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1.
The Diels-Alder reaction between cyclopentadiene and dienophiles in deanol derivatives containing bis(trifluoromethylsulfonyl)imide
anion as media have been studied. The effect of the substituents attached to the cation on the endo:exo selectivity as well
as the reaction yield have been evaluated in the absence and presence of Lewis acid catalyst - Y(OTf)3. Catalytic activity of metal triflates and the recycling of chosen catalytic systems have also been investigated
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2.
Magnesium-based composites of 75 wt% Mg — (10, 15, 20) wt% Mg2Ni0.7Co0.3 — (15, 10, 5) wt% C mechanically activated for 30
min under argon in a planetary mill, were obtained. Their absorption-desorption characteristics were investigated under a
pressure P = 1 MPa and temperatures of 623, 573, 473, 423 and 373 K. Desorption was carried out at 623 K and 573 K and a pressure
of 0.15 MPa. All the three composites showed improved hydriding kinetics as compared to pure magnesium. However, the desorption
temperature was somewhat higher than needed for practical application.
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3.
Nadezhda Rangelova Lachezar Radev Sanchi Nenkova Isabel M. Miranda Salvado Maria H. Vas Fernandes Michael Herzog 《Central European Journal of Chemistry》2011,9(1):112-118
Methylcellulose (MC) / SiO2 organic / inorganic hybrid materials have been prepared from MC and methyltriethoxysilane or ethyltrimethoxysilane, and characterized
by XRD, FTIR and AFM. XRD showed peak shifts. FTIR shows intermolecular hydrogen bonding between MC and SiO2. AFM depicts surface roughness which depends on the silica precursor and MC content.
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4.
5.
Iwona Binkowska Włodzimierz Gałęzowski Arnold Jarczewski 《Central European Journal of Chemistry》2010,8(3):582-586
Proton transfer reactions rates between carbon acids 1-nitro-1-(4-nitrophenyl)ethane (NPNE), 2-methyl-1-nitro-1-(4-nitrophenyl)propane
(MNPNP)) and phosphazenes (BEMP, BTPP, P1-t-Oct) in tetrahydrofuran have been measured, and the activation parameters were determined. The results are compared with
those previously obtained for P1-t-Bu phosphazene, guanidines and amidines.
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6.
Gréta Gergely Ferenc Wéber István Lukács Levente Illés Attila L. Tóth Zsolt E. Horváth Judit Mihály Csaba Balázsi 《Central European Journal of Chemistry》2010,8(2):375-381
Hydroxyapatite (HAp) was successfully produced from recycled eggshell, seashell and phosphoric acid. The phases obtained depended
on the ratio of calcined eggshell/ seashell to phosphoric acid, the calcination temperature and the mechanochemical activation
method (ball milling or attrition milling). The HAp structures were characterized by X-ray diffraction, scanning electron
microsopy and infrared spectroscopy. Attrition milling was more effective than ball milling, yielding nanosize, homogenous
and pure Hap.
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7.
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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8.
9.
Magda Milewska Katarzyna Guzow Wies?aw Wiczk 《Central European Journal of Chemistry》2010,8(3):674-686
The ability of new chelate ligands, benzoxazol-5-yl-alanine derivatives substituted in position 2 by heteroaromatic substituent,
to form complexes with selected metal ions in acetonitrile are studied by means of absorption and steady-state and time-resolved
fluorescence spectroscopy. Among the ligands studied, only azaaromatic derivatives form stable complexes with transition metal
ions in the ground state. Their absorption bands are bathochromically shifted enabling to use those ligands as ratiometric
sensors. The fluorescence of each ligand is quenched by metal ions, however, in the presence of Cd(II) and Zn(II) ions a new
red shifted emission band is observed.
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10.
The relative enthalpies of melts in the system KF - K2NbF7 were measured by drop-calorimetry at the temperatures 1058, 1140 and 1208 K as a function of composition. Heat capacities
of melted mixtures and enthalpies of mixing were determined using the experimental data. The molar heat capacity of melts
diverges slightly from additivity. The molar enthalpy of mixing of melts shows small negative deviation from ideality which
decreases with decreasing temperature. The thermal effect at mixing was assigned predominantly to association reactions producing
more complex fluoroniobate anions.
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11.
New chiral enantiopure ureas and thioureas with (R,R)-TADDOL backbone were synthesized. Bis-(thio)ureas with C2 symmetry were obtained from TADDOL iso(thio)cyanates and bifunctional
amino-(thio)ureas from TADDAMINE, respectively. These were tested for carboxylate recognition capacity and the association
constant was determined for the most stable complex.
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12.
Jorge García-Barrasa José M. López-de-Luzuriaga Miguel Monge 《Central European Journal of Chemistry》2011,9(1):7-19
Chemical methods provide an easy way to synthesize silver nanoparticles (Ag NPs) in solution. These metal nanoparticles have
a great potential for biomedical applications as an antibacterial, antifungal, and antiviral agent or in wound healing. The
adjustment of the parameters involved in these reactions permits a precise control over the size, shape, monodispersity, and
the surfaces of the nanoparticles. These nanoparticles are being used in the design of new hybrid organic-inorganic or inorganic
nanomaterials for biomedical applications.
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13.
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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14.
Azza A. Shoukry Mohamed M. Shoukry Mohamed N. Hafez 《Central European Journal of Chemistry》2010,8(4):797-805
The kinetics of base hydrolysis of glycine, histidine, and methionine methyl esters in the presence of [Pd(pip)(H2O)2]2+ complex, where pip is piperazine, is studied in aqueous solutions, at T = 25°C, and I = 0.1 mol dm−3. The rate of ester hydrolysis for glycine methyl ester is studied at different temperature and dioxane/water solutions of
different compositions. The kinetic data are fit under the assumption that the hydrolysis proceeds in one step. The activation
parameters for the base hydrolysis of the complexes are evaluated
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15.
Zhen-Yu Jiang Ji-Rong Wu Li Li Xi-Huai Chen Guo-Qiao Lai Jian-Xiong Jiang Yixin Lu Li-Wen Xu 《Central European Journal of Chemistry》2010,8(3):669-673
Lewis acid-assisted Br?nsted acid (LBA) catalysis was proposed for the iron-catalyzed Friedel-Crafts alkylation of indoles
with chalcones. This proposal was supported by the ESI-MS and cyclic voltammetry. The addition of acac to the iron-catalyzed
Friedel-Crafts alkylation of indoles with chalcones created a powerful catalytic system, which makes the alkylation reactions
occur easily under mild conditions.
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16.
Graphene multilayers have been prepared by mechanical method based on milling graphite in high efficient attritor mill. The
results showed that the best dispersion media is ethanol, and 10 hours of intensive milling proved to be the most efficient
way to separate the graphite layers as it was shown by scanning electron microscopy and X-ray diffraction measurements.
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17.
Thermodynamics and kinetics of adsorption of congo red (CR) on cellulose are studied at 308–328 K. In the used concentration
range of CR, interaction of CR with cellulose is exothermic and CR molecules adsorb chemically on cellulose surface. The effects
of contact time, temperature and initial concentration of CR on kinetics of its adsorption on cellulose were investigated.
The process proceeds according to the pseudo-second-order equation. Initial adsorption rate of adsorption is first-order in
CR and the intraparticle diffusion of CR molecules within cellulose is identified as the main rate-limiting step.
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18.
This article describes the simple hydrodehalogenation of halogenated anilines and their derivatives by the action of Raney
aluminium-nickel alloy in aqueous alkaline solution at room temperature. The reaction course was monitored by means of 1H
nuclear magnetic resonance (NMR) spectroscopy and GC-MS spectra.
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19.
Rayna Bryaskova Nelly Georgieva Dimitar Peshev 《Central European Journal of Chemistry》2010,8(5):1053-1058
Polyvinyl alcohol (PVA) and tetraethoxysilane (TEOS) hybrid materials were prepared by sol-gel methods and tested as matrices
for immobilization of Trichosporon cutaneum R57, capable of removing cadmium and copper ions from aqueous solutions. A kinetic model was applied and the effects of matrix
TEOS content on the copper and cadmium uptake equilibria and rate constants were investigated.
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20.
Sandip A. Sadaphal Kiran F. Shelke Swapnil S. Sonar Murlidhar S. Shingare 《Central European Journal of Chemistry》2008,6(4):622-626
1-benzyl-3-methyl imidazolium hydrogen sulphate [bnmim][HSO4] was found to be an effective catalyst for the condensation reaction of indoles and derivatives with benzaldehydes in microwave
irradiation with lower reaction time and higher yields to give bis(indolyl) methanes.
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