نتایج جستجو برای: reusability of the catalyst
تعداد نتایج: 22795218 فیلتر نتایج به سال:
data envelopment analysis (dea) is a powerful tool for measuring relative efficiency of organizational units referred to as decision making units (dmus). in most cases dmus have network structures with internal linking activities. traditional dea models, however, consider dmus as black boxes with no regard to their linking activities and therefore do not provide decision makers with the reasons...
A new efficient method for the synthesis of 2,3-dihydroquinazolin-4(1H)-ones and spiroquinazolinones via a condensation reaction of aldehydes and ketones with anthranilamide in the presence of nano Fe3O4@SiO2-SO3H as catalyst in ethanol has been described. The reactions are completed in short times, and the corresponding dihydroquinazolinones are produced with high yields. The present procedure...
An efficient, mild and environmentally friendly method was reported for the synthesis of An efficient, mild and environmentally friendly method was reported for the synthesis of pyranopyroles from aryl aldehydes, ethyl acetoacetate, malononitrile and hydrazine hydrate in the presence of catalytic amounts of Methyl imidazolium hydrogen sulfate ([Hmim][HSO4]) as an efficient catalyst. These synth...
in the name of allah , the compassionate the merciful abstract shath ( blasphemic utterace made during spiritual ) is a complicated concept that deserves reflection in gnosticism and sufism ( mysticism ) and estem and westem scholars have alwaya paid attention to it. although principal essence of gnostic belief is the holy divine law ,gnosticism has pure and unique thoughts . by glancing at t...
Synthesis of imidazo[1,2-a]pyridines over several solid supported catalysts has been investigated. Among these catalysts, ZnCl2 .SiO2 (silzic) showed excellent yields and short reaction times. The silzic catalyst could be recovered and reused in five reaction cycles. The present procedure offers several advantages such as short reaction time, simplicity of the reaction procedure, the eliminatio...
Nano TiO2 supported on SiO2 (Nano TiO2@SiO2) as a solid Lewis acid, was described to be an effective and reusable catalyst for one-pot three-component reaction of benzil, aryl aldehydes and ammonium acetate for the synthesis 2-aryl-4,5-diphenyl-1H-imdazoles synthesis. To explore the high efficacy of the catalytic system the four-component cyclization of benzil, aryl aldehydes, ammonium acetate ...
A simple and green synthetic strategy to prepare BaO/TiO2-ZrO2 as a solid base catalyst was reported. These materials with various amounts of BaO were prepared by the adsorption method. The physical and chemical properties of BaO/TiO2-ZrO2 were investigated by X-ray diffraction, X-ray fluorescence, specific surface area and BJH pore size distribution, FT-IR spectroscopy, scanning electron micro...
a simple and mild one-pot three-component reaction for the preparation 1,4-dihydropyridines has been developed from various aldehyde substrates, 1,3-dicarbonyl compounds (dimedone) and ammonium acetate (hantzsch method) in the presence of a catalytic amount of phospho sulfonic acid (psa) as an efficient and heterogeneous solid acid in etoh at room temperature. preparation of psa is straightforw...
any change in the refractive index of a laser active medium can lead to serious degradation of beam quality, laser beam modes, laser performance and variation in the intensity distribution. alteration in the refractive index of laser active medium is especially notable in high power lasers. it is clear that in the laser beam production, the pumping agent induces a great amount of heat which...
A new catalyst was prepared by promoting fly ash with hydrogen peroxide. The catalytic activity of H2O2 promoted fly ash (HPFA) was evaluated by synthesis 5(4H)-oxazolone and imidazolone derivatives under solvent free conditions. The possible mechanisms of synthesis reactions were also suggested. These proposed methods benefit in terms of low-cost catalyst, high yields, ease of workup, survival...
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