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1.
An effective method for the synthesis of sulfonylmethylated imidazopyridines was described with Ir(ppy)3 as photocatalyst under visible light irradiation. This reaction could be performed smoothly under mild conditions and has a wide substrate scope and good functional group tolerance. Meanwhile, desulfonylation of several selected compounds was easily achieved under reducing conditions to unveil the methyl group. The method may be an attractive strategy to install a methyl group on imidazopyridines.  相似文献   

2.
Co(ClO4))2·6H2O/bis-Schiff base complexes promoted the conjugate addition of indole toα,β-unsaturated ketones under mild conditions,giving the corresponding addition products with high yields.And the complex has been characterized with XRD and IR.  相似文献   

3.
Nanocrystalline TiO2 was used as an efficient and recyclable catalyst for the chemoselective trimethylsilylation of primary and less hindered secondary alcohols and phenols with hexamethyldisilazane(HMDS).All reactions were performed under mild and completely heterogeneous conditions in good to excellent yields.  相似文献   

4.
A novel SrSn(OH)6 photocatalyst with large plate and particle size were synthesized via a facile chemical precipitation method.The photocatalytic activity of the SrSn(OH)6 was evaluated by the removal of NO at ppb level under UV light irradiation.Based on the ESR measurements,SrSn(OH)6 photocatalyst was found to have the ability to generate the main active species of O2·-,·OH and 1 O2 during the photocatalyti...  相似文献   

5.
A catalytic multi-component reaction involving aromatic amine,aromatic aldehydes,mercapto acid as substrates and Bi(SCH2COOH)3 as catalyst under solvent free conditions,afforded thiazolidin-4-one in good yields.The efficiency of the catalyst was proved with a variety of substrates,ranging from electrondeficient to electron-rich aldehydes.  相似文献   

6.
A new method for the synthesis of 3-thioazaspiro[4,5]trienones was developed using Pd nanoparticle catalysts,which are highly efficient,environmentally friendly and recyclable.Alkynes and thiophene phenols are effectively cyclized by Pd/ZrO2 catalyst under visible light irradiation.The present protocol simply utilizes visible light as the safe and ecofriendly energy source,and the Pd/ZrO2 nanocomposite as photocatalyst provides a simple and practical approach to various 3-thioazaspiro[4,5]trienones in moderate conditions to high yields.  相似文献   

7.
An extensive analysis of iron-nitrogen-carbon(Fe-N-C)electrocatalysts synthesis and activity is presented concerning synthesis conditions such as initial Fe content,pyrolysis temperature and atmosphere(inert N2,reducing NH3,oxidizing Cl2 and their sequential combinations)and the influence of an external magnetic field on their performance in oxygen reduction reaction(ORR).Thermosetting porous polymers doped with FeCl3 were utilized as the Fe-N-C catalysts precursors.The pyrolysis temperature was varied within a 700-900℃range.The temperature and atmosphere of pyrolysis strongly affect the porosity and compositi on of the resultant Fe-N-C catalysts,while the in itial amount of Fe precursor shows much weaker impact.Pyrolysis under NH3 yields materials similar to those pyrolyzed under an inert atmosphere(N2).In contrast,pyrolysis under Cl2 yields carbon of peculiar character with highly disordered structure and extensive microporosity.The application of a static external magnetic field strongly enhances the ORR process(herein studied in an alkaline environment)and the enhancement correlates with the Fe content in the Fe-N-C catalysts.The Fe-N-C materials containing ferromagnetic iron phase embedded in N-doped microporous carbon constitute attractive catalysts for magnetic field-aided anion exchange membrane fuel cell technology.  相似文献   

8.
14-Aryl or alkyl-14H-dibenzo[a,j]xanthenes were prepared by condensation of 2-naphthol and aldehydes in the presence of Mg(HSO42 as an efficient,cheap,readily available and eco-friendly catalyst.This procedure has the advantages of high yields,easy work-up,short reaction times,and green conditions.  相似文献   

9.
A novel and practical method for the synthesis of 3,5-bis(trifluoromethyl)-4,5-dihydro-1H-pyrazoles by [3+2] cycloaddition reactions of α-(trifluoromethyl)styrenes with 2,2,2-trifluorodiazoethane (CF3CHN2) has been developed. The cyclization reaction proceeds smoothly in the presence of a catalytic amount of Et3N, affording a variety of bis(trifluoromethyl)-substituted 2-pyrazolines in good to excellent yields. This method also exhibits a broad substrate scope and tolerates various functional groups.  相似文献   

10.
Photolysis studies on formic acid (HCOOH) and formate ion (HCOO−) in presence of TiO2, a photocatalyst, as suspension in water were carried out separately using 350 nm ultraviolet light. The products, such as H2, CO, CO2 and CH4, generated during the experiments were monitored with varying the ambient, light exposure time, and the concentration of HCOOH/HCOO−. The yields of CO in all these systems increased with light exposure time. In aerated systems, CO yields were higher in contrast to the deoxygenated (Ar-purged) systems under identical conditions. It is proposed apparently that the formation of CO is taking place during the chemical reduction of in-situ generated CO2, a photo-mineralized product of HCOOH/HCOO−, but not through the direct photodecomposition or photodehydration (CO+H2O) of solute molecules. The rates of CO formation during 1.3 M HCOOH photolysis in presence of TiO2 photocatalyst were evaluated to be 0.21 and 0.13 μl/min in aerated and Ar-purged systems, respectively. As compared with HCOOH systems, the CO yields are lower when 0.2 M HCOONa was exposed to light under identical conditions. The CO growth rates were evaluated to be 0.07 and 0.046 μl·min−1 for aerated and deoxygenated HCOONa systems, respectively; moreover, the trend is quite similar to that of the HCOOH system. Under these conditions, the emission of H2 was also observed, and its yield was significantly higher in Ar-purged system as compared with the CO yields. However, in aerated system, the yields of these products were just opposite. The formation of low yield of methane was observed during photolysis of HCOOH/HCOO− ions. In CO2 ambient, the yields of CO and H2 varied drastically with time.  相似文献   

11.
Unprecedented divergent synthesis of gem-difluorovinylacetic acid and glutaric acid derivatives from α-CF3 alkenes with formate as the carbonyl source was disclosed.The reaction can undergo selective mono-or triple C-F bond cleavage by simply switching the photocatalyst and hydrogen atom transfer(HAT) catalyst under visible-light-induced conditions at room temperature.Foramte acts as both the C1 source and the reductant through the generation of CO2·- species,whi...  相似文献   

12.
An efficient green protocol for the preparation 3,4,6-trisubstituted 2-pyridone of employing a condensation reaction of cyanoacetamide and acetylacetone in the presence of KAl(SO42·12H2O in water has been described.The present procedure offers advantage such as shorter reaction time,simple workup,and excellent yields.  相似文献   

13.
A mild,efficient and eco-friendly process for the electrophilic nitration is described using N2O5 as a green nitrating agent in the presence of rare earth metal triflates[RE(OTf)3]under mild conditions.  相似文献   

14.
An efficient,convenient and green method has been introduced for the preparation of 14-aryl(alkyl)-14H-dibenzo[a,j]xanthene and 1,8-dioxooctahydroxanthene derivatives by the reaction of aldehydes with 2-naphthol and 5,5-dimethyl-1,3-cyclohexanedione, respectively,in the presence of ZrO(OTf)2 as a reusable catalyst under solvent-free conditions.In addition,very short reaction times, excellent yields,straightforward procedure,and relatively non-toxicity of the catalyst are other noteworthy advantages of the present method.  相似文献   

15.
The tandem reaction of photoinduced double hydrogen-atom transfer and deoxygenative transborylation for chemo-and site-selective reduction of nitroarenes into aryl amines under catalyst-free, room temperature conditions was disclosed in excellent yields. In this reaction, isopropanol(iPrOH) was used as hydrogen donor and tetrahydroxydiboron [B2(OH)4] as deoxygenative reagent with green, cheap, and commercially available credentials. In particular, a wide range of...  相似文献   

16.
Alcohols are selectively and efficiently protected as their tetrahydropranyl ethers in the presence of a catalytic amount of Fe(HSO4)3 in good to high yields. All reactions are performed under mild and completely heterogeneous reaction conditions.  相似文献   

17.
The one‐pot synthesis of a series of 1,2,4‐triazines from the reactions of semicarbazide or thiosemi‐carbazide with various α,β‐dicarbonyl compounds under reflux conditions in a EtOH‐H2O (9:1) mixture as solvent and catalyzed by nano‐sized silica supported FeCl3 (FeCl3@SiO2) was investigat‐ed. The FeCl3 content of the catalyst was measured by atomic absorption to get the adsorption ca‐pacity. The reactions gave high yields of the product and the catalyst was easily separated and re‐used for successive reaction runs without significant loss of activity.  相似文献   

18.
A simple synthesis of novel and known calix[4]resorcinarenes derivatives has been achieved by the condensation of resorcinol and different aromatic aldehydes in the presence of catalytic amounts of Fe3O4 nanoparticles under solvent-free conditions.The experimental conditions have been thoroughly optimized and established,allowing significant rate enhancements and good to excellent yields.The reactions can be run safely without using any toxic organic solvents under mild reaction conditions.The Fe3O4 nanoparticles were characterized by powdered X-ray diffraction(XRD),transmission electron microscopy(TEM) and FT-IR spectroscopy.  相似文献   

19.
A simple, mild and green approach has been developed for the synthesis of asymmetrical heterobiaryls under the irradiation of visible light without any oxidants and promoting reagents through using Pd/CeO2 nanocomposite photocatalyst. This method tolerates considerable functional groups such as electron-donating groups and electron-withdrawing groups through C-C cross-coupling.  相似文献   

20.
The oxidative dehydrogenation of alcohols to aldehydes catalyzed by Ag nanoparticles supported on Al2O3 was studied.The catalyst promoted the direct formation of imines by tandem oxidative dehydrogenation and condensation of alcohols and amines.The reactions were performed under mild conditions and afforded the imines in high yield(up to 99%) without any byproducts other than H2O.The highest activity was obtained over 5 wt%Ag/Al2O3 in toluene with air as oxidant.The reactions were also performed under oxidant-free conditions where the reaction was driven to the product side by the production of H2 in the gas phase.The use of an efficient and selective Ag catalyst for the oxidative dehydrogenation of alcohol in the presence of amines gives a new green reaction protocol for imine synthesis.  相似文献   

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