Search results for "Microwave irradiation"
showing 10 items of 31 documents
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).
Pyrido[2’,3’:4,5]pyrrolo[2,1-d][1,2,3,5]tetrazine-4(3H)-ones, a new class of temozolomide heteroanalogues
2009
Twelve derivatives of new ring system pyrido[2’,3’:4,5]pyrrolo[2,1-d][1,2,3,5]tetrazine were prepared in good yields by reaction of 2-diazo-3-ethoxycarbonyl-pyrrolo[3,2-b]pyridine with alkyl- or aryl-isocyanates. Nine derivatives, screened by the National Cancer Institute (Bethesda, MD) for the in vitro one dose primary anticancer assay against a panel of about 60 human tumor cell lines, showed no significant activity.
Simultaneous production of furfural and levulinic acid from pine sawdust via acid-catalysed mechanical depolymerization and microwave irradiation
2019
In this work pine sawdust was converted into levulinic acid (LA) and furfural. Sawdust was first pre-treated with sulfuric acid-catalysed mechanical depolymerization. The conversion reactions were then performed with microwave heating at 180 °C. To enhance the furfural yield and the efficient separation of furfural and LA, a biphasic water-toluene reaction system was used. The effect of an additional catalyst, AlCl3, on the yield of LA and furfural was also studied. According to the results the pre-treatment method enhanced the yields of LA. In addition, due to the microwave heating the reaction times were short. Additional AlCl3 catalyst enhanced the LA yield, however excellent furfural yi…
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…
ChemInform Abstract: Non-Conventional Methods and Media for the Activation and Manipulation of Carbon Nanoforms
2014
Very often, chemical transformations require tedious and long procedures, which, sometimes, can be avoided using alternative methods and media. New protocols, enabling us to save time and solvents, allow us also to explore new reaction profiles. This Tutorial Review focuses on the physical and chemical behavior of carbon nanoforms, CNFs (fullerenes, nanotubes, nanohorns, graphene, etc.) when non-conventional methods and techniques, such as microwave irradiation, mechano-chemistry or highly ionizing radiations are employed. In addition, the reactivity of CNFs in non-conventional media such as water, fluorinated solvents, supercritical fluids, or ionic liquids is also discussed.
Valorization of Wastewater from Table Olives: NMR Identification of Antioxidant Phenolic Fraction and Microwave Single-Phase Reaction of Sugary Fract…
2021
The table olive industry is producing a huge amount of wastewater, which is a post-processing cost and an environmental concern. The present study aims to valorize this processing by-product to obtain a value-added product, thereby enhancing resource efficiency and contributing to achieving sustainable development goals (SDGs). In this sense, a chemical reaction-based platform was developed to obtain valuable components, such as levulinic acid (LA) and 5-hydromethylfurfural (HMF). The products were then analyzed using NMR identification of the antioxidant phenolic fraction and microwave single-phase reaction of the sugary fraction. According to the results, the highest concentration of phen…
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…
Microwave-assisted, highly enantioselective addition of diethylzinc to aromatic aldehydes catalyzed by chiral aminonaphthols
2008
Abstract New optically active aminonaphthols were obtained by condensation of 2-naphthol, benzaldehyde and ( R )-(+)-1-(1-naphthyl)ethylamine or ( R )-(+)-1-(2-naphthyl)ethylamine. Their N-methylated derivatives were also synthesized. The new aminonaphthols 2 , 4 , 5 and 7 were found to catalyze the enantioselective ethylation of aryl aldehydes to 1-aryl-1-propanols (up to 92% ee). The reactions were accelerated greatly by microwave irradiation.
Brønsted and Lewis acid catalyzed conversion of pulp industry waste biomass to levulinic acid
2019
Enormous amounts of fiber sludge are generated annually by the pulp industry as a by-product. As a cellulose-rich material, its current usage, mainly as fuel, is inefficient from a material efficiency point of view. This work studied the utilization of fiber sludge from a Finnish and a Swedish pulp mill as a potential feedstock to produce levulinic acid, a valuable platform chemical. The conversion experiments of fiber sludge to levulinic acid were performed in a microwave reactor with a mixture of H2SO4 and Lewis acid as the catalyst. The reaction conditions, which included reaction time and temperature as well as the H2SO4 and Lewis acid concentrations, were studied in detail. The highest…
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…