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1.
Chromogenic benzo-12-crown-4, benzo-13-crown-4 and benzo-14-crown-4 ethers have been compared with monoaza-12-crown-4 and monoazal-13-crown-4 ethers. Of these compounds, monoaza-13-crown-4 exhibited the best analytical characteristics toward the selective determination of lithium. K(ex)Li/K(ex)Na was 525 for the monoaza-crown-4 compound. 相似文献
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Ma?gorzata Jó?wiak 《Thermochimica Acta》2004,417(1):27-30
Enthalpy of solution of crown ethers (15-crown-5 and benzo-15-crown-5) in water-acetone mixtures have been measured within the whole range of mole fraction at 298.15 K. The obtained data have been compared with those of the solution enthalpy of both crown ethers in the mixtures of water with dimethyl sulfoxide. The replacement of SO group with CO in the molecule of the organic solvent brings about an increase in the exothermic effect of the solution of 15-crown-5 and benzo-15-crown-5 ethers, especially in the mixtures with a medium water content. The observed effect is connected with the preferential solvation of the molecules of both crown ethers by acetone molecules in the water-acetone mixtures. The process of preferential solvation of 15-crown-5 and benzo-15-crown-5 ethers does not take place in the water-dimethyl sulfoxide mixture. 相似文献
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Reactions of 4"-iodobenzo-15-crown-5 ether with ethynylarenes or 4"-ethynylbenzo-15-crown-5 ether with haloarenes in the presence of catalytic amounts of PdIIcomplex salts, CuI, and Et3N gave 4"-(arylethynyl)benzo-15-crown-5 ethers in 55—80% yields. 相似文献
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4′-氨基苯并-18-冠-6分别与间-硝基苯甲醛、对-硝基苯甲醛、间-苯二甲醛及其取代物和对-苯二甲醛缩合制得6种新的Schiff碱型单冠醚和双冠醚。4′-甲酰基苯并-18-冠-6分别与4′-氨基苯并-15-冠-5、4′-氨基苯并-18-冠-6作用制得2个醚环大小相同和不同的Schiff碱型双(苯并冠醚)。这些双冠醚经硼氢化钠还原得到相应的6种新的仲按型双冠醚。 相似文献
6.
Javad Zolgharnein Ghasem Shahmoradi Khosrow Zamani Saeid Amani 《Journal of inclusion phenomena and macrocyclic chemistry》2007,59(1-2):99-103
The complexation reaction of phenylaza-15-crown-5, and 4-nitrobenzo-15-crown-5, benzo-15-crown-5 and dibenzopyrdino-18-crwon-6,
dibenzo-18-crown-6,dicyclohexyl-18-crown-6(cis and trans), and 18-crown-6 with Na+ ion in methanol have been studied by potentiometric method. The Na+ ion-selective electrode has been used both as indicator and reference electrode. The stoichiometry and stability constants
of complexes of these crown ethers with sodium ion were evaluated by MINIQUAD program. The major trend of stability of resulting
complexes of these macrocycle with Na+ ion varied in the order DCY18C6 > DB18C6 > 18C6 > DBPY18C6 > phenylaza-15C5 > benzo-15C5 > 4-nitrobenzo-15C5. The obtained
results in particular stability constant of complexes of DBPY18C6, phenylaza-15C5 and 4-nitrobenzo-15C5 with sodium ion in
comparison with other crowns ether are novel, and interesting. 相似文献
7.
Synthesis of Double-Armed Benzo-15-crown-5 and Their Complexation Thermodynamics with Alkali Cations
Yu Liu Jian-Rong Han Zhong-Yu Duan Heng-Yi Zhang 《Journal of inclusion phenomena and macrocyclic chemistry》2005,52(3):229-235
A series of double-armed benzo-15-crown-5 lariats (3–8) have been synthesized by the reaction of 4′, 5′-bis(bromomethyl)-benzo-15-crown-5 (2) with 4-hydroxybenzaldehyde, phenol, 4-chlorophenol, 4-methoxyphenol, 2-hydroxybenzaldehyde, and 4-acetamidophenol in 43 ~ 82% yields, respectively. The complex stability constants (K
S) and thermodynamic parameters for the stoichiometric 1:1 and/or 1:2 complexes of benzo-15-crown-5 1 and double-armed crown ethers 3–8 with alkali cations (Na+, K+, Rb+) have been determined in methanol–water (V/V=8:2) at 25 °C by means of microcalorimetric titrations. As compared with the parent benzo-15-crown-5 1, double-armed crown ethers 3–8 show unremarkable changes in the complex stability constants upon complexation with Na+, but present significantly enhanced binding ability toward cations larger than the crown cavity by the secondly sandwich complexation. Thermodynamically, the sandwich complexations of crown ethers 3-8 with cations are mostly enthalpy-driven processes accompanied with a moderate entropy loss. The binding ability and selectivity of cations by the double-armed crown ethers are discussed from the viewpoints of the electron density, additional binding site, softness, spatial arrangement, and especially the cooperative binding of two crown ether molecules toward one metal ion. 相似文献
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Synthesis of Double-Armed Benzo-15-crown-5 and Their Complexation Thermodynamics with Alkali Cations
A series of double-armed benzo-15-crown-5 lariats (3–8) have been synthesized by the reaction of 4′, 5′-bis(bromomethyl)-benzo-15-crown-5 (2) with 4-hydroxybenzaldehyde, phenol, 4-chlorophenol, 4-methoxyphenol, 2-hydroxybenzaldehyde, and 4-acetamidophenol in 43 ~ 82% yields, respectively. The complex stability constants (K
S) and thermodynamic parameters for the stoichiometric 1:1 and/or 1:2 complexes of benzo-15-crown-5 1 and double-armed crown ethers 3–8 with alkali cations (Na+, K+, Rb+) have been determined in methanol–water (V/V=8:2) at 25 °C by means of microcalorimetric titrations. As compared with the parent benzo-15-crown-5 1, double-armed crown ethers 3–8 show unremarkable changes in the complex stability constants upon complexation with Na+, but present significantly enhanced binding ability toward cations larger than the crown cavity by the secondly sandwich complexation. Thermodynamically, the sandwich complexations of crown ethers 3-8 with cations are mostly enthalpy-driven processes accompanied with a moderate entropy loss. The binding ability and selectivity of cations by the double-armed crown ethers are discussed from the viewpoints of the electron density, additional binding site, softness, spatial arrangement, and especially the cooperative binding of two crown ether molecules toward one metal ion.Graphical Abstract Synthesis of Double-Armed Benzo-15-crown-5 and Their Complexation Thermodynamics with Alkali CationsYU LIU*, JIAN-RONG HAN, ZHONG-YU DUAN and HENG-YI ZHANG
This revised version was published online in July 2005 with a corrected issue number. 相似文献
9.
M. Atanassova 《Russian Journal of Inorganic Chemistry》2007,52(8):1304-1311
The synergistic solvent extraction of 13 lanthanides with mixtures of 8-hydroxyquinoline (HQ) and the crown ethers (S) 18-crown-6
(18C6) or benzo-18-crown-6 (B18C6) in 1,2-dichloroethane has been studied. The composition of the extracted species has been
determined as LnQ3 · S. The values of the equilibrium constant and separation factor have been calculated. Here, the effect of the synergistic
agent (18C6 or B18C6) on the extraction process is discussed. 相似文献
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The benzo-9-crown-3 and benzo-12-crown-4 derivatives are formed by reaction of tetranitrodibenzo-18-crown-6 and tetranitrodibenzo-24-crown-8, respectively, with sodium methoxyethoxide in DMSO at 20C.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1474–1476, November, 1990. 相似文献
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Ma?gorzata Jó?wiak 《Thermochimica Acta》2004,417(1):31-41
Crown ethers are preferential solvated by organic solvents in the mixtures of water with formamide, N-methylformamide, acetonitrile, acetone and propan-1-ol. In these mixed solvents the energetic effect of the preferential solvation depends quantitatively on the structural and energetic properties of mixtures. The energetic properties of the mixtures of water with hydrophobic solvents (N,N-dimethylformamide, dimethylsulfoxide, N,N-dimethylacetamide, hexamethylphosphortriamide) counteract the preferential solvation of the crown ether molecules. The effect of the hydrophobic and acid-base properties of the mixture of water with organic solvent on the solvation of 12-crown-4, 15-crown-5, 18-crown-6 and benzo-15-crown-5 ethers was discussed. The solvation enthalpy of one -CH2CH2O- group in water, N,N-dimethylformamide and hexamethylphosphortriamide is equal to −24.21, −16.04 and −15.91 kJ/mol, respectively. The condensed benzene ring with 15-crown-5 ether molecule brings about an increase in the exothermic effect of solvation of the crown ether in the mixtures of water with organic solvent. 相似文献
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N. Zh. Saifullina K. A. Ibragimzhanov A. K. Tashmukhamedova Kh. M. Shakhidoyatov 《Chemistry of Heterocyclic Compounds》1999,35(7):821-824
The condensation of (benzo-15-crown-5)-4-thiocarboxamide with anthranilic acid is studied for the first time. Novel representative of crown ethers incorporating the quinazoline moiety is synthesized. Methylation of (benzo-15-crown-5)-4-thiocarboxamide proceeds anomalously giving (benzo-15-crown-5)-4-carbonitrile. (Benzo-15-crown-5)-4-thiocarboxamide is reacted with thioveratramide in order to compare the reaction paths.Mirzo Ulugbek Tashkent State University, Tashkent 700095, Republic of Uzbekistan; Institute of Plant Chemistry, Academy of Sciences of the Republic of Uzbekistan, Tashkent 700170. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 937–940, July, 1999. 相似文献
14.
Javad Zolgharnein Ghasem Shahmoradi Saeid Amani 《Journal of inclusion phenomena and macrocyclic chemistry》2008,60(1-2):163-167
The complexation reaction of phenylaza-15-crwon-5, 4- nitrobenzo- 15-crown-5, and benzo-15-crown-5 with Ag+, Tl+ and Pb2+ ions in methanol solution have been studied by a competitive potentiometric method. The Ag+/Ag electrode used both as an indicator and reference electrode in a concentration cell. The emf of cell monitored as the
crown ethers concentration varies through the titration. The stoichiometry and stability constants of resulting complexes
have been evaluated by MINIQUAD. The stoichiometry for all resulting complexes was 1:1. The stability of these metal ions
with derivatives of 15-crown-5 are in order phenylaza-15-crown-5 > Benzo-15-crown-5 > 4-nitrobenzo-15-crown-5, and for the
each used crown ethers are as Pb2+ > Ag+ > Tl+. The effect of the substituted group on the stability of resulting complexes was considered. The obtained results are novel
and interesting. 相似文献
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Extraction and determination of crown ethers from water samples using a membrane disk and gas chromatography 总被引:2,自引:0,他引:2
A method for rapid extraction and determination of some crown ethers in aqueous matrices using octadecyl-bonded silica membrane disks and gas chromatography is presented. Extraction efficiency and the influence of vacuum pressure. pH, and type and least amount of eluting solvent used to extract the crown ethers from the membrane disks were evaluated. Extraction efficiencies > 95% were obtained for benzo-15-crown-5, benzo-18-crown-6 and dicyclohexyl-18-crown-6 using 5 ml of acetonitrile as eluting solvent. The limit of detection of the proposed method for the determination of the crown ethers is reported. 相似文献
19.
A. D. Grebenyuk S. A. Andreev I. A. Stempnevskaya M. G. Levkovich A. K. Tashmukhamedova 《Chemistry of Heterocyclic Compounds》2000,36(12):1449-1456
A general method for the nitration of benzo crown ethers with potassium nitrate in polyphosphoric acid has been developed. Mono- and dinitro derivatives of benzo-12-crown-4, benzo-15-crown-5, dibenzo-18-crown-6, and dibenzo-24-crown-8 have been prepared. The role of complex formation in the regioselective tendency for the nitration of dibenzo-18-crown-6 has been demonstrated. 相似文献
20.
Sadatoshi Akabori Shigeo Miyamoto Hideo Tanabe 《Journal of polymer science. Part A, Polymer chemistry》1979,17(12):3933-3937
Allylation of sodium phenoxide in the presence of crown ethers produces a high ratio of O/O + C allylation when conducted in water, phenol, benzene, or diethyl ether. The striking increase in the product ratios is attributed to specific complexation of the crown ethers that facilitate the dissociation of the ion pair aggregate of the sodioderivative in benzene or diethyl ether. The crown ethers may act as a phase transfer catalyst when the reaction is run in water. Furthermore, the O/O + C ratios of the allylation strongly depend on the kind of crown ethers used. To examine their effect the allylation of sodium phenoxide was studied with various crown ethers, such as 18-crown-6, benzo-18-crown-6, benzo-15-crown-5, poly(vinylmonobenzo-15-crown-5), and poly(vinylmono-benzo-18-crown-6), as catalysts. It was found that among these crown ethers poly(vinylmono-benzo-15-crown-5) was the most effective catalyst. 相似文献