Sharif Digital Repository

Dracocephalum kotschyi essential oils obtained by hydrodistillation (HD), microwave-assisted hydrodistillation (MAHD), and solvent-free microwave extraction (SFME) were investigated by GC-FID (Gas Chromatography-Flame Ionization Detector) and GC-MS (Gas Chromatography-Mass Spectrometry). The percentage of oxygenated compounds was significantly increased from 62.52% in HD to 76.47% in MAHD, and 84.52% in SFME. Conversely, the monoterpene hydrocarbons were decreased from 30.84% in HD to 13.71% in MAHD, and 5.85% in SFME. The main compound in the essential oil obtained by HD is limonene, which accounted for more than 30% of the oil, while the percentage of this compound was reduced to 9.52% in... 

Three different spinel metal oxide catalytic systems including NiFe2O4, CuFe2O4 and CoFe2O4 were synthesized using co-precipitation technique and their catalytic activities were compared to each other in α-arylation of oxindole derivatives under the optimized reaction conditions. Both nickel ferrite and copper ferrite magnetic nanoparticles show approximately the same behavior in these reactions but cobalt ferrite ones indicate slightly different properties and were not as good as the other two catalysts. These superparamagnetic catalysts allowed that α-arylation of different types of oxindoles will occur in high yields under mild conditions and at very short times  

A convenient one-pot multi-component reaction of aromatic aldehydes, enolizable ketones or β-keto esters and acetonitrile in the presence of acetyl chloride and 10 mol% ZnO nanoparticles for the synthesis of β-acetamido ketones/esters at room temperature is described. © 2007 Elsevier B.V. All rights reserved  

The synthesis of 2-amino-3-aryl-5-substituted thiophenes as anti-inflammatory agents catalyzed by KF-Al2O3 under microwave irradiation is reported. Copyright © Taylor & Francis Group, LLC  

A magnetic nanocomposite was prepared based on magnetic Fe3O4 nanoparticles entrapped into a cross-linked nitrogen rich polymer which has high loading capacity for immobilization of gold nanoparticles. The synthesized catalyst was characterized using various methods including Atomic absorption spectroscopy (AAS), Transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FT-IR), Energy-dispersive X-ray spectroscopy (EDX), Thermogravimetric analysis (TGA), scanning electron microscope (SEM), Brunauer–Emmett–Teller (BET), VSM and X-ray diffraction (XRD) techniques. The catalyst was proven to be highly efficient for reduction of nitroarenes as well as Suzuki–Miyaura... 

This article reports the synthesis of a magnetic heterogeneous catalyst through the decoration of gold ions onto the cross-linked polymeric nanocomposite from 2,6-diaminopyridine. The activity of the resulting catalyst was then evaluated in the bromination of aromatic compounds. The nitrogen rich support showed a high affinity to gold ions, and the measured content of Au was 0.76 mmol g-1. The structure of the catalyst was fully characterized by using Fourier-transform infrared spectroscopy, thermogravimetric analysis, atomic absorption spectroscopy, transmission electron microscopy, scanning electron microscope, energy-dispersive X-ray spectroscopy, Brunauer-Emmett-Teller surface area... 

A novel and efficient multicomponent reaction for the synthesis of polysubstituted pyrrolidine derivatives is described under catalyst-free conditions using ultrasonic irradiation. The reactions were performed via a one-pot four-component condensation of secondary amines, carbon disulfide, isocyanides, and gem-dicyano olefins at room temperature to afford polysubstituted pyrrolidines diastereoselectively in 56-96% yields. This is the first report of a Mumm-type rearrangement with dithiocarbamates followed by intramolecular cyclization, which leads to the preparation of the key structure of pyrrolidine. This journal is © The Royal Society of Chemistry and the Centre National de la Recherche... 

A new magnetic heterogeneous catalyst was synthesized by immobilization of nickel ions onto a cross-linked polymeric nanocomposite composed of cyanuric chloride, ethylenediamine and functionalized magnetic nanoparticles. The resulting nitrogen rich support was capable of adsorbing large amounts of nickel ions (1.20 mmol g−1). The synthesized catalyst was characterized using AAS, TEM, FT-IR, EDX, TGA, SEM, BET and XRD techniques. The performance of the prepared catalyst was investigated in the C-N coupling of arylamines with aryl boronic acids. The reaction was carried out under a mild condition and good to moderate to good yields of products was obtained using only 5.0 mol% of the catalyst.... 

Herein we report a new organocatalyst for the asymmetric Michael addition of nitroalkanes to α,β-unsaturated aldehydes. This catalyst incorporates a basic imidazole group in addition to the secondary amine responsible for activation of the α,β-unsaturated carbonyl compounds via iminium ion formation. The new organocatalyst is capable of catalyzing the enantioselective carbon-carbon bond formation with a high degree of enantiocontrol providing products in enantiomeric excesses of up to 92% and yields of up to to 91 %. These results constitute the best results so far reported for organocatalyzed Michael additions of nitroalkanes to α,β-unsaturated aldehydes, and provide proof of principle that... 

Benzopyrans, or chromenes, are widespread in nature and are considered to be a privileged scaffold in medicinal chemistry. Herein, we report the first organocatalyzed asymmetric synthesis of chiral benzopyrans. The benzopyran unit is constructed through a domino reaction involving an oxa-Michael attack of salicylic aldehyde derivatives onto α,β-unsaturated aldehydes, activated through iminium-ion formation with the organocatalyst, followed by an intramolecular aldol reaction and subsequent elimination of water. This overall reaction sequence provides benzopyrans with aromatic C-2 substituents in up to 60% yield and 60% enantioselectivity, while C-2 aliphatic analogues can be obtained in 90%... 

A novel heterogeneous copper catalyst was synthesized in which poly(1-vinyl imidazole-co-ionic liquid) was used as a solid heterogeneous support. The catalyst was readily synthesized in a large scale amount. The catalyst has a high loading level of copper ions and can be used in low weight percentages. The resulting catalyst was highly active in the preparation of triazoles by the Huisgen 1,3-dipolar cycloaddition method. In some cases the catalytic turnover number and frequency reached 70 002 and 3889 h-1, respectively. The catalyst was recycled many times without significant loss of activity. This journal is  

Crystal-size distribution (CSD) is one of the most important parameters in sugar production. The objective is to grow crystals of uniform sizes or narrow CSD. CSD appears to be determined by the growth-rate history of the crystals and the relative supersaturation (SS) of the solution from which crystals growth takes place. Three methods for preparation of nucleation seeds were described and used for industrial crystallization of raw and white sugars; these are wet milling filtered sugar (ML), agitating saturated solution (AS) and powdered sugars (PD). Rosin-Rammler (RR) and mathematical models were adopted to investigate CSD and the uniformity of the produced crystals. Higher uniformity... 

A new heterogeneous copper catalyst was synthesized by immobilization of copper ions onto magnetic nanoparticles with a new ligand based on triazole. The catalyst was characterized using scanning and transmission electron microscopies, atomic absorption and Fourier transform infrared spectroscopies, and thermogravimetric, elemental and energy-dispersive X-ray analyses. The results confirmed that a good level of organic groups was immobilized on the magnetic nanoparticles. Huisgen cycloaddition reaction was chosen as a model reaction for the investigation of catalyst activity under green conditions. Phenylacetylene and benzyl bromide derivatives were used for the synthesis of triazoles. The... 

A new and efficient method has been developed for the synthesis of 5,7-diaryl-5,6,7,8-tetrahydropyrimido[4,5-d]pyrimidine-2,4-dione derivatives by cyclization of 6-aminouracils with N,N′-bis(arylmethylidene)arylmethanes (diimines). The products were formed in good yields and with very good anti-diastereoselectivity. The best yields were obtained when p-toluenesulfonic acid (PTSA) was used as the catalyst. The solvent also played an important role in the optimization. An amino-substituted 6-aminouracil and a corresponding sulfur analog could be successfully employed. In addition, various diimines, electron rich and neutral, could be successfully employed. The products are of relevance as... 

Abstract: Carbonyl compounds were prepared by selective oxidation of alcohols in the presence of recoverable Fe 3O 4@ SiO 2@ Pd magnetic nanocatalyst in aqueous media as a green solvent. Molecular oxygen served as an oxidant. The catalyst was removed from the reaction media by external magnetic field, washed with methanol, and reused for six more times without any considerable reduction in its reactivity. The chemoselectivity and regioselectivity of the catalyst can serve for selective oxidation of primary alcohols in the presence of secondary ones, and for oxidation of unhindered alcohols in the presence of hindered ones. Graphical Abstract: Selective and facile oxidation of alcohols to... 

Human society is becoming more intransigent on removing organic dyes from polluted water before discharging to the environment. To fulfill this goal, a magnetic metal-organic framework adsorbent based on functionalized magnetic Fe3O4 nanoparticles and highly water stable UiO-66 with high porosity and sensitivity to the external magnetic field was designed and synthesized via an easy step-by-step self-assembly technique. The synthesized adsorbent magnetic nanoparticles (Fe3O4@UiO-66) were applied to remove organic dyes, i.e., methyl orange (MO) and methylene blue (MB), from a contaminated aqueous solution. The experiments displayed that magnetic Fe3O4@UiO-66 has good adsorption uptake for MO... 

Human society is becoming more intransigent on removing organic dyes from polluted water before discharging to the environment. To fulfill this goal, a magnetic metal-organic framework adsorbent based on functionalized magnetic Fe3O4 nanoparticles and highly water stable UiO-66 with high porosity and sensitivity to the external magnetic field was designed and synthesized via an easy step-by-step self-assembly technique. The synthesized adsorbent magnetic nanoparticles (Fe3O4@UiO-66) were applied to remove organic dyes, i.e., methyl orange (MO) and methylene blue (MB), from a contaminated aqueous solution. The experiments displayed that magnetic Fe3O4@UiO-66 has good adsorption uptake for MO... 

A novel magnetically recoverable oxidation catalyst was prepared in which magnetic nanoparticles were entrapped in a tungstate functionalized poly(ionic liquid) matrix. Using H2O2 as an oxidant, a wide range of substrates including alcohols, sulfides and olefins were selectively oxidized with excellent yields. The resulting catalyst was characterized by FTIR, TGA, SEM, TEM, XRD, XRF, CHN, vibrating sample magnetometer (VSM) and atomic adsorption spectroscopy (AAS). The catalyst can be readily recovered and reused at least ten times under the described reaction conditions without significant loss of reactivity. This journal is