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1.
Subhash Chandra Ghosh Senthilkumar Muthaiah Yao Zhang Xiangya Xu Soon Hyeok Hong 《Advanced Synthesis \u0026amp; Catalysis》2009,351(16):2643-2649
Amides are synthesized directly from alcohols and amines in high yields using an in situ generated catalyst from easily available ruthenium complexes such as the (p‐cymene)ruthenium dichloride dimer, [Ru(p‐cymeme)Cl2]2, or the (benzene)ruthenium dichloride dimer, [Ru(benzene)Cl2]2, an N‐heterocyclic carbene (NHC) ligand, and a nitrogen containing L‐type ligand such as acetonitrile. The phosphine‐free catalyst systems showed improved or comparable activity compared to previous phosphine‐based catalytic systems. The in situ generated catalyst from [Ru(benzene)Cl2]2, an NHC ligand, and acetonitrile showed excellent activity toward reactions with cyclic secondary amines such as piperidine and morpholine. 相似文献
2.
C. U. Ingemar Odenbrand S. Lars T. Andersson 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1982,32(2):365-375
The chemical and physical characteristics of a ruthenium catalyst used in the hydrogenation of benzene to cyclohexene has been investigated. The active catalyst consists of metallic ruthenium obtained by hydrogen reduction of the precursor suspended in the alkaline aqueous phase. The precursor consists of hydrous oxides of ruthenium with a surface area of 27 m2 g?1. After reduction the surface area increases to 112 m2 g?1 and a drastic change in pore-size distribution occurs. The average pore diameter decreases from 28 to 13 nm and the number of pores < 8 nm increases substantially. The macroscopic particle size, in the range 25–40 μm, decreases along with the decreasing ruthenium concentration. Poisoning of the catalyst by corrosion products, mainly hydroxides of iron and chromium, is also discussed. 相似文献
3.
Tamsin E. Bell Guowu Zhan Kejun Wu Hua Chun Zeng Laura Torrente-Murciano 《Topics in Catalysis》2017,60(15-16):1251-1259
The use of ammonia as a hydrogen vector has the potential to unlock the hydrogen economy. In this context, this paper presents novel insights into improving the ammonia decomposition activity of ruthenium nanoparticles supported on carbon nanotubes (CNT) by nitrogen doping. Our results can be applied to develop more active systems capable of delivering hydrogen on demand, with a view to move towards the low temperature target of less than 150?°C. Herein we demonstrate that nitrogen doping of the CNT support enhances the activity of ruthenium nanoparticles for the low temperature ammonia decomposition with turnover frequency numbers at 400?°C of 6200 LH2 molRu ?1 h?1, higher than the corresponding value of unmodified CNT supports under the same conditions (4400 LH2 molRu ?1 h??1), despite presenting similar ruthenium particle sizes. However, when the nitrogen doping process is carried out with cetyltrimethylammonium bromide (CTAB) to enhance the dispersion of CNTs, the catalyst becomes virtually inactive despite the small ruthenium particle size, likely due to interference of CTAB, weakening the metal–support interaction. Our results demonstrate that the low temperature ammonia decomposition activity of ruthenium can be enhanced by nitrogen doping of the CNT support due to simultaneously increasing the support’s conductivity and basicity, electronically modifying the ruthenium active sites and promoting a strong metal–support interaction. 相似文献
4.
AnaM. Lozano Vila Stijn Monsaert Renata Drozdzak Stanislaw Wolowiec Francis Verpoort 《Advanced Synthesis \u0026amp; Catalysis》2009,351(16):2689-2701
We here report on the stability and catalytic activity of new indenylidene‐Schiff base‐ruthenium complexes 3a – f through representative cross‐metathesis (CM) and ring‐closing metathesis (RCM) reactions. Excellent activity of the new complexes was found for the two selected RCM reactions; prominent conversion was obtained compared to the commercial Hoveyda–Grubbs catalyst 2 . Moreover, excellent results were obtained for a standard CM reaction. Higher conversions were achieved with one of the indenylidene catalysts compared with Hoveyda–Grubbs catalyst. Unexpectedly, an isomerization reaction was observed during the CM reaction of allylbenzene. To the best of our knowledge, isomerization reactions in this model CM reaction in closed systems have never been described using first generation catalysts, including the Hoveyda–Grubbs catalyst. The first model CM reactions as well as the RCM reactions have been monitored using 1H NMR. The course of the CM reaction of 3‐phenylprop‐1‐ene ( 8 ) and cis‐1,4‐diacetoxybut‐2‐ene ( 9 ) was monitored by GC. The isomerization reaction was studied by means of GC‐mass spectrometry and in situ IR spectroscopy. All catalysts were structurally characterized by means of 1H, 13C, and 31P NMR spectroscopy. 相似文献
5.
Hui Li Dongsheng Chu Jun Liu Minghua Qiao Weilin Dai Hexing Li 《Advanced Synthesis \u0026amp; Catalysis》2008,350(6):829-836
A ruthenium‐phosphorus (Ru‐P) amorphous alloy catalyst was prepared by chemical reduction of ruthenium(III) ions [Ru3+] with hypophosphite [H2PO2−] in aqueous solution and was applied to the liquid‐phase hydrogenation of maltose. In comparison with other reference catalysts, Ru‐P showed significant activity as evident in the order: Ru‐P> Ru‐B≫ Ni‐P> Co‐P≫ Raney Ni. Furthermore, this catalyst was also found to be more durable during this hydrogenation process. Special emphasis was laid on a comparative study of Ru‐P and Ru‐B catalysts to get an insight into the excellent catalytic performances of Ru‐P. 相似文献
6.
A new polymeric ligand was synthesized through the reaction of 4‐(pyridinylimine)phenol and formaldehyde in a basic medium, and its corresponding polymer–nickel complexes were formed in a 1:1 molar ratio. The synthesized compounds were characterized using elemental and spectral analyses. The monomeric and polymeric Ni(II) complexes (C1 and C2, respectively) were evaluated as catalyst precursors for ethylene oligomerization, using methylaluminoxane as an activator at two different ethylene pressures. C2 was found to be a more effective pre‐catalyst than C1, with the co‐catalyst having a similar effect in both cases. C2 exhibited an activity of 1.282 × 106 g (mol Ni)?1 h?1 bar?1, with an Al:Ni ratio of 2000:1 at room temperature and 1 atm ethylene pressure. Meanwhile C1 exhibited an activity of 1.126 × 106 g (mol Ni)?1 h?1 bar?1 under similar experimental conditions. At 5 atm ethylene pressure, C1 favoured the formation of high‐density polyethylene, whereas C2 favoured the formation of branched low‐density polyethylene. Copyright © 2012 Society of Chemical Industry 相似文献
7.
Mitochondrial Fragmentation Is an Important Cellular Event Induced by Ruthenium(II) Polypyridyl Complexes in Osteosarcoma Cells
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Yanxin Du Xiaoyan Fu Hong Li Bolai Chen Yuhai Guo Guoyi Su Hu Zhang Feipeng Ning Yongpeng Lin Wenjie Mei Tianfeng Chen 《ChemMedChem》2014,9(4):714-718
A series of ruthenium(II) polypyridyl complexes were synthesized and evaluated for their in vitro anticancer activities. The results showed that ruthenium polypyridyl complexes, especially [Ru(bpy)2(p‐tFPIP)]2+ ( 2 a ; bpy=bipyridine, tFPIP=2‐(2‐trifluoromethane phenyl)imidazole[4,5‐f][1,10]phenanthroline), exhibited novel anticancer activity against human cancer cell lines, but with less toxicity to a human normal cell line. The results of flow cytometry and caspase activities analysis indicated that the 2 a ‐induced growth inhibition against MG‐63 osteosarcoma cells was mainly caused by mitochondria‐mediated apoptosis. DNA fragmentation and nuclear condensation as detected by TUNEL–DAPI co‐staining further confirmed 2 a ‐induced apoptotic cell death. Further, fluorescence imaging revealed that ruthenium(II) polypyridyl complexes could target mitochondria to induce mitochondrial fragmentation, accompanied by depletion of mitochondrial membrane potential. Taken together, these findings suggest a potential application of theses ruthenium(II) complexes in the treatment of cancers. 相似文献
8.
Razan Alaneed Yury Golitsyn Till Hauenschild Markus Pietzsch Detlef Reichert Jrg Kressler 《Polymer International》2021,70(1):135-144
A highly efficient approach for the synthesis of polyester‐based networks via aza‐Michael addition of primary amines to α,β‐unsaturated (vinyl) end groups of poly(glycerol adipate) (PGA) was achieved. By acylation of PGA with 6‐(Fmoc‐amino)hexanoic acid side chains via Steglich esterification, protected amine‐functionalized PGA was obtained. This was followed by the removal of fluorenylmethyloxycarbonyl (Fmoc) protecting groups and the synthesis of PGA‐based networks under catalyst‐free conditions. The successful conjugate addition of primary amines to vinyl end groups and network formation were confirmed using 13C magic angle spinning NMR and Fourier transform infrared spectroscopy. Network heterogeneity and defects were quantitatively investigated using 1H double‐quantum NMR spectroscopy. Finally, a hydrogel was prepared with potential biomedical applications. 相似文献
9.
A new catalyst separation and recycling protocol combining magnetic nanoparticles and host‐guest assembly was developed. The catalyst, (η6‐arene)[N‐(para‐toluenesulfonyl)‐1,2‐diphenylethylenediamine]ruthenium trifluoromethanesulfonate [Ru(OTf)(TsDPEN)(η6‐arene)] bearing a dialkylammonium salt tag, was easily separated from the reaction mixtures by magnet‐assisted decantation, on basis of the formation of a pseudorotaxane complex by using dibenzo[24]crown‐8‐modified Fe3O4 nanoparticles. The ruthenium catalyst has been successfully reused at least 5 times with the retention of enantioselectivity but at the expense of relatively low catalytic activities in the asymmetric hydrogenation of 2‐methylquinoline. 相似文献
10.
Gholam Hossein Zohuri Ali Bakhash Kasaeian Mahmoud Torabi Angagi Roghieh Jamjah Mohammad Ali Mousavian Mehersal Emami Saied Ahmadjo 《Polymer International》2005,54(6):882-885
Heterogeneous Ziegler–Natta catalyst of MgCl2 (ethoxide type)/TiCl4/diether was prepared. 2,2‐Diisobutyl‐1,3‐dimethoxy propane (DiBDMP), diether, was used as internal donor. Slurry polymerization of propylene was carried out using the catalyst in dry heptane while triethylaluminium (TEA) was used as co‐catalyst. The co‐catalyst effects, such as catalyst molar ratio, polymerization temperature, H2 pressure, external donor, triisobutylaluminium (TiBA) and monomer pressure, on the activity of the catalyst and isotacticity index (II) of the polymers obtained were studied. Rate of polymerization versus polymerization time is of a decay type with no acceleration period. There are an optimum Al/Ti molar ratio and temperature to obtain the highest activity of the catalyst. The maximum activity was obtained at 60 °C. Increasing the monomer pressure to 1 010 000 Pa linearly increased the activity of the catalyst. Addition of hydrogen to 151 500 Pa pressure increased activity of the catalyst from 2.25 to 5.45 kg polypropylene (PP) (g cat)?1 h?1 using 505 000 Pa pressure of monomer. The II decreased with increasing Al/Ti ratio, monomer pressure, hydrogen pressure and increased with increasing temperature to 60 °C, following with decrease as the temperature increases. Productivity of 11.55 kg (PP) (g cat)?1 h?1 was obtained at 1 010 000 Pa pressure of monomer and temperature of 60 °C. Addition of methyl p‐toluate (MPT) and dimethoxymethyl cyclohexyl silane (DMMCHS) as external donors decreased the activity of the catalyst sharply, while the II slightly increased. Some studies of the catalyst structure and morphology of the polymer were carried out using FTIR, X‐ray fluorescence, scanning electron microscopy and Brunauer–Emmett–Teller techniques. Copyright © 2005 Society of Chemical Industry 相似文献
11.
Kinetics of the liquid‐phase catalytic hydrogenation of m‐phenoxybenzaldehyde to m‐phenoxybenzyl alcohol have been investigated over the Raney nickel catalyst. Effects of hydrogen partial pressure (500‐2000 kPa), catalyst loading (1.6‐6.4 g.L?1), m‐phenoxybenzaldehyde concentration (0.2‐0.8 mol.L?1) and temperature (333‐363 K) on the progress of the reaction were studied. The speed of stirring > 15 rps has no effect on the initial rate of reaction. Effects of various catalysts and solvents on the hydrogenation of m‐phenoxybenzaldehyde have been investigated. The reaction was found to be first order with respect to the hydrogen partial pressure, catalyst loading and m‐phenoxybenzaldehyde concentration. Several Langmuir‐Hinshelwood type models were considered and the experimental data fitted to the model involving surface reaction, between dissociatively adsorbed hydrogen and molecularly adsorbed m‐phenoxybenzaldehyde. 相似文献
12.
Shashikant R. Kuchekar Haribhau R. Aher Somnath D. Bhumkar Ponnadurai Ramasami 《分离科学与技术》2020,55(14):2570-2582
ABSTRACT A selective and sensitive solvent extraction and spectrophotometric study of the ruthenium(III)–p-methylphenyl thiourea (PMPT) system is presented. The optimum conditions were determined by a critical study of acid concentration, reagent concentration, equilibration period, heating time and effect of solvent on the equilibrium. Ruthenium(III) forms 1:1 complex with PMPT in 20% ethanol and extracted into chloroform. Conformity to Beer’s law at 600 nm was observed up to 40 µg mL–1 of ruthenium. Molar absorptivity and Sandell’s sensitivity were found to be 2.31 × 103 L mol?1cm?1 and 0.044 μg cm?2, respectively. The detection limits were 0.11 μg mL?1 of ruthenium. The method is free from interferences from large number of cations and anions. Proposed method was successfully applied to the separation and determination of ruthenium from synthetic alloys, catalyst and water samples. Sequential separation and determination method for ruthenium(III), osmium(VIII) and iron(II) has been developed. 相似文献
13.
Muhammad Afzal Subhani Kai‐Sven Müller Peter Eilbracht 《Advanced Synthesis \u0026amp; Catalysis》2009,351(13):2113-2123
In this contribution, the synthesis of a new class of chiral polyamino alcohols (PAA) via a two‐step hydroaminomethylation/hydrolysis procedure is reported. The chiral polyamines are obtained by hydroaminomethylation of N‐olefinic oxazolidinones with different amines in first step followed by hydrolysis of the resulting polyamines to give the chiral PAA in the second step. The dendritic chiral PAA (Mw=1300–1400 g mol−1) are also synthesized efficiently through a multifold hydroaminomethylation/hydrolysis procedure. Furthermore, chiral PAA are investigated as ligands in ruthenium‐catalyzed asymmetric hydrogen transfer reduction of acetophenone to 1‐phenyl alcohol. 相似文献
14.
Simon Maechling Mirko Zaja Siegfried Blechert 《Advanced Synthesis \u0026amp; Catalysis》2005,347(10):1413-1422
A turnover number (TON) study of ruthenium‐based metathesis catalysts has been conducted for ring‐closing metathesis (RCM) in dilute solution. Unexpectedly the results indicate that 1st generation metathesis catalysts can give higher TON in RCM of simple unsubstituted terminal olefins than their second generation counterparts. In particular, the 1st generation Hoveyda–Grubbs catalyst showed unexpectedly high activity, particularly when compared to the 2nd generation catalysts. 相似文献
15.
Ethanolamine‐modified polyacrylonitrile (ETA‐m‐PAN) membrane is prepared by in situ modification integrated with a nonsolvent‐induced phase separation method for the first time. The results reveal that both the morphology and the separation performance of the modified membrane change greatly with condition parameters. The membrane formation mechanism is carefully investigated, which is related to the change in the molecular structure and hydrophilic property of ETA‐m‐PAN. The cross‐linked structure leads to the formation of ETA‐m‐PAN spongy membrane. The optimized condition parameters are determined by permeability‐selectivity analysis. Furthermore, the composite membrane with ETA‐m‐PAN as the selective layer is prepared by a dual‐casting method. The obtained membrane shows a good property, flux of 650L m?2 h?1 bar?1, 82% BSA rejection, and 84% water flux recovery ratio. This work demonstrates the great potential of this integrated method for new membrane preparation. 相似文献
16.
Yan‐Jiun Lee Dr. Yadagiri Kurra Prof. Dr. Wenshe R. Liu 《Chembiochem : a European journal of chemical biology》2016,17(6):456-461
A new type of click reaction between an alkyl phosphine and acrylamide was developed and applied for site‐specific protein labeling in vitro and in live cells. Acrylamide is a small electrophilic olefin that readily undergoes phospha‐Michael addition with an alkyl phosphine. Our kinetic study indicated a second‐order rate constant of 0.07 m ?1 s?1 for the reaction between tris(2‐carboxyethyl)phosphine and acrylamide at pH 7.4. To demonstrate its application in protein functionalization, we used a dansyl–phosphine conjugate to successfully label proteins that were site‐specifically installed with N?‐acryloyl‐l ‐lysine and employed a biotin–phosphine conjugate to selectively probe human proteins that were metabolically labeled with N‐acryloyl‐galactosamine. 相似文献
17.
Coordination polymerization of styrene with a ternary catalyst system composed of catalyst neodymium tricarboxylate (Nd), co‐catalyst Al(i‐Bu)3 (Al) and chlorinating agent trichloroethane (Cl) was carried out in cyclohexane. The effects of the catalyst system preparation procedure and of the reaction conditions on catalytic activity, molecular weight and molecular weight distribution of the resultant polymers were investigated. The catalytic activity depended mainly on the molar ratios of Al/Nd and of Cl/Nd and on the ageing temperature and polymerization temperature. High polymerization conversion and high catalytic activity could be obtained at high Al/Nd ratios and/or at high ageing temperature. The catalyst system exhibited high activity of 8.32 × 104 g polystyrene (mol Nd h)?1 at 50 °C. The molecular weight of the polymers obtained reached high weight‐average (Mw) values (Mw = 4.35 × 105 g mol?1) when Al/Nd = 8, but relatively low values (6000–11 000 g mol?1) at high Al/Nd ratios. Copyright © 2005 Society of Chemical Industry 相似文献
18.
Jian‐Liang Pan Mei‐Jywan Syu 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2004,79(10):1050-1056
Penicillin G acylase (PGA) is an important enzyme for the industrial production of 7‐amino‐3‐deacetoxy cephalosporanic acid (7‐ADCA) from cephalosporin G (Ceph‐G), and 6‐aminopenicillanic acid (6‐APA) from penicillin G (Pen‐G). These products are used for the manufacture of semi‐synthetic cephalosporins and penicillins. In this study, immobilized PGA was utilized to catalyze the conversion of Ceph‐G to 7‐ADCA. The optimal conditions were found to be an operating temperature of 45 °C, 0.2 M phosphate buffer, a substrate concentration of 30 mg cm?3 and a catalyst particle concentration of 0.01 g cm?3 (specific activity of 623.2 U g?1). Up to 45 °C the reaction was characterized by an activation energy of 38.66 kJ mol?1. Beyond 57.5 °C there was a sharp decline of activity, characterized by a deactivation energy of 235.88 kJ mol?1. Copyright © 2004 Society of Chemical Industry 相似文献
19.
Jens Theuerkauf Giancarlo Franci Walter Leitner 《Advanced Synthesis \u0026amp; Catalysis》2013,355(1):209-219
A continuous‐flow process for the asymmetric hydrogenation of methyl propionylacetate as a prototypical β‐keto ester in a biphasic system of ionic liquid and supercritical carbon dioxide (scCO2) is presented. An established ruthenium/2,2′‐bis(diphenylphosphino)‐1,1′‐binaphthyl (BINAP) catalyst was immobilised in an imidazolium‐based ionic liquid while scCO2 was used as mobile phase transporting reactants in and products out of the reactor. The use of acidic additives led to significantly higher reaction rates and enhanced catalyst stability albeit at slightly reduced enantioselectivity. High single pass conversions (>90%) and good enantioselectivity (80–82% ee) were achieved in the first 80 h. The initial catalyst activity was retained to 91% after 100 h and to 69% after 150 h time‐on‐stream, whereas the enantioselectivity remained practically constant during the entire process. A total turnover number of ∼21,000 and an averaged space‐time yield (STYav) of 149 g L−1 h−1 were reached in a long‐term experiment. No ruthenium and phosphorus contaminants could be detected via inductively coupled plasma optical emission spectrometry (ICP‐OES) in the product stream and almost quantitative retention by the analysis of the stationary phase was confirmed. A comparison between batch‐wise and continuous‐flow operation on the basis of these data is provided. 相似文献