Search results for "microwave irradiation"
showing 10 items of 31 documents
Microwave-Assisted Synthesis of Polysubstituted 4-Quinolones from Deprotonated α-Aminonitriles
2010
The α-alkylation of deprotonated N-aryl-α-aminonitriles with α-bromoesters furnishes intermediates that can be cyclized to 4-quinolones upon microwave irradiation. Alternatively, base-induced dehydrocyanation of the alkylation products furnishes enaminoesters, which can, for example, be converted into quinoline-3-carboxylates.
A novel synthetic approach to pyran-2,4-dione scaffold production: Microwave-assisted dimerization, cyclization, and expeditious regioselective conve…
2020
Abstract Here, we report a novel, green, simple, low-cost, and rapid methodology for the high-yield production of pyran-2,4-dione scaffolds under microwave irradiation. Regio- and stereoselective conversions of β-diketone systems into β-enaminones were achieved using 18 primary amines and four amino acid esters. Microwave-assisted further cyclization of 3-(β-substitutedvinyl)-6-phenyl-pyran-2,4-dione into 3-benzoyl-4,7-diphenyl-2H,5H-pyrano[4,3-b]pyran-2,5-dione via reaction with ethyl benzoyl acetate.
Microwave effects on germination and growth of radish (Raphanus sativus L.) seedlings
2002
Germination of radish seeds was delayed and reduced by low-power microwave exposure at 10.5 and 12.5 GHz. Irradiation decreased also hypocotyl growth rate. These effects were increased by rising of the microwave power and by the vertically polarised electromagnetic field. When the irradiation was suspended the seedling growth recovered.
Development of novel 1,4-benzodiazepine-based Michael acceptors as antitrypanosomal agents
2016
Novel 1,4-benzodiazepines, endowed with a Michael acceptor moiety, were designed taking advantage of a computational prediction of their pharmacokinetic parameters. Among all the synthesized derivatives, we identified a new lead compound (i.e., 4a), bearing a vinyl ketone warhead and endowed with a promising antitrypanosomal activity against Trypanosoma brucei brucei (IC50 = 5.29 µM), coupled with a lack of cytotoxicity towards mammalian cells (TC50>100 µM).
ChemInform Abstract: Green Conditions for the Suzuki Reaction Using Microwave Irradiation and a New HNT-Supported Ionic Liquid-Like Phase (HNT-SILLP)…
2014
Aryl iodides are coupled with conversions comparable to aryl bromides whereas conversions of aryl chlorides are significantly lower.
Nonadiabatic dynamics in strongly driven diffusive Josephson junctions
2019
By measuring the Josephson emission of a diffusive Superconductor-Normal metal-Superconductor (SNS) junction at a finite temperature we reveal a non-trivial sensitivity of the supercurrent to microwave irradiation. We demonstrate that the harmonic content of the current-phase relation is modified due to the energy redistribution of quasiparticles in the normal wire induced by the electromagnetic field. The distortion originates from the phase-dependent out-of-equilibrium distribution function which is strongly affected by the ac-response of the spectral supercurrent. For phases close to $\pi$, transitions accross the Andreev gap are dynamically favored leading to a supercurrent reduction. T…
Studies on Instabilities and Patterns in Evaporating Liquids at Reduced Pressure and/or Microwave Irradiation
1990
This paper summarizes our recent experimental and theoretical work on the instabilities in liquids and at interfaces which form during evaporation at reduced pressure and/or microwave irradiation. We have observed a variety of patterns (Benard rolls, Marangoni waves, Hickman interface deformations) which depend on the value of the reduced pressure and the power of the incident beam.
Caracterización de barita cubana y su reducción carbotérmica en horno de microondas
2007
The Cuban Barite (BaSO4) is characterized by X ray diffraction, chemical analysis and scanning electron microscopy. The principal components are identified and its characteristic morphology is shown. Its carbothermic reduction under microwave irradiation is carried out with the purpose of to improve the yield of this stage during the mineral transformation process in reagent of barium of diverse applications. La barita cubana (BaSO4) se ha caracterizado por difracción de rayos X, análisis químico y microscopía electrónica de barrido. Se han identificado sus componentes mayoritarios y así mismo se muestra su morfología característica. Se ha realizado su reducción carbotérmica en horno de mic…
The Essential Oil Composition ofEryngium foetidumL. in South Vietnam Extracted by Hydrodistillation under Conventional Heating and Microwave Irradiat…
2008
Abstract Essential oils of Eryngium foetidum L. (Apiaceae) in the South Vietnam isolated by hydrodistillation under conventional heating or microwave irradiation showed somewhat similar in chemical compositions. The microwave method gave a higher extraction yield in a much shorter time frame than the conventional heating protocol. Noticeably, the oil obtained from the microwave method showed a stronger antimicrobial activity than the other. Among all parts of the plant, inflorescence contained the highest oil content, and three-month old plant material was found richest in oil content as well. Physical, chemical and antibacterial properties of the oil products isolated from both methods wer…
Preparation of Catalysts and Photocatalysts Used for Similar Processes
2019
Abstract This chapter reports the main techniques used to synthesize powders and films of heterogeneous catalysts and photocatalysts, often used for similar processes. Traditional preparation processes of bulky (photo)catalysts including precipitation, sol–gel technique, hydrothermal or solvothermal method, solid-state reactions, and flame syntheses were briefly described. The sonochemical method and microwave irradiation technique were also considered. The syntheses of supported catalysts by different techniques, including deposition–precipitation, impregnation, and wet coating technologies were also described. Moreover, a survey is reported of methods to deposit thin films of catalysts on…