共查询到20条相似文献,搜索用时 51 毫秒
1.
The influence of substituents in close proximity to crown ether cavities, on the stability of complexes of the crown ethers with t-butylammonium salts, has been investigated. Crown ethers with intra-annular donor substituents (2–4) were prepared by the reaction of 2-acetylresorcinol (1) with polyethylene glycol ditosylates and subsequent modification of the acetyl group. Crown ethers with substituents above and below the plane of the crown ether 0 atoms were synthesized by the reaction of 2,2'-dihydroxy-1,1'-biphenyls with polyethylene glycol ditosylates. Chloromethylation of 5,5'-dimethyl-1,1'-biphenyl crown ethers (6) yielded 4,4'-bis(chloromethyl)-1,1'-biphenyl crown ethers (10). 3,3'-Disubstituted-1,1'-biphenyl crown ethers (13–24) were synthesized by the reaction of 3,3'-diallyl-2,2'-dihydroxy-1,1'-biphenyl (12) with polyethylene glycol ditosylates. The allyl groups of 13 were isomerized with sodium hydride to propen- 1-yl groups. Ozonolysis of 13 and 14 gave the corresponding dialdehydes (15 and 18) which were converted into other 3,3'-disubstituted biphenyl-20-crown-6 derivatives (RCH2COOMe, CH2COOH, CH2OH, CH2Cl, CH2OMe, OH and Me) by standard operations. The thermodynamic stability of the complexes of these functionalized crown ethers with t-butylammonium hexafluorophosphate has been studied in deuterochloroform in competition experiments with m-xyleno-18-crown-5 and benzo-15-crown-5 as the reference compounds. The nature of the 2-substituents in the crown ethers 2 and 3 has little effect on the stability of the complexes. The stability of the complexes of 3,3'-disubstituted biphenyl crown ethers depends of ringsize and the size and nature of the substituents. The most stable complexes are those of 24 (R = Me) and 14 (R=CH=CHMe).The Me groups in 24 represent the optimum between relief of O-O repulsion in the polyether ring and steric hindrance of complexation. The propen-1-yl substituents of 14 stabilize the complex because they provide extended π-electron donor stabilization. Substitution at the 4- and 4'-positions of the aryl groups has little effect on the stability of the complexes. 相似文献
2.
Six novel 2' - hydroxy - 1',3' - xylyl crown ethers (8a–e and 13)1 have been synthesized utilizing the allyl group to protect the OH function during the cyclization reaction. The macrocycles 6a-e were formed in yields of 26 to 52%, by intermolecular reaction of 4 - chloro - 2,6 - bis(bromomethyl) - 1 - (2 - propenyloxy)benzene (5) with polyethylene glycols; 6a was also obtained by an intramolecular cyclization reaction of monotosylate 14.A 30-membered ring with a 2' - hydroxy - 1',3' - xylyl sub-unit was obtained in 87% yield by reaction of ditosylate 9 with bis [2 - (o - hydroxyphenoxy)ethyl]ether (11) in the presence of cesium fluoride. The synthesis of crown ethers with a 2' - hydroxy - 1',3' - xylyl sub-unit (1c–e, H for CH3) by demethylation of the corresponding 2'-methoxy crown ethers 1c–e with lithium iodide were unsuccessful; it would appear that the demethylation reaction is restricted to 15- and 18-membered rings. One of the 2' - hydroxy - 1',3' - xylyl crown ethers 8d forms a crystalline 1:1-complex with water. 相似文献
3.
The preparation of several novel lariat ethers (macrocyclic crown polyethers having sidearms bearing pendant donor groups) is reported, These compounds are ethers derived from known 2-hydroxymethyl-15-crown-5 or -21-crown-7. The sidearms Include 2-aminophenyl, 2,4-diaminophenyl, 2-nitrophenyl, 2-(3'-nitrobiphenyl), and 2-(3'-aminobiphenyl). In several cases, the amino groups were converted into ammonium salts which showed substantial stabilization by intramolecular hydrogen bonding. Likewise, an -NH2+.,BF3- complex showed evidence of intramolecular hydrogen bonding. Diazotization of the aminobiphenyl residue produced an arenediazonium cation which underwent intramolecular crown complexation, as judged by infrared spectroscopic studies to form what we call an “ostrich molecule” complex. Addition of N,N-dimethylaniline to the intramolecular arenediazonium cation complex afforded an azo compound, but europium shift reagent studies showed clearly that the diazonium cation reacted outside the macroring. 相似文献
4.
1,1'-Dihydroxyferrocene reacts with chloroethers 7–11 forming the respective polyoxaferrocenophanes 2–6. These compounds behave analogously to the “crown” ethers. 相似文献
5.
Five polybrominated oxydiphenol derivatives have been isolated from various Great Barrier Reef collections and one Fijian collection of the sponge Dysidea herbacea: 3,4',5,6,6'-hexabromo-2, 2'-oxydiphenol (11), 3,4',5,6,6'-pentabromo-2,2'-oxydiphenol (12), 3.4',5,6,6'-pentabromo-2,2'-oxydiphenol 1-methyl ether (13), 3,4,4',5,6'-pentabromo-2,2'-oxydiphenol 1,1'-dimethyl ether (14) and 3,4',5,6'-tetrabromo-2,2'-oxydiphenol 1'-methyl ether (15).The structure of the first member of this series is determined by a new method involving 13C spin-lattice relaxation data. The contributions of nearby hydrogens to quaternary carbon spin-lattice relaxation times are calculated for various possible structures and compared with the experimental data, leading to an unequivocal proof of structure. The structures of the remaining compounds in the series are established principally by analysis of 13C chemical shifts and 13C-1H coupling constants. 相似文献
6.
Ultrahigh specific surface area muscovite with different ions at the surface (Li+, Na+, K+, Rb+, Cs+, Ca2+, Sr2+, Ba2+, Cu2+) was treated with aqueous solutions of low molecular weight crown ethers and polymers with crown ether substituents. The adsorption was assessed by UV analysis of the supernatant solution, and with TGA and IR spectroscopy of the mica solids. In contrast to other layered silicates, the low molecular weight crown ethers show no affinity to any of the muscovite surfaces. The polymers can adsorb, however, depending on the type of surface cation. The results indicate that at least some of the crown ether moieties are complexed to surface cations and that the diameter of the ions at the surface plays an important role in the adsorption process. 相似文献
7.
E. Yu. Kulygina V. I. Vetrogon S. S. Basok N. G. Luk’yanenko 《Russian Journal of General Chemistry》2005,75(4):628-631
The stability constants of complexes of 12-, 15-, and 18-membered diaza crown ethers, N,N′-dimethyl diaza crown ethers, and N,N′-bis(2-hydroxyethyl) diaza crown ethers with alkali and alkaline-earth metal ions in 95% aqueous methanol at 25°C were determined. The stability of the complexes of unsubstituted diaza crown ethers with alkali metal cations is low, probably because of stabilization of the exo,exo conformation of the ligands due to interaction of the nitrogen lone electron pairs with the solvent. The complexes with the double-charged cations are appreciably more stable. N,N′-Dimethyl diaza crown ethers form stable complexes with all the ions studied. As compared to the dimethyl derivatives, N,N′-bis(2-hydroxyethyl) diaza crown ethers form more stable complexes with the Na+, K+, Ca2+, Sr2+, and Ba2+ ions, which is due to participation of the side hydroxyethyl groups in the coordination.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 4, 2005, pp. 665–669.Original Russian Text Copyright © 2005 by Kulygina, Vetrogon, Basok, Luk’yanenko. 相似文献
8.
D. R. Sharafutdinova R. R. Fayzullin O. V. Bazanova Z. A. Bredikhina I. H. Rizvanov A. A. Bredikhin 《Journal of Analytical Chemistry》2013,68(14):1178-1182
Mixtures of unsubstituted 15-crown-5 and its analogues containing ortho- and para-methoxyphenoxymethyl substituents with sodium salts were investigated by matrix assisted laser desorption/ionization (MALDI) mass spectrometry. Peaks of cationized molecules [M+Na]+ and cluster ions [2M+2Na+An]+, where M is the crown ether molecule and An is monobasic acid anion, were observed in the mass spectra. It was shown that an increase of the shielding degree of the sodium cation in complexes with crown ethers, i.e., the lariat effect, led to a significant decrease in the intensity of peaks of the cluster ions. 相似文献
9.
1,1-Bis-(3',5'-di-t-butylphenyl)-2-benzenesulphonyl-hydrazine 11 and the corresponding 2-picryl-hydrazine 13 were synthesized. Oxidation of 11 afforded the stable hydrazyl 12 whose ESR spectrum could be simulated in terms of three hyperfine coupling constants. These experimental data leave no alternative but to assign larger proton hyperfine coupling constants to one aryl group in 12 than to the other. This non-equivalence was interpreted in terms of the Linnett theory. The picrylhydrazyl 14 does not give completely resolved ESR spectra. Structures were ascertained by IR, UV-vis, 1H NMR and 13C NMR spectra. 相似文献
10.
The extraction of UO
2
2+
, Am3+, and Th4+ by 1-phenyl-3-methyl-4-benzylpyrazolone with crown ethers was studies using 0.1M (NaClO4) aqueous phase and toluene. The crown ethers were 12C4, 15C5, 18C6, DB18C6 and DCH18C6. The synergic equilibrium constant did not show correlation between the cationic radii and the ether cavity size nor did the values follow a simple order of ether basicity. The ether basicity, steric effects, and the number of ether oxygens bound to the cation are the combined factors which seemingly determine the pattern of M(PMBP)n—CE interaction. 相似文献
11.
Summary Retention of crown ethers in reverse-phase HPLC has been determined by their bonding ability with cations present in the eluent. The dependence of retention of crown ethers on cation concentration exhibits an inflection and makes it possible to calculate stability constant for the crown ether-cation complex. It is shown that in 75% MeOH retention of antitumor antibiotic, actinomycin D, depends on [Na+] and not on [K+] at concentrations of K+ from 5×10–7 to 10–1 mol l–1. Hence, actinomycin D may be classified as an ionophore-antibiotic. 相似文献
12.
《European Polymer Journal》1986,22(2):97-101
Proton-driven cation transport against cation concentration gradient has been investigated using films of polyamic acid 18-crown-6 (1) and polyamide 18-crown-6 (3)/polyamic acid (5) mixtures as the polymeric membrane. Both membrane systems containing the crown ethers were found to act as efficient alkali metal ion pumps. The ion-transportability of the polyamic acid 18-crown-6 membrane decreased in the order K+ > Cs+ > Na+ > Li+, which is reflected in the cation-complexing ability of the 18-crown-6 moiety. The transport selectivity, however, was varied remarkably by the combined use of polyvinylpyrrolidone with (1) and, therefore, by the resulting increase in hydrophilicity of the membrane. The ion-selectivity in the transport through mixed membranes of (3) and (5) was also dependent on the membrane composition. For the proton-driven cation transport two mechanisms are proposed; in one of the transport mechanisms, the carboxylic group cooperates with the crown ether moiety and in the other the carboxylic group participates independently. 相似文献
13.
A. I. Vedernikov S. N. Dmitrieva L. G. Kuz’mina N. A. Kurchavov Yu. A. Strelenko J. A. K. Howard S. P. Gromov 《Russian Chemical Bulletin》2009,58(5):978-1001
Benzoaza-15-crown-5 ethers containing one or two nitrogen atoms in different positions of the macrocycle and bearing different
substituents at these atoms were synthesized. The structures of azacrown ethers and their metal complexes were studied by
X-ray diffraction. The stability constants of the complexes of azacrown ethers with Na+, Ca2+, Ba2+, Ag+, Pb2+, and EtNH3
+ ions were determined by 1H NMR titration in MeCN-d3. In free benzoazacrown ethers containing secondary nitrogen atoms bound to the benzene ring, as well as in N-acetyl derivatives, the N atoms are sp2-hybridized and have a planar geometry. The nitrogen lone pairs on the p orbitals are efficiently conjugated to the benzene
ring or the carbonyl fragment of the acetyl group, which is unfavorable for the complex formation. In addition, the formation
of complexes with benzoazacrown ethers containing secondary nitrogen atoms is hindered because the hydrogen atoms of the NH
groups are directed to the center of the macrocyclic cavity. In benzoazacrown ethers bearing N-alkyl substituents or secondary nitrogen atoms distant from the benzene ring, the N atoms show a substantial contribution
of the sp3-hybridized state and have a pronounced pyramidal configuration, which promotes the complex formation. The lead and calcium
cations form the most stable complexes due to the high affinity of Pb2+ ions for O,N-containing ligands, a high charge density on these ions, and the better correspondence of the cavity size of
the 15-membered macrocycles to the diameter of the Ca2+ ion. An increase in the stability of the complexes is observed mainly in going from monoazacrown ethers to diazacrown ethers
containing identical substituents at the N atoms and in the following series of substituents: C(O)Me < H < Me < CH2CO2Et. In the case of the CH2CO2Et substituents, the carbonyl oxygen atom is also involved in the coordination to the cation. The characteristic features
of the complexing ability of N-alkylbenzomonoaza-15-crown-5 ethers bearing the nitrogen atom conjugated to the benzene ring show that macro-cyclic ligands
having this structure are promising as selective and efficient complexing agents for metal cations. 相似文献
14.
The stability constants and the partial molal volume and isentropic partial molal compressibility changes of complex formation between cations and crown ethers in water at 25°C are presented. The cations involved are Na+, K+, Rb+, Cs+, Ca2+, and Ba2+, and the crown ethers are 12-crown-4, 15-crown-5, and 18-crown-6. Values of V of complex formation have been discussed in terms of two simple models, one based on the scaled particle theory, and the others on the Drude-Nernst continuum model. The results indicate that the charge of the potassium cation in 18-crown-6 is especially well screened from the water. On this basis hydration numbers of complexed cations have been calculated. This shows that the size of the cation compared to the crown ether hole is important for the contacts between complexed cations and water. 相似文献
15.
The rate of the thermal rearrangement of (S) 2 chloromethyl-1-ethylpyrrolidine [(S)-1a] to (R)-3-chloro-1-ethylpiperidine [(R) 2a] has been examined at three temperatures in benzene by PMR and polarimetry. The rearrangement was shown to be completely stereospecific and to obey a simple first order rate law. The calculated Ea ΔH3 and ΔS3 were 22 ± 2 (25°), 21 ± 2.5 (25°) and - 10 ± 2 e.u. (0°K) respectively. The effect of solvents having differing dielectric constants was also studied. A transition state 9'a and an ion pair intermediate 3a are suggested for the rearrangement. The stereochemical course of the reactions of (S)-1a, (R)-2a and (S)-2a with hydroxide and methoxide ions have been shown to be 100% stereospecific with an uncertainty of about 1%. The absolute configurations of all optically active reactants and products [(S)- and (R)-4a, (S)-4b (R)- and (S)-5a, (R)-5b, (S,S')-6a, (S,R')-7a and (R,R')-8a] were established by chemical correlations with known compounds or by ORD and chemical inference. The ring opening of both the primary and secondary aziridinium ion positions of 1-azonia-1-ethylbicyclo [3.1.0]hexane [(S)-3a] by nucleophiles proceeds entirely by SN2 processes. The conversion of (R)-1-ethyl-3-hydroxypiperidine [(R)-5a] to (S)-2a. HCl with thionyl chloride in chloroform proceeds by inversion with 4.8% racemization, whereas the thermal rearrangement of (S)-1a to (R)-2a occurs with complete retention of absolute configuration. 相似文献
16.
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
17.
Some 3',4'-cyclohexa-1',2'-dihydro- and 1',2'-cyclohexa-3',4'-dihydro-3,4,7,8-dibenzocoumarins 2 and 3 were prepared by catalytic condensation between a naphthol and a α-carbethoxy-cis- decalone (?1 or ?2). These compounds, when treated with Pd/C at 260°, undergo, beside aromatization, a complete decarboxylation of the lactone ring. A mechanism, involving H transfer through a π-allylic palladium complex is described. 相似文献
18.
Tsun-Hung Hsiao Tzu-Liang Wu Sandipan Chatterjee Chin-Yi Chiu Hon Man Lee Lorenzo Bettucci Claudio Bianchini Werner Oberhauser 《Journal of organometallic chemistry》2009,694(25):4014-4024
The imidazolium salts 1,1′-dibenzyl-3,3′-propylenediimidazolium dichloride and 1,1′-bis(1-naphthalenemethyl)-3,3′-propylenediimidazolium dichloride have been synthesized and transformed into the corresponding bis(NHC) ligands 1,1′-dibenzyl-3,3′-propylenediimidazol-2-ylidene (L1) and 1,1′-bis(1-naphthalenemethyl)-3,3′-propylenediimidazol-2-ylidene (L2) that have been employed to stabilize the PdII complexes PdCl2(κ2-C,C-L1) (2a) and PdCl2(κ2-C,C-L2) (2b). Both latter complexes together with their known homologous counterparts PdCl2(κ2-C,C-L3) (1a) (L3 = 1,1′-dibenzyl-3,3′-ethylenediimidazol-2-ylidene) and PdCl2(κ2-C,C-L4) (1b) (L4 = 1,1′-bis(1-naphthalenemethyl)-3,3′-ethylenediimidazol-2-ylidene) have been straightforwardly converted into the corresponding palladium acetate compounds Pd(κ1-O-OAc)2(κ2-C,C-L3) (3a) (OAc = acetate), Pd(κ1-O-OAc)2(κ2-C,C-L4) (3b), Pd(κ1-O-OAc)2(κ2-C,C-L1) (4a), and Pd(κ1-O-OAc)2(κ2-C,C-L2) (4b). In addition, the phosphanyl-NHC-modified palladium acetate complex Pd(κ1-O-OAc)2 (κ2-P,C-L5) (6) (L5 = 1-((2-diphenylphosphanyl)methylphenyl)-3-methyl-imidazol-2-ylidene) has been synthesized from corresponding palladium iodide complex PdI2(κ2-P,C-L5) (5). The reaction of the former complex with p-toluenesulfonic acid (p-TsOH) gave the corresponding bis-tosylate complex Pd(OTs)2(κ2-P,C-L5) (7). All new complexes have been characterized by multinuclear NMR spectroscopy and elemental analyses. In addition the solid-state structures of 1b·DMF, 2b·2DMF, 3a, 3b·DMF, 4a, 4b, and 6·CHCl3·2H2O have been determined by single crystal X-ray structure analyses. The palladium acetate complexes 3a/b, 4a/b, and 6 have been employed to catalyze the oxidative homocoupling reaction of terminal alkynes in acetonitrile chemoselectively yielding the corresponding 1,4-di-substituted 1,3-diyne in the presence of p-benzoquinone (BQ). The highest catalytic activity in the presence of BQ has been obtained with 6, while within the series of palladium-bis(NHC) complexes, 4b, featured with a n-propylene-bridge and the bulky N-1-naphthalenemethyl substituents, revealed as the most active compound. Hence, this latter precursor has been employed for analogous coupling reaction carried out in the presence of air pressure instead of BQ, yielding lower substrate conversion when compared to reaction performed in the presence of BQ. The important role of the ancillary ligand acetate in the course of the catalytic coupling reaction has been proved by variable-temperature NMR studies carried out with 6 and 7′ under catalytic reaction conditions. 相似文献
19.
Duygu Sahin Zeliha Hayvali 《Journal of inclusion phenomena and macrocyclic chemistry》2012,72(3-4):289-297
New benzo-15-crown-5 derivatives containing nitro, amine and imine groups were prepared. Nitro compound (1) was prepared after the reaction?4′,5′-bis(bromethyl)benzo-15-crown-5 and o-nitrophenol in the presence of NaOH. After reduction process by using hydrazine hydrate and Pd/C amine compound (2) was formed. New crown ether imine compounds (3–5) were synthesized by the condensation of corresponding crown ether diamine (2) with salicylaldehyde derivatives. Sodium complexes of the crown compounds (1a–5a) form crystalline 1:1 (Na+: ligand) complexes with sodium perchlorate. Nickel(II) complexes (3b–5b) with 1:1 (Ni2+:ligand) stoichiometries were also been synthesized from the Schiff bases (3–5). The results indicated that the Schiff base ligands coordinated through the azomethine nitrogen and phenolic oxygen. The extraction ability of compounds (1, 3, 4 and 5) were also evaluated in chloroform by using several alkali and transition metal picrates such as Li+, Na+, K+, Cr3+, Mn2+, Ni2+, Cu2+, Zn2+ and Pb2+. 相似文献
20.
Ralf Smounig C. Oliver Kappe Curt Wentrup Gert Kollenz 《Monatshefte für Chemie / Chemical Monthly》2003,134(4):509-518
Summary. Several new lariat-crown ethers bearing either bridged bisdioxine or tetraoxaadamantane units as chiral substituents are
prepared by reacting the corresponding amino-crown ether derivatives with the dimeric α-oxoketene, the latter obtained by
flash vacuum pyrolysis of a furan-2,3-dione precursor. Complexation properties towards differently charged metal ions are
investigated by 1H NMR titration to obtain complexation constants (K
c
-values for potassium/sodium rhodanides: 480–1100 mol dm−3), as well as extraction experiments to explore the metal ion transportation abilities of the new lariat crown derivatives.
In particular, a significantly increased ability to transport metal ions from water into chloroform was found with spherical
tetraoxaadamantyl derivatives when compared with the free amino-benzocrown ethers.
Corresponding author. E-mail: kollenz@kfunigraz.ac.at
Received July 5, 2002; accepted July 19, 2002 相似文献