نتایج جستجو برای: microwave synthesis
تعداد نتایج: 455524 فیلتر نتایج به سال:
substituted 2, 4- diphenyl quinolines were synthesized by a multicomponent domino reaction of anilines, aldehydes and terminal aryl alkynes. the synthetic pathway involves the formation of an imine, followed by the intermolecular addition of an alkyne to the imine. this intermediate immediately undergoes ring closure and oxidative aromatization. the reaction is catalyzed by natural kaolin, a st...
The present paper describes studies on the synthesis of the antiepileptic drug phenytoin, and of structurally related derivatives. First, the influence of the solvent has been investigated in the microwave-assisted synthesis of the drug, resulting in a yield improvement and a cleaner reaction. Second, a two-step reaction is described to synthesize selectively and in high yields phenytoin. The f...
Engineering students in a one-semester organic chemistry laboratory course prepared biodiesel by using either microwave or conventional heating in a discovery-based experiment. The laboratory design was to show improvement in student awareness about the use of microwave heating in organic synthesis in general, and specifically in the preparation of biodiesel. The students were polled before and...
Microwave irradiation has been successfully applied in organic chemistry. Spectacular accelerations, higher yields under milder reaction conditions and higher product purities have all been reported. Indeed, a number of authors have described success in reactions that do not occur by conventional heating and even modifications of selectivity (chemo-, regio- and stereoselectivity). The effect of...
Microwave-assisted synthesis and antioxidant properties of hydrazinyl thiazolyl coumarin derivatives
UNLABELLED BACKGROUND Coumarin derivatives exhibit a wide range of biological properties including promising antioxidant activity. Furthermore, microwave-assisted organic synthesis has delivered rapid routes to N- and O-containing heterocycles, including coumarins and thiazoles. Combining these features, the use of microwave-assisted processes will provide rapid access to a targeted coumarin...
While microwave enhancement of chemical syntheses has been demonstrated for a broad variety of chemical reactions, there is no accepted universal mechanism. Is the enhancement due to more efficient heating, to overheating, to nonuniform heating, or to nonthermal effects? Analyses are complicated due to the often significant spatial and temporal temperature variations in microwave reactor system...
We have previously developed water-based microwave (MW)-assisted peptide synthesis using Fmoc-amino acid nanopaticles. It is an organic solvent-free, environmentally friendly method for peptide synthesis. Here we describe water-based MW-assisted solid-phase synthesis using Boc-amino acid nanoparticles. The microwave irradiation allowed rapid solid-phase reaction of nanoparticle reactants on the...
In recent years, microwave irradiation using commercial domestic ovens for the optimization and acceleration of organic reactions has rapidly increased1−2.It has been reported that a variety of reactions such as Dielsalder , ene, Claisen reactions , Fischer cyclization, synthesis of heterocycles , hydrolysis of esters , hydrogenation, deprotection of benzyl ester, deacetylation of diacetates, o...
An efficient and rapid method for the synthesis of 3,4,5-substituted furan-2 (5H)-ones has been achieved through a three-component reaction of aniline, dialkyl acetylenedicarboxylate, and aromatic aldehydes using nano-colloidal silica-tethered polyhedral oligomeric silsesquioxanes with eight branches of 3-aminopropyltriethoxysilane (nano-colloidal silica @APTPOSS) as a superior catalyst under m...
A continuous flow reactor equipped with a low-loss flow channel and a microwave cavity was developed for synthesizing nanophosphors. A continuous solution synthesis of YVO4:Eu,Bi nanophosphor was succeeded through the rapid hydrothermal method using this equipment. Internal quantum efficiency of YVO4:Eu,Bi nanophosphor obtained by 20 minutes microwave heating is about 30% at 320 nm as high as t...
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