Hydration effect on the ion-pair extraction of lithium picrate by hydrophobic benzo-15-crown-5 ether into various less-polar diluents.

The ion-pair formation constant (K(MLA)(0) in mol(-1) dm(3)) for Li(B15C5)(+) with a picrate ion (Pic(-)) in water was determined by potentiometry with a K(+)-selective electrode at 25 degrees C and an ionic strength of 0, where B15C5 denotes benzo-15-crown-5 ether. Using the concentration equilibrium constants, K(MLA), estimated from this value, the extraction constants (mol(-2) dm(6) unit) of about ten diluents were re-calculated from previously reported extraction data. Also, the distribution constants of an ion-pair complex, Li(B15C5)Pic, between water and the diluents were re-estimated. A disagreement in the determined K(MLA) value between a solvent-extraction method and potentiometry was explained in terms of the Scatchard-Hildebrand equation; it came from the fact that the hydration of Li(I) in Li(B15C5)Pic was larger than that of free B15C5 in water. Then, the previously determined value by the former method was re-estimated using the potentiometric K(MLA) value.     

Complexation of tetrafluoroboric acid with benzo-15-crown-5

Russian Chemical Bulletin - The extraction of tetrafluoroboric acid from aqueous solutions to a solution of benzo-15-crown-5 (B15С5, 1 mol L-1) in chloroform is shown to occur due to...     

ESR studies of the alkali metal complexes of verdazyl-labeled benzo-15-crown-5

A verdazyl derivative of benzo-15-crown-5 ($\text{1}$) has been prepared, and the complex formation between the spin labeled crown ether ($\text{1}$) and the alkali metal salts has been studied by ESR spectroscopy.     

Photophysical and antimicrobial properties of new double-armed benzo-15-crown-5 ligands and complexes

Research on Chemical Intermediates - New double-armed crown ether ligands linked to pyridine derivatives have been synthesized and characterized. These macrocyclic ligands (1–5) have been...     

苯并-15-冠-5和二苯并-18-冠-6萃取分离铟(III)的研究

本文用斜率法、饱和法以及通过与萃取合物相对应的冠醚配合物晶体的制备及其性质研究, 探讨了In^3^+的萃取机理, 测定并计算了表观萃取平衡常数, 将此萃取体系应用于铟和某些体系应用于铟和某些金属离子的萃取分离, 亦获得较好的结果.     

Coprecipitation of 15-crown-5 ether complexes of lead and strontium with tungstosilicic acid

Lead as well as strontium form low solubility compounds of composition (ML₂)₂A·nH₂O, (M=Pb²⁺, Sr²⁺), in the presence of 15-crown-5 (L) and tungstosilicic acid (H₄A) in acid media as found by radiometric precipitation titration. “Sandwich” structure of crown-ether complexes of lead and strontium could be expected due to the small size of cavity of 15-crown-5. Coprecipitation of PbL_2/su2+ with crown complexes of strontium cation after adding tungstosilicic acid was studied in 0.01 mol·dm⁻³ HNO₃. A significant influence of H⁺ cation in 1 mol·dm⁻³ HNO₃ on coprecipitation of lead was observed. Formation of HL⁺ complexes by protonisation of 15-crown-5 competes to the formation of ML₂ ²⁺ complexes (approximately twenty percent of 15-crown-5 are used for creation of HL⁺ complexes). Formation of low solubility salts was utilised for separation of lead from strontium in 0.01 mol·dm⁻³ HNO₃. The ratio of constant stability of lead and strontium β‘ with 15-crown-5 in 0.01 mol·dm⁻³ HNO₃ was calculated. The separation factor S(Pb/Sr) depends on the ratio of stability constants β_PbL2/β_SrL2 The precipitation method can be used for separation of metals with high constant stability with crown ethers from solutions containing other metals in the case of gradual addition of crown.     

Molecular structures of compounds formed by benzo-15-crown-5 with calcium salts

X-ray structural and spectroscopic results are given on the compound formed by benzo-15-crown-5 with calcium perchlorate, Ca(ClO₄)₂·C₁₄H₂₀O₅·2H₂O; the combination does not involve any substantial change in the dihedral angles in the macrocycle, as the coordination sphere is constructed as a result of supplementing the positions occupied by the macrocycle oxygen atoms with three other atoms (oxygen atoms from the perchlorate group and two water molecules). The results are compared with published data on the structures of the compounds formed by benzo-15-crown-5 with NaClO₄, Mg(NCS)₂, CuCl₂, Ca(NCS)₂ and Ca(3,5-dinitrobenzoate)₂.Translated from Teoreticheskaya i Éksperimental' naya Khimiya, Vol. 24, No. 2, pp. 242–247, March–April 1988.     

Radiation-chemical changes of benzo-15-crown-5 in chloroform

NMR, IR and MS were used for identification of major products of radiolysis of benzo-15-crown-5 in chloroform. The crown ether exhibits high affinity towards inorganic products of radiolysis of chloroform resulting in the formation of complexes.     

Complexes of benzo-15-crown-5 with protonated primary amines and diamines

Three complexes of benzo-15-crown-5 (B15C5) with protonated primary amines [PhCH₂NH₃(B15C5)](ClO₄), [p-C₆H₄(CH₂NH₃)₂(B15C5)₂](ClO₄)₂, and [(CH₂)₄(NH₃)₂(B15C5)₂](SCN)₂ were isolated and studied in acetonitrile solutions by NMR, and in the solid state by X-ray crystallography. In all complexes, one B15C5 molecule was bound with each R-NH₃⁺ moiety with characteristic small separation of 1.84-1.86 Å between the nitrogen of the R-NH₃⁺ group and the O₅ mean plane of the crown residue. No sandwich-type complexes with a 1:2 R-NH₃⁺/B15C5 stoichiometry were observed. Binding affinities of B15C5 in acetonitrile were similar for all ammonium cations studied: K₁=550±10 M⁻¹ for [PhCH₂NH₃]⁺; K₁=1100±100 and K₂=400±30 M⁻¹ for [p-C₆H₄(CH₂NH₃)₂]²⁺; and K₁=1100±100 and K₂=300±30 M⁻¹ for [H₃N(CH₂)₄NH₃]²⁺. The complexation is primarily enthalpy-driven (ΔH°=−4.9±0.5 kcal/mol, ΔS°=−3.8±1.0 eu for PhCH₂NH₃⁺-B15C5), as determined by variable temperature ¹H NMR titrations.     

4’-acetyl benzo-15-crown-5 2-naphthyloxyacetyl hydrazone

Aryloxyacetic acid and its derivatives often possess many important biological activities. Some of them are used as herbicides and plant-growth regulators. In continuation of our previous work on synthesis and biological activities1,2,3, we decided to design series of compounds containing the aryloxyacetyl group and crown ether to study the variation of bioactivities and the effect of the substituents on the ability of the crown ether to bind metal ions4,5. Recently, we determined related crys…     

Thermochemistry of interactions of Na+ with benzo-15-crown-5 ether in acetonitrile-water mixtures at 298.15 K

Enthalpies of dissolution of benzo-15-crown-5 ether (B15C5) in mixtures of acetonitrile with water and in solutions of NaI and NaBPh₄ (I=0.05 mol dm^–3) in these mixtures were measured at 298.15 K. From the obtained results and appropriate literature data, the thermodynamic functions of B15C5/Na⁺ complex formation in acetonitrile-water mixtures were determined. The enthalpies of transfer of the complex B15C5/Na⁺ from pure acetonitrile to the examined mixtures were calculated and are discussed.     

Thermal decomposition of metal complexes V. Lanthanide(III) complexes of benzo-15-crown-5

Thermal dissociation reactions of lanthanide(III) nitrates and thiocyanates solid complexes of the cyclic polyether benzo-15-crown-5 were studied in dynamic atmosphere of dry nitrogen and under reduced pressure (5·10^?2 mm Hg). The complexes of lanthanide nitrates undergo dissociation with ligand decomposition while from those of lanthanide thiocyanates the ligand is released undecomposed. Values of enthalpy change and “activation energy” for the dissociation reactions of the complexes with lanthanide thiocyanate were obtained and briefly discussed.     

A green strategy for lithium isotopes separation by using mesoporous silica materials doped with ionic liquids and benzo-15-crown-5

Three new mesoporous silica materials IL15SGs (HF15SG, TF15SG and DF15SG) doped with benzo-15-crown-5 and imidazolium based ionic liquids (C₈mim⁺PF₆ ^?, C₈mim⁺BF₄ ^? or C₈mim⁺NTf ₂ ^? ) have been prepared by a simple approach to separating lithium isotopes. The formed mesoporous structures of silica gels have been confirmed by transmission electron microscopy image and N₂ gas adsorption–desorption isotherm. Imidazolium ionic liquids acted as templates to prepare mesoporous materials, additives to stabilize extractant within silica gel, and synergetic agents to separate the lithium isotopes. Factors such as lithium salt concentration, initial pH, counter anion of lithium salt, extraction time, and temperature on the lithium isotopes separation were examined. Under optimized conditions, the extraction efficiency of HF15SG, TF15SG and DF15SG were found to be 11.43, 10.59 and 13.07 %, respectively. The heavier isotope ⁷Li was concentrated in the solution phase while the lighter isotope ⁶Li was enriched in the gel phase. The solid–liquid extraction maximum single-stage isotopes separation factor of ⁶Li–⁷Li in the solid–liquid extraction was up to 1.046 ± 0.002. X-ray crystal structure analysis indicated that the lithium salt was extracted into the solid phase with crown ether forming [(Li_0.5)₂(B15)₂(H₂O)]⁺ complexes. IL15SGs were also easily regenerated by stripping with 20 mmol L^?1 HCl and reused in the consecutive removal of lithium ion in five cycles.     

f-Element/crown ether complexes: 21. Conformational changes in metal complexed versus hydrogen bonded benzo-15-crown-5 in the structure of [Y(OH2)3(NCMe)-(benzo-15-crown-5)][ClO4]3·benzo-15-crown-5·CH3CN

Crystalline [Y(OH₂)₃(NCMe)(benzo-15-crown-5)][ClO₄]₃·benzo-15-crown-5-CH₃CN can be obtained by slowly cooling a reaction mixture of Y(ClO₄)₃·n H₂O with benzo-15-crown-5 in a solution of acetonitrile and methanol (3 : 1) from 60°C to room temperature. The crystal structure of this complex has been determined at –150 and 20°C. The complex is triclinic,P . At –150°C the cell parameters area = 11.986(4),b = 12.071(7),c = 16.364(5) Å, = 93.56(3), = 98.68(3), = 109.68(4)°, vol = 2187 ų, andD _calc = 1.61 g cm^–3 forZ = 2 formula units. 3633 independently observed [F _o 5(F _o)] reflections were used in the final least-squares refinement leading to an agreement index ofR = 0.048. The Y(III) ion coordination geometry approximates a tricapped trigonal prism with three water molecules and three benzo-15-crown-5 oxygen atoms forming the prism, with the two remaining benzo-15-crown-5 oxygen atoms and the acetonitrile molecule completing the coordination as capping atoms. The three water molecules hydrogen bond a second crown ether molecule and two of the perchlorate anions. The two acetonitrile molecules have contacts with perchlorate oxygen atoms close enough for some weak interaction. One perchlorate is ordered, one is partially disordered as is the coordinated solvent molecule, and the third anion is totally disordered. The two unique crown ether molecules have distinctively different conformations.For Part 20, see reference [1].     

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.     

Syntheses and spectroscopic characterization of double-armed benzo-15-crown-5 derivatives and their sodium and potassium complexes

A series of new benzo-15-crown-5 derivatives (1–6) containing formyl and imine groups were prepared. New formyl crown ethers (1 and 2) were prepared by reaction of 4′,5′-bis(bromomethyl)benzo-15-crown-5 with 2-hydroxy-3-methoxybenzaldehyde (o-vanillin) and 2-hydroxy-5-methoxybenzaldehyde in the presence of NaOH. New Schiff bases (3–6) were synthesized by the condensation of corresponding aldehydes with 1,3-diaminopropane and 1,4-diaminobutane. Sodium and potassium complexes (1a–6a and 1b–6b) of the crown compounds forming crystalline complexes of 1:1 (Na⁺:ligand) and 1:2 (K⁺:ligand) stoichiometries were also synthesized. The structures of the aldehydes 1 and 2, imines 3–6 and complexes (1a–3a and 1b–3b) were confirmed on the basis of elemental analyses, IR, ¹H- and ¹³C-NMR, and mass spectroscopy.