Chromogenic benzo- and monoaza-12-crown-4, 13-crown-4 and 14-crown-4 lithium-selective crown ethers

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.     

Synthesis of bis-benzo-15-crown-5 and bis-benzo-18-crown-6-ethers

Bis-crown ethers with benzo-15-crown-5 and benzo-18-crown-6 moieties bridged by different length of polyethylene ethers have been successfully synthesized.     

Recyclization of tetranitrodibenzo-18-crown-6 and tetranitrodibenzo-24-crown-8 into monobenzocrown ethers

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.     

Molecular structure and properties of benzo-12-crown-4 and acetylbenzo-12-crown-4

Conclusion Significant differences were found in the conformational states of B12C4 and acB12C4 in solution, which are capable of affecting the complexation properties and physiological activity of these polydentate ligands.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1051–1055, May, 1988.     

Temperature study of the intramolecular interactions in 15-crown-5 and 18-crown-6

The Raman CH stretching spectra of 15-crown-5 and 18-crown-6 in water solution are studied in the temperature interval 5–80°C. The method of Fourier deconvolution is applied to resolve the overlapped bands in the complex isotropic and anisotropic spectra. The intramolecular coupling constants and the unperturbed CH stretching frequency are calculated for all studied temperatures. The temperature dependencies are discussed in comparison with the temperature dependencies for 12-crown-4 obtained previously.     

A stereoselective reduction of dibenzo-18-crown-6 ether to dicyclohexyl-18-crown-6 ether

Dibenzo-18-crown-6 ether is reduced to dicyclohexano-18-crown-6 ether under very mild conditions (room temperature and atmospheric hydrogen pressure) in the presence of rhodium salt and phase-transfer reagents. Control over the stereoselectivity of the reduction can be achieved through the proper choice of the phase-transfer agent. Moreover, at higher pressure, the stereoselectivity can be increased up to a 95/5 ratio of the syn/anti isomers of the dicyclohexano-18-crown-6 ether.     

Cation selectivity of 13-crown-4 and bis(13-crown-4) derivatives

The cation selectivity of liquid-membrane electrodes based on 18 derivatives of 13- crown-4 and bis(13-crown-4) is reported. When these compounds are dissolved in 1,2-dichlorobenzene, the electrodes exhibit MgCl⁺ selectivity which depends on the nature of the bonds connecting the crown ether rings.     

The effect of properties of water-organic solvent mixtures on the solvation enthalpy of 12-crown-4, 15-crown-5, 18-crown-6 and benzo-15-crown-5 ethers at 298.15 K

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.     

Experimental, Theoretical and Biological Activity Study on the Acyl-Substituted Benzo-18-crown-6, Dibenzo-18-crown-6 and Dibenzo-24-crown-8

Hexadecanoyl, dihexadecanoyl, dioctadecaneoyl, di-10-undecenoyl, and dicis-9-octadecenoyl derivatives of benzo[18]crown-6, dibenzo[18]crown-6 and dibenzo[24]-8 were synthesized by the condensation of carboxylic acids (palmitic, stearic, oleic and undecenoic acid) with benzo and dibenzo crown ethers in the presence of zinc chloride. The extraction equilibrium constants of such macrocyclic ethers with long side chains were estimated using chloroform/water and dichloromethane/water membranes transfer of Na-PAR (4-(2-pyridylazo)-resorcinol mono sodium monohydrate) with UV–Vis spectroscopy. It was found that they were in the range of 10.88–11.71 in dichloromethane and 8.04–11.77 in chloroform. These results actually show that the Na+ binding effect of macrocyclic ethers depends on the type and the length of side chains. The geometrical properties of the molecules were studied employing semi-empirical calculations by simulated annealing technique. The frontier molecular orbital energies and dipole moments were also examined. The biological activity results showed that the synthesized crown ethers have no activity against the studied microorganisms.     

Hydration to benzo-15-crown-5, benzo-18-crown-6 and the benzo-18-crown-6-potassium ion complex in the low-polar organic solvents.

The coextraction of water with benzo-15-crown-5 (B1SC5), benzo-18-crown-6 (B18C6) and the B18C6-K+ complex into seven low-polar solvents, i.e., carbon tetrachloride (CTC), chloroform (CF), dichloromethane (DCM), 1,2-dichloroethane (1,2-DCE), benzene (BZ), chlorobenzene (CB) and o-dichlorobenzene (o-DCB), has been investigated. The mean hydration number, nH2O, of these solutes in the water-saturated organic solvents was determined. There is a trend that the nH2O values for any solutes increase with increasing the water concentration in the solvents. Those of B18C6 and B15C5 converge at almost 0.8 for B18C6 and 0.4 - 0.5 for B15C5 in the solvents with the relatively high water concentration, i.e., CF, 1,2-DCE, DCM, and nitorobenzene (NB). The nH2O value of B15C5 is about one-half of that of B18C6 for a given organic solvent. The dominant species of the B18C6-K+ complex in these solvents is non-hydrated. From these results, the hydration equilibrium constants, KH2O, in the organic solvents were estimated.     

The syntheses and complexing properties of oxo-12-crown-3 and oxo-18-crown-5

Derivatives of 12-crown-4 and 18-crown-6 in which one of the ethereal oxygens is replaced by a CO group have been synthesised and their complexing abilities towards both metal and organic cations have been assessed. Variable temperature ¹H decoupled ¹³C n.m.r. spectroscopy reveals the presence of anisometric species in solution when a $\text{1}$:1 complex is formed between oxo-18-crown-5 and (S)-PhCHMeNH₃⁺ClO₄.     

Conformational analysis of 12-crown-4

An extensive conformational analysis of 12-crown-4 was performed. A new method for the generation of the approximate geometry was proposed and applied. More than 100 new low energy conformations of the compound were calculated.     

Twelve-membered crown ethers: Crystal structures of benzo-12-crown-4 and naphtho-12-crown-4

The crystal structures of two 12-membered crown ethers, benzo-12-crown-4 (1) and naphtho-12-crown-4 (2), have been determined by X-ray analysis. Both structures are molecular. Compound1 is monoclonic,P2₁/b,a=8.466(3),b=8.019(3),c=33.590(10) Å, =90.99(3)^o. The unit cell contains two crystallographically independent molecules of1 with similar conformations. Compound2 is also monoclinic,P2₁/a,a=24.148(8),b=14.535(4),c=7.987(5) Å, =102.87(2)^o. Two independent molecules in the unit cell have significantly different conformations. Supplementary data relating to this publication have been deposited with the British Library as Supplementary Publication No. SUP 82145 (19 pages).     

Raman study of 12-crown-4, 15-crown-5, 18-crown-6 and their complexation with metal cations using Fourier deconvolution of CH stretching spectra

The Raman CH stretching spectra of 12-crown-4, 15-crown-5 and 18-crown-6 and their complexes with some metal cations— Li⁺, Na⁺, K⁺ and Cu⁺ in water solutions are studied. For the first time Fourier deconvolution is applied to resolve the overlapped components in the corresponding isotropic and anisotropic spectra. A model is introduced which explains the variety of components in the spectra by means of splitting of the unperturbed CH stretching frequency owing to intramolecular interactions and Fermi resonance. The coupling constants of these interactions, as well as all parameters according to the model, are calculated for studied crowns and their complexes. The differences in the number and intensity of the resolved components in the spectra of the various crowns are explained with the corresponding differences in the coupling constants and model parameters. It is established that complexation leads to some increase in the unperturbed stretching frequency, probably owing to the increase in strain of the crown molecule. It is concluded that 15-crown-5 forms 2:1 and 1:1 complexes with K⁺ and Na⁺ cations respectively and 12-crown-4 forms a 2:1 complex with the Na⁺ cation.     

氯甲基化-二苯并-14-冠4的合成

以邻苯二酚和1,3-二溴丙烷为原料,高产率(50.24％)地制备了二苯并-14-冠-4(1);1在多聚甲醛和浓盐酸存在下与四丁基溴化胺反应,合成了氯甲基化-二苯并-14-冠4,其结构经1H NMR和IR表征.     

二环己基并18冠6的制备方法

二苯并-18－冠-6;二环己基并18冠6的制备方法