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1.
Recyclable Palladium Catalysts for the Heck/Sonogashira Reaction under Microwave‐assisted Thermomorphic Conditions 下载免费PDF全文
Norman Lu Kwan‐Yu Lin Chieh‐Keng Li Chih‐Chieh Kung Yun‐Peng Yeh Yao‐Yi Cheng Ling‐Kang Liu 《中国化学会会志》2015,62(1):64-72
The reaction of allyl palladium(II) chloride dimer and 4,4′‐bis(RfCH2OCH2)‐2,2′‐bpy, 1a–b , in the presence of AgOTf resulted in the synthesis of cationic palladium complex, [Pd(η3‐allyl)(4,4′‐bis‐(RfCH2OCH2)‐2,2′‐bpy)](OTf), 2a–b where Rf = C9F19 ( a ), C10F21 ( b ), respectively. The reaction of [PdCl2(CH3CN)] or K2PdCl4 with 1b , gave rise to the synthesis of [PdCl2(4,4′‐bis‐(C10F21CH2OCH2)‐2,2′‐bpy)], 3b . The quantitatively determined solubility curves of 2a–b and 3b in DMF indicated dramatic increase of solubility for 2a – b and 3b from ?40 to 90 °C. The catalyst‐recoverable Pd‐catalyzed Heck/Sonogashira reactions were successfully achieved in DMF with microwave‐assistance. The cationic Pd‐catalyzed Heck arylation of methyl acrylate was selected to demonstrate the feasibility of recycling 2a–b using DMF as a solvent under microwave‐assisted thermomorphic conditions. At the end of each cycle, the product mixtures were cooled, and then the catalysts were recovered by decantation. The Heck arylation catalyzed by 2b under microwave‐assisted mode exhibited good recycling results favoring the trans product. To our knowledge, this is the first example of cationic Pd‐catalyzed Heck arylation under microwave‐assisted thermomorphic conditions. Additionally, recoverable 3b ‐catalyzed Sonogashira reactions were also achieved successfully in DMF. The reactions under microwave‐assistance gave much better results in yield and in efficiency than that under conventional thermal heating. 相似文献
2.
The activity of [Pd(C6H4CH2 NH2‐κ2‐C‐N)PPh3MOBPPY]OTf complex, A (MOBPPY = 4‐methoxybenzoylmethylenetriphenyl‐ phosphoraneylide), was investigated in the Heck–Mizoroki C? C cross‐coupling reaction under conventional heating and microwave irradiation conditions. The complex is an active and efficient catalyst for the Heck reaction of aryl halides. The yields were excellent using a catalytic amount of [Pd(C6H4CH2 NH2‐κ2‐C‐N)PPh3MOBPPY]OTf complex in N‐methyl‐2‐pyrrolidinone (NMP) at 130 °C and 600 W. In comparison to conventional heating conditions, the reactions under microwave irradiation gave higher yields in shorter reaction times. Copyright © 2010 European Peptide Society and John Wiley & Sons, Ltd. 相似文献
3.
The activity of [Pd{C6H4(CH2N(CH2Ph)2)}(μ‐Br)]2 complex was investigated in cross‐coupling reactions of triethoxy(phenyl)silane with various aryl halides under microwave irradiation. This complex is an efficient and stable catalyst for the synthesis of substituted biphenyls that is non‐sensitive to air and moisture. The combination of dimeric complex as homogenous catalyst, microwave irradiation, DMF as microwave‐active polar solvent and TBAF as microwave‐active additive led to excellent yields in short reaction times. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
4.
Confined Ultrathin Pd‐Ce Nanowires with Outstanding Moisture and SO2 Tolerance in Methane Combustion 下载免费PDF全文
Dr. Honggen Peng Cheng Rao Prof. Ning Zhang Xiang Wang Wenming Liu Wenting Mao Lu Han Prof. Pengfei Zhang Prof. Sheng Dai 《Angewandte Chemie (International ed. in English)》2018,57(29):8953-8957
An efficient strategy (enhanced metal oxide interaction and core–shell confinement to inhibit the sintering of noble metal) is presented confined ultrathin Pd‐CeOx nanowire (2.4 nm) catalysts for methane combustion, which enable CH4 total oxidation at a low temperature of 350 °C, much lower than that of a commercial Pd/Al2O3 catalyst (425 °C). Importantly, unexpected stability was observed even under harsh conditions (800 °C, water vapor, and SO2), owing to the confinement and shielding effect of the porous silica shell together with the promotion of CeO2. Pd‐CeOx solid solution nanowires (Pd‐Ce NW) as cores and porous silica as shells (Pd‐CeNW@SiO2) were rationally prepared by a facile and direct self‐assembly strategy for the first time. This strategy is expected to inspire more active and stable catalysts for use under severe conditions (vehicle emissions control, reforming, and water–gas shift reaction). 相似文献
5.
Grisel Corro Carlos Cano J.L.G. Fierro 《Journal of molecular catalysis. A, Chemical》2010,315(1):35-42
The catalytic oxidation of methane was studied over calcined and reduced Pt–Pd/γ-Al2O3 catalysts, in the presence and the absence of SO2 in the CH4–O2 reaction feed. The effect of sulfation (SO2 + O2 for 4 h at 500 °C) was also studied on the catalyst resistance to deactivation by sulfur poisoning. Sulfating the calcined Pt–Pd/γ-Al2O3 catalysts resulted in a strong deactivation for the CH4–O2 reaction. However, the catalytic activity of the reduced-sulfated Pt–Pd/γ-Al2O3 catalyst for CH4–O2 reaction remained rather unaffected in the presence and in the absence of SO2 in the reaction feed. XPS analysis revealed, over reduced-sulfated Pt–Pd/γ-Al2O3 catalysts, the presence of Pt(0) metallic surface species on which SO2 interactions may be faster related to Pd surface species. The presence of Pt(0) may be necessary to prevent the interactions between SO2 and Pd surface species. Long time catalytic tests showed that the activity of a reduced Pt–Pd/γ-Al2O3 catalysts for CH4–O2 reactions remained rather unaffected despite the presence of SO2 in the reaction feed. 相似文献
6.
V. V. Lesnyak V. K. Yatsimirskii I. N. Gut O. Yu. Boldyreva 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2008,82(9):1456-1459
The influence of hydrogen-containing molybdenum and tungsten bronzes on the catalytic activity of palladium composite catalysts for the oxidation of H2, CO, and CH4 was studied. It was found that the composite catalysts containing H x MO3 phases (M = W or Mo), which were formed by the reduction of MoO3 and WO3 oxides with hydrogen in the presence of deposited Pd, showed higher catalytic activity in the oxidation of small molecules (H2, CO, and CH4) with excess oxygen than the traditional Pd/Al2O3 deposited catalyst with the same content of the deposited metal. It was shown that the thermal stability of the H x MO3 phases was the limiting factor influencing the activity of these composite catalysts. 相似文献
7.
Dr. Anna Dall'Anese Dr. Massimo Tosolini Chiara Alberoni Dr. Gabriele Balducci Dr. Maurizio Polentarutti Prof. Dr. Claudio Pellecchia Prof. Dr. Paolo Tecilla Prof. Dr. Barbara Milani 《欧洲无机化学杂志》2023,26(1):e202200481
The last two decades have witnessed the development of homogeneous catalysts for ethylene homo- and co-polymerization reactions based on late transition metals. When Pd(II) is the metal of choice, the best ligand-metal combination deals with either bidentate nitrogen-donor molecules or phosphinobenzene sulfonate derivatives. In this contribution we have investigated the coordination chemistry to Pd(II) of a bidentate phosphorus ligand, namely 4,5-bis(diphenylphosphino)acenaphthene ( 1 ). Starting from the neutral complex, [Pd( 1 )(CH3)Cl], we obtained the cationic derivatives [Pd( 1 )(CH3)(L)][SbF6], with L being either CH3CN or 3,5-lutidine. Using in situ NMR spectroscopy we investigated the reaction of [Pd( 1 )(CH3)(NCCH3)][SbF6] with ethylene, at room temperature, and ambient ethylene pressure. We discovered that [Pd( 1 )(CH3)(NCCH3)][SbF6] acts as a catalyst for butenes and hexenes synthesis with the relevant Pd-ethyl intermediate as the catalyst resting state. At the same time the color of the solution turned from pale yellow to light red due to the formation of the dinuclear species [Pd(μ-η2−C6H5)PPh)−PPh2]2[SbF6]2. Both the neutral Pd(II) complex, activated in situ by NaSbF6, and the monocationic acetonitrile derivative were tested in the ethylene homopolymerization reaction at high pressure, leading to low molecular weight, branched, polyethylene. 相似文献
8.
Hyun Ook Seo Jaeyoung Lee Kwang‐Dae Kim Yuan Luo Nilay Kumar Dey Young Dok Kim 《Surface and interface analysis : SIA》2011,43(11):1371-1376
Behaviors of Pd structures with different thicknesses supported by Ta2O5/Ta in the reaction with oxygen and CO were studied by XPS and SEM. For the samples with a Pd thickness of 3 nm, a new low‐binding‐energy component appeared in the Pd 3d level upon O2 exposure at ~200 °C and was reduced in intensity after a subsequent CO exposure at 150 and 200 °C. The change in the Ta 4f state could also be found upon oxygen and CO exposure, indicating that both Pd and the Ta‐oxide substrate participate in the chemical reactions. For the sample with a higher Pd thickness, a positive shift in the Pd 3d level due to the oxidation of Pd was observed after exposure to O2 at a higher temperature (280 °C). A subsequent CO exposure at ~150 °C could not reduce Pd‐oxide layers, as confirmed by the unchanged Pd 3d spectra after CO treatment, i.e. Pd‐oxide was not reactive for CO oxidation. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
9.
The polymerization of norbornene with bis(β‐ketonaphthylamino) palladium(II), Pd{CH3C(O)CHC[N(naphthyl)]CH3}2, in combination with tris(pentafluorophenyl)borane (B(C6F5)3), was investigated by varying the B:Pd(II) molar ratio, monomer concentration, reaction temperature, and time. The catalytic activity was found to reach 2.8 × 104 gPolymer/(molPd?h) and the obtained polynorbornene (PNBE) was confirmed to be vinyl addition polymer and showed good thermo‐stability (Tdec > 350°C), but exhibited poor solubility in organic solvents due to the relative higher stereo regularity. Pd{CH3C(O)CHC[N(naphthyl)]CH3}2/B(C6F5)3 system is also an active catalyst for copolymerization of norbornene and 5‐norbornene‐2‐yl acetate (NBE‐OCOCH3) in toluene with moderate yields (in 9.2–36.5% yields) and produces the addition‐type copolymer with relatively high molecular weights (0.96 × 104–2.13 × 104 g/mol). The incorporation of functional group in the copolymer can be controlled up to 0.9–23.5 mol% by varying the NBE‐OCOCH3 monomer feed ratios from 10 to 90%. The copolymers are proved to be noncrystalline and show good solubility in common organic solvents and excellent thermal stability up to 350°C. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
10.
The catalytic activity of dimeric [Pd{C6H2(CH2CH2NH2)–(OMe)2,2,3}(μ‐Br)]2 and monomeric [Pd{C6H2(CH2CH2NH2)–(OMe)2,2,3}Br(PPh3)] complexes as efficient, stable and air‐ and moisture‐tolerant catalysts was investigated in the Suzuki, Stille and Hiyama cross‐coupling and homo‐coupling reactions of various aryl halides. Substituted biaryls were produced in excellent yields in short reaction times using catalytic amounts of these complexes. The monomeric complex was demonstrated to be more active than the corresponding dimeric catalyst for the cross‐coupling reaction of unreactive aryl bromides and chlorides. The combination of homogeneous metal catalysts and microwave irradiation gave higher yields of products in shorter reaction times. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
11.
A series of α‐(fluoro‐substituted phenyl)pyridines have been synthesized by means of a palladium‐catalyzed cross‐coupling reaction between fluoro‐substituted phenylboronic acid and 2‐bromopyridine or its derivatives. The reactivities of the phenylboronic acids containing di‐ and tri‐fluoro substituents with α‐pyridyl bromide were investigated in different catalyst systems. Unsuccessful results were observed in the Pd/C and PPh3 catalyst system due to phenylboronic acid containing electron‐withdrawing F atom(s). For the catalyst system of Pd(OAc)2/PPh3, the reactions gave moderate yields of 55% –80%, meanwhile, affording 10% –20% of dimerisation (self‐coupling) by‐products, but trace products were obtained in coupling with 2,4‐difluorophenylboronic acids because of steric hinderance. Pd(PPh3)4 was more reactive for boronic acids with sterically hindering F atom(s), and the coupling reactions gave good yields of 90% and 91% without any self‐coupling by‐product. 相似文献
12.
Two new Fe3O4 microspheres‐supported semi‐homogeneous catalysts, namely Fe3O4‐G4‐polyaminoamido (PAMAM) dendrimers‐Pd(0) and Fe3O4‐polyethylene glycols (PEGs)‐Pd(0) were synthesized and characterized by X‐ray powder diffraction, infrared spectrum, scanning electron microscopy, transmission electron microscopy, X‐ray photoelectron spectroscopy and thermal gravimetric analysis, which can catalyze Suzuki coupling reactions. The performance of catalysts was tested for the reactions of aryl halides with phenyl boronic acid and compared with a heterogeneous catalyst Fe3O4‐(3‐aminopropyl)triethoxysilane (APTS)‐Pd(0), in which Fe3O4‐G4‐PAMAM dendrimers‐Pd(0) shows the best activity among the three catalysts. The order of the catalytic activities is Fe3O4‐G4‐PAMAM dendrimers‐Pd(0)>Fe3O4‐PEGs‐Pd(0)>Fe3O4‐APTS‐Pd(0). The catalysts can be quickly and completely recovered by simply applying a magnet of 105 mT and the efficiencies remain unaltered even after four recycles. 相似文献
13.
Yingbin Zheng Xiaoshan Feng Daifeng Lin Enhui Wu Yongjin Luo Yufeng You Baoquan Huang Qingrong Qian Qinghua Chen 《中国化学》2020,38(2):144-150
Summary of main observation and conclusion A series of electrospun LaCoO3 perovskites derived from CoX2 (X =CH3COO-,NO3-) were prepared and investigated for total propane oxidation.It is shown that pure rhombohedral perovskite LaCoO3 from Co(CH3COO)2 can be obtained at a relatively low temperature,400 ℃,benefitting from the complexation effect of CH3COO-.On the other hand,CH3COO-can accelerate the complete decomposition of polymer.The low-temperature process can protect LaCoO3 nanoparticles from growing up. 相似文献
14.
CeO2‐promoted Na‐Mn‐W/SiO2 catalyst has been studied for catalytic oxidation of methane in a micro‐stainless‐steel reactor at elevated pressure. The effect of operating conditions, such as GHSV, pressure and CH4/O2 ratio, has been investigated. 22.0% CH4 conversion with 73.8% C2‐C4 selectivity (C2/C3/C4 = 3.8/1.0/3.6) was obtained at 1003 K, 1.5 × 105 h?;1 GHSV and 1.0 MPa. The results show: Elevated pressure disadvantages the catalytic oxidation of methane to C2‐C4 hydrocarbons. Large amounts of C3 and C4 hydrocarbons are observed. The unfavorable effects of elevated pressure can be overcome by increasing GHSV; the reaction is strongly dependent on the operating conditions at elevated pressure, particularly dependent on GHSV and ratio of CH4/O2. Analyses by means of XRD, XPS and CO2‐TPD show that CO2 produced from the reaction makes a weakly poisoning capacity of the catalyst; information of changeful valence on Ce and Mn was detected over the near‐surface of the Ce‐Na‐W‐Mn/SiO2 catalyst; the existence of Ce3+/Ce4+ and Mn2+/Mn3+ ion couple supported that the reaction over the catalyst followed the Redeal‐Redox mechanism. Oxidative re‐coupling of C2H6 and CH4 in gas phase or over surface of catalyst produces C3 or C4 hydrocarbons. 相似文献
15.
Meiliu Wang Weizheng Weng Haozhuan Zheng Xiaodong Yi Chuanjing Huang Huilin Wan 《天然气化学杂志》2009,18(3):300-305
Oscillations in temperatures of catalyst bed as well as concentrations of gas phase species at the exit of reactor were observed during the partial oxidation of methane to synthesis gas over Ru/Al2O3 in the temperature range of 600 to 850 °C. XRD, H2-TPR and in situ Raman techniques was used to characterize the catalyst. Two types of ruthenium species, i.e. the ruthenium species weakly interacted with Al2O3 and that strongly interacted with the support, were identified by H2-TPR experiment. These species are responsible for two types of oscillation profiles observed during the reaction. The oscillations were the result of these ruthenium species switching cyclically between the oxidized state and the reduced state under the reaction condition. These cyclic transformations, in turn, were the result of temperature variations caused by the varying levels of the strongly exothermic CH4 combustion and the highly endothermic CH4 reforming (with H2O and CO2) reactions (or the less exothermic direct partial oxidation of methane to CO and H2), which were favored by the oxidized and the metallic sites, respectively. The major pathway of synthesis gas formation over the catalyst was via the combustion-reforming mechanism. 相似文献
16.
17.
This paper reports a green magnetic quasiheterogeneous efficient palladium catalyst in which Pd0 nanoparticles have been immobilized in self‐assembled hyperbranched polyglycidole (SAHPG)‐coated magnetic Fe3O4 nanoparticles (Fe3O4‐SAHPG‐Pd0). This catalyst has been used for effective ligandless Pd catalyzed Suzuki–Miyaura coupling reactions of different aryl halides with substituted boronic acids at room temperature and in aqueous media. Herein, SAHPG is used as support; it also acts as a reducing agent and stabilizer to promote the transformation of PdII to Pd0 nanoparticles. Also, this environmental friendly quasiheterogeneous catalyst is employed for the first time in the synthesis of new pyrimido[4,5‐b]indoles via oxidative addition/C? H activation reactions on the pyrimidine rings, which were obtained with higher yield and faster than when Pd(OAc)2 was used as the catalyst. Interestingly, the above‐mentioned catalyst could be recovered in a facile manner from the reaction mixture by applying an external magnet device and recycled several times with no significant decrease in the catalytic activity. 相似文献
18.
Dr. Qin Wang Dr. Wenjing Jia Dr. Baocang Liu Prof. Dr. Wenzhi Zhao Dr. Changyan Li Prof. Dr. Jun Zhang Prof. Dr. Gang Xu 《化学:亚洲杂志》2012,7(10):2258-2267
Herein, we report a facile surfactant‐assisted solvothermal synthetic method to prepare nearly monodisperse spherical CeO2 nanocrystals. A good control of the size of CeO2 nanocrystals in the range of 100–500 nm was achieved by simply varying the synthetic parameters such as reaction time, volume ratio of ethanol to water (R), molar ratio of PVP, and concentration of Ce(NO3)3?6 H2O in solution. A possible mechanism for the growth of spherical CeO2 nanocrystals is proposed. The obtained CeO2 nanocrystals with a surface area of up to 47 m2g?1 were then employed as a catalyst support. By loading Au‐Pd nanoparticles (about 3 wt. %) onto the CeO2 support, an Au‐Pd/CeO2 catalyst was prepared that exhibited high catalytic activity for HCHO oxidation. At the low temperature of 50 °C, the percentage of HCHO conversion was 100 %, suggesting potential applications in preferential oxidation and other catalytic reactions. These Au‐Pd/CeO2 catalysts may also find applications in indoor formaldehyde decontamination and industrial catalysis. The facile solvothermal method can be extended to the preparation of other metal oxide nanocrystals and provides guidance for size‐ and morphology‐controlled synthesis. 相似文献
19.
The activity of dimeric [Pd{C6H4(CH2N(CH2Ph)2)} (μ‐Br)]2 complex as an efficient, air‐ and moisture‐tolerant catalyst was investigated in amination reactions of various aryl halides with secondary amines. Substituted tertiary aryl amines were produced in excellent yields and short reaction times using catalytic amounts of this dimeric complex in DMSO at 120°C. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
20.
Chandan Kumar Pal Swagatika Sahu Ranjan Kumar Sahu Rajesh Kumar Singh Ashis Kumar Jena 《应用有机金属化学》2019,33(8)
A convenient method for the synthesis of magnetically recyclable palladium nanoparticles (Fe3O4‐Pd) is described. The catalytic application of the Fe3O4‐Pd nanoparticles was explored for the first time in oxidative coupling between amides and olefins. p‐Toluenesulfonic acid plays a significant role in the oxidative amidation reaction. The reaction proceeds at room temperature, resulting in (Z)‐enamides under ambient air in the absence of co‐catalyst and ligand. The superparamagnetic nature of Fe3O4‐Pd facilitates easy, quantitative recovery of the catalyst from a reaction mixture, and it can be reused for up to three consecutive cycles with a slight decrease in catalytic activity. 相似文献