Tactic poly(crown ether)s with pendant benzocrown ethers

Summary Tactic and atactic poly(crown ether)s, poly(methacryloyloxymethylbenzo-15-crown-5), were synthesized by polymer reaction of the respective poly(methacrylic acid) with chloromethylbenzo-15-crown-5 and radical polymerization of methacryloyloxymethylbenzo-15-crown-5. By solvent extraction of alkali metal picrates with these poly(crown ether)s, the isotactic poly(crown ether) was found to be a little more selective for K⁺ and Rb⁺ than the syndiotactic and atactic ones.     

Liquid–Liquid Extraction of Alkali Metal Cations by Calix[4]crowns with Pendant Groups

Abstract

The selective liquid–liquid extraction of alkali metal cations from the aqueous phase to the organic phase was carried out by using calix[4]crowns bearing two pendant groups with donor sites. It was found that calix[4]crown‐4 and calix[4]crown‐5 extractants with two pendant groups exhibit higher extraction efficiency than the parent compounds and possess obvious selectivity for Na⁺ and K⁺, respectively.     

RADIUM SEPARATION THROUGH COMPLEXATION BY AQUEOUS CROWN ETHERS AND ION EXCHANGE OR SOLVENT EXTRACTION

ABSTRACT

The effect of three water-soluble, unsubstituted crown ethers (15-crown-5 (15C5), 18-crown-6 (18C6) and 21-erown-7 (21C7) on the uptake of Ca, Sr, Ba and Ra cations by a sulfonic acid cation exchange resin, and on the extraction of the same cations by xylene solutions of dinonylnaphthalenesulfonic acid (HDNNS) from aqueous hydrochloric acid solutions has been investigated. The crown ethers enhance the sorption of the larger cations by the ion exchange resin, thereby improving the resin selectivity over calcium, a result of a synergistic interaction between the crown ether and the ionic functional groups of the resin. Similarly, the extraction of the larger alkaline earth cations into. xylene by HDNNS is strongly synergized by the presence of the crown ethers in the aqueous phase. Promising results for intra-Group IIa cation separations have been obtained using each of the three crown ethers as the aqueous ligands and the sulfonic acid cation exchange resin. Even greater separation factors for the radium - calcium couple have been measured with the crown-ethers and HDNNS solutions in the solvent extraction mode. The application of the uptake and extraction results to the development of radium separation schemes it discussed and a possible flowchart for the determination of ²²⁶Ra/²²⁸Ra in natural waters is presented.

     

EFFECTS OF STRUCTURAL VARIATION WITHIN PROTON-IONIZABLE CROWN ETHERS UPON THE SELECTIVITY AND EFFICIENCY OF SOLVENT EXTRACTION OF ALKALI METAL AND ALKALINE EARTH CATIONS

Lipophilic crown ethers with pendant proton-ionizable groups are novel complexing agents for use in solvent extraction of alkali metal and alkaline earth cations. A variety of crown carboxylic acids, crown phosphonic acid monoesters, and crown phosphonic acids have been synthesized to probe the effect of structural variation within the complexing agent upon selectivity and efficiency in solvent extraction. Synthetic routes to these novel extractants and results from competitive solvent extractions of alkali metal cations and of alkaline earth cations from aqueous solutions into chloroform are summarized     

Evaluation of Transport Capacity through Liquid Membranes of Some Crown Ether‐Siloxane Copolymers

The complexation ability of some linear crown ether‐siloxane copolymers of ester or amide type with cations as K⁺ and NH₄⁺ was investigated spectrophotometrically in order to select the polysiloxane receptors that achieve good ion transport ability by bulk liquid membrane systems. The transport properties of the potassium picrate through a liquid membrane using siloxane‐crown ether polyamide as carrier were discussed.     

The synthesis and complexation study of some novel 3-methoxyphenyl chromenone crown ethers using conductometry

7,8-Dihydroxy-3-(3,4-dimethoxyphenyl)-2H-chromenones, 7,8-dihydroxy-3-(3,5-dimethoxyphenyl)-2H-chromenones and 7,8-dihydroxy-3-(3,4,5-trimethoxyphenyl)-2H-chromenones, o-dihydroxy-3-methoxyphenylcoumarins, were prepared from 2,3,4-trihydroxybenzaldehyde and corresponding methoxyphenylacetic acid in NaOAc/Ac₂O, respectively. 3-Methoxyphenyl-7,8-dihydroxy-2H-chromenone reacted with the polyethylene glycol ditosylate or dichloride in CH₃CN/alkali carbonate to afford [12]crown-4, [15]crown-5 and [18]crown-6-chromonones.The chromatographically purified novel chromenone crown ethers were identified with IR, ¹H NMR, ¹³C NMR and low and high resolution mass spectroscopy and elemental analysis.Stability constants for the 1:1 complexes of Na⁺ and K⁺ with different substituted methoxyphenyl derivatives of coumarino[12]crown-4, coumarino[15]crown-5 and coumarino[18]crown-6 (5a–5i) have been determined by conductometry at 25 °C in a binary solvent, dioxane/water. For all the coumarino crown ether derivatives, the stability constant decreases for K⁺ ion compared to Na⁺ ion.The selectivity sequence of these crown ethers in dioxane/water has showed an irregular order with respect to their cavity size.     

SURVEYING THE EXTRACTION OF CESIUM NITRATE BY 1,3-ALTERNATECALIX[4]ARENE CROWN-6 ETHERS IN 1,2-DICHLOROETHANE

ABSTRACT

The extraction of cesium nitrate from a mixture of alkali metal nitrates by calix7lsqb;4]arene crown-6 ethers in 1,2-dichloroethane diluent has been surveyed at 25 °C. The results reveal that smaller substituents (but larger than C₂,) at the phenolic positions of the calixarene opposite the crown ether increase both the extraction efficiency and the cesium selectivity. Benzo substituents on the crown ether tend to decrease extraction strength while increasing cesium-to-sodium selectivity. Conversely, a cyclohexano group on the crown ether has a negative impact on both extraction strength and selectivity.     

Binding of the cationic fluorophore Auramine-0 to neutral and charged poly(vinylbenzo-18-crown-6) in water

Summary The cationic fluorophore Auramine-0 strongly interacts with poly(vinylbenzo-18-crown-6), a polymer which in water behaves as a typical polysoap. The intrinsic binding constant at 25°C was found to be 2.2 × 10⁴ M^–1. The binding can be modified by adding crown ether-complexable cations such as K⁺ or Cs⁺. Complexation converts the neutral polycrown ether into a polycation causing repulsion of the cationic fluorophore and a decrease in the observed fluorescence. There is some indication that the cation of the dye specifically interacts with a crown ligand.     

Ligands for selective metal ion extraction: A molecular modeling approach

We present a density functional theory (DFT) based study on interaction of alkali metal cations (Li⁺ and Na⁺) with macrocyclic crown ethers of different ring sizes. The minimum energy structures, binding energies, and binding enthalpies of crown ether–cation complexes have been determined with a correlated hybrid density functional, namely Becke’s three-parameter functional, B3LYP using a split valence basis function, 6-311++G(d, p). Geometry optimizations for all the crown ether–cation complexes were carried out with several initial guess structures based on semi-empirical PM3 optimized results. For both metal ions, the calculated values of binding energy and binding enthalpy increase with the increase in size of the crown ether ring, i.e. with the increase in the number of donor oxygen atoms in crown ether. The calculated values of gas phase binding energy for lithium ions are always higher than those for sodium ions in the case of all macrocyclic crown ethers studied at present. The calculated values of binding enthalpy are in good agreement with the reported experimental data.     

Ion-Pair Sorption of Alkali Metal Chlorides by Crown Ether Carboxamide Resins

Abstract

Ten crown ether carboxamide resins are prepared by condensation polymerization of N,N-dialkyl sym-(R)dibenzo-16-crown-5-oxyacetamide monomers with formaldehyde in formic acid. Competitive ion-pair sorption of alkali metal chlorides from aqueous methanol solutions by these novel resins reveals that both sorption selectivity and efficiency are influenced by: 1) the conformational positioning of the pendant carboxamide group with respect to the crown ether cavity; 2) the length of the N,N-dialkyl chains on the pendant carboxamide group; 3) the methanol content of the aqueous methanol solution; 4) the concentration of alkali metal chlorides in the sample solution; and 5) the temperature of the sample solution. The highest sorption efficiency and Na⁺ selectivity are obtained for a resin prepared from N.N-dibutyl sym-(propyl)dibenzo-16-crown-5-oxacetamide monomer in which the geminal propyl group orients the carboxamide-containing side arm over the crown ether cavity. Lengthening the alkyl chains in the carboxamide group is detrimental to both sorption efficiency and selectivity. A very sharp response of alkali metal chloride sorption to the methanol content of the sample solution is noted for the crown ether resins which possess preorganized carboxamide side arms.     

Immobilized resins and liquid extractants for potassium extraction from concentrated brines

Extraction of potassium ions from concentrated chloride solutions of alkali and alkaline-earth cations with Cyanex^® 301 [bis(2,4,4-trimethylpentyl)dithiophosphinic acid] and a crown ether has been studied. The extractant was used in toluene solution or supported on a styrene-divinylbenzene resin (1.5 % crosslinked) and showed synergistic behaviour and high preference for potassium over sodium, magnesium and calcium.     

Modification of poly acrylic acid using calix[4]arene derivative for the adsorption of toxic heavy metals

Poly acrylic acid (PAA) was grafted with p‐t‐butyl calix[4]arene diamine (distal cone) (2) to adsorb toxic heavy metal and alkali metal cations. The grafting method includes the amidation reaction of PAA with calixarene diamine derivative 2 which was carried out in N,N‐dimethylformamide (DMF) and N–methyl‐2‐pyrrolidone (NMP) as solvents. The modified PAAs (PAA‐C1 and PAA‐C2) were characterized by FTIR, ¹H‐NMR, thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). PAA‐C1 and PAA‐C2 were used to evaluate the sorption properties of some toxic heavy metal cations (Co²⁺, Cu²⁺, Cd²⁺, Hg²⁺), alkali metal cations (Na⁺, K⁺, Cs⁺), and Ag⁺. Results showed that the modified PAAs were good sorbents for heavy metal and alkali metal cations. The main goal of this project is to design hydrophobically modified PAA that is suitable for ion selective membranes and chemical sensor devices for adsorption of toxic heavy metals. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

THE SYNERGISTIC SOLVENT EXTRACTION OF RADIUM FROM ALKALINE NITRATE MEDIA BY DICYCLOHEXANO-21-CROWN-7 COMBINED WITH 2-METHYL-2-HEPTYL NONANOIC ACID EQUtUBRIUM REACTIONS AND METAL ION COMPETITION∗

The equilibria in the solvent extraction of radium from aqueous sodium nitrate/sodium hydroxide solutions by toluene solutions of dicyclohexano-21-crown-7 (DC21C7). 2-methyl-2-heptylnonanioc acid (HMHN). and mixtures of the two reagents are examined. The mixed reagents are synergistic in the extraction of radium and selective for radium over other alkali and alkaline earth elements. The dependencies of the extraction on pH and reagent concentration were utilized in computer modeling to estimate the stochiometry of the extracted complexes and equilibria involved the extraction. Three organic-phase species were identified in the extraction under basic (pH 11-13) conditions. With A = MHN^?. B = DC21C7 and assuming NaA is a 10-fold aggregate they are. RaA₂B.NaA. Log K = 3.57: RaA NaA. Log K = 0.99: and B 2NaA. Log K = ? 0.41. The effect of the presence of various concentrations of sodium     

Solvent Extraction of Alkali Metal Cations from Aqueous Solutions by Crown Ether Carboxylic Acids

Abstract

Competitive solvent extractions of alkali metal cations from aqueous solutions by the crown ether carboxylic acids sym-dibenzo-13-crown-4-oxyacetic acid, 2; sym-dibenzo-19-crown-6-oxyacetic acid, 3, and sym-dibenzo-14-crown-4-oxyacetic acid, 4, in chloroform have been conducted. Influences of aqueous phase pH and metal ion concentrations upon the concentrations of metals and complexing agent in the organic phase are assessed and compared with those reported for sym-dibenzo-16-crown-5-oxyacetic acid, 1. Extraction selectivity orders of K > Rb > Na ≈ Cs > Li, K > Rb ≥ Na ≈ Cs > Li, and K > Na > Rb > Cs ≈ Li were found for extractions using 2, 3, and 4, respectively. In terms of selectivity and metal extractability, 3 surpasses 1, 2, and 4.     

Synthesis and characterization of new monomeric and polymeric phthalocyanines

Monomeric (M = 2Li or 2H) and polymeric (M = 2H, Zn, Cu, Co, or Ni), where M is metal or hydrogen, phthalocyanines were prepared by the tetramerization reaction of bisphthalonitrile monomer with appropriate materials. The electrical conductivities of the polymeric phthalocyanines, which were measured as gold sandwiches, were found to be 10⁻¹⁰–10⁻⁷ S/cm in vacuo and in air. The binding property of a Co‐containing polymeric phthalocyanine ( 10 ) toward alkali, alkaline‐earth, and some heavy cations was studied in tetrahydrofuran. The extraction affinity of 10 for K⁺ was found to be the highest in the heterogeneous phase extraction experiments. The disaggregation property of a Ni‐containing polymeric phthalocyanine ( 11 ) was investigated with K⁺, Na⁺, and NH₄⁺ cations. The intrinsic viscosities of all polymers were also measured by means of viscometry. All the novel compounds were characterized with elemental analysis, ultraviolet–visible, Fourier transform infrared, NMR, and mass spectrometry spectral data, and differential thermal analysis/thermogravimetry. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Liquid Membrane Separations of Metal Cations Using Macrocyclic Carriers

Abstract

The selectivity in water and methanol solvents of macrocyclic crown ether ligands toward univalent and bivalent cations is well known. Incorporation of these ligands into chloroform liquid membranes separating water and salt solution phases results in a system showing selective cation transport. The cation transport rates of single cations across these liquid membranes have been correlated with equilibrium constant values for cation-macrocycle interaction in methanol. This correlation has been extended to binary cation mixtures of Cs⁺ with Li⁺, Na⁺, K⁺, and Rb⁺. A model for cation transport from these cation mixtures has been reduced to an equation which gives good agreement between measured and predicted transport rates across our liquid membranes.     

Rapid Separation of Tl+ and Pb2+ from Various Binary Cation Mixtures Using Dicyclohexano-18-crown-6 Incorporated into Emulsion Membranes

Abstract

Relative transport rates of metal cation nitrates (Na⁺, K⁺, Rb⁺, Cs⁺, Ag⁺, Tl⁺, Ca²⁺, Sr²⁺, Ba²⁺, and Pb²⁺) in a water-toluene-water emulsion membrane system were measured. The toluene component contained the surfactant Span 80 and the crown ether dicyclohexano-18-crown-6. The aqueous receiving phase contained Li₄P2O₇. When each metal cation was individually present in the aqueous source phase, metal extraction was complete within 10 min with the order of extraction being Tl⁺ > Cs⁺ > Ag⁺ > Rb⁺ > K⁺ ≥m Na⁺ and Pb⁺ > Ca²⁺ > Sr²⁺ > Ba²⁺ for uni-and bivalent cations, respectively. Significant extraction was found for all cations except Na⁺, K⁺, and Ba²⁺. Some metal ions were concentrated nearly 10-fold in a 10-min period. Relative transport rates were determined when binary cation mixtures of either Tl⁺ or Pb²⁺ were present at equal concentrations with each of the remaining metal ions in the source phase. Tl⁺, when present with either Na⁺, Cs⁺, or Rb⁺, was selectively extracted from the source phase. Complete and nearly exclusive extraction of Pb²⁺ was observed in the presence of all cations including Tl⁺. The enrichment ratios of Pb²⁺ in the binary mixtures were approximately 10 while those of the second cation were less than 0.5 except for Sr²⁺ which was 0.86. Corresponding separation factors for Pb²⁺ ranged from 1000 to > 6000.     

Quantitative Analysis of Cs Extraction by Some Dialkoxycalix[4]Arene-Crown-6 Extractants

Cesium extraction from acidic media by seven dialkoxy-calix[4]arene-crown-6 compounds in several diluents was studied. 2-Nonanone was found to be a suitable diluent for cesium extraction. Nitric acid concentration variation reveals a maximum distribution ratio, whose position depends on extractant and diluent. This maximum was explained quantitatively by a competitive extraction of H⁺. An analytical mass-action extraction model accounting for activity effects is proposed that fits correctly the different datasets. The analysis showed a nitrate hyper-stoichiometry in alkyl ketone diluents. This effect yields efficient back-extraction at low acidity. Benzo substitution on the crown ether lowers nitric acid extraction, improves sodium separation, but also degrades potassium and rubidium separation.     

EXTRACTION OP MANGANESE(II) BT MIXTURES OP DIDODECYLNAPHTHALENESOLFONIC ACID AND r-BUTYL- CYCLOHEXANO-15-CROWN-5: SPECTRAL EVIDENCE FOR THE FORMATION OF A MANGANESE(II) - CROWN ETHER COMPLEX

Addition of t-butylcyclohexano-15-crown-5 (tBC-15C5) induces a synergistic effect in the extraction of Mn²⁺ ion with didodecylnaphthalenesulfonic acid (HDDNS). This synergism is the result of the inner-sphere complexation of the crown ether to the manganese(II) ion. The formation of this complex, first suggested by distribution studies, has been confirmed by FTIR experiments. The C-O-C stretching bands for the crown ether ligand shift to lower frequency when Mn²⁺ ion is extracted into a CC14 solution of HDDNS and tBC15C5. A similar C-O-C Btretching band is observed for the crystalline complex [Mn(15C5 ) (Bu₃CS0₃)₂] (where 15C5 = 15-crown-5 and Bu = n-butyl).Formation of analogous complexes is not observed for Fe³⁺, co²⁺,N²⁺,cu²⁺, or zn²⁺ under similar conditions.     

Thioglycolate-elicited rat macrophages exhibit alterations in incroporation and oxidation of fatty acids

Incorporation and oxidation of fatty acids (FA) were investigated in resident and thioglycolate-clicited (TG-elicited) rat macrophages (Mϕ). Both cell types presented a time-dependent incorporation of [¹⁴C]-labeled palmitic acid (PA), oleic acid (OA), linoleic acid (LA), and arachidonic acid (AA) up to 6h. The total amount of [¹⁴C]-FA incorporated by resident Mϕ after 6 h was: AA>PA=LA>OA. TG-elicited cells presented a 50% reduction in the incorporation of LA, PA, and AA, whereas that of OA remained unchanged as compared to resident Mϕ. The FA were oxidized by resident Mϕ as follows: LA>OA>PA>AA. TG elicitation promoted a reduction of 42% in LA oxidation and a marked increase in AA oxidation (280%). The increased oxidation of AA in TG-elicited cells may account for the lower production of prostaglandins in Mϕ under these conditions. The full significance of these findings for Mϕ function, however, remains to be examined.