نتایج جستجو برای: acidic catalyst
تعداد نتایج: 77393 فیلتر نتایج به سال:
Fructose can be efficiently converted to 5-hydroxymethylfurfural by using the functionalized ionic liquid 3-(2-chloroethyl)-1-methylimidazolium chloride as both solvent and catalyst in the presence of water. This work advances the field and is distinct from earlier efforts in the sense that the observed yields of HMF from fructose are rather high and the reaction conditions rather mild and neut...
Oxidative coupling of methylamines with an aminyl radical to construct amides was developed in the presence of an I2/TBHP catalyst under acidic conditions via the two cleavages of the sp(3) C-N bond of aryl-methylamines and the sp(2) C-N bond of N-substituted formamides respectively. This transition-metal-free protocol provides a novel synthetic tool for the construction of N-substituted amides...
Single-walled carbon nanotubes (SWNTs) were synthesized by disproportionation of carbon monoxide on an aerogel-supported Fe/Mo catalyst. A simple acidic treatment followed by an oxidation process produced a high purity (> 99%) of SWNTs. The nanotubes obtained are bundled SWNTs and free of amorphous-carbon coating. Several factors that affect the yield and the quality of the SWNTs were also stud...
The combinations of 1-butyl-3-methylimidazolium chloride with NbCl5 yielded ionic mixtures with different melting point temperatures and acidity depending on the niobium molar fraction. The mixtures were characterized by thermal (DSC) and spectroscopic (FT-IR and H NMR) analysis. The Pechmann reactions of different phenols with ethylacetoacetate, producing coumarins, was used as model to evalua...
Schiff bases are aldehyde or ketone like compounds in which the carbonyl group is replaced by an imine or azomethine group. They are widely used for industrial purposes and also exhibit a broad range of biological activities. The reaction is acid catalysed, however only aldehydes and ketones which do not aldolize easily in acidic media, can be condensed with amines in presence of strong acid ca...
An efficient procedure has been researched for the solvent-free synthesis of bis(indolyl)methanes via a one-pot reaction of indoles and aldehydes or ketones promoted by PEG1000-based dicationic acidic ionic liquid (PEG1000-DAIL). The catalyst PEG1000-DAIL could be reused seven times with excellent results. Furthermore, through this method, a highly chemoselective reaction of benzaldehyde and ac...
An effective chiral Lewis acid-catalyzed asymmetric Baylis-Hillman reaction is described. Good to high enantioselectivities were obtained using 3 mol % chiral catalyst. Novel camphor-derived dimerized ligands were prepared from the condensation of (+)-ketopinic acid with the corresponding diamines and hydrazine under acidic conditions. When alpha-naphthyl acrylate was used as a Michael acceptor...
In this paper, we introduce Brønsted acidic ionic liquid (BAIL), (4-sulfobutyl) tris (4-sulfophenyl) phosphonium hydrogen sulfate as a green and efficient catalyst for the synthesis of 2,3-disubstituted quinoxaline derivatives via the one-pot condensation reaction of various o-phenylenediamine with 1,2-diketone derivatives. At all experiments, the desired products were synthesized successfully....
Diaryl sulfoxides are synthesized from aryl benzyl sulfoxides and aryl chlorides via three sequential catalytic cycles all promoted by a NiXantPhos-based palladium catalyst. The key step is S-arylation of a sulfenate anion. An air- and moisture-stable precatalyst derived from NiXantPhos efficiently facilitates the transformation. Various functional groups, including those with acidic protons, w...
The first catalytic asymmetric Fischer indolization is reported. In the presence of a 5 mol % loading of a novel spirocyclic chiral phosphoric acid, 4-substituted cyclohexanone-derived phenylhydrazones undergo a highly enantioselective indolization. Efficient catalyst turnover was achieved by the addition of a weakly acidic cation exchange resin, which removes the generated ammonia. The reactio...
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