Separation of alkali and alkaline earth metals by polyethers using extraction chromatography. Effect of diluent

The separation of alkali and alkaline earth metals by means of an acyclic polyether, 1,13-bis(8-chinolinyl)-1, 4, 7, 10, 13-pentaoxatridecane (CPOD), and cyclic polyethers, benzo-15-crown-5 (BC), dibenzo-18-crown-6 (DBC) and dicyclohexyl-18-crown-6 (DCHC), using extraction chromatography has been studied. The alkali metals can be effectively separated using SCN⁻ ions. Different elution sequences for these groups were observed using chloroform and mesitylene and diluents for the polyethers.     

Complex formation of D-mannonaphto-18-crown-6-ether and enantiomers of phenylalanine in water studied by different physochemical methods

Complex formation of D-mannonaphto-18-crown-6-ether 1 with D- and L-phenylalanine (Phe) and their derivatives was studied using conduction and titration microcalorimetry in aqueous solution, and solvent–solvent (water–chloroform) extraction. The thermal effects accompanying the complexation process were determined, but the chiral recognition effects were very small. The chiral differentiation of amino acid was observed in the experiments of the extraction from water to chloroform phase containing chiral receptor.     

Separation of nitrophenols. Equilibriums in bi- and tri-phasic systems

The paper presents experimental data obtained in the study of liquid–liquid partition equilibriums in biphasic system in order to optimize the process of transport through bulk liquid membranes (triphasic partition systems). The partition equilibriums of some nitrophenols using chloroform as extraction solvent and membranary solvent, respectively, were studied. The influence of the pH on the partition equilibriums was investigated. The repartition constants and the pK_a values of the studied nitrophenols were calculated. Nitrophenols were transferred in triphasic system from a feed phase with pH 2, through a chloroform liquid membrane, into a receiving phase with pH 12, with efficiencies over 90%.     

PMR investigation of the hydration of macrocyclic polyethers

PMR was used to investigate the reaction of water dissolved in chloroform with ten macrocyclic polyethers, differing from each other by the kind of donor atoms, the size of the cavity, and the character of the substituants in the macrocycle. The curves representing the shift of the proton signal of water as function of the concentration of the macrocyclic polyether in chloroform were used to calculate the stability constants of the associates of the macrocyclic polyethers with water with the composiiton 11. The analysis of the association constants obtained showed that, according to their ability to coordinating water, the investigated macrocyclic polyethers can be placed into the following order: diaza-18-crown-6 > dicyclohexyl-18-crown-6 > kryptand(2.2.2) > 18-crown-6 > dibenzo-18-crown-6 > dibenzo-24-crown-8 > 15-crown-6 > benzo-15-crown-5 > dithio-18-crown-6 > benzo-12-crown-4.Translated from Teoreticheskaya i Eksperimental'naya Khimiya, Vol. 21, No. 2, pp. 248–252, March–April, 1985.     

改变相比/顶空气相色谱法测定饮用水中的氯仿及其分配常数

推导了改变气液相比／顶空气相色谱法的基本关系式。测定了20℃时氯仿在纯水中的液气分配常数为8．04，与文献值一致，测定标准水样品的浓度是97．83μg/L，相对误差0．68％，实测在实验室旋转一周的氯化消毒饮用水中氯仿含量为119．62μg/L，实验方法是测定3个具有不同相比的顶空浓度，然后通过回归分析建立的线性方程来计算。     

A comparative study of different extraction systems for the spectrophotometric determination of potassium with 18-crown-6

A comparative study on the extractive-spectrophotometric determination of potassium with 18-crown-6 employing different colored counterions and organic extraction solvents is described.Extraction systems using methyl orange/chloroform, bromcresol purple/chloroform and bromcresol green/benzene demonstrated good preliminar features for such purpose and are studied in detail. Analytical performance characteristics including: sensitivity, selectivity, precision, linearity, etc. are given for each method. The main disadvantage of this type of determinations is the lack of reproducibility. Some explanations to this fact are discussed.A new method for the determination of trace amounts of potassium based on its extraction into chloroform with 18-crown-6 and methyl orange is proposed. The linear working range goes from 0.5 to 7 ppm of potassium, the apparent molar absorptivity being 8.8 × 10³ liters mol^?1 · cm^?1, and the precision, expressed in terms of relative standard deviation, of ±4.6%.     

Absorption spectroscopic study of synergistic extraction of praseodymium with benzoyl acetone in presence of crown ether

The extraction behaviour of Pr(III) from aqueous nitric acid medium employing benzoylacetone has been studied in presence of two crown ethers, viz., 15-crown-5 and benzo-15-crown-5 in chloroform medium using UV-vis absorption spectroscopy. The binary equilibrium constant (logk(ex)) for the complex [Pr(benzoylacetonate)(NO3(-))2(H(2)O)] in organic phase was found to be 1.170. The overall equilibrium constants (logK) for the ternary species [Pr(benzoylacetonate)(crown ether)(NO3(-))(2)] were estimated to be 4.01 and 4.41 for 15-crown-5 and benzo-15-crown-5, respectively. The trend in the equilibrium constant values were very much in accordance with the nature of substitution of the donor moiety. The extraction of Pr(III) by the benzoylacetone-crown ether combination was maximum at pH 3.0 and extraction decreases with increase in pH. It has been found that the extent of extraction of Pr(III) in organic phase as the binary as well as ternary complex [Pr(benzoylacetonate)(NO3(-))(2)(H(2)O)] and [Pr(benzoylacetonate)(crown ether)(NO3(-))(2)] increases with increase in concentration of the ligand. Similar trend is observed in the extraction by only donors. Enthalpies and entropies of formation for the ternary extraction process have been estimated. In addition, the effect of NaNO(3) as foreign salt was also studied and it was observed that with increase in ionic strength, percentage extraction increases.     

Extraction of alkali metal picrates with poly- and bis(crown ether)s

Extraction of alkali metal picrates by new poly- and bis(crown ether)s containing benzo-15-crown-5 and benzo-18-crown-6 moieties was carried out with chloroform as water-immiscible solvent. The poly- and bis(crown ether)s were found to extract the picrates more effectively than the corresponding monocyclic crown ethers. In particular, poly- and bis(benzo-15-crown-5), and bis(benzo-18-crown-6) are remarkably effective extracting reagents for potassium and rubidium, and for caesium, respectively. Extraction equilibrium constants and the complexation constants in the chloroform phase were also evaluated and the contribution of the complexation constants to the extractability is discussed.     

Extraction of strontium from nitric acid solutions by selected crown ethers

The extraction of Sr from nitric acid solutions by the crown ethers, 12-crown-4, 15-crown-5, 18-crown-6 and DB 18-crown-6 dissolved in chloroform has been investigated. Sr is reasonably well extracted by 18-crown-6 compared to other crown ethers from different nitric acid solutions. The extraction is strongly dependent on the concentration of HNO₃ and nitrate salts. Preliminary studies indicate that¹³⁷Cs is also extracted to a limited extent by 18-crown-6 from nitrate medium. Stripping of Sr was achieved by an aqueous solution of low acidity, the crown ether being regenerated for subsequent extraction.     

Influence of polar solvents upon the complex formation of 18-crown-6 with cations in chloroform

The complex formation of crown ethers with cations in nonpolar medium with small amounts of polar solvents added has been studied. The goal has been to get deeper insight into the influence of solvation (hydration) of the salts for the formation of complexes with the macrocyclic ligand 18-crown-6 (18C6). A linear dependence of the reaction enthalpy for complex formation between 18C6 and alkali metal cations in chloroform in the presence of water or methanol has been observed. The presence of acetonitrile or acetone has had no influence upon the measured reaction enthalpies. The influence of methanol on the complex formation between 18C6 and alkali metal cations in chloroform is weaker than in the case of water. This underpins the selective solvation of alkali cations in chloroform after the addition of small amounts of water or methanol. The experiments have been performed using calorimetric titrations.     

Reply to W.H. Gries' comments on “Ion Implantation Standards as a Spark Source Mass Spectrometric Surface Analysis Calibration Technique.” Anal. Lett. 12(A10), 1123 (1979)

Abstract

The spectrophotometric determination of Bromhexi ne Canfosulfonate (BC) from the pair ionic makes with Co (SCN)₄ ⁼ and its extraction in chloroform was studied. The BC partition coefficient in the water-chloroform system was determined. The BC determination method was applied to syrups which contained Acetyl-Sulphamethoxi-pyridacine (ASMP), Sulphadimidine (SD), Guayacol-gly-ceryl-ether (GGE) and Sodium benzoate (SB). The method is exact and accurate.     

Microcalorimetric determination of thermodynamic parameters for ionophore-siderophore host-guest complex formation

Thermodynamic parameters (delta H, delta S, and delta G) were determined by microcalorimetry in wet chloroform for host-guest assembly formation involving second-sphere complexation of the siderophore ferrioxamine B by crown ether (18-crown-6, cis-dicyclohexano-18-crown-6, benzo-18-crown-6) and cryptand (2.2.2 cryptand) hosts. Similar data were also collected for the same hosts with the pentylammonium ion guest, which corresponds to the pendant pentylamine side chain of ferroxamine B. Host-guest assembly formation constants (Ka) obtained from microcalorimetry agree with values obtained indirectly from chloroform/water extraction studies in those cases where comparable data are available. On the basis of a trend established by the pentylammonium guest, an enhanced stability relative to the crown ethers is observed for the assembly composed of ferrioxamine B and 2.2.2 cryptand that is due to entropic effects. Trends in delta H and delta S with changes in host and guest structure are discussed and attributed directly to host-guest complex formation, as solvation effects were determined to be insignificant (delta Cp = 0).     

冠醚配合物的研究 XI: 若干苯并-18-冠-6甲基衍生物液膜传输碱金属离子

本文研究了2,3-苯并-11-甲基-18-冠-6,2,3-苯并-8,15-二甲基-18-冠-6和2,3-苯并-8, 11, 15-三甲基-18-冠-6的氯仿液膜对Na^+, K^+, Rb^+的传输速率。结果指出,传输速率随膜相冠醚浓度增是加而增加, 两者成线性关系; 当冠醚的醚环上甲基数增加则传输速率减小; 对同一冠醚, 不同金属离子的传输速率与相应配合物稳定常数的大小顺序有一致关系; 冠醚传输金属离子时, 阴离子一起迁移, 阴离子水合能力越强则传输能力越小; 传输速率与搅拌速度成线性关系。     

Second-Sphere Coordination of Ferrioxamine B and Association of Deferriferrioxamine B, CH(3)(CH(2))(4)NH(3)(+), NH(4)(+), K(+), and Mg(2+) with Synthetic Crown Ethers and the Natural Ionophores Valinomycin and Nonactin in Chloroform

The interaction of ferrioxamine B, FeHDFB(+), through a protonated amine side chain, with various host ionophore structures to form a host-guest complex in the second coordination shell has been investigated. Host-guest association constants (K(a)) in water saturated chloroform are reported for synthetic crown ethers with different cavity size and substituents (18-crown-6 and its dicyclohexano, benzo, and dibenzo derivatives; dibenzo and dicyclohexano derivatives of 24-crown-8; and dibenzo-30-crown-10). The natural ionophores valinomycin and nonactin were also found to form stable second-sphere complexes with ferrioxamine B in wet chloroform. Results are reported for both picrate and perchlorate salts of FeHDFB(+). Since the protonated amine side chain of ferrioxamine B may be viewed as a substituted amine, the host-guest association constants for FeHDFB(+) are compared to the interaction of Mg(2+), K(+), NH(4)(+), CH(3)(CH(2))(4)NH(3)(+), and H(4)DFB(+) with the same ionophores. This is the first report of nonactin complexation of this series of cations in an organic medium of low polarity and one of the few reports of valinomycin complexation. To the best of our knowledge these are the first reported stability constants for the association of (Mg(2+),2pic(-)) with natural and synthetic ionophores in chloroform. K(a) values for ferrioxamine B complexation by the synthetic crown ethers are influenced by ring size and substituent. Despite significant preorganization capabilities, the large cavities of valinomycin, nonactin and benzo-30-crown-10 do not form as stable host-guest assemblies with bulky substituted amine cations such as ferrioxamine B as does cis-dicyclohexano-18-crown-6.     

Crown Ether As The Phase-Transfer Catalyst for Free Radical Polymerization of Hydrophobic Vinyl Monomers

Various crown ethers were used as phase-transfer catalysts for free radical polymerizations of some water-insoluble vinyl monomers such as acrylonitrile, methylmethacrylate and styrene with persulfate as initiator. The catalytic abilities of these crown ethers for free radical polymerization of acrylonitrile with S₂O₈^2?ion as an initiator were in the order: 18-crown-6 > 15-crown-4 > 12-crown-4 > benzo-15-crown-5 > dibenzo-18-crown-6. Among various persulfates such as Na₂S₂O₈ K₂S₂O₈ and (NH₄)₂S₂O₈, ammonium persulfate was the optimum initiator for the polymerization of acrylonitrile catalyzed by 18-crown-6 or 15-crown-5. Among the organic solvents used, chloroform seems to be the best solvent for the catalytic polymerization of acrylonitrile. An apparent activation energy of 72.9 kJ mol^?1 was observed for the polymerization of acrylonitrile. The catalytic reaction rates of free radical polymerization for these hydrophobic vinyl monomers were in the order: acrylonitrile > methylmethacrylate > styrene > isoprene. Effects of concentrations of crown ether, initiator, and nitrogen on the polymerization of these vinyl monomers were investigated.     

Thermodynamic study of solvent extraction of 15-crown-5- and 18-crown-6-s-block metal ion complexes and tetraalkylammonium ions with picrate anions into chloroform

Enthalpy and entropy changes for ion-pair extractions of tetraalkylammonium ions (R(4)N(+)) with picrate anions, overall extractions of s-block metal picrates with 15-crown-5 (15C5) and 18-crown-6 (18C6) and the partition of 15C5 itself were determined between chloroform and water. The distribution behaviour of crown ethers and the extraction process of s-block metal picrates with the crown ethers are discussed in detail on molecular grounds from the thermodynamic point of view. Moreover, enthalpy and entropy changes for ion-pair extractions of 1:1 15C5- and 18C6-s-block metal ion complexes with picrate anions are calculated from these experimental thermodynamic parameters and the literature values for complex-formation reactions of the crown ethers with the s-block metal ions in water. Enthalpy and entropy changes are negative for overall extractions of all the s-block metal picrates with 15C5 and 18C6. The extractions of the metal picrates with 15C5 and 18C6 at 25 degrees are completely enthalpy driven. Plots of thermodynamic parameters for ion-pair extractions of R(4)NA vs. the number of carbon atoms of R(4)N(+) show a linear relationship. From these experimental data, contributions of a methylene group and an ether oxygen atom to the thermodynamic parameters of the ion-pair extraction of R(4)NA and the partition of the crown ethers, respectively, between chloroform and water were obtained. Enthalpy and entropy changes for ion-pair extractions of 15C5- and 18C6-s-block metal picrate complexes were compared with those of R(4)NA. A striking difference in the ion-pair extraction process was found between the crown ether complexes and R(4)NA.     

Isosteviol and some of its derivatives as receptors and carriers of amino acid picrates

The ability of diterpenoid isosteviol 1 (ent-16-oxobeyeran-19-oic acid) and some of its derivatives with ester and amide groups to bind amino acid picrates in the course of their transport through a liquid chloroform membrane was observed for the first time. Isosteviol was very competitive with dibenzo-18-crown-6 and N,N′-bis(isostevioyl)-1,4-phenylenediamine 5 was even more effective in transportation of d,l-tryptophan through a liquid chloroform membrane.     

The synergistic extraction of thorium(IV) and uranium(VI) with mixtures of 3-phenyl-4-benzoyl-5-isoxazolone and crown ethers

The extraction of thorium(IV) and uranium(VI) from nitric acid solutions has been studied using mixtures of 3-phenyl-4-benzoyl-5-isoxazolone (HPBI) and dicyclohexano-18-crown-6, benzo-18-crown-6, dibenzo-18-crown-6 or benzo-15-crown-5. The results demonstrate that these metal ions are extracted into chloroform as Th(PBI)(4) and UO(2)(PBI)(2) with HPBI alone and as Th(PBI)(4) . CE and UO(2)(PBI)(2) . CE in the presence of crown ethers (CE). The equilibrium constants of the above species have been deduced by non-linear regression analysis. The addition of a CE to the metal chelate system enhances the extraction efficiency and also improves the selectivities between thorium and uranium. IR spectral data of the extracted complexes were used to further clarify the nature of the complexes. The binding to the CEs by Th(PBI)(4) and UO(2)(PBI)(2) follows the CE basicity sequence but with DC18C6 and DB18C6, steric effects become more important.     

Synthesis,crystal structure,and alkali metal picrate extraction capabilities of molecular clips based on diphenylglycoluril and benzocrown ethers

A convenient method for the synthesis of a series of molecular clips based on the diphenylglycoluril framework and benzocrown ether moieties by the reaction of bis(cyclomethoxymethylene)diphenylglycoluril with benzocrown ethers in polyphosphoric acid is proposed. X-ray diffraction analysis of molecular clips with the benzo-12-crown-4 and benzo-15-crown-5 fragments showed that both compounds are chloroform solvates with the stoichiometry clip:chloroform 1:1. By theoretical and experimental methods the existence of obtained clips in an anti–anti conformation was proved. The complexation properties of the obtained molecular clips were examined toward alkali metal and ammonium ions by FABMS spectrometry and extraction experiments.     

Extraction of uranium with crown ether carboxylic acids for neutron activation analysis

Uranium in aqueous solution can be extracted by sym-dibenzo-16-crown-5-oxy-acetic acid and its modified analogue 2-/sym-dibenzo-16-crown-5-oxy/-hexanoic acid into chloroform in the pH range 5.5–6.0. The extraction method combined with neutron activation analysis provides a sensitive method for the determination of uranium in natural waters.