Tetrabutylammonium hexatungstate,[TBA]2[W6O19],has been used as an efficient,inexpensive,and recyclable green catalyst for the one-pot three-component synthesis of 1,8-dioxodecahydroacridines by the reaction of dimedo...Tetrabutylammonium hexatungstate,[TBA]2[W6O19],has been used as an efficient,inexpensive,and recyclable green catalyst for the one-pot three-component synthesis of 1,8-dioxodecahydroacridines by the reaction of dimedone with aromatic or aliphatic aldehydes in the presence of a nitrogen source(ammonium acetate or aromatic amines) under neat conditions.There are several advantages to the current process over the standard procedures available in the literature,including shorter reaction times(7-14 min),higher yields,facile work-up,and minimal environmental impact.Furthermore,the catalyst can be conveniently recovered and reused.展开更多
Sulfonic acid-functionalized silica-coated nano-Fe3O4 particles(Fe3O4@SiO2-SO3H) have been prepared as a novel heterogeneous acid using a facile process.The material was subsequently identified as an efficient catalys...Sulfonic acid-functionalized silica-coated nano-Fe3O4 particles(Fe3O4@SiO2-SO3H) have been prepared as a novel heterogeneous acid using a facile process.The material was subsequently identified as an efficient catalyst for the synthesis of a variety of tetraketone derivatives via the Knoevenagel condensation and Michael addition reactions of aromatic aldehydes to dimedone,1,3-indanedione,and 1,3-dimethyl barbituric acid.The catalyst could be readily recovered using a simple external magnet and reused several times without any significant loss in activity.The current catalytic process is both sustainable and economical because it operates under aqueous conditions,the catalyst can be recovered and reused,and the reactions themselves require only a short time and provide the products in high yield.展开更多
A simple and efficient procedure for the preparation of silica-bonded N-propylpiperazine sodium n-propionate(SBPPSP) by the hydrolysis of silica-bonded N-propylpiperazine methyl n-propionate(SBPPMP) in hydrochloric ac...A simple and efficient procedure for the preparation of silica-bonded N-propylpiperazine sodium n-propionate(SBPPSP) by the hydrolysis of silica-bonded N-propylpiperazine methyl n-propionate(SBPPMP) in hydrochloric acid(0.5 mol/L) followed by treatment with saturated sodium bicarbonate is described.The SBPPMP was obtained by the reaction of 3-silica-bonded N-propylpiperazine and methyl acrylate in methanol.SBPPSP was used as a recyclable basic catalyst for the synthesis of 3,4-dihydropyrano[c]chromenes by the reaction of aromatic aldehydes,malononitrile,and 4-hydroxycoumarin in aqueous ethanol(1:1 v/v) under reflux conditions.Biscoumarins were also obtained via condensation of aldehydes and 4-hydroxycoumarin in aqueous ethanol(1:1 v/v) under reflux conditions.The catalyst could be recycled several times without any additional treatment.展开更多
A Ni/Al layered double hydroxide(LDH) nanoparticle modified carbon ceramic electrode(Ni/Al LDH/NMCC) was fabricated and used for the electrocatalytic oxidation of methanol and ethanol in alkaline media.Cyclic voltamme...A Ni/Al layered double hydroxide(LDH) nanoparticle modified carbon ceramic electrode(Ni/Al LDH/NMCC) was fabricated and used for the electrocatalytic oxidation of methanol and ethanol in alkaline media.Cyclic voltammetric(CV) studies showed that it gave a significantly higher activity for methanol and ethanol oxidation and can be used as an electrocatalytic anode for fuel cells.The kinetic parameters of the electron transfer coefficient(α) and number of electrons involved in the rate determining step(nα) for the oxidation of methanol and ethanol were determined using CV.The anodic currents showed a linear dependence on the concentration of methanol and ethanol.展开更多
Amino-functionalized SBA-15(SBA-Pr-NH2) has been used as a new basic nanocatalyst in the one-pot synthesis of spirooxindole derivatives via the three-component condensation reaction of isatins,activated methylene reag...Amino-functionalized SBA-15(SBA-Pr-NH2) has been used as a new basic nanocatalyst in the one-pot synthesis of spirooxindole derivatives via the three-component condensation reaction of isatins,activated methylene reagents,and dimedone in an aqueous medium.SBA-Pr-NH2 has been established as an efficient heterogeneous nanoporous solid basic catalyst(pore size of 6 nm) that can be easily handled and removed from the reaction mixture by simple filtration,and also recovered and reused without noticeable loss of reactivity.展开更多
A Ni-Zn binary metal coating was electrochemically deposited on a copper electrode that was coated with nickel(bottom layer).This was then etched in concentrated alkaline solution(30 wt% NaOH) to produce a nanoporous ...A Ni-Zn binary metal coating was electrochemically deposited on a copper electrode that was coated with nickel(bottom layer).This was then etched in concentrated alkaline solution(30 wt% NaOH) to produce a nanoporous Ni electrocatalytic surface for borohydride electro-oxidation in alkaline solution.The bulk and surface compositions of the coating before and after alkaline leaching were determined by atomic absorption spectroscopy and energy dispersive X-ray analysis.The surface morphology was investigated by scanning electron microscopy.The characterization showed that the leached Ni/Zn-Ni coating has a nanoporous structure.Electrocatalytic activity for borohydride electro-oxidation was assessed by cyclic voltammetry and electrochemical impedance spectroscopy.The improved activity of the electrode was related to the removal of corrosion products and the formation of nanopores and cracks during alkaline leaching.Cyclic voltammetry studies confirmed that the alkaline leaching process improved the activity of the Ni/Zn-Ni coating in comparison to that of a smooth Ni deposit,and it gave an anodic peak current density that was 21 times higher.展开更多
LaFe0.9Co0.1O3(LFCO) perovskite nanoparticles were prepared using a sol-gel method.The physical and chemical properties of the catalyst were determined using X-ray diffraction(XRD),transmission electron microscopy,sca...LaFe0.9Co0.1O3(LFCO) perovskite nanoparticles were prepared using a sol-gel method.The physical and chemical properties of the catalyst were determined using X-ray diffraction(XRD),transmission electron microscopy,scanning electron microscopy,scanning tunneling microscopy,energy dispersive X-ray spectroscopy,thermogravimetric analysis,and Fourier transform infrared spectroscopy.The catalytic activity of the sample was evaluated using aerobic oxidation of thiols to disulfides.The XRD results indicated that the LFCO had a good crystalline phase at 750 °C.The experimental data revealed that the LFCO particles were nano-sized.LFCO nanoparticles can catalyze the oxidation of various thiols,including aromatic and aliphatic thiols.The effects of reaction parameters such as temperature,solvent,and the amount of catalyst on the oxidation of 4-chlorothiophenol were investigated.In comparison with reactions using the corresponding neat complexes,i.e.,Co(NO3)2.6H2O and Fe(NO3)3.9H2O,higher yields were obtained in the oxidation reaction catalyzed by LFCO nanoparticles.展开更多
Indium incorporated silica samples with different indium contents were synthesized using a template free sol-gel method.The silica used was extracted from rice husk(RH) and the resulting catalyst was labeled as RH-xIn...Indium incorporated silica samples with different indium contents were synthesized using a template free sol-gel method.The silica used was extracted from rice husk(RH) and the resulting catalyst was labeled as RH-xIn(x = 5%,10%,15%,and 20%).From the N2 adsorption analysis the presence of type IV isotherm in RH-blank and RH-xIn indicated the mesoporous nature of the catalysts.In the XRD pattern,a broad band at ca.2θ = 25° was observed for all the catalysts which showed them to be amorphous.TEM micrographs revealed that the material is composed of nanoparticles.Friedel-Craft benzoylation of toluene was carried out using the RH-xIn catalyst.The optimum conditions for the benzoylation of toluene were determined and at 373 K,100% conversion and 89% selectivity for the para-product(i.e.4-methylbenzophenone) were obtained.展开更多
基金supported by Islamic Azad University,Mashhad Branch
文摘Tetrabutylammonium hexatungstate,[TBA]2[W6O19],has been used as an efficient,inexpensive,and recyclable green catalyst for the one-pot three-component synthesis of 1,8-dioxodecahydroacridines by the reaction of dimedone with aromatic or aliphatic aldehydes in the presence of a nitrogen source(ammonium acetate or aromatic amines) under neat conditions.There are several advantages to the current process over the standard procedures available in the literature,including shorter reaction times(7-14 min),higher yields,facile work-up,and minimal environmental impact.Furthermore,the catalyst can be conveniently recovered and reused.
基金supported by the Faculty of Chemistry and Office of Gifted Student at Semnan University
文摘Sulfonic acid-functionalized silica-coated nano-Fe3O4 particles(Fe3O4@SiO2-SO3H) have been prepared as a novel heterogeneous acid using a facile process.The material was subsequently identified as an efficient catalyst for the synthesis of a variety of tetraketone derivatives via the Knoevenagel condensation and Michael addition reactions of aromatic aldehydes to dimedone,1,3-indanedione,and 1,3-dimethyl barbituric acid.The catalyst could be readily recovered using a simple external magnet and reused several times without any significant loss in activity.The current catalytic process is both sustainable and economical because it operates under aqueous conditions,the catalyst can be recovered and reused,and the reactions themselves require only a short time and provide the products in high yield.
基金Persian Gulf University Research Council for partial support of this work, PGU/FS/6-2/1390/694
文摘A simple and efficient procedure for the preparation of silica-bonded N-propylpiperazine sodium n-propionate(SBPPSP) by the hydrolysis of silica-bonded N-propylpiperazine methyl n-propionate(SBPPMP) in hydrochloric acid(0.5 mol/L) followed by treatment with saturated sodium bicarbonate is described.The SBPPMP was obtained by the reaction of 3-silica-bonded N-propylpiperazine and methyl acrylate in methanol.SBPPSP was used as a recyclable basic catalyst for the synthesis of 3,4-dihydropyrano[c]chromenes by the reaction of aromatic aldehydes,malononitrile,and 4-hydroxycoumarin in aqueous ethanol(1:1 v/v) under reflux conditions.Biscoumarins were also obtained via condensation of aldehydes and 4-hydroxycoumarin in aqueous ethanol(1:1 v/v) under reflux conditions.The catalyst could be recycled several times without any additional treatment.
文摘A Ni/Al layered double hydroxide(LDH) nanoparticle modified carbon ceramic electrode(Ni/Al LDH/NMCC) was fabricated and used for the electrocatalytic oxidation of methanol and ethanol in alkaline media.Cyclic voltammetric(CV) studies showed that it gave a significantly higher activity for methanol and ethanol oxidation and can be used as an electrocatalytic anode for fuel cells.The kinetic parameters of the electron transfer coefficient(α) and number of electrons involved in the rate determining step(nα) for the oxidation of methanol and ethanol were determined using CV.The anodic currents showed a linear dependence on the concentration of methanol and ethanol.
基金supported by the Research Councils at Alzahra University and university of Tehran
文摘Amino-functionalized SBA-15(SBA-Pr-NH2) has been used as a new basic nanocatalyst in the one-pot synthesis of spirooxindole derivatives via the three-component condensation reaction of isatins,activated methylene reagents,and dimedone in an aqueous medium.SBA-Pr-NH2 has been established as an efficient heterogeneous nanoporous solid basic catalyst(pore size of 6 nm) that can be easily handled and removed from the reaction mixture by simple filtration,and also recovered and reused without noticeable loss of reactivity.
基金supported by Renewable Energy Organization of Iranthe financial support of the Office of Vice Chancellor in Charge of Research of University of Tabriz
文摘A Ni-Zn binary metal coating was electrochemically deposited on a copper electrode that was coated with nickel(bottom layer).This was then etched in concentrated alkaline solution(30 wt% NaOH) to produce a nanoporous Ni electrocatalytic surface for borohydride electro-oxidation in alkaline solution.The bulk and surface compositions of the coating before and after alkaline leaching were determined by atomic absorption spectroscopy and energy dispersive X-ray analysis.The surface morphology was investigated by scanning electron microscopy.The characterization showed that the leached Ni/Zn-Ni coating has a nanoporous structure.Electrocatalytic activity for borohydride electro-oxidation was assessed by cyclic voltammetry and electrochemical impedance spectroscopy.The improved activity of the electrode was related to the removal of corrosion products and the formation of nanopores and cracks during alkaline leaching.Cyclic voltammetry studies confirmed that the alkaline leaching process improved the activity of the Ni/Zn-Ni coating in comparison to that of a smooth Ni deposit,and it gave an anodic peak current density that was 21 times higher.
文摘LaFe0.9Co0.1O3(LFCO) perovskite nanoparticles were prepared using a sol-gel method.The physical and chemical properties of the catalyst were determined using X-ray diffraction(XRD),transmission electron microscopy,scanning electron microscopy,scanning tunneling microscopy,energy dispersive X-ray spectroscopy,thermogravimetric analysis,and Fourier transform infrared spectroscopy.The catalytic activity of the sample was evaluated using aerobic oxidation of thiols to disulfides.The XRD results indicated that the LFCO had a good crystalline phase at 750 °C.The experimental data revealed that the LFCO particles were nano-sized.LFCO nanoparticles can catalyze the oxidation of various thiols,including aromatic and aliphatic thiols.The effects of reaction parameters such as temperature,solvent,and the amount of catalyst on the oxidation of 4-chlorothiophenol were investigated.In comparison with reactions using the corresponding neat complexes,i.e.,Co(NO3)2.6H2O and Fe(NO3)3.9H2O,higher yields were obtained in the oxidation reaction catalyzed by LFCO nanoparticles.
基金supported by Universiti Sains Malaysia RU research grant(1001/PKIMIA/814019 and 1001/PKIMIA/811092)Universiti Sains Malaysia Graduate Assistantship to KLS
文摘Indium incorporated silica samples with different indium contents were synthesized using a template free sol-gel method.The silica used was extracted from rice husk(RH) and the resulting catalyst was labeled as RH-xIn(x = 5%,10%,15%,and 20%).From the N2 adsorption analysis the presence of type IV isotherm in RH-blank and RH-xIn indicated the mesoporous nature of the catalysts.In the XRD pattern,a broad band at ca.2θ = 25° was observed for all the catalysts which showed them to be amorphous.TEM micrographs revealed that the material is composed of nanoparticles.Friedel-Craft benzoylation of toluene was carried out using the RH-xIn catalyst.The optimum conditions for the benzoylation of toluene were determined and at 373 K,100% conversion and 89% selectivity for the para-product(i.e.4-methylbenzophenone) were obtained.
