共查询到20条相似文献,搜索用时 15 毫秒
1.
E. Makrlík P. Vaňura P. Selucký 《Journal of Radioanalytical and Nuclear Chemistry》2013,295(3):2077-2081
From extraction experiments and γ-activity measurements, the exchange extraction constants corresponding to the general equilibrium C+(aq) + 1·Cs+(nb) ?1·C+ (nb) + Cs+(aq) taking place in the two–phase water–nitrobenzene system (C+ = methylammonium, ethylammonium, propylammonium, ethanolammonium, diethanolammonium, triethanolammonium, protonated tyramine, protonated dopamine, protonated DL–noradrenaline; 1 = hexaethyl p-tert-butylcalix[6]arene hexaacetate; aq = aqueous phase, nb = nitrobenzene phase) were evaluated. Furthermore, the stability constants of the 1·C+ complex species in nitrobenzene saturated with water were calculated; they were found to increase in the following cation order: protonated tyramine < protonated dopamine < triethanolammonium < diethanolammonium < protonated DL-noradrenaline < propylammonium < ethanolammonium < ethylammonium < methylammonium. 相似文献
2.
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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3.
E. Makrlík P. Selucký P. Vaňura 《Journal of Radioanalytical and Nuclear Chemistry》2013,295(1):767-770
From extraction experiments and γ-activity measurements, the exchange extraction constants corresponding to the general equilibrium C+(aq) + 1·Na+(nb) ? 1·C+(nb) + Na+(aq) taking place in the two-phase water–nitrobenzene system (C+ = univalent organic cation, 1 = benzo-18-crown-6; aq = aqueous phase, nb = nitrobenzene phase) were evaluated. Moreover, the stability constants of the 1·C+ complex species in nitrobenzene saturated with water were calculated; they were found to increase in the following cation order: protonated tyramine, protonated l-valine methyl ester < protonated dopamine < protonated serotonin < methylammonium < protonated hexamethylenetetramine < ethanolammonium < protonated dl-noradrenaline. 相似文献
4.
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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5.
Charles A. Mebi Joshua J. Trujillo Anwar A. Bhuiyan 《Central European Journal of Chemistry》2012,10(4):1218-1222
A new organometallic complex coupling photoactive coumarin to a diironhexacarbonyl unit has been successfully prepared and its composition and electronic structure confirmed by elemental and spectroscopic analyses. Emission spectral analysis of the complex reveals photoinduced intramolecular electron transfer from coumarin to the iron-carbonyl moiety. The compound is electrochemically reduced at −1.24 V vs. Fc/Fc+. This reduction is irreversible, attesting to the instability of the complex. Electrochemical evolution of hydrogen in the presence of the complex has been studied and results are discussed. 相似文献
6.
Y. Toh M. Oshima M. Koizumi A. Kimura Y. Hatsukawa 《Journal of Radioanalytical and Nuclear Chemistry》2008,276(1):217-220
From extraction experiments and γ-activity measurements, the exchange extraction constants corresponding to the general equilibrium M+(aq)+NaL+(nb)⇔ML+(nb)+Na+(aq) taking place in the two-phase water-nitrobenzene system [M+=Li+, K+, Rb+, Cs+; L = p-tert-butylcalix[4]arene-tetrakis (N, N-dimethylthioacetamide); aq = aqueous phase, nb = nitrobenzene phase] were evaluated. Furthermore,
the stability constants of the ML+ complexes in water saturated nitrobenzene were calculated; they were found to increase in the cation order Cs+<Rb+<K+<Li+<Na+. 相似文献
7.
Vincenzo Siano Ilaria D’Auria Fabia Grisi Chiara Costabile Pasquale Longo 《Central European Journal of Chemistry》2011,9(4):605-609
Grubbs II generation catalyst (3), bearing a fluorinated imidazolinium ligand, was investigated in cross metathesis (CM), ring closing metathesis (RCM) and
ring opening polymerization metathesis (ROMP) for a variety of substrates. Kinetic studies showed reduced stability of the
catalyst in methylene chloride following the first 15 minutes of reaction preventing a higher efficiency despite the very
high activity. Beneficial solvent effects on the catalyst stability were observed by performing RCM in C6F6.
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8.
From extraction experiments and γ-activity measurements, the exchange extraction constants corresponding to the general equilibrium
M+(aq)+NaL+(nb)⇔ML+(nb)+Na+(aq) taking place in the two-phase water-nitrobenzene system (M+ = Li+, H3O+, NH4+, Ag+; L = hexaethyl calix[6]arene hexaacetate; aq = aqueous phase, nb = nitrobenzene phase) were determined. Furthermore, the
stability constants of the ML+ complexes in water saturated nitrobenzene were calculated; they were found to increase in the cation order H3O+<NH4+<Li+<Ag+. 相似文献
9.
A theoretical study of the complexation of cyclo[8]pyrrole dication, 2, and the corresponding system in neutral form, 3, with six anionic molecules has been carried out up to the B3LYP/6–311++G(2d,2p) computational level. The effect of the water
solvation has been taken into account by means of the PCM method. The gas phase results correspond to the very large interaction
energies expected for the interaction of molecules of opposite charge. In all the complexes, the analysis of the electron
density by means of the Atoms In Molecules (AIM) methodology shows the presence of eight intermolecular interactions between
the individual molecules. The results, using the water solvent model, indicate that the 2:SO4
2− complex is more stable than the 2:NO3
−, in agreement with experimental results.
相似文献
10.
E. Makrlík P. Selucký P. Vaňura J. Budka 《Journal of Radioanalytical and Nuclear Chemistry》2010,286(1):155-159
From extraction experiments and γ-activity measurements, the exchange extraction constants corresponding to the general equilibrium C+(aq) + Cs+(nb) ⇔ C+(nb) + Cs+(aq) taking part in the two-phase water–nitrobenzene system (C+ = organic cation; aq = aqueous phase, nb = nitrobenzene phase) were evaluated. Furthermore, the individual extraction constants
of 15 organic cations in the mentioned two-phase system were calculated. 相似文献
11.
Rafal Kruszynski 《Central European Journal of Chemistry》2008,6(4):542-548
2,4-dinitrophenylhydrazine hydrochloride hydrate (I) was determined by X-ray crystallography, and the intermolecular interaction
energies were calculated in terms of Natural Bond Orbital analysis. The asymmetric unit of (I) consists of a dinitrophenylhydrazinium
cation, a chloride anion and a water molecule. The interatomic distances and angles in (I) show no unusual values. In the
structure there are intermolecular N—H⊎⊎⊎O, N—H⊎⊎⊎Cl, O—H⊎⊎⊎Cl, C—H⊎⊎⊎O hydrogen bonds with bonding energy ranging form 16.03
to 0.76 kcal mol−1. These hydrogen bonds create the following N1 motifs: 6D, S(5), S(6), C(6), C(9). N1D motifs become infinite at the third level and are 2C32(6), C32(7).
相似文献
12.
From extraction experiments and γ-activity measurements, the exchange extraction constants corresponding to the general equilibrium M+(aq)+CsL+(nb)⇔ML+(nb)+Cs+(aq) taking place in the two-phase water-nitrobenzene system (M+ = Li+, Na+, K+, Rb+; L = hexaethyl p-tert-butylcalix[6]arene hexaacetate; aq = aqueous phase, nb = nitrobenzene phase) were determined. Moreover, the stability constants
of the ML+ complexes in water saturated nitrobenzene were calculated; they were found to increase in the cation order Rb+<Cs+<K+<Na+<Li+. 相似文献
13.
Attila Pallagi Ágost Tasi Attila Gácsi Miklós Csáti István Pálinkó Gábor Peintler Pál Sipos 《Central European Journal of Chemistry》2012,10(2):332-337
The solubility of Ca(OH)2 in aqueous NaOH solutions up to 12.50 M at 25°C has been determined. The solubility data obtained for NaOH concentrations
lower than 3 M was compared with those published in the literature. The solubility of Ca(OH)2 steadily decreases with the increasing NaOH concentration. The solubility data obtained at a constant ionic strength (I =
1 M Na(Cl,OH)) enabled the determination of the conditional solubility product of Ca(OH)2(s) (lgLCa(OH)2 = − 4.10 ± 0.02). Formation of the hydroxo complex CaOH+(aq) was invoked to describe the variation of [Ca2+]T with [OH−]T. Its conditional stability constant was found to be lgKCaOH+ = 0.97 ± 0.02. The experimental protocol employed was proven to be suitable for accurate solubility determinations in rapidly
equilibrating systems comprising of highly concentrated, alkaline solutions and containing analytes in the ppm range.
相似文献
14.
E. Makrlík P. Vaňura P. Selucký 《Journal of Radioanalytical and Nuclear Chemistry》2014,300(3):947-951
The exchange extraction constants corresponding to the general equilibrium C+(aq) + 1·Cs+(nb) ? 1·C+ (nb) + Cs+(aq) occurring in the two-phase water–nitrobenzene system (C+ = protonated α-amino acid methyl ester, 1 = hexaethyl p-tert-butylcalix[6]arene hexaacetate; aq = aqueous phase, nb = nitrobenzene phase) were evaluated on the basis of extraction experiments and γ-activity measurements. Further, the stability constants of the 1·C+ cationic complex species in nitrobenzene saturated with water were calculated; they were found to increase in the following cation order: protonated l-tryptophan methyl ester < protonated l-phenylalanine methyl ester < protonated l-leucine methyl ester < protonated l-methionine methyl ester < protonated l-valine methyl ester. 相似文献
15.
Bang-Tun Zhao Xiao-Min Zhu Qi-Ming Peng Zhen-Ning Yan Franck Le Derf Marc Sallé 《Central European Journal of Chemistry》2011,9(6):1102-1108
A novel redox-active calix[4]arene-TTF 5 was prepared by the reaction of p-tert-butylcalix[4]arene 4 with the tosylated TTF 3 in the presence of cesium fluoride. The structure of the dyad 5 was identified by X-ray diffraction analysis, and the preliminary electrochemical properties of 5 were investigated by cyclic voltammetry (CV), for which two reversible one-electron waves were observed. Moreover, the UV-vis
absorption spectra studies show that the dyad 5 undergoes progressive oxidation at the TTF moiety in presence of increasing amounts of Cu2+ or Hg2+.
相似文献
16.
A. N. Chekhlov 《Russian Journal of General Chemistry》2009,79(9):1821-1824
A new complex compound bis[(dibenzo-18-crown-6)potassium]bis(μ2-chloro)-tetrachlorodicuprate( II), {[K(Db18c6)]2Cu2Cl6} (I) was prepared and its crystal structure was investigated by XRD analysis. Complex molecule I consist of anion [Cu2Cl6]2− located in a crystallographic center of inversion, and two centrosymmetrical to each other complex cations [K(Db18c6)]+ of “guest-host” type: the cation K+ is located in the cavity of the crown-ligand Db18c6 and is coordinated by all its six O atoms, and also by one Cl atom of
anion [Cu2Cl6]2−. The coordination of this cation K+ is enlarged up to hexagonal-bipyramidal due to the formation of unusual coordination bond K+ → π(
相似文献
17.
Jorge Luis Sague Doimeadios 《Central European Journal of Chemistry》2008,6(4):505-508
Herein, the first example of a co-crystal system formed by an imidazolium nitrate, a carbene precursor, and copper (II) nitrate,
{[Cu(NO3)2(H2O)2]L1(NO3)2} (1) (L1 = 1,1′-dibenzyl-3,3′-butyl-diimidazolium-2,2′-diylidene) is reported. These two building blocks are connected in the solid
state through hydrogen bonds to generate a three-dimensional supramolecular network.
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18.
Noora Kuuloja Tuula Kylmälä Youjun Xu Robert Franzén 《Central European Journal of Chemistry》2008,6(3):390-392
Xenbucin 1, an analgesic drug, was synthesized in 4 steps using two different routes. The biaryl fragment could successfully be produced
via a Pd/C catalysed Suzuki coupling in water using sodium tetraphenylborate as a phenylation reagent. Overall yields of the
routes were 36% and 59%, respectively.
相似文献
19.
Pál Perjési Krisztina Takács-Novák Zsuzsanna Rozmer Pál Sohár Richard E. Bozak Theresa M. Allen 《Central European Journal of Chemistry》2012,10(5):1500-1505
Cyclic chalcone analogues (2–5) and their ferrocenyl counterparts (6–10) were synthesized and their logP and P388 cyctotoxity were investigated. The structures of the newly synthesized compounds were confirmed by IR 1H and 13NMR spectroscopy. Comparison of conjugation and stereochemistry of the respective derivatives showed similar characteristics compared to ones with some higher degree of conjugation in the ferrocenyl series. Comparison of logP of the ferrocenyl derivatives determined by a validated RP-TLC method showed the ferrocenyl derivatives to have higher logP TLC. The results demonstrate that the differences in three dimensional shape, conjugation and lipophilicity do not have strong influence on the P388 cytotoxicity of the investigated phenyl (1−5) and ferrocenyl (6−10) enones. 相似文献
20.
Sushilkumar A. Jadhav 《Central European Journal of Chemistry》2012,10(5):1640-1646
Two new long-chain carboxylic acids (1, 2) bearing strong fluorescent group pyrene as ligands for Self-Assembled Monolayers (SAMs) have been synthesized. The multistep targeted synthesis is accomplished by use of Pyren-1-yl methylamine hydrochloride and employing simplified synthetic protocols. Compound 2 contains a chiral center purposely introduced along the atom chain in order to make it suitable for chiro-optical studies of the resulting SAMs. 相似文献