نتایج جستجو برای: acidic solvents
تعداد نتایج: 78820 فیلتر نتایج به سال:
The oxidation of n-pentanol by tetramethylammonium fluorochromate in acidic solution wasstudied using spectrophotometric technique. The reaction was arranged to be under pseudo firstorderconditions respect to the oxidant. A Michaelis-Menten type kinetic was observed respect tothe substrate. The reaction is catalyzed by hydrogen ions. Dependences of the reaction rates ontemperature and different...
Synthesis of amphiphilic, cyclic di- and tetrasaccharides, which incorporate a methylene moiety at the inter-glycosidic bond, is reported. The amphiphilic properties of the new cyclic tetrasaccharide host were identified through assessing the solubilities of guests in aqueous and in organic solvents. The glycosidic bond stability of the cyclic tetrasaccharide under aqueous acidic condition was ...
In this work, we describe the synthesis of a novel 9-aminoacridine derivative that presents surprisingly different colors when exposed to neutral, acidic or basic mediums with potential application as pH indicator in organic solvents. Furthermore, pKa and molar absorptivity values were determined and theoretical studies supported by density functional theory (DFT) calculations were performed to...
In an inorganic material, a measure of the Lewis basicity of a solvent is commonly provided by the optical basicity, i.e. the ability of the solvent molecules to donate their electrons to an acidic species. This quantity is known to vary with the polarizability of the Lewis base. In protic solvents, the Lewis definition of basicity is barely used; it is replaced by the more purpose-built Brønst...
The change of distance between individual graphene oxide sheets due to swelling is the key parameter to explain and predict permeation of multilayered graphene oxide (GO) membranes by various solvents and solutions. In situ synchrotron X-ray diffraction study shows that swelling properties of GO membranes are distinctly different compared to precursor graphite oxide powder samples. Intercalatio...
Phenolic extract of leaves of Basilicum polystachyon (L) Moench was tested for in vitro antimicrobial activity against five bacteria (Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus subtilis, Micrococcus leuteus) and three fungi (Fusarium oxysporum, Aspergillus niger, Helminthosporium oryzae). Efficacy of organic solvents, methanol and ethanol, as agents for extraction...
Refluxing a slightly acidic /?-BuOH solution of RhCKPPh,), and 2-chloro-, 2,4-dichloro-, or 2,4,6-trichloroazobenzene affords cyclometalated complexes (1) via loss of one phosphine ligand and oxidative addition of the ortho -C-Cl bond. X-ray structural analysis indicates a frcws-position of the two triphenylphosphine ligands. The reaction proceeds only in polar solvents like alcohols or dimethy...
H and C nuclear magnetic resonance (NMR) spectra were recorded at 400 MHz on a Bruker ARX-400 NMR spectrometer (Germany) with tetramethylsilane as internal standard. Column chromatography was performed using Merck (Germany) silica gel (230-400 mesh). Thin layer chromatography (TLC) was performed using Merck silica gel GF254, 0.25 mm thickness. For visualization, TLC plates were placed under aci...
We report here an efficient and green method for Biginelli condensation reaction of aldehydes, β-ketoesters and urea or thiourea catalyzed by Brønsted acidic ionic liquid [Btto][p-TSA] under solvent-free conditions. Compared to the classical Biginelli reaction conditions, the present method has the advantages of giving good yields, short reaction times, near room temperature conditions and the ...
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