst was designed and prepared by simple N-sulfonyl reaction of (1R,2R)-(+)-(1,2)-DPEN and sulfonyl chloride resin. It was employed for the aforementioned addition without any additive and satisfactory results (80.5% conversion; 84.3% ee) were obtained. Meanwhile, the structural and textural properties of the catalyst were characterized by infrared spectroscopy (FT-IR), elemental analysis, SEM, and N2 adsorption and desorption experiments. Finally, the generality of the catalyst was investigated. 相似文献
15.
Kiyoshi Endo Yuichi Matsuda 《Journal of polymer science. Part A, Polymer chemistry》1999,37(20):3838-3844
Copolymerization of styrene (St) and butadiene (Bd) with nickel(II) acetylacetonate [Ni(acac)2]-methylaluminoxane (MAO) catalyst was investigated. Among the metal acetylacetonates [Mt(acac)x] examined, Ni(acac)2 showed a high activity for the copolymerization of St and Bd giving copolymers having high cis-1,4-microstructure in Bd units in the copolymer. The effect of alkylaluminum as a cocatalyst on the copolymerization of St and Bd with the Ni(acac)2-MAO catalyst was observed, and MAO was found to be the most effective cocatalyst for the copolymerization. The monomer reactivity ratios for the copolymerization of St and Bd with the Ni(acac)2-MAO catalyst were determined to be rSt = 0.07 and rBd = 3.6. Based on the obtained results, it was presumed that the random copolymers with high cis-1,4-microstructure in Bd units could be synthesized with the Ni(acac)2-MAO catalyst without formation of each homopolymer. The polymerization mechanism with the Ni(acac)2-MAO catalyst was also discussed. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3838–3844, 1999 相似文献
16.
A new chiral Mn(III)–Salphe catalyst was synthesized from natural amino acid (R)-phenylalanine and 3,5-di-tert-butyl-hydroxybenzaldehyde and applied to the asymmetric epoxidations of unfunctionalized olefins in ionic liquids. Satisfactory enantioselectivities (79% < ee < 93%) and good yields were achieved when NaClO was used as oxidant. We found that both the pH value (11.3) and reaction temperature (15 °C) were crucial for the epoxidation reactions. In our reaction system, NH4OAc was unnecessary. We proposed that alcoholic hydroxyls in the Mn(III)–Salphe compound played the role of axial ligand. However, the reaction time was longer than when using Jacobsen's catalyst because of the structure of the Mn(III)–Salphe compound, in which coordination geometries by the two alcoholic hydroxyls with certain angles affected the substrate approaching the Mn(V) = 0 center. The chiral ligand was characterized by the combination of infrared, ultraviolet, and visible spectra and 1H NMR. Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file. 相似文献
17.
Masoud Nasr-Esfahani Tooba Abdizadeh 《Phosphorus, sulfur, and silicon and the related elements》2013,188(5):596-608
Abstract Vanadatesulfuric acid (VSA), as a novel and heterogeneous catalyst, was used for an efficient synthesis of 3,4-dihydropyrimidin-2(1H)-ones (thiones) using an aldehyde, urea, or thiourea and an acyclic β-dicarbonyl compound under solvent-free conditions. VSA is prepared via the reaction of sodium metavanadate and chlorosulfonic acid in high purity. The catalyst was characterized by FTIR, X-ray diffraction (XRD), and transmission electron microscopy (TEM) analysis. Compared to the classical Biginelli reactions, this method consistently has the advantage of high yields, simple workup, short reaction times, and reusability of the catalyst. Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file. 相似文献
18.
The reaction between thallium(I) and [CoIIIW12O40]5- in the presence of ruthenium(III) as catalyst proceeds viainitial outer-sphere oxidation of the catalyst to ruthenium(VI). The ruthenium(IV) thus generated will oxidize thallium(I)
to an unstable thallium(II) which by reacting with oxidant gives the final product, thallium(III). The formation of ruthenium(II)
by direct two-electron reduction of the catalyst by thallium(I) is thermodynamically less favorable. The reaction rate is
unaffected by the [ H+ ], whereas it is catalyzed by chloride ion . The formation of reactive chlorocomplex,TlCl, in a prior equilibrium is the
reason for the chloride ion catalysis. Increasing the relative permittivity of the medium increases the rate of the reaction,
which is attributed to the formation of an outer-sphere complex between the catalyst and oxidant.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
19.
This article reports the use of a binary single‐site catalyst system for synthesizing comb‐branched polypropylene samples having isotactic polypropylene (iPP) backbones and atactic polypropylene (aPP) side chains from propylene feedstock. This catalyst system consisted of the bisiminepyridine iron catalyst {[2‐ArN?C(Me)]2C5H3N}FeCl2 [Ar = 2,6‐C6H3(Me)2] ( 1 ) and the zirconocene catalyst rac‐Me2Si(2‐MeBenz[e]Ind)2ZrCl2 ( 2 ). The former in situ generated 1‐propenyl‐ended aPP macromonomer, whereas the latter incorporated the macromonomer into the copolymer. The effects of reaction conditions, such as the catalyst addition procedure and the ratio of 1 / 2 on the branching frequency, were examined. Copolymer samples having a branching density up to 8.6 aPP side chains per 1000 iPP monomer units were obtained. The branched copolymers were characterized by 13C NMR and differential scanning calorimetry. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1152–1159, 2003 相似文献
20.
Mujie Yang Min Zheng Anita Furlani Maria Vittoria Russo 《Journal of polymer science. Part A, Polymer chemistry》1994,32(14):2709-2713
Homogeneous polymerization of propargyl alcohol (OHP) with Pd (C?CCH2OH)2(PPh3)2 [Pd?C] catalyst in CHCl3-CH3OH mixed solvent system has been investigated. [Pd?C] was found to be a novel effective catalyst for the OHP polymerization. Some features, kinetic behavior, and effect of solvent for the OHP polymerization are described and discussed. The overall polymerization activation energy was found to be 75.6kJ/mol and the rate equation can be expressed as Rp = kp[OHP] [Pd?C]0.7, where kp = 3.14 × 10-4 L0.7/ mol0.7 S (60°C). Polypropargyl alcohol (POHP) obtained is a brown powder with a number-average molecular weight (M?n) of 103-2 × 103, and soluble in MeOH, DMF, and DMSO. Conducting properties of the resulting POHP were investigated. © 1994 John Wiley & Sons, Inc. 相似文献