共查询到20条相似文献,搜索用时 15 毫秒
1.
Andris Zicmanis Galina Vavilina Svetlana Drozdova Peteris Mekss Maris Klavins 《Central European Journal of Chemistry》2007,5(1):156-168
Alkylation of indole salts in different ionic liquids is reported. Ionic liquids increase the alkylation reaction rate of
ambident indole anion and reduce the effects of counter ions and/or additives, the alkylation reaction rates being independent
of the presence of small amounts of protic solvents or water.
相似文献
2.
Hadi M. Marwani 《Central European Journal of Chemistry》2010,8(4):946-952
In this study, spectroscopic investigation of chiral and achiral room temperature ionic liquids is achieved. New ionic liquids
were prepared via metathesis, accomplished by the reaction of either L-phenylalanine ethyl ester hydrochloride, chlorpromazine hydrochloride
or 1,10-Phenanthroline monohydrate hydrochloride with lithium bis(trifluoromethane) sulfonamide in water. The resulting ionic
liquids were produced in high yield and purity. The results obtained by use of 1H NMR and IR experiments were in very good agreement with the chemical structures of the synthesized ionic liquids. In addition,
the results of thermal gravimetric analysis suggested that these ionic liquids have good thermal stability. UV-Vis and fluorescence
spectroscopy measurements indicated that these ionic liquids are strongly optically absorbent and fluorescent. Lastly, time-based
fluorescence steady-state measurements demonstrated the high photostability of these ionic liquids.
相似文献
3.
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.
相似文献
4.
Behaviour of pure water and water mixture with benzene or chloroform adsorbed onto ordered mesoporous silicas 总被引:1,自引:0,他引:1
Vladimir M. Gun’ko Vladimir V. Turov Alexander V. Turov Vladimir I. Zarko Vasiliy I. Gerda Victor V. Yanishpolskii Inna S. Berezovska Valentin A. Tertykh 《Central European Journal of Chemistry》2007,5(2):420-454
Structural characteristics of synthesized ordered mesoporous silicas MCM-41, MCM-48 and SBA-15 were studied using XRD, nitrogen
adsorption and FTIR methods. Pure water and mixtures with water/benzene and water/chloroform-d adsorbed onto silicas were studied by 1H NMR spectroscopy with layer-by-layer freezing-out of bulk and interfacial liquids. Concentrated aqueous suspensions of MCM-48
and SBA-15 were studied by thermally stimulated depolarization current (TSDC) method. Benzene and chloroform-d can displace a portion of water to broad pores from the pore walls and from narrower pores, especially in the case of a large
excess of an organic solvent. This process is accompanied by diminution of both interaction energy of water with an adsorbent
surface and freezing temperature depression of adsorbed water. The effect of nonpolar benzene on pore water is much stronger
than that of weakly polar chloroform-d. Modifications of the Gibbs-Thomson relation to describe the freezing point depression of mixtures of immiscible liquids
confined in pores allow us to determine distribution functions of sizes of structures with unfrozen pore water and benzene.
Former address: Pisarzhevskii Institute of Physical Chemistry, 31 Prospect Nauki, Kiev, Ukraine 相似文献
5.
Melinda Fekete Mercedesz Töröncsi Lajos Novak 《Central European Journal of Chemistry》2008,6(1):33-37
Palladium-catalyzed amination reactions of quinoline triflate and the effect of a Pd catalyst, its ligands, solvents, bases,
and temperature were studied. This method facilitated an easier pathway for the preparation of aminoquinoline derivatives
as potential precursors of new serotoninerg agents.
相似文献
6.
Hybrid density functional theory calculations at the mPW1PW91/6-31+G(d,p) level of theory have been used to investigate the
optimized structures and other molecular properties of five different series of thiosemicarbazones. The investigated compounds
were obtained from acenaphthenequinone, isatin and its derivatives, and alloxan. The focus of the study is the isomerism and
the NMR characterization of these thiosemicarbazones. It was found that only one isomer is expected for thiosemicarbazones
and methylthiosemicarbazones, while for dimethylthiosemicarbazones, two isomers are possible. All investigated thiosemicarbazones
exhibit a hydrazinic proton that is highly deshielded and resonates far downfield in the proton NMR spectra. This proton is
a part of a characteristic sixmembered ring, and its NMR properties are a result of its strong, intermolecular hydrogen bond.
The relationships between the calculated 1H and 13C NMR chemical shifts and various geometric parameters are reported.
相似文献
7.
Abdülhadi Baykal Nermin Kasapoğlu Yüksel Köseoğlu Ali Cemil Başaran Hüseyin Kavas Muhammet S. Toprak 《Central European Journal of Chemistry》2008,6(1):125-130
A series of Ni-doped cobalt ferrites NixCo1−xFe2O4 (x = 0.0, 0.4, 0.6, 0.8, and 1.0) were prepared using microwave-induced combustion. Nickel, cobalt, and ferric nitrates were
used as starting materials and glycine as fuel. The influence of Ni content on the lattice parameter, stretching vibrations,
and magnetization was studied. XRD, FTIR, and SEM were used for structure, composition, and morphology investigation. A porous
network structure was observed with average particle size 60–67 nm. All samples had a cubic spinel structure. The unit cell
parameter “a” decreases linearly with nickel concentration due to the smaller ionic radius of nickel. Magnetization measurements
showed that coercivity decreased as Ni content increased; it increased with decreasing temperature.
相似文献
8.
Petr Bělina Petra Šulcová Miroslav Trojan Pavel Mazurek 《Central European Journal of Chemistry》2007,5(3):706-714
New binary lanthanum-aluminum triphosphates were synthesized by thermal-condensation method from H3PO4, La2O3 and Al(OH)3. These pigments could be potentially used as special inorganic pigments; their corrosion-inhibition properties were widely
studied. Synthesis conditions were determined on the basis of DTA and TG measurements. The products were also characterized
by X-ray diffraction analysis. Physical properties — density by pycnometric method, particle size distribution, oil number
and critical pigment volume concentration (CPVC), pH and specific conductivity of their aqueous extracts were also determined.
相似文献
9.
Abdülhadi Baykal Yüksel Köseoğlu Mehmet Şenel 《Central European Journal of Chemistry》2007,5(1):169-176
Heating hydrous manganese (II) hydroxide gel at 85 °C for 12 hours produces Mn3O4 nanoparticles. They were characterized by X-ray powder diffraction (XRD) and infrared spectroscopy (FTIR). The particle size
estimated from the SEM and X-ray peak broadening is approximately 32 nm, showing them to be nanocrystalline. EPR measurements
confirm a typical Mn2+signal with a highly resolved hyperfine structure.
相似文献
10.
This paper presents an experimental characterization of two sources of calcium carbonate, limestone and calcium carbonate precipitate (CCP) used in wet flue gas desulphurization processes. Characterization of the two carbonate sources was carried out by chemical analysis, IR spectra, thermal behavior, particle size distribution for CCP, BET surface area and absorption capacity of SO2 in calcium carbonate suspensions. The absorption temperature, suspension concentration and carbonate grain size were found to be the most influential parameters in the absorption capacity measurements. 相似文献
11.
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.
相似文献
12.
Ksenija R. Kumrić Tatjana M. Trtić-Petrović Ljubiša M. Ignjatović Jožef J. Čomor 《Central European Journal of Chemistry》2008,6(1):65-69
Lutetium has been determined by differential pulse anodic stripping voltammetry in an acidic solution containing Zn-EDTA.
Lutetium (III) ions liberated zinc (II), which was preconcentrated on a hanging mercury drop electrode and stripped anodically,
resulting in peak current linearly dependent on lutetium (III) concentration. Less than 0.4 ng mL−1 lutetium could be detected after a 2 min deposition.
相似文献
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.
相似文献
14.
Yuhai Sun Yujun Feng Hongwei Dong Zhi Chen Likun Han 《Central European Journal of Chemistry》2007,5(2):620-634
A series of homologous gemini surfactants possessing identical hydrophobic chains but different ionic head groups (cationic,
anionic, zwitterionic) were synthesized, and their aqueous solution properties were examined. The results showed that the
surface activities of gemini surfactants are superior to those of corresponding conventional monomeric surfactants, and molecular
arrangements of gemini surfactants at the air-water interface are tighter than those of corresponding conventional surfactants.
It was also found that zwitterionic gemini surfactant possesses the highest surface activity among the three surfactants.
The behavior at the air-water interface is closely related to the molecular structural features of surfactants, which provide
an indication for synthesizing highly-efficient surfactants.
相似文献
15.
Li-Wen Xu Ming-Song Yang Jian-Xiong Jiang Hua-Yu Qiu Guo-Qiao Lai 《Central European Journal of Chemistry》2007,5(4):1073-1083
Ionic liquid-functionalized mesoporous materials exhibited high catalytic activity in versatile organic reactions, such as
cycloaddition of carbon dioxide (CO2) with epoxide, aza-Michael addition of amines to α, β-unsaturated carbonyl compounds, and the Biginelli reaction of aldehyde, ethyl acetoacetate and urea. Recycling of the catalyst
in these reactions could be carried out and the catalyst used at least five times without significant loss in activity.
相似文献
16.
The geometry, frequency and intensity of the vibrational bands of 8-hydroxyquinoline and its 5,7-dichloro, 5,7-dibromo, 5,7-diiodo
and 5,7-dinitro derivatives were obtained by the density functional theory (DFT) calculations with Becke3-Lee-Parr (B3LYP)
functional and 6-31G* basis set. The effects of chloride, bromide, iodide and nitro substituent on the vibrational frequencies
of 8-hydroxyquinoline have been investigated. The assignments have been proposed with aid of the results of normal coordinate
analysis. The observed and calculated spectra are found to be in good agreement.
相似文献
17.
Adina Raducan Alexandra Olteanu Mihaela Puiu Dumitru Oancea 《Central European Journal of Chemistry》2008,6(1):89-92
The kinetics of the reaction between malachite green (MG) and sodium hydroxide (MG fading) was studied using a spectrophotometric
method in the presence of two cationic surfactants, cetyl-benzyl-dimethyl-ammonium chloride (CBDAC) and hexadecyl-trimethylammonium
bromide (HTAB) and one anionic surfactant, sodium dodecyl sulphate (SDS) at concentrations below and above critical micellar
concentrations. The cationic surfactants have a catalytic effect, while the anionic surfactant has an inhibitory effect on
the reaction. A kinetic model describing the influence of surfactant on reaction rate was developed. The results are discussed
on the basis of electrostatic and hydrophobic interactions between the kinetic micelles and malachite green.
相似文献
18.
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.
相似文献
19.
A palladium complex with an aminophosphine ligand has been prepared and investigated as a catalyst precursor in Suzuki coupling
reactions in toluene. Nanoparticles composed of elemental palladium have been isolated from the reaction media and analyzed
using transmission electroscopic microscope (TEM), which shows the essential catalysts palladium nanoparticles to have a size
of ca. 3.0 nm.
dedicate to the 60th birthday of Prof. Dr. Yuan Kou 相似文献
20.
Joanna Kurczewska Radosław Pankiewicz Grzegorz Schroeder 《Central European Journal of Chemistry》2012,10(5):1452-1458
Silica surface was modified with quaternary ammonium salts to give three matrices of different chain length. The synthesized supports were characterized by elemental analysis and infrared spectroscopy, as well as scanning electron microscopy and semi-empirical parametric method 5. Their exchange capacities for ClO4 −, F−, NO3 − and CH3COO− ions were investigated by conductometric titration. The amount of exchanged chloride ions from the matrix was studied for different initial anions concentration. The functionalized silica gel showed very good ability of perchlorate ions exchange from the water solution in room temperature. The anion-exchange properties were also studied in comparison to different number of reactive sites in the matrices. The increased number of chloride at the silica surface took effect on increased ability of ClO4 − anion exchange 相似文献