Sharif Digital Repository

A highly efficient magnetic Brønsted acid catalyst was synthesized based on immobilization of 2-methylimidazole functionalized by chlorosulfonic acid on the surface of silica-coated magnetic nanoparticles (Fe3O4@SiO2-2mimSO3H). The catalyst has an excellent activity and recyclable for at least 6 reaction runs and is proven to be highly effective in the synthes is of α-aminophosphonate compounds in a green way. The facile recovery of the catalyst is carried out by applying an external magnet device. It is both "green" and efficient. The catalyst was fully characterized by techniques of TEM, SEM, FT-IR, TGA, and elemental analysis (CHNS)  

The effect of CoSALEN on anti-oxidative properties of fullerene C60 in the presence of O2 in cumene was investigated. A comparison was made between the role of the CoSALEN as a catalyst in the C60 oxidation and oxidation in the presence of an initiator, i.e., AIBN. A mechanism is proposed for the catalytic role of CoSALEN in oxidation of C60. Oxidation of octadecylaminofullerene C60 at the same conditions reveals that oxidation could be a result of hydroperoxidation of the unreacted sites of C60. We conclude that C60 as well as its aminoderivatives enhance the efficiency of CoSALEN in the oxidation of cumene due to their radical scavenging property of their unreacted double-bond sites. ©... 

The thermal decomposition of manganese and cobalt-terephthalate Metal-Organic Framework precursors was utilized as a synthetic route for fabrication of Co3O4, Mn3O4 and Mn2O3 nanoparticles. The prepared metal oxide nanoparticles of Co3O4, Mn3O4 and Mn2O3 possess average size diameter of 40, 60 and 80 nm respectively. The findings demonstrate that spinel structure nanoparticles of Co3O4 and Mn3O4 exhibit efficient catalytic activity toward heterogeneous olefin epoxidation in the presence of tert-butyl hydroperoxide. In... 

Anchoring of copper sulfate in layered poly(imidazole-imidazolium) coated magnetic nanoparticles provided a highly stable, active, reusable, high loading, and green catalyst for the click synthesis of 1,2,3-triazoles via a one-pot cycloaddition of alkyl halide, azide, and alkyne (Cu-A3C). The catalyst was characterized by FTIR, TGA, TEM, SEM, XRD, EDAX, VSM and AAS. High selectivity, broad diversity of alkyl/benzyl bromide/chloride and alkyl/aryl terminal alkynes, and good to excellent yields of products were obtained using 0.7 mol% catalyst. The catalyst was readily recovered and reused up to 6 times without significant loss of activity  

A highly efficient and simple procedure for the synthesis of quinazolin-4(3H)-ones from the condensation of 2-aminobenzamide with triethylorthoesters in presence of a catalytic amounts of heteropolyacids in various solvents is reported  

Palladium catalysts supported on functionalized multi-wall carbon nanotubes were synthesized for hydro-purification of crude terephthalic acid containing 2100ppm 4-carboxybenzaldehyde (4-CBA) as impurity. PdCl2 and Pd(OAc)2 were used as precursors. Palladium loadings were 0.05 to 0.6wt.% with catalysts reduced at 200 to 400°C. Catalysts prepared from both precursors with least 0.3wt.% palladium resulted in 99%+ removal of 4-CBA. The most desired selectivity was obtained for the catalyst with PdCl2 as precursor, reduction temperature of 300°C, and palladium loading of 0.3wt.%. This catalyst had slightly better performance than the commercial catalyst (0.5wt.% of palladium on activated carbon)... 

Palladium catalysts supported on functionalized multi-wall carbon nanotubes were synthesized for hydro-purification of crude terephthalic acid containing 2100ppm 4-carboxybenzaldehyde (4-CBA) as impurity. PdCl2 and Pd(OAc)2 were used as precursors. Palladium loadings were 0.05 to 0.6wt.% with catalysts reduced at 200 to 400°C. Catalysts prepared from both precursors with least 0.3wt.% palladium resulted in 99%+ removal of 4-CBA. The most desired selectivity was obtained for the catalyst with PdCl2 as precursor, reduction temperature of 300°C, and palladium loading of 0.3wt.%. This catalyst had slightly better performance than the commercial catalyst (0.5wt.%... 

A heterogeneous tungstate-based catalyst has been prepared for selective oxidation of sulfides to sulfoxides in the presence of 30% H2O2. The catalyst was prepared via immobilization of high amounts of WO4 2− onto the cross-linked poly(ammonium ethyl acrylamide) coated magnetic nanoparticles (MNP). FT-IR, TEM, TGA, VSM, XRD, EDX, and CHN analysis were used for characterization of catalyst. Variety of sulfides successfully converted to the related sulfoxides using 1 mol% of catalyst at room temperature in high yields. The catalyst was easily recovered and reused up to 6 times without loss of activity  

The purpose of this study is to predict the activation barriers and enthalpy for elementary steps in the process of Fischer-Tropsch (F-T) on the surfaces of Fe(110), Cu(111) and Fe/Cu alloys catalyst using "Unity Bond Index-Quadratic Exponential Potential" method aimed at predicting the activity and selectivity on the basis of energy criteria. The elementary steps, such as dissociation of CO, hydrogenation of carbidic carbon, C-C chain growth by insertion of CH2 versus CO into the metal-alkyl bonds, and chain termination, which lead to hydrocarbons (alkanes versus α-olefins) or oxygenates are discussed in detail. The results show that metallic Fe(110) is necessary to produce the carbidic... 

A novel heterogeneous catalyst has been synthesized based on the distillation-precipitation-polymerization of methyl acrylate onto modified magnetic nanoparticles followed by the amidation of the methyl ester groups using N,N-dimethylethylenediamine. The resulting poly(dimethylaminoethyl acrylamide) coated magnetic nanoparticles (MNP@PDMA) catalyst was characterized using an array of sophisticated analytical techniques, including FT-IR, TGA, SEM, TEM, CHN, vibrating sample magnetometer (VSM), and XRD analysis. The resulting heterogeneous base catalyst allowed the performance of a domino Knoevenagel condensation/Michael addition/cycloaddition reaction toward the synthesis of... 

A highly chemoselective methodology is described for the N-methylation of functionalized anilines with dimethyl carbonate (MeOCO2Me, DMC) in the presence of ZrOCl2·8H2O. Dimethyl carbonate, which usually promotes methylation at T > 120 C and eventually under inert atmosphere, was activated in the presence of zirconium oxychloride for the desired transformation at 90 C under aerobic conditions. Aminophenols showed good reactivity in this transformation and produced the corresponding N-methylanilines, as the major products, with high selectivity. Catalyst reusability study confirmed that ZrOCl2·8H2O is a recyclable catalyst and its catalytic activity was remained unchanged at least after eight... 

This review mainly discusses the application of oxido-peroxido Molybdenum(VI) complexes as catalysts or mediators in homogeneous or heterogeneous catalytic systems for oxidations of olefins, sulfides, alcohols, alkanes, and amines toward the synthesis of a variety of organic compounds, such as epoxides, sulfoxides, aldehydes and ketones, carboxylic acids, alcohols and nitroso compounds  

Platinum extraction from spent reforming catalysts in iodine solutions under atmospheric pressure and at temperatures up to 95°C was previously investigated in our group. In this system, platinum is oxidized from the spent catalyst with tri-iodide. In some of the experiments, it was observed that platinum extraction peaked and then decreased. This indicates that a precipitation reaction slowly occurs that removes the dissolved Pt ions from the solution. Power-law rate equation for the Pt extraction to PtI6 2- and the precipitation of the dissolved platinum to PtI 4(s) was implemented to model the experimental Pt extraction data. The activation energies for the platinum dissolution reaction... 

For the first time, the mechanism of Fischer esterification between acetic acid and ethanol over silica-functionalized propylsulfonic acid (silica-propyl-SO3H) catalyst was explored by means of computational modeling techniques. For this purpose, 6-edge-atom cage-like cluster comprising Si-O-Si sequences has been selected to represent the surface of the catalyst. The results indicate that the reaction goes through concerted transition states. In all optimized structures no proton (H+) transfer occurs from catalyst to the substrates and the role of the catalyst is via the activation of the substrates through the formation of strong hydrogen bonds (H-bonds). Furthermore, the energetic diagram... 

In this study, we have reported the preparation of bi-supported Ziegler-Natta catalysts using magnesium ethoxide and graphene oxide as support. The polymerization process was carried out in slurry phase using triisobutylaluminum as a co-catalyst.The XRD analysis of TiCl4/graphene oxide/Mg(OEt)2 catalyst demonstrated that the space between the layers of graphene oxide had increased to 0.2 nm.The catalyst was characterized by XPS, BET, BJH, SEM, and TGA. The catalyst activity was studied for various Al/Ti molar ratios, and the catalyst activity was optimum at Al/Ti molar ratio of 315. © 2016, Pleiades Publishing, Ltd  

A simple, rapid, and highly efficient method for the preparation of symmetrical aliphatic, aromatic, and heteroaromatic disulfides is reported. Addition of NBS to an alkyl- or arylthiol under catalyst-free conditions in dichloromethane solution produces the corresponding disulfides in nearly quantitative yields  

A series of heterogeneous catalysts including different molar ratios of CaO/talc was synthesized to study the transesterification reaction of canola oil and methanol under different reaction conditions. Characterization and kinetic results revealed that the activity of this catalyst was enhanced due to the increase of CaO/talc molar ratio value leading to an improvement in the biodiesel production. Moreover, the effect of various parameters on the activity of the undertaken catalysts was studied in order to determine the optimum process conditions. Leaching measurements and the durability of the CaO/talc catalyst under several reaction cycles were evaluated and proved it to be a stable... 

Abstract: We report robust green synthesis of novel 1,2,3-triazole-based sulfonamides bearing different motifs such as fluorine under click conditions in presence of a copper-based magnetically recoverable and reusable heterogeneous nanocatalyst. The organocopper catalyst at 0.5 mol.% was highly recyclable (up to five times) when recovered using an external magnet without significant loss in catalytic activity. The mild reaction conditions and excellent yields (69–95 %) make this protocol an attractive method for efficient synthesis of the title compounds. The structure of product 3a was determined by Röntgen crystal structure analysis. Graphical Abstract: [Figure not available: see... 

The disposal of polychlorinated biphenyls (PCBs) as persistent organic pollutants from the environment has been normally performed by isolation from soil or water because of their biological activity and toxic potential. In the present investigation, catalytic hydrodehalogenation was used to detoxify PCBs-contaminated transformer oil. All reactions were directed on an oil containing 11.09 wt% of PCBs utilizing palladium supported on multi-walled carbon nanotubes (Pd/MWCNTs). The amount of hexa-chlorine homologues reduced considerably from 5.07% to less than 800 ppm utilizing HDC at the atmosphere of argon. Moreover, the amounts of long half-lives and bioaccumulative congener of PCB 153...