Fabrication and characterization of tungsten-containing mesoporous silica for heterogeneous oxidative desulfurization

A series of functional,tungsten-containing mesoporous silica materials（W-SiO2） have been fabricated directly from an ionic liquid that contained imidazole and polyoxometalate,which acted as mesoporous template and metal source respectively.These materials were then characterized through X-ray diffraction（XRD）,transmission electron microscopy（TEM）,Raman spectroscopy,Fourier transform infrared spectra（FTIR）,diffuse reflectance spectra（DRS）,and N2 adsorption-desorption,which were found to contain tungsten species that were effectively dispersed throughout the structure.The as-prepared materials W-SiO2 were also found to possess a mesoporous structure.The pore diameters of the respective sample W-SiO2-20 determined from the TEM images ranged from 2 to 4 nm,which was close to the average pore size determined from the nitrogen desorption isotherm（2.9 nm）.The materials were evaluated as catalysts for the heterogeneous oxidative desulfurization of dibenzothiophene（DBT）,which is able to achieve deep desulfurization within 40 min under the optimal conditions（Catalyst（W-SiO2-20）= 0.01 g,temperature = 60℃,oxidant（H2O2）= 20 μL）.For the removal of different organic sulfur compounds within oil,the ability of the catalyst（W-SiO2-20） under the same conditions to remove sulfur compounds decreased in the order：4,6-dimethyldibenzothiophene Dibenzothiophene Benzothiophene 1-dodecanethiol.Additionally,they did not require organic solvents as an extractant in the heterogeneous oxidative desulfurization process.After seven separate catalytic cycles,the desulfurization efficiency was still as high as 90.3%.From the gas chromatography-mass spectrometer analysis,DBT was entirely oxidized to its corresponding sulfone DBTO2 after reaction.A mechanism for the heterogeneous desulfurization reaction was proposed.

加兰他敏重要中间体溴那维定的合成

以6-溴异香草醛和酪胺为原料,经一锅法进行连续的两步还原胺化制得N-甲基-N-(4-羟基苯乙基)-2-溴-5-羟基-4-甲氧基苯甲胺(4),收率85%。以5%聚乙二醇为相转移催化剂,氯仿为溶剂,铁氰化钾为氧化剂,对4进行氧化偶联,合成了加兰他敏的重要中间体溴那维定,收率39%,其结构经1H NMR,IR和MS确证。

Rh_2O_3/mesoporous MO_x-Al_2O_3(M = Mn,Fe,Co,Ni,Cu,Ba)catalysts:Synthesis,characterization,and catalytic applications

Recently,a one-pot self-assembly method was proposed for the synthesis of mesoporous Al2O3 and MOx-Al2O3 composite materials.However,few attempts have been made to use mesoporous MOx-Al2O3 composites to support metal oxides for catalysis.In the present work,mesoporous MOx-Al2O3（M = Mn,Fe,Co,Ni,Cu,Ba）materials were prepared by a one-pot self-assembly method using Pluronic P123 as a structure-directing agent.The obtained mesoporous materials were loaded with Rh2O3 nanoparticles via impregnation with Rh（NO3）3 followed by calcination in air at 500°C.The resulting catalysts were characterized by X-ray diffraction,N2 adsorption-desorption measurements,transmission electron microscopy,inductively coupled plasma optical emission spectrometry,X-ray photoelectron spectroscopy,and their catalytic activity and stability for CO oxidation and N2O decomposition were tested.The Rh2O3 nanoparticles were found to be on the order of1 nm in size and were highly dispersed on the high surface area mesoporous MOx-Al2O3 supports.A number of the Rh2O3/mesoporous MOx-Al2O3 catalysts exhibited higher catalytic activity than the Rh2O3/mesoporous Al2O3 prepared for comparison.

One-pot cascade conversion of xylose to furfuryl alcohol over a bifunctional Cu/SBA-15-SO3H catalyst

The conversion of hemicellulose-derived xylose to furfuryl alcohol is a practical procedure for producing value-added chemicals from biomass.In this study,a bifunctional Cu/SBA-15-SO3 H catalyst was employed for the one-pot catalytic conversion of xylose to furfuryl alcohol with a yield of up to 62.6% at the optimized conditions of 140℃,4 MPa,and for 6 h in a biphasic water/n-butanol solvent.A high reaction temperature resulted in further hydrogenation to 2-methyl furan,while a high hydrogen pressure led to a side hydrogenation reaction to xylitol.The biphasic solvent allowed xylose solvation as well as furfuryl product extraction.The acidic-SO3 H sites and Cu sites co-existed,maintained a balance,and cooperatively catalyzed the cascade conversion.Excessive acidic sites and large pores could promote the xylose conversion,although a low furfuryl alcohol yield was obtained.This catalytic system could be potentially applied to the one-pot synthesis of furfuryl alcohol from hemicellulose-derived xylose.

Extrapolation of the gold-catalyzed cycloisomerization to the palladium-catalyzed cross-coupling/cycloisomerization of acetylenic alcohols for the synthesis of polysubstituted furans:Scope and application to tandem processes

This paper describes the development of an integrated approach for the preparation of diverse furan derivatives from acetylenic alcohols by gold and palladium catalyzed π-activation chemistry.Notably,this new method was found to be amenable to cyclooctyl-containing substrates,which represents a significant extension to this methodology compared with our previous reports.Furthermore,this newly developed method allowed for the direct construction of cyclooctyl furans from their synthetic precursors under Sonogashira conditions.Experimental results revealed that palladium played two major functions in these reactions,including（1） an essential catalyst in the cross-coupling reaction of the substrates;and（2）facilitating the cyclization of the acetylenic alcohol intermediates through a typical π-activation process.The scope of this chemistry was highlighted by the one-pot synthesis of 3-iodofuran,which provided an opportunity for further functionalization（via coupling methods）.Finally,the AuBr3 protocol was also elaborated to domino cyclization/C-H activation reactions,as well as the cyclization of acyclic precursors.Taken together,the results of this study demonstrate that gold and palladium catalysts can be used to complement each other in cyclization reactions.

One-pot synthesis of cyclic aldol tetramer and ?, β-unsaturated aldol from linear aldehydes using quaternary ammonium combined with sodium hydroxide as catalysts

One-pot synthesis of cyclic aldol tetramer and α, β-unsaturated aldol from C3-C8 linear aldehydes using phase-transfer catalyst（PTC）, quaternary ammonium, combined with sodium hydroxide as catalysts was investigated. Butanal was subjected for detail investigations to study the effect of parameters. It was found that the selectivity of cyclic aldol tetramer depends greatly on the operating conditions of the reaction, especially the PTC/butanal molar ratio. The average selectivity of 2-hydroxy-6-propyl-l, 3, 5-triethyl-3-cyclohexene-1-carboxaldehyde（HPTECHCA） was 54.41% using tetrabutylammonium chloride combined with 14%（mass fraction） Na OH as catalysts at 60 ℃for 2 h with a PTC-to-butanal molar ratio of 0.09：1. Pentanal was more likely to generate cyclic aldol tetramer compared with other aldehydes under the optimum experimental conditions. Recovery of the PTC through water washing followed by adding enough sodium hydroxide from the washings was also demonstrated.

Synthesis of 2-Methyl-4-methoxyaniline from o-Nitrotoluene Using Pt/C and Acidic Ionic Liquid as Catalyst System

2-Methyl-4-methoxyaniline （MMA） was synthesized by one-pot method through the hydrogenation and Bamberger rearrangement of o-nitrotoluene in methanol using acidic ionic liquid and 3% Pt/C as catalyst system. The effects of ionic liquid type, dosage of ionic liquid and 3% Pt/C, reaction temperature and reaction pressure on o-nitrotoluene conversion and MMA selectivity were investigated. The results indicated that the imidazolium-based acidic ionic liquid which contains SO3H-functionalized cation showed higher selectivity to MMA than other acidic ionic liquids used in this work. Using 1-（propyl-3-sulfonate）-3-methylimidazolium hydrosulfate （[HSO3-pmim][HSO4]） as the acid catalyst, the selectivity to MMA was as high as 67.6% at 97.8% of o-nitrotoluene conversion. As 3% Pt/C increased from 0.01 g to 0.025 g, the selectivity to MMA decreased from 73.4% to 62.5%, because of the hydrogenation of intermediate o-methyl-phenylhydroxylamine to o-toluidine becoming more dominant. An increase in hydrogen pressure also had obviously dramatic effect in lowering the MMA selectivity. After easy separation from the products, the catalyst system could be reused at least 3 times.

阿斯巴甜合成工艺研究

探讨了以天冬氨酸和苯丙氨酸为原料制备甜味剂阿斯巴甜的合成工艺。首先对合成的各步反应进行了研究 ,然后考察了前三步反应每步之间连接的可能性 ,最后实现了中和之前各步反应的一锅化。一锅化法的总收率达到了 63 .6%左右 ,并且α 异构体与 β 异构体的比率达到 95.4∶4 .

One-pot synthesis of Li_3VO_4@C nanofibers by electrospinning with enhanced electrochemical performance for lithium-ion batteries

Electrospinning is firstly used to one-pot synthesis of Li3VO4@C nanofibers in a large scale. Although with the presence of organic sources in synthesis process, the pure phase Li3VO4 with superior nanofibrous morphology is still successfully obtained through adjusting different heat treatment processes and different vanadium sources. The prepared Li3VO4@C nanofibers exhibit a unique structure in which nanosized Li3VO4 particles are uniformly embedded in amorphous carbon matrix. Compared with LiBVO4/C powder, Li3VO4@C nanofibers display enhanced reversible capacity of 451 mAhg^-1 at 40mAg^-1 with an increased initial coulombic efficiency of 82.3%, and the capacity can remain at 394 mAh g ^-1 after 100 cycles. This superior electrochemical performance can be attributed to its unique structure which ensures a high reactivity by nanosized Li3VO4, more stable electrode/electrolyte interface by carbon encapsulation, improved electronic conductivity and buffered volume changes by flexible carbon matrix. The electrospinning technology provides an effective method to obtain high performance Li3VO4 as a promising anode material for lithium-ion batteries.

Facile and efficient one-pot synthesis of 2-arylbenzoxazoles using hydrogen tetrachloroaurate as catalyst under oxygen atmosphere

In this paper, we presented a novel method for the facile and efficient one-pot synthesis of 2-arylbenzoxazoles, which were directly synthesized from 2-aminophenol and aldehydes catalyzed by hydrogen tetrachloroaurate (HAuCl4·4H2O) under an oxygen atmosphere with anhydrous tetrahydrofuran (THF) as solvent or in solvent-free condition. The results show that this method could bring excellent yields as high as 96%. THF was proven to be the best choice among several solvents screened and the reaction was tolerated with a variety of aromatic aldehydes possessing electron-donating or withdrawing groups. The advantages of the present method lie in catalytic process using economic and environmentally benign dioxygen as oxidant.

Ultrathin ZnO membranes a few atomic layers in thickness

For the first time we fabricated ZnO membranes with thicknesses of 2.4 nm by a facile one-pot synthesis in aqueous solution.The crystal analysis revealed that the hexagonal ZnO membranes were about 10 atomic layers in thickness.The ZnO membranes bent,scrolled,intersected with each other,and self-assembled to particles in micrometre size.The hierarchical assemblies showed sponge-like structures with room inside.In the growth process,a cationic polyelectrolyte was utilized to modulate growth behavior of the ZnO crystals.As a result,the preferred growth direction of ZnO membranes is along 0110,which was perpendicular to[0001]growth direction in a typical hydrothermal synthesis.The growth mechanism of the membranes was also discussed.