Extraction and transport of lithium ion by a crown ether-alkylphosphoric acid system [1]

Mixed carrier systems composed of crown ethers and alkylphosphoric acids have been studied as lithium ionophores using a solvent extraction technique and in transport across liquid membranes. The combination of dibenzo-14-crown-4 and bis(2-ethylhexyl) phosphoric acid showed a synergistic enhancement on both lithium ion selectivity and transport rate. The synergistic effects depended strongly upon crown ether structure and the enhancement was observed only when the metal cation corresponded to the crown ether's cavity diameter. Complex formation in the organic phase was assessed by use of FAB-mass spectrometry.     

Synthese und extraktionseigenschaften von 2-(sym-dibenzo-14-krone-4-oxy)essigsäure bzw. -n-hexansäure

(Synthesis and extraction behaviour of 2-(sym-dibenzo-14-crown-4-oxy)-acetic and -hexanoic acid)An improved synthesis for carboxylic acid derivatives of dibenzo-14-crown-4- using sodium amide is described. The reagents were studied for the extraction of alkali and alkaline earth metal ions. The dependence of the metal distribution on pH and ligand concentration is used to evaluate the composition of the extracted species. (2-sym-Dibenzo-14-crown-4-oxy)hexanoic acid is a very good extractant for alkaline earth metal ions but is also if interest for lithium.     

Extraktion von alkali- und erdalkalimetallionen mit (sym-dibenzo-14-krone-4-oxy)- und (sym-dibenzo-16-krone-5-oxy)-carbonsäuren

(Extraction of alkali on alkaline earth metal ions with (sym-dibenzo-14-crown-4-oxy)- and (sym-dibenzo-16-crown-5-oxy)-carboxylic acids.)The extraction of lithium, sodium, potassium, calcium and some other metal ions with dibenzo-4-crown-4-oxy- and dibenzo-16-crown-5-oxycarboxylic acids containing the groups -CH₂COOH, -(CH₂)₂COOH, -(CH₂)₃COOH, -CH(C₂H₅)COOH and -CH(C₄H₉)COOH was studied. The extraction increases as a function of the lipophilic character of the carboxylic acid group. Calcium, barium and strontium ions are better extracted than Li⁺, Na⁺ and K⁺; there are only small differences among the alkaline earth metal ions. Evaluated from the extraction data, the composition of the extracted species was 1:1 (metal/ligand) for Li⁺, and 1:2 for CaCa²⁺; Na⁺ and K⁺ favour the formation of 1:2 complexes with dibenzo-14-crown-4-derivatives bbut 1:1 complexes with dibenzo-16-crown-5-oxy-carboxylic acids. The dependence of the distribution ratio on pH does not provide unequivocal evidence for the composition of the extracted compounds.     

Cation transport at 25°c from binary Na+Mn+, Cs+Mn+ and Sr2+Mn+ nitrate mixtures in a H2OCHCl3H2O liquid membrane system containing a series of macrocyclic carriers

Cation fluxes from binary mixtures of either Na⁺, Cs⁺ or Sr²⁺ with other alkali metal cations, alkaline earth metal cations, and Pb²⁺ through a H₂OCHCl³H₂O bulk liquid membrane system containing one of several macrocyclic carriers have been determined Nitrate salts were used in all cases. The most selective transport of Na⁺ over all other cations studied was found with the carrier cryptand [2.2.1]. Selective transport of Na⁺ relative to Li⁺, Cs⁺ and the alkaline earth cations was found with cryptand [2.2.2B] and cryptand [2.2.2D]. The ligands 21-crown-7 and dibenzo-24-crown-8 showed selective transport of Cs⁺ over the second cation in all cases. Several macrocycles showed selectivity for Sr²⁺ over the second cation with the macrocycle 1,10-diaza-18-crown-6 showing the highest selectivity for this cation of all ligands studied. Relative fluxes from binary cation mixtures are rationalized in terms of macrocycle cavity size, donor atom type and ring substituents.     

Potentiometric Selectivities of Dibenzo-16-crown-5 Compounds for Alkali and Alkaline Earth Metal Cations and Ammonium Ions

Potentiometric selectivities toward alkali and alkaline earth metal cations and ammonium ions are utilized to probe the complexation of these cationic species by dibenzo-16-crown-5 lariat ethers. Attachment of one or two pendant groups to the central carbon of the three-carbon bridge in dibenzo-16-crown-5 markedly alters the potentiometric responses of the ionophores when incorporated in solvent polymeric membrane electrodes. Results obtained for dibenzo-16-crown-5 compounds with coordinating side arms containing ether, carboxylic acid, ester, and amide groups provide insight into the role of the side arm in metal ion complexation by lariat ether compounds.     

Synthesis and certain properties of extraction microencapsulated systems

Microencapsulated materials containing di(2-ethylhexyl)phosphoric acid, tributyl phosphate, monoethanolamine, dibenzo-18-crown-6, and 18-crown-6 as extractant were synthesized. Physico-chemical characteristics of the samples were obtained. An effect of extractant and also of a solvent addition in the course of synthesis and also composition of a crown ether on morphology of microencapsulated systems was determined using electron microscopy.     

Liquid-Membrane Transport of Rare Earth Metal Ions Facilitated by Di(2-Ethylhexyl) Phosphoric Acid: Comparison with the Results of Corresponding Centrifugal Partition Chromatography

Abstract

Selective liquid-membrane transport of rare earth metal ions were found to be effectively attained by the use of di(2-ethylhexyl)phosphoric acid (D2EHPA) carrier. This finding was obtained on the basis of the idea that liquid-membrane transport phenomena would be basically correlated with those of “separator-aided centrifugal partition chromatography”, a separation technique based on the counter-current continuous extraction method. For the rare earth metal ion samples direct comparison of liquid-membrane transport with the corresponding centrifugal partition chromatography by employing the same two-phase liquid systems both containing D2EHPA showed that a close parallelism in the results obtained with the two separation systems.     

FIA Potentiometric and Solvent Extraction Studies of Alkali Metal and Alkaline Earth Cation Complexation by bis(Tert-butylbenzo)-21-crown-7

Abstract

A flow injection analysis study of the potentiometric selectivity of bis[4(5)-tert-butylbenzo]-21-crown-7 (D(tBB)21C7) for cesium over the other alkali metal cations and three alkaline earth cations has been conducted. A PVC matrix membrane containing D(tBB)21C7 as an ionophore was coated on the tip of a silver wire incorporated in a flow cell. No selectivity for cesium over rubidium and only low selectivity over potassium were noted. However, very high selectivities for cesium over sodium, lithium, strontium, calcium, and magnesium were observed. Selectivity of D(tBB)21C7 in the solvent extraction of alkali metal cations was determined by the picrate extraction method. The percent extraction into deuteriochloroform decreased in the order cesium, rubidium > potassium » sodium » lithium. Thus good agreement was observed between the responses of D(tBB)21C7 towards alkali metal cations in polymeric membrane electrodes and in solvent extraction.     

Guanidinium-selective PVC membrane electrodes based on crown ethers

Guanidinium-selective membrane electrodes were constructed with dibenzo-24-crown-8, dibenzo-27-crown-9, tribenzo-27-crown-9 or dibenzo-30-crown-10. The detection limits and selectivity coefficients towards different interfering ions, such as Li⁺, Na⁺, K⁺, NH⁺₄, Mg²⁺ and Ca²⁺ were determined. The electrode with dibenzo-27-crown-9 shows linear response over the range 10^?1–10^?4 M, with selectivity coefficients about 10^?2 for most alkali and alkaline earth metal ions.     

Facilitated transport from ternary cation mixtures through water—chloroform—water membrane systems containing macrocyclic ligands

Cation fluxes were determined for various three-component, equimolar mixtures of alkali metal, alkaline earth, and Pb²⁺ cations in a H₂O---CHCl₃---H₂O liquid membrane system incorporating macrocyclic polyethers as carriers. Carrier ligands studied were 18-crown-6, dicyclohexano-18-crown-6, 1,10-diaza-18-crown-6, 21-crown-7, dibenzo-24-crown-8, and cryptand [2.2.2]. Correlations were found between transport and relative cation:polyether cavity radii, the type of substituents present on the polyether ring, and the type and number of donor atoms present. All the ligands studied transported Pb²⁺ at higher rates than the other Mⁿ⁺ in the mixtures. Transport behavior in these multi-cation systems can be predicted from Mⁿ⁺—polyether complex stability constant data in most cases.     

固定化冠醚树脂的特性及离子色谱应用研究 Ⅱ.间接光度检测中苦味酸淋洗剂的一些性质

本文报道用固定化冠醚作色谱填料的无抑制柱间接光度离子色谱法中高灵敏度淋洗剂的性能。苦味酸具有稳定的生色基团和较高的摩尔吸光系数,光学性质良好,是间接光度离子色谱法中优良的淋洗剂。苦味酸浓度以4×10~(-6)mol/L 为最佳。在苦味酸中引入少量甲醇、乙醇、丙酮或氯仿,对提高淋洗剂的灵敏度有利。在苦味酸浓度相同的条件下比较几种填料,其色谱峰高按如下次序递增,固定化二苯并-18-冠-6<固定化二苯并-30-冠-10<固定化苯并-15-冠-5。     

Evaluation of alkali and alkaline earth metal cation selectivities of lariat ether amides by electrospray ionization mass spectrometry

Lariat ethers with pendant amide groups have shown promise as new ion sensors because of their selectivity towards particular metal ions. In this study we report alkali and alkaline earth metal binding selectivities of dibenzo-16-crown-5 and fifteen dibenzo-16-crown-5 lariat ether amides (LEAs) as determined by electrospray ionization mass spectrometry (ESI-MS). Additionally, the influence of the acid/base nature of the solution on metal cation selectivity is investigated. The validity of using ESI-MS for determination of selectivities is established by analogous experiments using hosts with known binding constants for the same metal cations and solvent systems. Collisionally activated dissociation (CAD) is used to evaluate the influence of the alkali metal cation binding on the fragmentation of the LEAs.     

Extraction of Co(II) and Ni(II) ammine cations from aqueous solutions into chloroform by highly lipophilic crown carboxylic acids

The proton-ionizable crown ethers, 2-[(sym-dibenzo-14-crown-4)oxy]-decanoic acid (1), 2-[sym-dibenzo-16-crown-5)oxy]decanoic acid (2), and 2-[sym-dibenzo-19-crown-6)oxy]decanoic acid (3) efficiently extract Co(II) and Ni(II) ammine cations from highly alkaline aqueous solutions (pH>10) into chloroform. For extractions of the individual metal species,2 is more efficient than1 or3. In competitive extraction systems, good selectivity for Co(II) ammine cations over Ni(II) ammine cations is observed.     

A template effect in the synthesis of dibenzo-14-crown-4 derivatives

A new series of 4-substituted derivatives of dibenzo-14-crown-4 including 4-nitro-DB14-crown-4 ( 2a ), 4-bromo-DB14-crown-4 ( 2b ), 4-chloro-DB14-crown-4 ( 2c ) and 4-formyl-DB14-crown-4 ( 2d ) has been synthesized with and without a lithium cation template. No matter with or without the template, a satisfactory correlation between the nature of the substituent group on the benzene ring and the reaction yield is observed. The larger σ values for the substituent groups gave lower yields.     

Acylation of Dibenzo-18-crown-6 with Alkali-metal Acetates in Polyphosphoric Acid

The acylation of dibenzo-18-crown-6 by lithium, sodium, and potassium acetates in polyphosphoric acid was studied. Complexes of dibenzo-18-crown-6 with the acetates were obtained. A new method is proposed for the production of mono- and diacetyldibenzo-18-crown-6 by the reaction of dibenzo-18-crown-6 complexes with metal acetates in polyphosphoric acid. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1146–1149, August, 2005.     

Selective separation of alkali metal cations by bulk chloroform membranes containing lipophilic crown ether phosphonic acid monoethyl esters

A series of crown ether phosphonic acid monoethyl esters with crown ether ring size variation from 12-crown-4 to 24-crown-8 is used in bulk chloroform membranes to separate alkali metal cations from mixtures. Selective proton-coupled transport of alkali metal cations from weakly alkaline aqueous phases is achieved. With individual ionizable crown ether carriers, transport selectivity for Li⁺, Na⁺, K⁺, and Rb⁺-Cs⁺ is achieved. A closely related lipophilic phosphonic acid monoethyl ester derivative with a cyclohexyl unit in place of the crown ether exhibits transport selectivity for Li⁺. However, the corresponding phosphonic acid diethyl ester is devoid of transport activity. Effects of structural variation within the carrier upon the selectivity and efficiency of competitive alkali metal cation transport are assessed.     

Bis(Dialkylphosphinylmethyl)Alkylamines as the Liquid and Membrane Extractants of Rare Earth and Trace Metal Ions

Abstract

A large number of new lipophilic mono- and bisphosphinylamines were synthesized on the basis of the Kabachnik–Fields reaction and extraction and membrane transport properties of the synthesized compounds toward the rare earth and alkaline metal were studied. Aminophosphonyls demonstrate extracting efficiency and selectivity toward Sc(III), In(III), Y(III), and Ga(III) rare earth elements. The mixture of reactants bis(dialkylphosphinylmethyl)alkylamine, and thio- and dithiophosphoric acid shows selectivity toward lithium ions.     

Effects of concentration of neutral carrier and addition of organophosphorus compounds on alkali metal ion-selectivity of the dibenzo-14-crown-4 liquid-membrane electrode

The lithium ion selectivity of the dibenzo-14-crown-4 (DB14C4) liquid-membrane electrode increases with the concentration of DB14C4 om the membrane. The lithium ion selectivity was enhanced by an addition of organophosphorus compounds such as trioctyl phosphine oxide.     

Targeted preparation of highly efficient lithium extractants based on 14-membered crown ethers

Modification of benzene rings in dibenzo-14-crown-4 by hydrogenation of a cyclohexane moiety or introduction of tert-butyl substituents leads to macrocycles superior to benzo-15-crown-5 in extraction of lithium salts from aqueous solutions and in resistance to leaching into the aqueous phase.     

On the rate-limiting steps in the membrane transport of cations across liquid membranes by dibenzo-18-crown-6 and lipophilic crown ether carboxylic acids

The influence of stirring rate on the transport of cations across unsupported liquid membranes was examined in several systems. Systems known to be rate limited by diffusion, dibenzo-18-crown-6/KNO₃ and anti-(8NH)₂18-6A₂/Sr²⁺, showed continuous variation of transport rate over the range 100-600 rpm in stirring speed. In contrast, systems utilizing the carrier 14NH18-6A/K⁺showed plateau regions above approximately 300 rpm. Such a plateau is consistent with a rate limiting interracial process which, with previous evidence, is presumed to be the rate limiting adsorption/desorption of the carrier surfactant from the interface