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1.
Raffael Schuecker Kurt Mereiter Felix Spindler Walter Weissensteiner 《Advanced Synthesis \u0026amp; Catalysis》2010,352(6):1063-1074
Potentially trans‐chelating diphosphine ligands based on a ferrocenyl‐aryl backbone were synthesised in a four‐step sequence and the molecular structures in the solid state of two representatives were determined by X‐ray diffraction. High throughput screening of these ligands in rhodium‐, ruthenium‐ and iridium‐mediated hydrogenations of a variety of alkenes and ketones revealed that these ligands can deliver high enantioselectivity for alkenes (up to 98% ee) but are less selective when ketones are used as the substrates. The coordination behaviour of one ligand in its square planar palladium and platinum dichloride complexes was studied by 31P NMR and only trans‐chelated complexes, together with oligomeric by‐products, were observed. Reaction with the (p‐cymene)ruthenium dichloride dimer, [RuCl2(p‐cymene)]2, resulted in a mixture of diastereomeric complexes. 相似文献
2.
The reactions of the N,N′‐diarylimidazolium and N,N′‐diarylimidazolinium salts with chlorosulfonic acid result in the formation of the respective disulfonated N‐heterocyclic carbene (NHC) precursors in reasonable yields (46–77%). Water‐soluble palladium catalyst complexes, in situ obtained from the respective sulfonated imidazolinium salt, sodium tetrachloropalladate (Na2PdCl4) and potassium hydroxide (KOH) in water, were successfully applied in the copper‐free Sonogashira coupling reaction in isopropyl alcohol/water mixtures using 0.2 mol% catalyst loading. The preformed (disulfonatedNHC)PdCl(cinnamyl) complex was used in aqueous Suzuki–Miyaura reactions at 0.1 mol% catalyst loading. The coupling protocol reported here is very useful for Sonogashira reactions of N‐ and S‐heterocyclic aryl bromides and chlorides with aryl‐ and alkylacetylenes. 相似文献
3.
Synthesis,properties and thermal stability of water‐soluble poly(potassium 1‐hydroxyacrylate‐co‐styrene) copolymer
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The present work investigates the structure properties of copolymers using thermogravimetric analysis, hot stage microscopy, static light scattering, field emission scanning electron microscopy, X‐ray diffraction analysis and a Brookfield viscometer. Poly(potassium 1‐hydroxyacrylate) (PKHA) is a water‐soluble polymer. However, the copolymer of styrene and 2‐isopropyl‐5‐methylene‐1,3‐dioxolan‐4‐one is not water soluble at equal molar ratio because the polystyrene reduces the solubility. The effect of styrene on poly(potassium 1‐hydroxyacrylate‐co‐styrene) copolymer, i.e. poly(KHA‐co‐St), was investigated for the increasing solubility of the copolymer. The solubility was increased at a lower molar ratio of styrene such as 0.4 in the copolymer. It was found that the copolymer was soluble in water when a content ratio of 68/32 mol% of homopolymer was incorporated in poly(KHA68‐co‐St32) copolymer as determined by NMR analysis. Also the poly(KHA68‐co‐St32) copolymer was found to be salt tolerant, possessed water absorption capacity and was thermally stable up to 183 °C. Moreover, it is shown that the polystyrene content plays a key role in the thermal stability of the copolymer. © 2017 Society of Chemical Industry 相似文献
4.
Bismuth triflate was found to be an efficient catalyst in the Sakurai reaction of allyltrimethylsilanes with N‐alkoxycarbonylamino sulfones. The reaction proceeded smoothly with a low catalyst loading of Bi(OTf)3⋅4 H2O (2–5 mol%) to afford the corresponding protected homoallylic amines in very good yields (up to 96%). A sequential allylation reaction followed by ring‐closing metathesis delivers 6–8 membered 3‐Cbz‐protected cycloalkenylamines. 相似文献
5.
PaulF. Thomson Pallavi Lagisetty Jan Balzarini Erik DeClercq MaheshK. Lakshman 《Advanced Synthesis \u0026amp; Catalysis》2010,352(10):1728-1735
Palladium‐catalyzed C N bond forming reactions of 6‐bromo‐ as well as 6‐chloropurine ribonucleosides and the 2′‐deoxy analogues with arylamines are described. Efficient conversions were observed with palladium(II) acetate/Xantphos/cesium carbonate, in toluene at 100 °C. Reactions of the bromonucleoside derivatives could be conducted at a lowered catalytic loading [5 mol% Pd(OAc)2/7.5 mol% Xantphos], whereas good product yields were obtained with a higher catalyst load [10 mol% Pd(OAc)2/15 mol% Xantphos] when the chloro analogue was employed. Among the examples evaluated, silyl protection for the hydroxy groups appears better as compared to acetyl. The methodology has been evaluated via reactions with a variety of arylamines and by synthesis of biologically relevant deoxyadenosine and adenosine dimers. This is the first detailed analysis of aryl amination reactions of 6‐chloropurine nucleosides, and comparison of the two halogenated nucleoside substrates. 相似文献
6.
Hu He Ke‐Yin Ye Qing‐Feng Wu Li‐Xin Dai Shu‐Li You 《Advanced Synthesis \u0026amp; Catalysis》2012,354(6):1084-1094
Iridium‐catalyzed asymmetric etherifications of allylic carbonates with 2‐vinylphenols and 2‐allylphenols were realized. With a catalyst generated from 2 mol% of [Ir(cod)Cl]2 (cod=cycloocta‐1,5‐diene) and 4 mol% of the phosphoramidite ligand L2 , the etherification products were obtained in excellent ees and then subjected to the ring‐closing metathesis reaction providing an efficient synthesis of enantioenriched 2H‐chromene and 2,5‐dihydrobenzo[b]oxepine derivatives. 相似文献
7.
A stoichiometric and 2 mol% Ba deficient samples in the formulation 0.5BaTiO3‐0.5BiMg1/2Ti1/2O3 (BT‐BMT) were processed via a mixed oxide solid‐state route. The deficient sample exhibited a high relative permittivity (2100±15%) over the temperature range 90‐450°C and a low dielectric loss (tanδ < 0.01), maintained up to high temperature (430°C). The samples exhibited intrinsic conduction mechanism and showed an n‐type character. By introducing 2 mol% Ba vacancies, a dramatic influence on the dielectric loss was observed which was mainly associated with the trapping of electrons by barium‐oxygen vacancy pair associated with the intentionally produced cation vacancies. Thus, control of composition by creating deficiency allows fine tuning of the dielectric properties of BT‐BMT ceramics for applications in high‐temperature multilayered ceramic capacitors. 相似文献
8.
High Electric‐Induced Strain and Temperature‐Dependent Piezoelectric Properties of 0.75BF–0.25BZT Lead‐Free Ceramics
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0.75BiFeO3–0.25Ba(ZrxTi1?x) + 0.6 wt% MnO2 (0.75BF–0.25BZT) ceramics with Mn addition were prepared by the solid‐state reaction method. The high‐field strain and high‐temperature piezoelectric properties of 0.75BF–0.25BZT ceramics were studied. Introduction of Zr in the solid solutions decreased the Curie temperature slightly, and improved the dielectric and piezoelectric properties obviously. The piezoelectric properties of 0.75BZT–0.25BT ceramics reached the maximum at Zr content of 10 mol%. The Curie temperature Tc, dielectric constant ε and loss tanδ (1 kHz), piezoelectric constant d33, and planner electromechanical coupling factor kp of 0.75BF–0.25BZT ceramics with 10 mol% Zr were 456°C, 650, 5%, 138 pC/N, and 0.30, respectively. The high‐field bipolar and unipolar strain under an electric field of 100 kV/cm reached up to 0.55% and 0.265%, respectively, which were comparable to those of BiScO3–PbTiO3 and “soft” PZT‐based ceramics. The typical “butterfly”‐shaped bipolar strain and frequency‐dependent peak‐to‐peak strain indicated that the large high‐field‐induced strain may be due to non‐180° domain switching. Rayleigh analysis reflected that the improved piezoelectric properties resulted from the enhanced extrinsic contribution by Zr doping. The unipolar strain of 0.75BF‐0.25BZT ceramics with 10 mol% Zr was almost linear from RT to 200°C. These results indicated that 0.75BF–0.25BZT ceramics were promising candidates for high‐temperature and lead‐free piezoelectric actuators. 相似文献
9.
Chi‐Ren Chen Shuangliu Zhou Deepak Baburao Biradar Han‐Mou Gau 《Advanced Synthesis \u0026amp; Catalysis》2010,352(10):1718-1727
Highly efficient coupling reactions of benzylic bromides or chlorides with aryltitanium tris(isopropoxide) [ArTi(O‐i‐Pr)3] catalyzed by a simple palladium(II) acetate/tris(p‐tolyl)phosphine [Pd(OAc)2/ P(p‐tolyl)3] system are reported. The coupling reactions proceed in general at room temperature employing low catalyst loadings of 0.02 to 0.2 mol%, affording coupling products in excellent yields of up to 99%. For benzylic bromides bearing strong electron‐withdrawing cyano (CN) or trifluoromethyl (CF3) substituents, the reactions require a higher catalyst loading of 1 mol%, or the reactions are carried out at 60 °C. The catalytic system also tolerates (1‐bromoethyl)benzene bearing β‐hydrogen atoms while using a catalyst loading of 1 mol% to afford the coupling product in a 70% yield. 相似文献
10.
Rafal Loska ChandraM. Rao Volla Pierre Vogel 《Advanced Synthesis \u0026amp; Catalysis》2008,350(18):2859-2864
In the presence of iron(II) chloride (FeCl2; 20 mol%) and potassium tert‐butoxide (t‐BuOK; 4 equiv.) in dimethyl sulfoxide (DMSO), aryl and heteroaryl iodides undergo stereoselective Mizoroki–Heck C C cross‐coupling reactions with styrenes at 60 °C giving the corresponding (E)‐alkenes. The best yields are obtained upon adding a ligand (80 mol%) such as proline or picolinic acid. Aryl bromides and pyridinyl bromides are also coupled with styrenes but in lower yields. 相似文献
11.
Rubn S. Ramn Christophe Pottier Adrin Gmez‐Surez Steven P. Nolan 《Advanced Synthesis \u0026amp; Catalysis》2011,353(9):1575-1583
The formation of 4‐alkoxy‐2(5H)‐furanones was achieved via tandem alkoxylation/lactonization of γ‐hydroxy‐α,β‐acetylenic esters catalyzed by 2 mol% of [2,6‐bis(diisopropylphenyl)imidazol‐2‐ylidine]gold bis(trifluoromethanesulfonyl)imidate [Au(IPr)(NTf2)]. The economic and simple procedure was applied to a series of various secondary propargylic alcohols allowing for yields of desired product of up to 95%. In addition, tertiary propargylic alcohols bearing mostly cyclic substituents were converted into the corresponding spiro derivatives. Both primary and secondary alcohols reacted with propargylic alcohols at moderate temperatures (65–80 °C) in either neat reactions or using 1,2‐dichloroethane as a reaction medium allowing for yields of 23–95%. In contrast to [Au(IPr)(NTf2)], reactions with cationic complexes such as [2,6‐bis(diisopropylphenyl)imidazol‐2‐ylidine](acetonitrile)gold tetrafluoroborate [Au(IPr)(CH3CN)][BF4] or (μ‐hydroxy)bis{[2,6‐bis(diisopropylphenyl)imidazol‐2‐ylidine]gold} tetrafluoroborate or bis(trifluoromethanesulfonyl)imidate – [{Au(IPr)}2(μ‐OH)][X] (X=BF4, NTf2) – mostly stop after the alkoxylation. Analysis of the intermediate proved the exclusive formation of the E‐isomer which allows for the subsequent lactonization. 相似文献
12.
The Mn+1AXn phases Cr2GeC and Cr2GaC were synthesized with high phase‐purity directly from Cr2O3; Ge or Ga; and C using a single‐step carbothermal reduction. X‐ray diffraction and scanning electron microscope analysis of the materials shows them to be >99 mol% Cr2GeC and 92 mol% Cr2GaC, respectively. Extension to non‐Cr systems is briefly demonstrated by applying the method to the synthesis of V2GeC. 相似文献
13.
Anticancer Potency Studies of Coordination Driven Self‐Assembled Arene–Ru‐Based Metalla‐Bowls
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Dr. Anurag Mishra Yong Joon Jeong Jae‐Ho Jo Prof. Se Chan Kang Prof. Myoung Soo Lah Prof. Ki‐Whan Chi 《Chembiochem : a European journal of chemical biology》2014,15(5):695-700
New tetranuclear cationic metalla‐bowls 5 – 7 with the general formula [Ru4(p‐cymene)4(N∩N)2(OO∩OO)2]4+ (N∩N=2,6‐bis(N‐(4‐pyridyl carbamoyl)pyridine, OO∩OO=2,5‐dihydroxy‐1,4‐benzoquinonato ( 5 ), OO∩OO=5,8‐dioxydo‐1,4‐naphthaquinonato ( 6 ), OO∩OO=hoxonato ( 7 )) were prepared by the reaction of the respective dinuclear ruthenium complexes 2 – 4 with a bispyridine amide donor ligand 1 in methanol in the presence of AgO3SCF3.These new molecular metalla‐bowls were fully characterized by analytical techniques including elemental analysis as well as 1H and 13C NMR and HR‐ESI‐MS spectroscopy. The structure of metalla‐bowl 6 was determined from X‐ray crystal diffraction data. A UV/visible study was also carried out for the entire suite of new complexes. As with recent studies of similar arene–Ru complexes, the inhibition of cell growth by metalla‐bowls was established against SK‐hep‐1 (liver cancer), AGS (gastric cancer), and HCT‐15 (colorectal cancer) human cancer cell lines. Inhibition of cell growth by 6 was found to be considerably stronger against all cancer cell lines than the anticancer drugs, doxorubicin and cisplatin. In particular, in colorectal cancer cells, expression of the cancer suppressor genes APC and p53 was increased following exposure to 6 . 相似文献
14.
FTIR study of the hydrogen bonding interactions within blends of different ratios of poly(styrene‐co‐acrylic acid) containing 18, 27, and 32 mol% of acrylic acid (SAA) and poly(styrene‐co‐N,N‐dimethylacrylamide) containing 17 mol% of N,N‐dimethylacrylamide (SAD‐17) was carried out qualitatively and quantitatively in the temperature range varying from room temperature to 210°C. Two new bands characterizing these interactions appeared in the 1800–1550 cm–1 region at 1730 cm–1 and 1616 cm–1 and are attributed to “liberated” carbonyl group of the acidic copolymer and the “associated amide” carbonyl group, respectively. Equilibrium constants describing both the self‐association K2 and inter‐association KA and the enthalpy of hydrogen bonding formation in the different blends were experimentally determined using a curve fitting analysis of the infra‐red spectra as a function of temperature using the appropriate equations derived from the Painter‐Coleman association model. The obtained results confirm the miscibility of these blends in the considered temperature range from the negative values of the total free energy of mixing ΔGM. Optimization of the extent of intermolecular interactions between the two polymers in these blends is investigated. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers 相似文献
15.
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
16.
Toni Ivas Erwin Povoden‐Karadeniz Nicholas Grundy Eva Jud‐Sierra Jurgen Grässlin Ludwig J. Gauckler 《Journal of the American Ceramic Society》2013,96(2):613-626
New phase diagram data and a thermodynamic assessment of the CeO‐Gd2O3‐CoO system using the CALPHAD approach are presented. This information is needed to understand the surprisingly low sintering temperature (950°C–1050°C) of CeO2‐based materials doped with small amounts of transition metal oxide (e.g., CoO). Experimental phase equilibria between 1100°C and 1300°C are reported based on the analysis of annealed and molten samples. No isolated compound exists in the ternary. At 1300°C the Co solubility in the ternary compounds Ce1?x?yGdxCoyO2?x/2?y (fluorite) is 2.7 mol% and is less than 1 mol% in the Gd2?xCexO3+x/2 (bixbyite). The Ce solubility in the perovskite GdCoO3?δ was found to be 1 mol%. The lowest temperature eutectic melt in the ternary has a composition of 57.2 mol% Co and 41.1 mol% Gd melting at an onset temperature of 1303 ± 5°C, which is close to the binary eutectic in the Gd2O3‐CoO system at 60 ± 2 mol% Co and 1348 ± 1°C. 相似文献
17.
Stabilization of CO2‐in‐water emulsions with high internal phase volume using PVAc‐b‐PVP and PVP‐b‐PVAc‐b‐PVP as emulsifying agents
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Li Wen Liwen Wang Shuyi Fang Lei Bao Dongdong Hu Yuan Zong Ling Zhao Tao Liu 《应用聚合物科学杂志》2018,135(23)
Two newly‐designed hydrocarbon surfactants, that is, poly(vinyl acetate)‐block‐poly(1‐vinyl‐2‐pyrrolidone) (PVAc‐b‐PVP) and PVP‐b‐PVAc‐b‐PVP, were synthesized using reversible addition–fragmentation chain transfer polymerization and used to form CO2/water (C/W) emulsions with high internal phase volume and good stability against flocculation and coalescence up to 60 h. Their structures were precisely determined by nuclear magnetic resonance, gel permeation chromatography, thermal gravimetric analysis, and differential scanning calorimetry. Besides low temperature and high CO2 pressure, the surfactant structures were the key factors affecting the formation and stability of high internal phase C/W emulsions, including the polymerization degrees of CO2‐philic block (PVAc) and hydrophilic block (PVP), as well as the number of hydrophilic tail. The surface tension of the surfactant aqueous solution and the apparent viscosity of the C/W emulsions were also measured to characterize the surfactants efficiency and effectiveness. The surfactants with double hydrophilic tails showed stronger emulsifying ability than those with single hydrophilic tail. The great enhancement of the emulsions stability was due to decrease of the interface tension as well as increase of the steric hindrance in the water lamellae, preventing a frequent collision of CO2 droplets and their fast coalescence. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46351. 相似文献
18.
Jens Christoffers Heiko Oertling Necl
nal 《Advanced Synthesis \u0026amp; Catalysis》2000,342(6):546-553
Michael reactions of β‐keto esters 1a—1h with methyl vinyl ketone ( 2a ) catalyzed by FeCl3 · 6 H2O (5 mol%) proceed with up to 99% yield. Conversion of β‐keto esters 1a—1e derived from chiral alcohols with 2a result in only very low diastereoselectivities (max. de 20%). A bis‐β‐keto ester 1i and a bis‐vinyl ketone 2b — both valuable monomers for poly‐Michael reactions — are synthesized from common starting materials in up to gram quantities. 相似文献
19.
Hydrogen and carbon dioxide adsorption with tetra‐n‐butyl ammonium semi‐clathrate hydrates for gas separations
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Hiroyuki Komatsu Masaki Ota Yoshiyuki Sato Masaru Watanabe Richard L. Smith Jr. 《American Institute of Chemical Engineers》2015,61(3):992-1003
Gas adsorption rates of H2, CO2, and H2‐CO2 gas mixture (H2/CO2 = 3.4) with tetra‐n‐butyl ammonium salt (bromide, chloride, and fluoride) semi‐clathrate hydrate particles were measured at 269 K to assess their properties for gas separation. Equilibrium gas occupancies in the S‐cages of the particles were in order of (high to low) for hexagonal structure‐I, tetragonal structure‐I, and superlattice of cubic structure‐I structures with the maximum fractional occupancy by CO2 being about 40%. The CO2 diffusion rate depended on the anion size of the salt, which is attributed to distortion of the S‐cage that is close to the molecular size of CO2. Simulations of semi‐clathrate hydrate particles with theory showed that H2/CO2 selectivities could be as high as 36 (3.0 mol% TBAF) and that selectivities for an ideal membrane (3.3 mol% TBAF) could be >100 (269 K, 0.3–4.5 MPa). Semi‐clathrate hydrates have wide application as separation media for gas mixtures. © 2014 American Institute of Chemical Engineers AIChE J, 61: 992–1003, 2015 相似文献
20.
Mechanical properties of 1 mol% CeO2‐10 mol% Sc2O3 co‐doped and stabilized ZrO2 synthesized through hydro/solve‐thermal method
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Yuchen Liu Xiaoyu Chen Rui Yao Songyi Liao Weiping Chen Donghong Nie Yueming Wang Feng Zheng 《International Journal of Applied Ceramic Technology》2017,14(3):474-485
Ultra‐fine 1 mol% CeO2‐10 mol% Sc2O3 co‐doped and stabilized ZrO2 (1Ce10ScSZ) powders with average grain size less than 10 nm in diameter were prepared by hydro/solve‐thermal method using either deionized water, ethanol, or methanol as solvent. As‐synthesized powders were characterized in terms of phase structure, particle morphology, and chemical composition by X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), high‐resolution transmission electron microscopy (HRTEM), and inductively coupled plasma‐optical emission spectroscopy (ICP‐OES), respectively. Sintering studying was conducted on pellets of 15 mm in diameter and 3 mm in thickness under uniaxial compaction using 25 MPa at either 600, 800, 1000, 1100, 1200, 1400, or 1500°C for 1 hour. Phase transitions and grain morphologies of those sintered samples were characterized by XRD and field emission scanning electron microscopy (FESEM). Mechanical properties were characterized on dense pellets sintered at 1500°C by nanoindentation. Experimental results showed that ethanol was more effective to synthesize agglomerate‐free 1Ce10ScSZ powders as compared with deionized water and methanol. Choice of solvent affected the environment of hydro/solve‐thermal solution, which led to variation of chemical compositions of powders and porosities of sintered pellets, and therefore, influenced their mechanical performance. Our study showed that solvent was important to make dense, thin, and mechanically robust 1Ce10ScSZ electrolyte for potential applications in electrochemical devices. Absolute values of hardness (H) and Young's modulus (E) measured from our samples are much higher and more consistence than those results obtained from commercial vendors reported in literatures. 相似文献