Lipophilic Crown Ether Carboxylic Acids Research Articles

New lipophilic crown ethers with intraannular carboxylic acid groups: Synthesis and alkali metal cation extraction

A six-step synthetic route to four lipophilic crown ethers with intraannular carboxylic acid groups and ring sizes of 15-crown-4, 18-crown-5, 21-crown-6 and 24-crown-7 is described. Eight new polyether compounds that bear inward-facing bromo and formate ester substituents are prepared as synthetic intermediates. Selectivities and efficiencies of the four new lipophilic crown ether carboxylic acids in competitive alkali metal cation extraction from aqueous solutions into chloroform are evaluated.

Effect of solvent in competitive alkali metal cation transport across bulk liquid membranes by a lipophilic lariat ether carboxylic acid carrier

Fluxes and selectivities for competitive alkali metal cation transport across bulk liquid membranes by the lipophilic crown ether carboxylic acid carrier sym-(octyl)dibenzo-16-crown-5-oxyacetic acid have been determined in a variety of chlorinated hydrocarbon and aromatic hydrocarbon solvents. The membrane solvents include: dichloromethane, chloroform, carbon tetrachloride, 1,2-dichloroethane, 1,1,1-trichloroethane, o-dichlorobenzene, toluene and p-xylene. The total alkali metal cation and Na + fluxes, as well as the Na +/K + and Na +/Li + transport selectivity ratios, are compared with selected properties of these organic solvents using the Schmidt, Swain, Koppel–Palm and Kamlet–Taft models. The best correlations are obtained for the Na + flux and the Na +/K + transport selectivity.

Competitive, proton-coupled, alkali metal cation transport across polymer-supported liquid membranes containing sym-(decyl)-dibenzo-16-crown-5-oxyacetic acid: Variation of the alkyl 2-nitrophenyl ether membrane solvent

Alkali metal cation transport across porous polypropylene-supported liquid membranes containing a lipophilic crown ether carboxylic acid in a series of alkyl 2-nitrophenyl ethers has been studied. Both the efficiency and selectivity of cation transport are influenced by alkyl group variation in the membrane solvent. For homologous series of normal alkyl and isoalkyl 2-nitrophenyl ethers, the dielectric constant of the membrane solvent provides the best correlation with the cation transport rate. In terms of the efficiency and selectivity of cation transport, 2-nitrophenyl pentyl and hexyl ethers surpass 2-nitrophenyl octyl ether.

Effect of ring size variation within lipophilic crown ether carboxylic acids on the selectivity and efficiency of competitive alkali-metal cation solvent extraction into chloroform

Competitive solvent extraction of alkali-metal cations from aqueous solutions into chlororform by a series of lipophilic crown ether carboxylic acids with varying ring sizes is reported. Extraction selectivity for Li{sup +} is observed for lipophilic crown ether carboxylic acids with 12-15-membered polyether rings containing four oxygen atoms. For lipophilic 14-crown-4-carboxylic acids, very high Li{sup +}/Na{sup +} selectivity coefficients of 17-20 are observed with no detectable extraction of K{sup +}, Rb{sup +}, or Cs{sup +}. Lipophilic crown ether carboxylic acids which contain 15-crown-5, 18-crown-6, and 21-crown-7 rings exhibit good selectivities for Na{sup +}, K{sup +}, and Cs{sup +}, respectively. In contrast, poor extraction selectivity is observed for lipophilic crown ether carboxylic acids with 24-crown-8, 27-crown-9, and 30-crown-10 rings.

Preconcentration of lanthanides from natural waters with a lipophilic crown ether carboxylic acid

Lipophilic crown ether carboxylic acids such as 2-( sym-dibenzo-16-crown-5-oxy)stearic acid with a cavity size comparable to the ionic radius of rare-earth elements are selective chelation agents for preconcentration and separation of lanthanides from natural waters for NAA. Interfering matrix elements such as sodium and bromine can be simultaneously eliminated during the extraction. The lanthanides can be back-extracted into a dilute acid solution for NAA, thus providing a large preconcentration factor. This two-step extraction method appears suitable for the determination of lanthanides in natural waters and in biological samples.

Transport of trivalent lanthanides through a surfactant membrane containing an ionizable macrocyclic polyether

Trivalent lanthanides can be effectively transported from an aqueous source phase to a receiving phase at a lower pH through a surfactant membrane containing a lipophilic crown ether carboxylic acid, 2- ( sym-dibenzo-16-crown-5-oxy)hexanoic acid. The activation energies for the transport of lanthanides in this system are in the order of 3-4 kJ/mol, suggesting the process is diffusion controlled. This surfactant membrane also shows a selectivity of Lu 3+/La 3+ by 1.25 in the transport process.

Synthesis of lipophilic crown ethers with pendant carboxylic acid groups

AbstractSynthetic routes to thirteen highly lipophilic crown ether carboxylic acids are described. Seven contain 12–15‐membered crown ether units with four ring oxygens and are designed for lithium ion complexation. Three others possess large ring 24‐crown‐8, 27‐crown‐9, and 30‐crown‐10 units. Six new hydroxymethyl crown ethers are prepared as synthetic intermediates.

Interfacial surface charge and the selectivity of cation transport through a liquid membrane by a lipophilic crown ether carboxylic acid

A kinetic model has been developed to describe the transport selectivities exhibited by a liquid membrane system incorporating a lipophilic crown ether carboxylic acid carrier. Under conditions of rate-limiting cation/carrier complex desorption from the interface, the rate an ion is extracted is related to the fraction of interfacial sites occupied by the carrier complex of that ion. The fractional site coverage is related to bulk aqueous concentrations and the surface charge by a modified Stern adsorption isotherm. Experimental values of constants of complexation and acidity at the interface were determined from single-ion transport studies and were utilized to correlate transport selectivities for binary K+/Na+ and Sr2+/K+ mixtures. The overall transport selectivity is shown to be a composite of both thermodynamic and kinetic factors. The relevance of the model to extraction and transport in related systems is discussed.

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/KNO 3 and anti-(8NH) 218-6A 2/Sr 2+, 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

Membrane transport systems. VI. Complexation of cations by lipophilic crown ether carboxylic acids

The complexation of alkali metal and alkaline earth cations by crown ether carboxylic acids has been studied by potentiometric titration and by infrared and nuclear magnetic resonance spectroscopy. Complexation in methanol–water solution is governed by the electrostatic interactions between the cation and the carboxylate, hence discrimination among cations on the basis of ionic radius is poor. The isomers syn and anti (8NH)218-6A2 exhibit differing complexation behaviour towards cations with the anti isomer giving the stronger complexes. Interaction between the carboxylates across the face of the macrocycle of syn (8NH)218-6A2 can be inferred from the potentiometric data. Combined infrared and nuclear magnetic resonance studies of the complexes in chloroform solution show that the cation is held as an asymmetric tight ion pair with the carboxylate. The dimeric salt (4NH18-6)2Ca exhibits both a tight and a symmetric or loose ion pair between the cation and the two carboxylates. The substituents on the macrocycle are pseudoaxially disposed and in some cases gauche ethylenedioxy units can be recognized from the spectra. The complexes are monomeric in solution and in most cases the conformations are unaffected by small amounts of water in the chloroform solution. The structural results correlate with observations from transport experiments.

Synthesis of highly lipophilic crown ether carboxylic acids

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis of highly lipophilic crown ether carboxylic acidsRichard A. Bartsch, Yung Liu, Sang Ihn Kang, Byungki Son, Gwi Suk Heo, Paul G. Hipes, and Lyndra J. BillsCite this: J. Org. Chem. 1983, 48, 25, 4864–4869Publication Date (Print):December 1, 1983Publication History Published online1 May 2002Published inissue 1 December 1983https://doi.org/10.1021/jo00173a016RIGHTS & PERMISSIONSArticle Views531Altmetric-Citations57LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (872 KB) Get e-Alerts Get e-Alerts

Competitive transport of alkali metal ions from aqueous media into toluene solutions of 2-( sym-dibenzo-16-crown-5-oxy)-decanoic acid. A comparative study

Competitive permeation of alkali metal ions from an alkaline source phase into or through a toluene phase facilitated by the lipophilic crown ether carboxylic acid 2-( symdibenzo-16-crown-5-oxy)-decanoic acid is studied in liquid—liquid extraction, bulk liquid membrane transport, and emulsion liquid membrane transport. Most rapid transport was obtained in emulsion liquid membrane experiments. Some differences in selectivity orders for alkali metal permeation were observed for the three separation techniques.

Competitive transport of alkali metal ions from aqueous solutions into toluene by highly lipophilic crown ether carboxylic acids

Efficiencies and selectivities of competitive alkali metal transport into toluene by 2-((sym-dibenzo-16-crown-5)oxyl)-decanoic acid and (sym-bis(4(5)-tert-butylbenzo)-16-crown-5)oxy)acetic acid are determined in solvent extraction, bulk liquid membrane transport, and liquid surfactant membrane transport (water-in-oil-in-water emulsion) and compared with those previously measured for solvent extraction and bulk liquid membrane transport with chloroform as the organic phase. 4 figures, 2 tables.

Comparison of highly lipophilic crown ether carboxylic acids for transport of alkali metal cations from aqueous solutions into chloroform

Comparison of highly lipophilic crown ether carboxylic acids for transport of alkali metal cations from aqueous solutions into chloroform

Solvent extraction of alkali metal cations from aqueous solutions by highly lipophilic crown ether carboxylic acids

Competitive solvent extractions of alkali metal cations from water into chloroform by 2-(sym-dibenzo-16-crown-5-oxy)-butanoic acid (5), 2-(sym-dibenzo-16-crown-5-oxy)hexanoic acid (6), 2-sym-dibenzo-16-crown-5-oxy)octanoic acid (7), 2-(syn-dibenzo-16-crown-5-oxy)decanoic acid (8), and 5-(sym-dibenzo-16-crown-5-oxy)pentanoic acid (9) are reported. For 6, 7, and 8 the complexing agents are sufficiently lipophillic that they remain totally in the organic phase when chloroform solutions of the crown ether carboxylic acids are contacted with highly alkaline aqueous alkali metal salt solutions.