共查询到20条相似文献,搜索用时 15 毫秒
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Kleitz F Solovyov LA Anilkumar GM Choi SH Ryoo R 《Chemical communications (Cambridge, England)》2004,(13):1536-1537
Exceptional control of the phase behavior of highly ordered large pore mesostructured silica (with the choice of Fm3m, Im3m or p6mm symmetry) is achieved using a triblock copolymer (EO(106)PO(70)EO(106)) and butanol at low acid concentrations. 相似文献
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I. A. Novakov M. Artico A. Mai D. Rotili B. S. Orlinson L. L. Brunilina M. B. Nawrozkij 《Russian Chemical Bulletin》2012,61(7):1399-1418
The review describes the flourishing synthesis and brief structure-anti-HIV-1 activity relationships of 6-(arylmethyl)pyrimidin-4(3H)-one derivatives. 相似文献
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Tüysüz H Lehmann CW Bongard H Tesche B Schmidt R Schüth F 《Journal of the American Chemical Society》2008,130(34):11510-11517
We report here a detailed study on the surface topology of well-known ordered mesoporous silica (SBA-15, MCM-41, and KIT-6) and a series of nanocast Co 3O 4, Co 3O 4/CoFe 2O 4 composites by high resolution scanning electron microscopy (HR-SEM). Images of the MCM-41 structure were obtained at a resolution of the pore size, as well as a real space image of the gyroid silica surface of KIT-6 for two different aging temperatures, clearly revealing the differences of the aging procedures. By using the low voltage HR-SEM technique with extremely high resolution, we could very clearly show the influence of the template properties on the structure of the nanocast metal oxides. 相似文献
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Bremer A Ruff CM Girnt D Müllich U Rothe J Roesky PW Panak PJ Karpov A Müller TJ Denecke MA Geist A 《Inorganic chemistry》2012,51(9):5199-5207
The N-donor complexing ligand 2,6-bis(5-(2,2-dimethylpropyl)-1H-pyrazol-3-yl)pyridine (C5-BPP) was synthesized and screened as an extracting agent selective for trivalent actinide cations over lanthanides. C5-BPP extracts Am(III) from up to 1 mol/L HNO(3) with a separation factor over Eu(III) of approximately 100. Due to its good performance as an extracting agent, the complexation of trivalent actinides and lanthanides with C5-BPP was studied. The solid-state compounds [Ln(C5-BPP)(NO(3))(3)(DMF)] (Ln = Sm(III), Eu(III)) were synthesized, fully characterized, and compared to the solution structure of the Am(III) 1:1 complex [Am(C5-BPP)(NO(3))(3)]. The high stability constant of log β(3) = 14.8 ± 0.4 determined for the Cm(III) 1:3 complex is in line with C5-BPP's high distribution ratios for Am(III) observed in extraction experiments. 相似文献
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Fatemeh Rajabi 《Tetrahedron letters》2009,50(52):7256-4418
Chemoselective deprotection of aryl acetates is successfully carried out in excellent yield using a mesoporous silica-supported (Salen) Co(II) catalyst. The catalyst shows high thermal stability and also can be recovered and reused at least 10 times without any significant loss of its catalytic activity. The present process is environmentally benign and economical. 相似文献
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《Journal of Coordination Chemistry》2012,65(5):833-839
The hydrothermal reactions of lanthanide ions, oxalates and benzenedicarboxylate with ratio of 4 : 1 : 8 at 190°C afford the three-dimensional coordination polymer Na2[Nd4(OX)(BDC)6(H2O)6] (OX = oxalate and BDC = 1,3-benzenedicarboxylate dianion). Crystal data: C25H18NaNd2O17 M = 901.86, Triclinic, P 1, a = 10.335(6), b = 11.497(6), c = 12.238(7) Å, α = 93.015(9), β =114.892(8)°, γ = 95.970(10)°, V = 1304.3(12) Å3, Z = 2, F(000) = 870, R 1 = 0.0322, wR 2 = 0.0683. The central oxalate of the unit cell coordinates with four lanthanides to form a four metal cluster [Ln4(OX)]. The luminescence spectrum shows weak photoluminescence in infrared and near-infrared. 相似文献
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Selman A. Berger 《Mikrochimica acta》1984,84(3-4):275-282
Summary DbPH, a quadridentate chelating agent, was studied as a solvent extraction reagent for Cu(II), Co(II), and Ni(II). In all cases 11 complexes were extracted; however for Cu(II) and Co(II) ion-paired species exist, while for Ni(II) only neutral complexes were extracted. In all cases an extraction efficiency of 35–60% was observed unlike the greater than 90% observed for similar mono-hydrazone derivatives. The steric hindrance probably present in the bis adduct prevented a more efficient extraction.
Presented at the 18th Middle Atlantic Regional Meeting of the American Chemical Society, Newark, New Jersey, May 21, 1984. 相似文献
Diacetyl-bis-(2-pyridyl)hydrazon (DbPH) als Extraktionsmittel für Cu(ll), Co(II) und Ni(II)
Zusammenfassung DbPH bildet mit Cu(II), Co(II) und Ni(II) Komplexverbindungen im Verhältnis 11; diese sind für Cu und Co ionisierbar, im Falle des Ni läßt sich ein neutraler Komplex extrahieren. Die Extraktion erreicht jedenfalls nur 35–60% im Gegensatz zu mehr als 90% bei ähnlich gebauten Monohydrazon-Derivaten. Sterische Hinderung dürfte hierfür die Ursache sein.
Presented at the 18th Middle Atlantic Regional Meeting of the American Chemical Society, Newark, New Jersey, May 21, 1984. 相似文献
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Combined with the advantages of low melting point,high thermal stability and strong acidity,a multipleSO_3H functioned ionic liquid(MIL) was developed successfully as a curing agent to promote the curing reaction of phthalonitrile-terminated poly(phthalazinone ether nitrile)(PPEN-Ph).The curing kinetics over differential scanning calorimetry(DSC) showed that both the initial curing temperature T_(p0') and apparent activation energy Ea'(based on Kissinger equation) were reduced significantly over MIL(207.9℃ and 101.5 kJ/mol) compared to the common curing agent ZnCl_2(268.5℃ and 201.5 kJ/mol).Moreover,under identical curing conditions,the resulting thermosetting resin over former(T_(d5%)=526.1℃) showed better thermal stability than that over latter(T_(d5%)=512.1 ℃).These results indicated that MIL should be a good candidate as a curing agent for phthalonitrile resins. 相似文献
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Micellar media under neutral conditions catalyzed successful reductive amination of aldehydes and ketones by bis(triphenylphosphine)(tetrahydroborato)zirconium(II), [Zr(BH4)2(Ph3P)2], as a newly developed hydride transfer agent and a highly water tolerant tetrahydroborate reagent. 相似文献
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F. Rajabi 《Journal of the Iranian Chemical Society》2010,7(3):695-701
Cobalt(II) Schiff base functionalized mesoporous silica was synthesized from covalent attachment via the introduction of Co(OAc)2 to salicylaldimine functionalized mesoporous silica. The catalyst proved to be chemoselective one for the acetalization of aldehydes to the corresponding acetals in alcohol. The immobilized catalyst can be easily recovered and reused for at least ten reaction cycles without significant loss of its catalytic activity. 相似文献
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Raj Kumar 《Tetrahedron letters》2005,46(48):8319-8323
Commercially available copper(II) tetrafluoroborate hydrate has been found to be a highly efficient catalyst for dimethyl/diethyl acetal formation in high yields from aldehydes and ketones by reaction with trimethyl/triethyl orthoformate at room temperature and in short period. Acetalisation was carried out under solvent-free conditions with electrophilic aldehydes/ketones. For weakly electrophilic aldehydes/ketones (e.g., benzaldehyde, cinnamaldehyde and acetophenone) and for aldehydes having a substituent that can coordinate with the catalyst, the corresponding alcohol was used as solvent. 相似文献
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Novel cis-chelated bidentate bis(NHC)-Pd(II) complexes derived from 1,1′-binaphthyl-2,2′-diamine (BINAM) bearing weakly coordinating acetate or trifluoroacetate counterions have been synthesized and their structures have been characterized by X-ray diffraction of single crystals. We found that these bis(NHC)-Pd(II) complexes were highly effective in the allylation of aldehydes with allyltributyltin to give the corresponding products in good to excellent yields in most cases at room temperature. 相似文献
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A convenient and highly efficient method for the Lewis acid-catalyzed trans-selective hydrosilylation of alkenes has been developed. The mechanism of this novel protocol operates via direct addition of silylium type species across C=C bond followed by trapping of the resultant carbenium ion with boron-bound hydride. A number of diversely substituted silanes possessing both aryl and alkyl groups at silicon atom were efficiently prepared using this hydrosilylation methodology. The possibility to employ aryl-containing hydrosilanes in this reaction opens broad capabilities for the synthesis of alcohols via a trans-selective hydrosilylation/Tamao-Fleming oxidation sequence, complementary to the existing cis-selective hydroboration/oxidation protocol. 相似文献
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Daniele Balducci Simone Contaldi Ilaria Lazzari Gianni Porzi 《Tetrahedron: Asymmetry》2009,20(12):1398-1401
A new, practical and very convenient stereocontrolled synthesis of (S)-2′,6′-dimethyltyrosine [(S)-Dmt] 4 was accomplished in a good yield, starting from the chiral synthon 1,4-N,N-[(S)-phenylethyl]-piperazine-2,5-dione 1. The procedure, which is an extension of our original strategy and occurs with a high level of stereoselectivity (>98%), is simple and inexpensive allowing us to prepare the unnatural α-aminoacid (S)-Dmt also on a multi-gram scale. 相似文献
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Facile construction of symmetric biaryls using (BeDABCO)2Pd2Cl6 as an efficient and highly active catalyst under microwave irradiation
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An efficient catalytic system using (BeDABCO)2Pd2Cl6 (BeDABCO, benzyl‐1,4‐diazabicyclo[2.2.2]octane) was developed for the homo‐coupling reaction of various aryl halides. Due to the combination of ionic homogeneous metal catalyst and microwave irradiation, symmetric biaryls were produced in excellent yields and short reaction times in N‐methyl‐2‐pyrrolidone at 120 °C. BeDABCO as an efficient ligand and also a quaternary ammonium salt had an efficient stabilizing effect on the Pd(0) species in this coupling reaction. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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[reaction: see text] The gold-catalyzed cyclization reactions of 2-oxo-3-butynoic esters or disubstituted-1,2-diones with a variety of nucleophiles are described, which offer an efficient and straightforward route to substituted 3(2H)-furanones under mild reaction conditions. The Au(III) catalysts are also highly effective in the hydration of these activated alkynes. 相似文献