Microwave Irradiation Research Papers - Academia.edu (original) (raw)
An efficient and direct procedure has been developed for the preparation of amidoalkyl naphthols by a one-pot condensation of aryl aldehydes, β-naphthol and urea or amides, in the presence of potassium dodecatungstocobaltate trihydrate... more
An efficient and direct procedure has been developed for the preparation of amidoalkyl naphthols by a one-pot condensation of aryl aldehydes, β-naphthol and urea or amides, in the presence of potassium dodecatungstocobaltate trihydrate [K5CoW12O40 · 3H2O, (1 mol%)] as a heterogeneous catalyst. The reactions were carried out in 1,2-dichloroethane at room temperature or under solvent-free media at elevated temperature. The present methodology offers several advantages such as excellent yields, simple procedure and the catalyst exhibited remarkable reusability.
Pure and doped WO3-x nanoparticles were prepared by facile microwave irradiation method and investigated for strong photocatalytic activity due to the great importance of oxygen vacancies (V0). In the present study, pure and "Fe (~3wt.%)"... more
Pure and doped WO3-x nanoparticles were prepared by facile microwave irradiation method and investigated for strong photocatalytic activity due to the great importance of oxygen vacancies (V0). In the present study, pure and "Fe (~3wt.%)" doped WO3-x nanoparticles and their crystalline nature were evaluated using powder X-ray diffraction (XRD). Bandgap analysis on W17O47 has band gap values due to the movement of oxygen vacancies. The morphological nature of the prepared products was observed by FE-SEM analysis. The observed photocatalytic behavior of the prepared compounds under visible light irradiation and the corresponding efficiency was found to be more than 50%.
A new class of modified C-nucleosides has been synthesized according to the 1,3-dipolar cycloaddition methodology. The obtained compounds are structurally related to natural pseudouridine, where the sugar moiety is replaced by an... more
A new class of modified C-nucleosides has been synthesized according to the 1,3-dipolar cycloaddition methodology. The obtained compounds are structurally related to natural pseudouridine, where the sugar moiety is replaced by an isoxazolidine ring. Different experimental conditions, and the effect of additives on the cycloaddition process, have been examined; the best results were obtained when the cycloaddition reaction was performed
Jerusalem artichoke (Helianthus tuberosus L.) tubers are industrial crop considered as a promising source for inulin production. "Green" method was performed for accelerated inulin extraction from Helianthus tuberosus L. tubers by the... more
Jerusalem artichoke (Helianthus tuberosus L.) tubers are industrial crop considered as a promising source for inulin production. "Green" method was performed for accelerated inulin extraction from Helianthus tuberosus L. tubers by the application of microwave irradiation. Further pretreatment of the water extract with acetone and ethanol yielded inulin (20%) with purity 89% and degree of polymerization 18. Jerusalem artichoke inulin was characterized by FTIR and NMR spectroscopy. For the first time eco-friendly synthesis of acetylated Jerusalem artichoke inulin was performed by the reaction with acetic anhydride, without toxic solvent, but only with sodium acetate as catalyst under microwave irradiation for 60 s. The degree of acetylation (DA=2.1) and the structure of inulin esters were confirmed by 1 H and 13 C NMR. The suggested microwave acetylation shortens significantly the esterification reaction.
Microwave-initiated synthesis of polyacrylamide-grafted sodium alginate, a graft copolymer with wide variety of applications has been reported in this study. The effect of reaction parameters (i.e., irradiation time and monomer... more
Microwave-initiated synthesis of polyacrylamide-grafted sodium alginate, a graft copolymer with wide variety of applications has been reported in this study. The effect of reaction parameters (i.e., irradiation time and monomer concentration) onto the percentage grafting has been investigated. The resulting polymer has been characterized by a variety of characterization techniques such as intrinsic viscosity measurement, Fourier transform infrared spectra, 13C NMR spectra, elemental analysis, thermogravimetric analysis, molecular weight determination using static light scattering analysis, and scanning electron micrographs. Further, the flocculation efficiency of this graft copolymer has been investigated in coal suspension. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Mg doped ZnO nanoparticles were prepared by chemical synthesis associated with microwave irradiation method. The prepared samples were characterised by XRD, FT-IR, SEM, EDAX, UV and PL methods. The X-ray diffraction pattern revealed the... more
Mg doped ZnO nanoparticles were prepared by chemical synthesis associated with microwave
irradiation method. The prepared samples were characterised by XRD, FT-IR, SEM, EDAX, UV and PL methods. The X-ray diffraction pattern revealed the prepared sample was crystalline in nature. FT-IR results help to identify the presence of functional groups in the prepared samples. The morphology and purity of samples were analysed by
Scanning Electron Microscopy (SEM) and Energy dispersion X-ray Diffraction (EDAX) analysis. The optical
properties were studied using ultra-violet spectroscopy (UV) and Photo Luminance spectroscopy (PL). The
synthesized materials will be used as catalysis for the degradation of various pollutants, gas sensors, solar cells and LED devices.
This work presents a complete method for the screening and confirmation analysis of diuretics in human urine by gas chromatography–mass spectrometry (GC–MS). The method comprises a pretreatment stage (extraction, preconcentration and... more
This work presents a complete method for the screening and confirmation analysis of diuretics in human urine by gas chromatography–mass spectrometry (GC–MS). The method comprises a pretreatment stage (extraction, preconcentration and derivatization to form the corresponding methyl derivatives) and the subsequent analysis of the derivatized extracts by GC–MS. Particularly, the derivatization stage, necessary to form the methyl derivatives of the compounds detectable by the GC–MS technique, is carried out under microwave irradiation rather than with direct thermal heating, thus reducing the incubation time from 3 h to 10 min. Microwave assisted derivatization also allowed an improvement of the limits of detection (LODs) for all the compounds here considered. The technique is particularly suitable for the rapid analysis of huge population of samples, as it is the case of urine analysis by the antidoping laboratories, and especially in all those occasions where rapid response times are requested.
A catalyst-free highly efficient synthesis of 3(5)-amino-5(3)-(het)aryl-1,2,4-triazoles in aqueous medium was performed using conventional heating and microwave irradiation. The tautomerism in the products was investigated using NMR... more
A catalyst-free highly efficient synthesis of 3(5)-amino-5(3)-(het)aryl-1,2,4-triazoles in aqueous medium was performed using conventional heating and microwave irradiation. The tautomerism in the products was investigated using NMR spectroscopy and X-ray crystallography. The effects of the substitution, temperature, solvents, and concentration on the tautomerism were studied. The triazoles were found to exist in 1H-forms, the 4H-form was not observed either in solid state or in solution. In general, 5-amino-1,2,4-triazoles were electronically preferred in the tautomeric equilibrium, but some exceptions from the established relationship were also identified.
The salient features of clays, their modified forms (pillared and 'doped' with reagents) and their application in organic synthesis are described. A wide variety of chemical reactions such as addition, isomerization,... more
The salient features of clays, their modified forms (pillared and 'doped' with reagents) and their application in organic synthesis are described. A wide variety of chemical reactions such as addition, isomerization, rearrangement, electrophilic substitution etc. are presented ...
N,N′-Pyromelliticdiimido-di-l-methionine (3) was prepared from the reaction of pyromellitic dianhydride (1) with l-methionine (2) in glacial acetic acid and pyridine solution at refluxing temperature. The direct polycondensation reaction... more
N,N′-Pyromelliticdiimido-di-l-methionine (3) was prepared from the reaction of pyromellitic dianhydride (1) with l-methionine (2) in glacial acetic acid and pyridine solution at refluxing temperature. The direct polycondensation reaction of the monomer diimide–diacid (3) with 1,3-phenylenediamine (4a), 1,4-phenylenediamine (4b), 2,6-diaminopyridine (4c), 3,5-diaminopyridine (4d), 4,4′-diaminodiphenylether (4e) and 4,4′-diaminodiphenylsulfone (4f) was carried out in a medium consisting of triphenyl phosphate, N-methyl-2-pyrolidone, pyridine and
A potassium iodide catalysed method for the selective N-monoalkylation anilines with alkylhalides and alkyltosylates under microwave irradiation is described. The corresponding N-alkylanilines are obtained in good yields with only minor... more
A potassium iodide catalysed method for the selective N-monoalkylation anilines with alkylhalides and alkyltosylates under microwave irradiation is described. The corresponding N-alkylanilines are obtained in good yields with only minor quantities of dialkylation by-products.
A series of 1,3,5-triazine derivatives that contain aniline, coumarins (4-hydroxy coumarin and 7-hydroxy-4-methyl coumarin) and different piperazine moieties as substituent on the carbon atoms of the triazine ring have been synthesized by... more
A series of 1,3,5-triazine derivatives that contain aniline, coumarins (4-hydroxy coumarin and 7-hydroxy-4-methyl coumarin) and different piperazine moieties as substituent on the carbon atoms of the triazine ring have been synthesized by a simple and efficient synthetic protocol. Comparative studies were performed on above series, which were synthesized with conventional and microwave heating methods. The microwave method was observed to be more beneficial as it provides an increase in yield and 90–95% reduction time. All the synthesized compounds were then examined for their efficacy against two Gram −ve bacteria (Escherichia coli and Pseudomonas aeruginosa), two Gram +ve bacteria (Staphylococcus aureus and Bacillus subtilis) and two fungal species (Candida albicans and Aspergillus niger) with an intent to overcome multiple drug resistance to the pathogenic strains. All the synthesized compounds were structurally elucidated by IR, 1H NMR, 13C NMR and elemental analysis.