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1.
Ketoximes undergo deprotection in CH3CN/acetone/H2O (3:6:1) in the presence of 20-40 mol% BiBr3/5 mol% Bi(OTf)3. Bismuth(III) salts are relatively non-toxic, insensitive to air and inexpensive. These features coupled with the use of a relatively non-toxic solvent system make this method an attractive alternative to existing routes for deprotection of ketoximes.  相似文献   

2.
A highly catalytic method for the synthesis of dihydrobenzopyrans from salicylaldehydes has been developed. An extension of this method to the synthesis of a pyrano[2,3,b]benzopyran has also been achieved. Bi(OTf)3·xH2O (1 < x < 4) (0.1 mol%) smoothly catalyzes the condensation of substituted salicylaldehydes with 2,2-dimethoxypropane to give the corresponding substituted 3,4-dihydro-2H-1-benzopyrans as a mixture of diastereomers (9:1) in moderate yields. The relative configuration of the methoxy groups in the two diastereomers was established by NOE experiments. The advantages of this method include the use of an easy to handle, inexpensive and relatively non-toxic catalyst.  相似文献   

3.
The study of structural and electrical properties of three pure bismuth molybdate phases, α-Bi2Mo3O12, β-Bi2Mo2O9 and γ-Bi2MoO6, prepared by the spray drying technique, is described and discussed. The structure of polycrystalline, layered samples investigated by means of XRD and Raman spectroscopy was found to be monoclinic for the α- and β-phases and orthorhombic for the γ-phase. The microstructure of the as-prepared samples was not sufficiently developed under the given conditions of preparation, however, the thermal treatment can improve it. The high polarizability of Bi3+ cations with their lone-pair electrons influences the stability of the disordered oxygen sublattice. All as-prepared phases undergo a slight structural change in the temperature region of 280–430°C resulting in a decrease of the electrical conductivity probably due to an order ⇄ disorder transition in the oxygen arrangement during the sample heating. The change of electrical conductivity observed was found to be reversible in the high-temperature region and irreversible in the low-temperature one. The blocking of oxygen transport by the bismuth lone-pair electrons results in an increase of the activation energy and a decrease of the electrical conductivity in the high-temperature region. Relatively high relative dielectric permittivities ɛr, 36–52, were observed in dependence on the investigated phase.__________From Elektrokhimiya, Vol. 41, No. 5, 2005, pp. 523–528.Original English Text Copyright © 2005 by Hartmanova, Le, Driessche, Hoste, Kundracik.This article was submitted by the authors in English.  相似文献   

4.
Bismuth titanates, Bi2Ti2O7 (BIT), with well-defined spherical structures were synthesized by a facile hydrothermal process without the use of any surfactant or template. XRD and SEM studies have shown that spheres could be fabricated in high yields by simply manipulating the concentrations of hydroxide ions. In this case, hydroxide ions seem to play a pivotal role in controlling the formation of seeds and growth rates of the BIT particles. On the basis of structural analysis of samples obtained at different concentrations of OH, we also proposed a plausible mechanism to account for the formation of these distinctive morphologies under different conditions. The as-prepared BIT microspheres with good stability exhibited higher photocatalytic activities in the degradation of Rhodamine B (RhB) under visible light irradiation than that in commercial P25 TiO2. Furthermore, the enhanced photocatalytic performance for RhB degradation was also investigated with assistance of a small amount of H2O2.  相似文献   

5.
With MnSO4, NaOH and K2S2O8 as the raw materials, the amorphous and δ-type manganese dioxide (MnO2) is separately prepared by using different chemical precipitation-oxidation methods. The results of charge–discharge and electrochemical impedance spectroscopy (EIS) tests show that (i) the specific capacitance of the amorphous MnO2 reaches to 301.2 F g−1 at a current density of 200 mA g−1 and its capacitance retention rate after 2000 cycles is 97%, which is obviously higher than 250.8 F g−1 and 71% of the δ-type one, respectively; (ii) good electrochemical capacitance properties of the amorphous MnO2 should be contributed to easy insertion/extraction of ions within the material; (iii) when 5 wt% Bi2O3 is coated on the amorphous MnO2, its specific capacitance increases to 352.8 F g−1 and the capacitance retention rate is 90% after 2000 cycles.  相似文献   

6.
A simple, straightforward, and highly efficient diastereoselective multicomponent one-pot synthesis of a series of pharmaceutically interesting functionalized piperidine derivatives has been developed based on a low-cost and environmentally benign Bi(NO3)3·5H2O catalyst via tandem reactions of 1,3-dicarbonyl compounds, aromatic aldehydes, and various amines in ethanol at room temperature. High atom-economy, good yields, eco-friendliness, and mild reaction conditions are some of the important features of this protocol.  相似文献   

7.
The precipitation of bismuth(III) from nitrate solutions on addition of aqueous solutions of tartaric acid and sodium tartrate was studied by X-ray phase analysis, thermogravimetry, IR spectroscopy, and chemical analysis. Conditions for the formation of [Bi(NO3)(H2O)3]C4H4O6 and [Bi(C4H4O6)(C4H5O6)] · 3H2O were determined.  相似文献   

8.
采用熔融冷却法制备了铕掺杂的硼铋钙玻璃。研究了不同硼铋比(n_B/n_(Bi))和钙离子浓度条件下的密度、摩尔体积、折射率等物理性质,分析了玻璃的结构、光学性质和热稳定性。实验结果表明,Eu~(3+)较好的熔融于玻璃中,形成发光中心,在465 nm蓝光激发下,613 nm处有较为强烈的发射,光谱强度值随nB/nBi变化不明显,但随Ca O浓度升高而逐渐递减。玻璃结构总体呈现非晶态,对称性相对较低,结构致密程度和对称性均随nB/nBi的降低而降低,随CaO浓度的升高而升高。玻璃结构主要组成为[BO_3]三角体、[BiO_3]三角体,[BO4]四面体和[BiO_6]八面体,不存在[BO_3]组成的硼六元环。研究结果表明,此系列硼铋钙玻璃能有效匹配蓝光芯片发射红光,且具有熔点低、热稳定较好、折射率相对适宜的特点。  相似文献   

9.
Aqueous solutions of bismuth(III) nitrilotriacetates BiNta · 2H2O and M3Bi(Nta)2 ·nH2O (M = Na, K, Rb, Cs, NH4, CN3H6, n = 0–4) and the K[Bi(Edta)(Tu)2] complex (Edta4– is the anion of ethylenediaminetetraacetic acid, Tu is thiocarbamide) are studied by the 1H NMR method at room temperature in the pH interval from 2 to 11. The formation of two types of bismuth nitrilotriacetate complexes in solutions is established. They are characterized by the presence (type 1) or absence (type 2) of the Bi–N bond. Their ratio, depending on the composition and pH of the solution, is determined. The K[Bi(Edta)(Tu)2] compound in solutions occurs as one form. The pH values at which the substance begins to decompose are determined for each compound.  相似文献   

10.
采用熔融冷却法制备了铕掺杂的硼铋钙玻璃。研究了不同硼铋比(nB/nBi)和钙离子浓度条件下的密度、摩尔体积、折射率等物理性质,分析了玻璃的结构、光学性质和热稳定性。实验结果表明,Eu3+较好的熔融于玻璃中,形成发光中心,在465 nm蓝光激发下,613 nm处有较为强烈的发射,光谱强度值随nB/nBi变化不明显,但随CaO浓度升高而逐渐递减。玻璃结构总体呈现非晶态,对称性相对较低,结构致密程度和对称性均随nB/nBi的降低而降低,随CaO浓度的升高而升高。玻璃结构主要组成为[BO3]三角体、[BiO3]三角体,[BO4]四面体和[BiO6]八面体,不存在[BO3]组成的硼六元环。研究结果表明,此系列硼铋钙玻璃能有效匹配蓝光芯片发射红光,且具有熔点低、热稳定较好、折射率相对适宜的特点。  相似文献   

11.
New hexamethylenetetramine complexes of antimony and bismuth trichloride were synthesized through a solid phase reaction of hexamethylenetetramine and antimony or bismuth trichloride. The formula of the complex is MCl3(C6H12N4)2⋅H2O (M=Sb, Bi).The crystal structure of the complexes belongs to monoclinic system and the lattice parameters: a=1.249 nm, b=1.4583 nm, c=1.6780 nm andβ=91.78° for SbCl3(C6H12N4)2⋅H2O and a=1.3250 nm, b=1.3889 nm, c=1.7449 nm and β=98.94° for BiCl3(C6H12N4)2⋅H2O. Far-infrared spectra reveal that the antimony or bismuth ion is coordinated by the nitrogen atom of the hexamethylenetetramine. The thermal analysis also demonstrates the complex formation between the antimony or bismuth ion and hexamethylenetetramine. The intermediate and final residues in the thermal decomposition process have been analyzed to check the pyrolysis reaction. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

12.
Bismuth(III) bis(trifluoromethanesulfonyl)amide (Bi(NTf2)3, 3) has been prepared from the reaction of protiodemetallation of tri-p-tolylbismuth by a stoichiometric amount of bis(trifluoromethanesulfonyl)amine (1). The intermediates BiPh3−n(NTf2)n (n=2 (4), 1 (5)) resulting from the reaction of 1 with triphenylbismuth have also been isolated. The amide 3 was able to catalyze the benzoylation and the benzenesulfonylation of toluene.  相似文献   

13.
Sol-Gel Derived Bismuth Titanate Thin Films with c-Axis Orientation   总被引:1,自引:0,他引:1  
Bismuth titanate (Bi4Ti3O12), a member of the layered perovskite family, has a unique set of ferroelectric properties, which include a high remanent polarization, low coercive field, and high Curie temperature, that make it a possible candidate for data storage applications. For this investigation, bismuth titanate, or BiT, films were fabricated via sol-gel method to examine the effect of processing on phase development and orientation. Solutions were deposited onto platinized silicon, and then heat treated for one hour at temperatures ranging from 550°C to 700°C in 100% O2. It was found that c-axis orientated BiT films could be formed at temperatures as low as 550°C by using bismuth oxide template layers, while films without bismuth oxide templating possessed a random orientation over the same temperature range.  相似文献   

14.
A variety of thioamides and thioureas are rapidly transformed to their oxo derivatives with Bi(NO3)3·5H2O in excellent yields. However, thiono esters and thioketones are converted to their corresponding carbonyl compounds in only poor yields. Bi(NO3)3·5H2O is relatively non-toxic, insensitive to air and inexpensive. These features coupled with the selective deprotection of thioamides and thioureas in the presence of thiono esters and thioketones make this method an attractive alternative to the existing routes for deprotection of thiocarbonyl compounds.  相似文献   

15.
Heteroleptic triorganobismuth (V) complexes of general formula, R3Bi(OOCR')2 ( 1 – 7 ), where R = C6H5 ( 1 – 3 ), p‐CH3C6H4 ( 4 – 7 ) and R' = 3,5‐Cl2C6H3 ( 1 , 5 ); 3,4,5‐(OCH3)3C6H2 ( 2 , 6 ); 3‐CH3C6H4 ( 3 , 7 ); 2‐OH‐3‐OCH3C6H3 ( 4 ) have been synthesized and fully characterized by FT‐IR, 1H &13C NMR spectroscopy, single crystal X‐ray crystallography and elemental analysis. The molecular geometry observed for the compounds is predominantly distorted trigonal bipyramidal, the fact which was subsequently authenticated through X‐ray analyses for ( 1 – 4 ). All the synthesized compounds have been bio‐assayed for antileishmanial (Leishmania tropica KWH23) and Jack beans urease inhibitory activity, and human Lymphocytes were used to measure the general toxicity. Of these, ( 4 ) proved to be highly effective against the target species (Leishmania tropica KWH23), while being non‐toxic towards the mammalian cells at levels below 0.74 μgmL?1, making it highly promising drug candidate. The high activities for ( 2 , 4 , and 6 ) against Jack beans Urease as compared to the reference standard demonstrate their significance in searching of therapeutic agents in future programs. The significant binding score of ( 2 & 4 ) against H. pylori in molecular docking studies further revealed their importance in future drug discovery processes.  相似文献   

16.
In the title compound, Bi2B8O15, the Bi atom is coordinated to five or six O atoms. The B atoms exhibit two kinds of hybridization, sp2 and sp3, seen in the BO3 triangles and BO4 tetrahedra, respectively. Three BO3 triangles are connected to form a B3O6 planar ring. All atoms in the structure are connected together to form an infinite three‐dimensional network.  相似文献   

17.
Bismuth titanate films were fabricated onto highly oriented LaNiO3 electrode grown on SrTiO3(100) and LaAlO3(012) substrates using spin-coating technique with metal naphthenates as starting materials. (00l)/(h00)-oriented bismuth titanate films on LaNiO3/SrTiO3 and LaNiO3/LaAlO3 were obtained by pyrolysis at 500°C, followed by annealing at 750°C. In-plane alignment and surface morphology of the films analyzed by pole-figure analysis ( scanning) and field emission scanning electron microscope showed an imperfect epitaxy with polycrystalline structure.An erratum to this article can be found at  相似文献   

18.
More than 80 years after Paneth’s report of dimethyl bismuth, the first monomeric BiII radical that is stable in the solid state has been isolated and characterized. Reduction of the diamidobismuth(III) chloride Bi(NONAr)Cl (NONAr=[O(SiMe2NAr)2]2−; Ar=2,6‐iPr2C6H3) with magnesium affords the BiII radical .Bi(NONAr). X‐ray crystallographic measurements are consistent with a two‐coordinate bismuth in the +2 oxidation state with no short intermolecular contacts, and solid‐state SQUID magnetic measurements indicate a paramagnetic compound with a single unpaired electron. EPR and density functional calculations show a metal‐centered radical with >90 % spin density in a p‐type orbital on bismuth.  相似文献   

19.
Results on the influence of mechanoactivation (3–30 min) in a planetary ball mill on the composition, crystal structure, IR spectra and morphology of EuCl3·6H2O, dibenzoylmethane (HDBM) and mixtures of EuCl3·6H2O — HDBM and EuCl3·6H2O — HDBM — 1,10-phenathroline (phen) are presented. Mechanoactivation leads to a decrease of interplanar distances of the EuCl3·6H2O and HDBM and partial synthesis of Eu(DBM)3 and Eu(DBM)3·phen in the respective mixtures. The fluorescence properties of the products of activation (excitation and emission spectra, lifetime of the excited states) are similar to those of the complexes produced by the conventional “wet” methods, but the strongest excitation of the mechanochemically produced solid state samples is achieved at higher wavelength. Crystals of different forms (prismatic, needle-, long-length-leaf- and rod-like) are formed by mechanoactivation of the mentioned mixtures.  相似文献   

20.
The electrocatalytic activity of bimetallic BiPd catalysts supported on Sibunit carbon towards hydrogen oxidation/evolution reactions (HOR/HER) was studied in a gas diffusion electrode (GDE) setup. Catalysts were synthesized by deposition of Pd on the carbon support, followed by impregnation of Pd/C precursor with Bi(NO3)3 solution and reduction in hydrogen. Transmission electron microscopy and local EDX elemental analysis revealed that BiPd/C catalysts contain bimetallic particles with narrow size distribution with maxima at 3.2–4.1 nm. X-ray diffraction evidenced that bimetallic particles are constituted by Pd–Bi solid solution. It was shown that modification of Pd/C by bismuth increases the specific activity of palladium towards HOR/HER by a factor of 3.  相似文献   

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