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Microwave irradiation

Tìm thấy 20+ kết quả cho từ khóa "Microwave irradiation"

Dehydration behavior and kinetics of kurnakovite under microwave irradiation

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Dehydration behavior and kinetics of kurnakovite under microwave irradiation. Abstract:In this research, the dehydration behavior of kurnakovite was studied under microwave irradiation. The kinetic parameters of the dehydration reaction were determined using different kinetic models. Kurnakovite was characterized by the techniques of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM) before and after the dehydration process.

Platinum or nickel nanoparticles decorated on silica spheres by microwave irradiation technique

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There was a significant difference in the silica material after microwave treatment and so some additional treatments after the synthesis of silica material can be applied in order to obtain much purer material. Decoration of Pt and Ni nanoparticles on the spherical silica was achieved using microwave irradiation

Boric acid as an efficient and green catalyst for the synthesis of 2-amino-4,6-diarylnicotinonitrile under microwave irradiation in solvent-free conditions

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Boric acid as an efficient and green catalyst for the synthesis of. 2-amino-4,6-diarylnicotinonitrile under microwave irradiation in solvent-free conditions. Abstract: Microwave irradiation has been used to improve the one-pot synthesis of substituted 2-amino-4,6-diarylnicoti- nonitrile in the presence of boric acid as an efficient and green catalyst under solvent-free conditions within 48–60 s.

Synthesis of tetrahydropyrimidinium salts and their in situ catalytic activities towards the Buchwald–Hartwig amination reaction under microwave irradiation

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General procedure for the Buchwald–Hartwig amination reaction under microwave irradia- tion. The Buchwald–Hartwig amination reaction under microwave irradiation was conducted in a CEM Discover apparatus.

A novel one-pot and rapid synthesis of polyfunctionalized benzo[a]pyrimido[5’,4’:5,6] pyrido[2,3-c]phenazine derivatives under microwave irradiation

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Key words: Multicomponent reactions, microwave irradiation, p -TSA, benzo[ a ]pyrimido[5’,4’:5,6]pyrido[2,3-c]phenazine.. Synthesis of benzo[ a]pyrimido[5’,4’:5,6]pyrido[2,3- c]phenazine derivatives.

Synthesis, characterization, and microwave-assisted catalytic activity in Heck, Suzuki, Sonogashira, and Buchwald–Hartwig cross-coupling reactions of novel benzimidazole salts bearing N-phthalimidoethyl and benzyl moieties

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A mixture of the benzimidazole salts (1–5), Pd(OAc) 2 , and K 2 CO 3 in DMF-H 2 O catalyzed, in high yield, the Suzuki–Miyaura and the Heck–Mizoroki cross-coupling reactions assisted by microwave irradiation in 5 min. The novel benzimidazole salts (1–5), Pd(OAc) 2 , Cs 2 CO 3 , PEG, and Cu nanoparticles catalyzed, in high yield, the Sonogashira coupling reaction promoted by microwave irradiation in 10 min.

Synthesis and exploration of catalytic activity of Fe - Mil 101 material in friedel crafts benzoylation reaction

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Experiments survey the efficiency of microwave irradiation applied to Fe-MIL-101. Microwave irradiation Conventional heating. Fe-MIL-101 material. PXRD patterns indicate the successful synthesis of Fe-MIL-101 (Figure 1). PXRD patterns of as-synthesized and activated Fe-MIL-101.. The thermal gravimetric analysis (TGA) pattern of Fe-MIL-101 was shown in Figure 2. TGA curve of Fe-MIL-101 shows that Fe-MIL-101 is thermally stable until 300 ° C.. TGA pattern of activated Fe-MIL-101.

A rapid, efficient, and green synthesis of benzo[a]chromeno[2,3-c]phenazine derivatives via microwave assistance and DABCO catalyzed a novel domino cyclization

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The design of novel MDRs using microwave irradiation for the synthesis of simple and complex bioactive heterocycles has remained a significant topic in the drug discovery process and the analysis of drugs 11,12.

Thermal conversion of glycerol to value-added chemicals: pyridine derivatives by one-pot microwave-assisted synthesis

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In this research, one-pot syntheses of monocyclic pyridine derivatives were investigated by the thermal reaction of glycerol in the presence of an ammonium salt under microwave irradiation. The main benefit of this research was a one-pot reaction in a closed system under microwave heating conditions and it was expected to prevent polymerization of both glycerol and in situ formed acrolein in the acidic medium, thus resulting in higher yields of pyridines.

Comparative study of microwave-assisted and conventional synthesis of ibuprofen-based acyl hydrazone derivatives

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In the conventional method the yields are lower compared to microwave irradiation.. The MWI power was optimized by carrying out the experiment at 50 W, 100 W, 200 W, 300 W, and 400 W for 5 min in the synthesis of 3. The results showed that the yield of product 3 was improved as the MWI power increased from 50 W to 100 W but as the MWI power increased continuously, the yield of the products decreased.

Microwave assisted, sequential two-step, one-pot synthesis of novel imidazo[1,2-a] pyrimidine containing tri/tetrasubstituted imidazole derivatives

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Firstly, the synthesis of 2-(4,5-diphenyl-1-p-tolyl-1H-imidazol-2-yl)imidazo[1,2-a]pyrimidine (3) from imidazo[1,2-a]pyrimidine-2-carbaldehyde, p-toluidine, benzil, and ammonium acetate was determined as a model reaction, and some optimization studies under microwave irradiation were carried out on it (Table 1).. 10 - 5.0 equiv. Synthesis of tri/tetrasubstituted imidazoles (1-10).. Some important HMBC correlations, 1 H NMR and 13 C NMR spectra of compound 5 were given in Figure 2.

Physicochemical, functional, antioxidant and antibacterial properties of chitosan extracted from shrimp wastes by microwave technique

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Rapid N-phthaloylation of chitosan by microwave irradiation. Effect of molecular weight and degree of deacetylation of chitosan on the formation of. Correlation between physicochemical characteristics and binding capacities of chitosan products. Microwave mediated rapid synthesis of chitosan. Growth inhibitory effect on bacteria of chitosan membranes regulated with deacety- lation degree.

Multiwall carbon nanotube-supported molybdenum catalysts for ammonia decomposition reaction under microwave effect

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They discussed that the reduction observed in the apparent enthalpy of the reaction under microwave irradiation could have been due to the additional energy being put into the carbon by means of microwaves. A specific microwave effect on the mechanism was proposed as the reason for a great change in the apparent thermodynamic of the reaction, resulting in higher conversion values at lower reaction temperatures.

The effect of temperature and concentration for methanol electrooxidation on Pt-Ru catalyst synthesized by microwave assisted route

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heating. by microwave irradiation to prepare efficient Pt@C, Ru@C, and Pt-Ru@C electrocatalysts.

Microwave-assisted synthesis and characterization of Co(II) phthalocyanine and investigation of its catalytic activity on 4-nitrophenol oxidation

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Due to the insolubility of phthalocyanines in organic and/or inorganic solvents, one of the most significant aims of research on the chemistry of phthalocyanines is to improve their solubility in various solvents. 4,5 Phthalocyanines obtained from substitution to the peripheral or nonperipheral positions of long or voluminous alkyl chains are provided in order to dissolve in common organic solvents. 8,9 On the other hand, increased attention has been focused on the application of microwave irradiation

Synthesis, cytotoxic assessment, and molecular docking studies of 2,6-diaryl-substituted pyridine and 3,4- dihydropyrimidine-2(1H)-one scaffolds

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Finally, 0.015 g of the nanocatalyst and 400 W of microwave irradiation under solvent-free conditions were obtained as the optimum conditions.. After optimization of the reaction conditions, reactions of ethyl acetoacetate with a wide range of substituted aldehydes (1a–1r) and urea were performed in the presence of CoFe 2 O 4 @silica sulfuric acid MNPs under solvent-free conditions with microwave irradiation within 3–5 min (Table 3). The yields of all of the reactions were good to excellent.

Application of guanidine and its salts in multicomponent reactions

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Guanidine can be used as catalyst and also as a reactant in the synthesis of heterocycles in conventional, microwave, or solvent-free conditions. In most cases, using a base with guanidine salts is necessary for synthesis of heterocyclic compounds. Because of the ionic structure of guanidine salts, using microwave irradiation will be suitable for synthesis of heterocylic compounds.. et al

Convenient synthesis of new polysubstituted isoindole-1,3-dione analogues

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For the synthesis of another norcantharimide derivative, the imide 5 was reacted with dichloroketene under microwave irradiation. 1 H and 13 C NMR spectroscopic data confirmed the addition of dichloroketene to the C=C bond.. We assume that the ketene approaches the C=C double bond from the less congested side to give the tricyclic compound 12, similar to the hydroxylation reaction of alcohol 7. The structure of 12 was assigned by 1 H and 13 C NMR spectra.

Synthesis of novel benzimidazole salts and microwave-assisted catalytic activity of in situ generated Pd nanoparticles from a catalyst system consisting of benzimidazol salt, Pd(OAc) 2 , and base in a Suzuki-Miyaura reaction

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There are extensive studies about the Suzuki-type C–C cross-coupling reaction incorporating microwave irradiation with high yield in a short time using various ligands other than benzimidazole moiety.

Synthesis of 5-membered heterocycles using benzoylacetonitriles as synthon

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Synthesis of benzothiazole 141 in excellent yield was achieved via microwave irradiation of a 1:1 mixture of compound 1 and o-aminothiophenol (Scheme 47). R K 2 CO 3 , EtOH, ref lux R CO 2 Et HS. CH 2 CO 2 Et (68%) Scheme 47.. 2-Alkylidene-3-phenylthiazoles were prepared as organic intermediates, useful in the synthesis of biological active substances.