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The complex formation of Ag+ with polyether 18-crown-6 (18C6) and their solvation have been studied using calorimetric and potentiometric methods in H2O-EtOH solvents in wide range of ethanol concentration. The standard enthalpies of dissolution AgNO3, AgClO4 and 18C6 in aqueous-ethanol solvents are obtained. The stability of a complex [Ag18C6]+ grows with increasing the EtOH content a solvent. Using the method based on the thermodynamic characteristics of solvation
of metal-ion, ligand and complex-ion the interpretation of the results has been given.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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《Analytical letters》2012,45(9):1625-1641
Abstract The solvent extraction studies of Pd(II), V(V), Co(III), Cu(II), Ni(II) and Fe(II)-PAR [4 - (2-pyridyl azo)-resorcinol] complexes with dicyclohexyl-18-crown-6 have been investigated in 1,2-dichloroethane as a solvent. It was observed that the complexes of Pd(II), V(V), Co(III), Cu(II), Ni(II) and Fe(II)-PAR were extracted into organic phase. In order to investigate the effect of enthalpy and entropy in the extraction of metal-PAR complexes, an attempt has been made to explore the temperature effect. In the extraction studies, it was observed that the entropy effect is one of the major factors for the selective extraction. The shape of the complexes may be one of the causes for the extractability of metal-PAR complexes with potassium dicyclohexyl-18-crown-6. The planar palladium-PAR-SCN? complex was easily extracted into organic phase in comparison with other complexes. 相似文献
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D. V. Kuznetsov S. A. Andreev A. K. Tashmukhamedova 《Chemistry of Natural Compounds》2006,42(5):515-516
Diazonium salts were prepared by diazotization of 4′-amino-, 4′,4″-, and 4′,5″-diaminodibenzo-18-crown-6. Their coupling products
with kojic acid (5-hydroxy-2-hydroxymethyl-γ-pyrone) were synthesized for the first time: 4′-(6-aza-5-hydroxy-2-hydroxymethyl-γ-pyronyl)-, 4′,4″-di-(6-aza-5-hydroxy-2-hydroxymethyl-γ-pyronyl)-, and 4′,5″-di-(6-aza-5-hydroxy-2-hydroxymethyl-γ-pyronyl)-dibenzo-18-crown-6.
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Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 415–416, September–October, 2006. 相似文献
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The acylation of dibenzo-18-crown-6 by lithium, sodium, and potassium acetates in polyphosphoric acid was studied. Complexes
of dibenzo-18-crown-6 with the acetates were obtained. A new method is proposed for the production of mono- and diacetyldibenzo-18-crown-6
by the reaction of dibenzo-18-crown-6 complexes with metal acetates in polyphosphoric acid.
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Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1146–1149, August, 2005. 相似文献
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K. M. Valikhanov M. G. Levkovich A. K. Tashmukhamedova 《Chemistry of Natural Compounds》2001,37(4):361-363
New derivatives of dibenzo-18-crown-6 were prepared by condensing 4,4(5)-dibenzo-18-crown-6-dicarboxylic acid dichloride with salsolidine and salsoline. The structures of these compounds were proved by PMR and IR spectral methods. 相似文献
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Usacheva T. R. Lendencov S. F. Sharmin V. A. 《Journal of Thermal Analysis and Calorimetry》2002,70(1):209-216
The thermodynamic parameters (DrG0, Dr
H
0, TDr
S
0) of the reaction of [Ag18C6]+ complex formation were obtained for a wide range of H2O-DMSO mixtures from the calorimetric data at 298.15 K. The relation between the thermodynamic parameters of complex formation
and solvation of each reagent was investigated.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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Thomas M. Fyles Richard D. Gandour 《Journal of inclusion phenomena and macrocyclic chemistry》1992,12(1-4):313-332
A procedure for displaying macrocylic torsion angles as a map on polar coordinates is discussed with reference to the solid-state conformations of l8-crown-6 and its complexes. The maps aid in comparisons of related structures, in the perception of pseudo-symmetry elements, and in the classification of the conformations of 18-crown-6. Only four conformational groups are found in the 1 : 1 complexes of 18-crown-6 with sodium, potassium, rubidium, cesium, thallium(I), calcium and strontium cations. The relationship of donor number, mean cavity radius and effective ionic radius combined with skeletal drawings of the donors and the polar map of the torsion angles provide a composite picture of the structures and insight into the balance between cation-donor interaction energy and conformational energy.This paper is dedicated to the memory of the late Dr C. J. Pedersen. 相似文献
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The dibenzo-18-crown-6 derivatives such as di(nitrobenzo)-18-crown-6 and di(aminobenzo)-18-crown-6 were synthesized by nitration reaction and catalytic hydrogenation with high selectivity. The chemical structures were determined by FTIR, 1H NMR, 13C NMR, and UV. Regarding the mixture of Ac2O and HNO3 as nitrating agent, the reaction exhibited commendable trans-isomer selectivity. Effects of nitrating agent ratio, reaction temperature and reaction time on yield of trans-di(nitrobenzo)-18-crown-6 were investigated. The yield of trans-di(nitrobenzo)-18-crown-6 was 62.9% for nitrating agent ratio of 1/1, reaction temperature of 50?°C and reaction time of 5?h. Moreover, effect of reaction time on trans-di(aminobenzo)-18-crown-6 was also studied. 相似文献
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Electric potentials of MK-40 cation-exchange membrane, which is immersed in aqueous solutions of KCl, RbCl, and macrocyclic polyether 18-crown-6, have been measured. The possibility of preliminary calculations of biionic and multiionic potentials from equilibrium constants of ionic exchange and electrochemical mobilities of cations in the sulfo cationite is demonstrated.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1489–1490, August, 1995. 相似文献
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Roman Luboradzki Janusz Lipkowski Yurii A. Simonov Marina S. Fonari Edward V. Ganin Arkadii A. Yavolovskii 《Journal of inclusion phenomena and macrocyclic chemistry》1995,23(3):181-193
An X-ray—diffraction study is reported for two molecular complexes containing 3,4-diamino-1,2,5-oxadiazole as guest (G) with 18-crown-6 (18-C-6) andcis-anti-cis-dicyclohexano-18-crown-6 (DCH-6B) as host. Both complexes are of the polymeric-chain structure with the guest molecule bridging two crown neighbours. ComplexI: [18-C-6*G*H2O], 111, monoclinic,P21/n,a=8.171(1),b=15.042(2),c=16.209(6) Å, =101.15(2)°, finalR-factor 0.068. ComplexII: [DCH-6B*G], 11, monoclinicC2/c,a=21.212(4),b=9.380(2),c=13.049(3) Å, =108.61(3)°, finalR 0.047. 相似文献
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在Lewis酸催化剂存在下,1,4-二氯甲氧基丁烷对冠醚二苯并-18-冠-6(1)进行氯甲基化修饰使其转变成氯甲基化冠醚(2),其结构经1HNMR,13C NMR,IR及MS表征。2与交联聚乙烯醇(CPVA)微球表面的羟基发生亲核取代反应实现冠醚的固载化,制得固载有冠醚的功能微球(3)。实验结果表明,1的氯甲基化反应易于进行,在两个苯环上分别发生了对称的氯甲基化反应,2为对称的四取代产物。通过2的氯甲基与CPVA的羟基之间的亲核取代反应,1可容易地化学固载到CPVA表面。 相似文献
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NIU Mei-Ju ② DOU Jian-Min WANG Da-Qi LI Da-Cheng 《结构化学》2006,25(6):757-760
1 INTRODUCTION Since the report about unusual coordination num- bers and arrangements to metal ions of crown ether compounds by Pedersen[1], the crown ether compounds have attracted much attention. Due to their novel coordination modes, crown ethers have been widely used in catalyst, solvent extraction, iso- tope separation, bionics, material chemistry, host- guest chemistry and supramolecular chemistry[2~5]. So it is vital to study the synthesis of new crown ethers and their crystal stru… 相似文献
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Lucia Mutihac Radu Mutihac Titus Constantinescu Constantin Luca 《Journal of inclusion phenomena and macrocyclic chemistry》1994,17(1):45-51
The possibility of separating in cationic form some -amino acids (L-Methionine, L-Leucine, L-Isoleucine, L-Valine, L-Phenylalanine, L--Alanine and L-Cysteine) from mixtures in the presence of picrate anion has been investigated by means of active transport assisted by a pH gradient through liquid membranes. 18-Crown-6 in 1,2-dichloroethane has been used as a selective carrier. The effect of stirring rates at different volumes of the membrane, suggests a diffusional rate-limiting process of the amino acid transport. 相似文献
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Zirconium was quantitatively extracted with 2.5 × 10?2 M dicyclohexyl-18-crown-6 in dichloromethane from 8.5 M hydrochloric acid. It was stripped with 0.5 M hydrochloric acid and was determined spectrophotometrically as its complex with Arsenazo III. Hafnium was not extracted under these conditions, but from the residual aqueous phase it was extracted with 7.0 × 10?2 M dicyclohexyl-18-crown-6 in dichloromethane from 9.0 M hydrochloric acid. It was stripped with 0.1 M perchloric acid and determined spectrophotometrically at 540 nm as its complex with xylenol orange. The separation of zirconium and hafnium from other metals is also described. 相似文献