共查询到20条相似文献,搜索用时 46 毫秒
1.
Lakshman S. Gadekar Shivshankar R. Mane Santosh S. Katkar Balasaheb R. Arbad Machhindra K. Lande 《Central European Journal of Chemistry》2009,7(3):550-554
Natural scolecite has been found as an effective catalyst for the one-pot synthesis of 2,4,5-triarylimidazole derivatives
via a three component reaction using benzil or benzoin, aldehydes and ammonium acetate. This method provides several advantages
such as being environmentally benign, reusable, possessing high yields with increased variations of the substituents in the
product and preparative simplicity.
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2.
Phase equilibria established in the PbO - BiVO4 system over the whole component concentration range up to 1000°C have been investigated. A phase diagram has been constructed
using DTA and XRD.
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3.
Vivek Srivastava 《Central European Journal of Chemistry》2010,8(2):269-272
Sulphonimide based organocatalyst was used to catalyze the aldol reaction in ionic liquid media. On the basis of yield and
selectivity the ionic liquid mediated system was found superior in comparison with organic solvents. The added advantages
of this ionic liquid mediated organocatalysis are easy recovery of product and the recyclability of the organocatalyst.
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4.
5.
Eugenia D. Teodor Simona C. Liţescu Antonela Neacşu Georgiana Truică Camelia Albu 《Central European Journal of Chemistry》2009,7(3):560-568
The study aims to establish several definite criteria which will differentiate Romanian amber and Baltic amber to certify
the local or Baltic origin of the materials found in archaeological sites on the Romanian territory, by using light microscopy
and performing analytical methods, such as Fourier transform infrared spectroscopy-variable angle reflectance and liquid chromatography
with mass spectrometry detection. Experiments especially by Fourier transformed infrared spectroscopy, were applied to a wide
range of samples with controlled origin. The methods were optimised and resulted in premises to apply the techniques to analysis
of the archaeological material.
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6.
Nitin A. Mirgane Sandip B. Kotwal Anil V. Karnik 《Central European Journal of Chemistry》2010,8(2):356-360
Ionic liquids (IL) are gaining importance as green solvents. Imidazolium ionic liquid [bmim]+[Cl]−, an environmentally benign solvent, was found to promote the Diels-Alder reaction between anthrone and maleimides at room
temperature with excellent yields. The ionic liquid played a dual role as solvent and catalyst.
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7.
Tuula Kylmälä Jan Tois Youjun Xu Robert Franzén 《Central European Journal of Chemistry》2009,7(4):818-826
Diflunisal and Felbinac, two FDA-approved NSAIDs and other biphenyl carboxylic acids were prepared in one step by a simple
and clean Suzuki cross-coupling reaction using an easily synthesized, air and moisture stable, palladium-diamine complex.
The yield (93%) for the one-step preparation of Diflunisal is the best reported without using a glovebox and a phoshine-based
catalyst.
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8.
The oxidation processes of 2,6-diisopropylnaphthalene and 4,4′-diisopropylbiphenyl with oxygen in the presence of a catalyst,
composed of copper(II) chloride and tetrabutylammonium bromide, were investigated. It was found that, in essence, only one
isopropyl group undergoes oxidation, and obtained mixtures contained mainly peroxide, alcohol, ketone and only small amounts
of hydroperoxide.
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9.
Chiral aminosulfonamides containing imidazolium group were used as ligands for the ruthenium(II)-catalyzed asymmetric transfer
hydrogenation of prochiral ketones in ionic liquid, affording good to excellent conversions and enantiomeric excesses. The
catalytic system could be easily recovered and reused several times.
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10.
Octavian Staicu Domnina Razus Valentin Munteanu Dumitru Oancea 《Central European Journal of Chemistry》2009,7(3):478-485
The heterogeneous catalytic ignition of lean to stoichiometric n-butane/air mixtures were studied at various total pressures
between 10 and 100 kPa and at temperatures equal to or larger than the critical ignition temperatures. The induction periods,
ignition and extinction temperatures were measured under strict isothermal conditions. The discussion presented in this paper
is based on several literature models. The data analysis allowed for the determination of the overall kinetic parameters.
The rigorous isothermal conditions indicated that the extinction temperatures are lower than the ignition, a behavior different
from the results obtained in stagnation-point flow reactors.
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11.
A novel hydroxyamino phosphane was synthesised through the reaction of 2-imidazolidinone with ClPPh2 and subsequently reaction
of the resulting bisphosphino derivative with the Grignard reagent BrMgC5H11. The interaction of the pentyl substituent with one of the two phosphino groups and the structure in solution is shown by
multinuclear NMR-spectroscopy..
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12.
Bingcheng Yang Feifang Zhang Xinmiao Liang 《Central European Journal of Chemistry》2012,10(3):472-479
This review summarizes the development of capillary ion chromatography (CIC) over approximately the last 5 years. It mainly
focuses on the technologic aspects of several key components associated with CIC, including micropump, microscale electrodialytic
eluent generator, microscale suppressor and the detector.
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13.
Ghasem Rezanejade Bardajee Farnaz Jafarpour Hamid Samareh Afsari 《Central European Journal of Chemistry》2010,8(2):370-374
In this report, a rapid, efficient and environmental friendly synthesis of 3-carboxycoumarins under ultrasound irradiation
in water media is described. The Knoevenagel condensation of Meldrum’s acid with substituted benzaldehydes in the presence
of zirconium oxide chloride (ZrOCl2·8H2O) and ultrasonic irradiation in water gave the corresponding 3-carboxycoumarins in good to excellent yields.
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14.
Renata Farkas Mercedesz Törincsi Pal Kolonits Jenö Fekete Oscar Jimenez Alonso Lajos Novak 《Central European Journal of Chemistry》2010,8(2):300-307
During the diazo-coupling reaction, nucleophilic displacement of a nitro group was also observed. This was the main reaction
(1→7) when the starting amine bore either a chlorine or methoxy group at the para position (1b–c). The newly prepared compounds (7) might serve as convenient building blocks in synthesis of some heterocycles.
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15.
Kateřina Vítková Markéta Pechová Jan Petr Joanna Znaleziona Václav Ranc Vítězslav Maier Juraj Ševčík 《Central European Journal of Chemistry》2010,8(2):273-277
A method for the fast determination of yohimbine, a potent adrenoreceptor antagonist used for the treatment of sexual dysfunctions,
is proposed in this article. MEKC under basic and acidic conditions (sodium borate, pH 9.5 and sodium phosphate, pH 2.5) with
SDS was developed. The effect of the experimental parameters, e.g. pH, SDS concentration and injection time, on yohimbine
migration was also studied. Both methods were validated in terms of linearity, limits of detection and quantification, accuracy,
and precision using caffeine as an internal standard. The application for the determination of yohimbine in hand-made medicaments
is also investigated in this study.
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16.
The reaction mechanism between AlX and HX (X = Br, Cl, and F) have been characterized in detail using DFT as well as the ab initio method. The reaction yielding AlX3 and molecular hydrogen was calculated to be highly exothermic. The present calculations also show that the possible routes
to the trihalides species start more favorable with the primary insertion product AlX2H than with the biadduct AlX(HX)2 one.
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17.
Dmytro A. Tykhanov Irina I. Serikova Fedor G. Yaremenko Alexander D. Roshal 《Central European Journal of Chemistry》2010,8(2):347-355
The 1H-NMR and quantum chemical analysis of the stability of tautomers of cinnamoyl pyrone derivatives and vinylogs has been studied.
The relationship between the structure of the most stable tautomer and its spectral properties has been investigated. It has
been determined that the tautomer of highest stability (88–100 molar %) has an α-pyrone structure and exhibits a trans-conformation
in the cinnamoyl fragment. An intense fluorescence of dyes has been observed in non-polar solvents with cinnamoyl fragments
having electron-donating substituents or several double bonds in the polymethine chain. A gradient in solvent polarity resulted
in fluorescence quenching which permits the use of the dyes as intensometric fluorometric probes for medium polarity examination.
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18.
Francis E. Appoh Marcy J. Manning Teri J. Gullon Margaret A. Hansen Emily C. Bevans Krista D. M. Hogan Courtney S. Turner Christopher M. Vogels Andreas Decken Stephen A. Westcott 《Central European Journal of Chemistry》2008,6(3):359-364
The Ugi reaction with formylphenylboronic acid derivatives as the carbonyl component proceeds to give the corresponding boron-containing
dipeptide derivatives (Ugi products) in good yields.
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19.
Ardeshir Shokrollahi Mojtaba Shamsipur Fahimeh Jalali Hamid Nomani 《Central European Journal of Chemistry》2009,7(4):938-944
A simple, sensitive and selective flotation method is described for the preconcentration and atomic absorption spectrometric
determination of zinc ion in water and blood samples. At a solution pH of 5.2, 4-(2-pyridylazo-resorcinol) and Triton X-114
were used as hydrophobic ligand and non-ionic surfactant, respectively. The chemical variables affecting the preconcentration
process were optimized. Under the optimized experimental conditions, the selective preconcentration and determination of as
low zinc concentration as 6.5 μg L−1 can be made. The proposed method was successfully applied to the preconcentration and low-level determination of zinc in
different water and blood serum samples.
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20.
Rodica Buhaceanu Ioan Sarghie Adriana Barsanescu Viorica Dulman Ioan Bunia 《Central European Journal of Chemistry》2009,7(4):827-835
The sorption capacity of three weak base ion exchangers based on acrylic copolymers functionalized with ethylenediamine, triethylenetetramine
and N, N- dimethylamino propylamine for Ag(I) ions was evaluated. Adsorption experiments were carried out by batch method.
The effect of pH, crosslinking degree of copolymers, amount of sorbent, initial ion concentration, contact time and temperature
was studied. The parameters which characterize the retention process were estimated using Langmuir and Freundlich isotherm
models, the best fitting being for the first model. Kinetic data were fitted to pseudo-first order, pseudo-second order and
intraparticle diffusion models. Experimental data were in good agreement with the pseudo second order.
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