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51.
In this research, we have used Fe3O4@nano-cellulose–OPO3H as magnetic bio-based nanocatalyst for the synthesis of 2,3-dihydroquinazolin-4(1H)-ones via condensation of 2-aminobenzamide and different aldehydes. The major advantages of the present methodology are good yields, ecofriendly catalyst, and easy workup.  相似文献   
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Using both classical reflux and microwave-mediated conditions, a series of new spiroindoloindolizidines was synthesized by multicomponent 1,3-dipolar cycloaddition of azomethine ylides in unprecedented exo/endo stereocontrolled. Both conditions easily afforded two identical and separable exo/endo diastereomeric ratios of cycloadducts. However, the ratio of two diastereomeric products obtained from conventional conditions was reversed in all examined cases when the reactions were explored under microwave-mediated conditions. As expected, utilizing the microwave-assisted conditions produced higher yields and reaction rates compared to classical conditions. The structure and exact stereochemistry of synthesized cycloadducts were determined by applying various 2D-NMR spectroscopic techniques and single-crystal X-ray diffraction. Finally, the mechanism of the reaction has been briefly investigated by using density functional theory (DFT) calculations.  相似文献   
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In this research, synthesis of pyrrolo isoquinoline derivatives in excellent yields was performed using the multicomponent reaction of isoquinoline, alkyl bromides, 2-hydroxyacetophenone, or its derivatives, dimethyl carbonate as a green reagent and KF/clinoptinolite nanoparticles as a catalyst in the aqueous media at 80°C. The Punica granatum peel water extract was used as the green media for the synthesis of PG-KF/clinoptilolite nanoparticles in high yield. The PG-KF/clinoptilolite nanoparticles show a significant basic catalytic role in these reactions in preparing the product in high yield and used for several times. In addition, for studying the antioxidant ability of some of the synthesized compounds, diphenyl-picrylhydrazine (DPPH) radical trapping and power of ferric reduction tests are employed. The short time of the reaction, high yields of the product, easy separation of the catalyst and products are some of the advantages of this procedure.  相似文献   
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Research on Chemical Intermediates - Acid–base copolymer materials are of considerable interest because of their fundamental implications for acid–base bifunctional catalysis...  相似文献   
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A novel biochar-based graphitic carbon nitride was prepared through calcination of Zinnia grandiflora petals and urea. To provide acidic and ionic-liquid functionalities on the prepared carbon, the resultant biochar-based graphitic carbon nitride was vinyl functionalized and polymerized with 2-acrylamido-2-methyl-1-propanesulfonic acid, acrylic acid and the as-prepared 1-vinyl-3-butylimidazolium chloride. The final catalytic system that benefits from both acidic (–COOH and –SO3H) and ionic-liquid functionalities was applied as a versatile, metal-free catalyst for promoting some model acid catalyzed reactions such as Knoevenagel condensation and Biginelli reaction in aqueous media under a very mild reaction condition. The results confirmed high activity of the catalyst. Broad substrate scope and recyclability and stability of the catalyst were other merits of the developed protocols. Comparative experiments also indicated that both acidic and ionic-liquid functionalities on the catalyst participated in the catalysis.  相似文献   
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Nano-TiO2 as an eco-friendly and efficient nanocatalyst was applied for quinoxaline preparation with improved yield.In this protocol,diketones and 1,2-diamines were condensed in the presence of catalyst at room temperature.  相似文献   
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In consideration the radiological properties of materials and studying the scattering processes in atomic and nuclear physics, the effective atomic and mass numbers is widely employed. These numbers have been calculated for any mixed or composite materials in interaction with high energy photons (Linac in radiation therapy). A pair equation in terms of these numbers is obtained. The first equation has been derived from the conservation of mass energy law and the second by minimizing the binding energy from the semiempirical mass formula (Myers and Swiatecki formula) that gives a relation between atomic and mass numbers for stable nuclei approximately. By these equations one can obtain the effective atomic and mass numbers for any compound or mixed materials uniquely. These numbers are calculated for some materials and compared with the other studies.  相似文献   
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