جستجوی مقالات مرتبط با کلیدواژه « واکنش چند جزئی » در نشریات گروه « شیمی »

The maim elements of chromite ore were deduced by X-ray fluorescence (XRF) after collection and grinding. The presence of irregular designs in the form of cavities with size of 50 to 200 micrometers and sometimes nanometers in the structure of this catalyst using solid surface morphology with SEM and TEM electron micrograph scanning was confirmed. In a one-pot three component reaction of diver's aromatic aldehydes, barbituric acid and urea or thiourea, pyrimidopyrimidine (5 , 6 –dihydro – 5 – aryl pyrimido [4 , 5 - d] pyrimidine – 2 , 4 , 7 (1H , 3H , 8H ) - trione) heterocyclic products were prepared in the presence of chromite ore as natural catalyst. There was no need for the column purification of the products in these reactions. Moreover, this methodology offered several advantages such as good yields, simple procedure and simple purification steps. Using water as solvent made the process environmentally and economically benign.

In the present study, with the knowledge of the properties and advantages of various nano-porous materials, nanoparticles of manganese oxide (II) were exchanged on the zeolite-Y surface (covalent bond) and its structure was characterized by using various techniques such as FT-IR, XRD, BET, FESEM, and EDX analyses. In the following, the manganese oxide/zeolite (MnO2@zeolite-Y) as a green active nanocatalyst for the synthesis of ethyl 2-((1H-benzo[d]imidazole-2-ylamine)(ariyl)methylthio) acetate were used via a one-pot multicomponent reaction of aryl aldehydes, 2-amino benzimidazole, and ethyl 2-mercaptoacetate in a water-ethanol solvent and room temperature. This catalytic method has many advantages, such as the use of non-toxic, low-cost, available, and recyclable acidic nanocatalyst (Lewis), the short reaction time, the ease of separating pure products, the use of green solvents, and mild conditions. The present method also promises that in the future it can be used as a convenient synthetic route for the preparation of new sulfur-bearing peptide derivatives based on 2-amino benzimidazole core under moderate conditions.

In this work, facile and efficient procedures were described for the synthesis of 4,7-dihydro[1,2,4]triazolo[1,5-a]pyrimidine-6-carboxamides via three-component reaction of aryl aldehyde, acetoacetanilide and 3-amino-1,2,4-triazole. The reactions were performed using p-toluenesulfonic acid monohydrate in refluxing EtOH or trityl chloride under solvent-free conditions at 80 ºC. Comparison of the results shows that both organic catalysts are effective for the synthesis of these fused heterocyclic compounds. Some advantages of these methods are short reaction times, good to excellent yields and easy to operate. Additionally, all products were obtained through simple filtration and no need for column chromatography or tedious work-up, which is an important factor to reduce environmental pollutions.

A simple, efficient one-pot three-component reaction of alkyl isocyanides, acetylenic esters, and hydrazones proceeded at dichloromethane at room temperature afford as highly functionalized ketenimines. The reaction between benzaldehyde derivatives with isatin or benzhydrazide provides hydrazones in good to excellent yields. 1,3-Dipolar intermediates result from alkyl isocyanides to acetylenic esters in the presence of acidic proton, for example, hydrazones proceeded at ketenimines. The functionalized ketenimines caused a suitable substrate for organic compounds. The present procedure carries the advantage that not only is the reaction performed under neutral conditions, but also the substances can be mixed without any activation or catalyst.

Catalysts in chemical reactions improve the reaction conditions, increase the speed and yield of the products. So, they play a prominent role in various industries such as the chemical industry, petroleum industry, and pharmaceutical chemistry. In this work, an efficient and co-friendly method for the synthesis of 1,2,4,5-tetrasubstituted imidazoles via a four-component condensation of benzil, aldehydes, primary amines and ammonium acetate in the presence of a magnetic nanocatalyst, ZnS-ZnFe2O4, in ethanol under refluxing conditions is presented. Magnetic ZnS-ZnFe2O4 was prepared via a simple method and characterized by energy-dispersive X-ray analysis (EDAX), field-emission scanning electron microscopy (FESEM), X-Ray diffraction pattern (XRD) and vibrating sample magnetometer (VSM). This protocol has advantages such as high yields of the products, use of a green solvent, simple and chromatography-free work-up procedure. Most importantly, the catalyst can be conveniently recovered from the reaction mixture by using external magnet and reused for at least three times without significant decrease in catalytic activity.

 In this research paper, a simple, efficient and green procedure was reported for the one pot preparation of 2,3-dihydroquinazoline-4(1H)-one derivatives using silicotungstic acid as catalyst. Hydroquinazolinone derivatives can obtained from condensation of isatoic anhydride, aromatic aldehydes and ammonium acetate in good yields. The reaction completed at 100 oC within 10-15 min with yields of 88-94%. Shorter reaction times and higher yields were chieved under under solvent-free conditions.