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 tetrafluoroborate with crown ethers and its application to silicate rock analysis

Summary The extraction behaviour of tetrafluoroborate with crown ethers was studied. A high distribution ratio of tetrafluoroborate is obtained by extraction with dicyclohexano-18-crown-6 (DC18C6) in an organic solvent of high dielectric constant from potassium fluoride solution. The molar ratios of crown ether to KBF₄ in the extracted species are probably 1:1 for DC18C6, dibenzo-18-crown-6 and 18-crown-6, and 2:1 for benzo-15-crown-5 and 15-crown-5. The flow-injection extraction-spectrophotometric determination of tetrafluoroborate with Brilliant Green was worked out. Many rock reference samples were analyzed for boron (1–150 ppm).     

双冠醚的研究(Ⅶ)——Schiff碱型和仲胺型双(苯并-18-冠-6)的合成

4′-氨基苯并-18-冠-6分别与间-硝基苯甲醛、对-硝基苯甲醛、间-苯二甲醛及其取代物和对-苯二甲醛缩合制得6种新的Schiff碱型单冠醚和双冠醚。4′-甲酰基苯并-18-冠-6分别与4′-氨基苯并-15-冠-5、4′-氨基苯并-18-冠-6作用制得2个醚环大小相同和不同的Schiff碱型双(苯并冠醚)。这些双冠醚经硼氢化钠还原得到相应的6种新的仲按型双冠醚。     

Macrocycles as components of gas-chromatographic phases

The use of crown compounds (18-crown-6, benzo-18-crown-6, dibenzo-18-crown-6, benzo-15-crown-5, dibenzo-24-crown-8, 4,13-diaza-18-crown-6,4,13-dibenzyl-diaza-18-crown-6, and cryptand [2.2.2]) as components of stationary phases in the determination of organic compounds by gas chromatography is studied. The polarity, selectivity, efficiency, and working temperature ranges of stationary phases based on crown ethers and cryptand as well as conventional stationary phases for gas chromatography are compared. The influence of the type and number of heteroatoms, the conformational lability of the cavity, and the presence of substituents on the polarity and selectivity of the stationary phases under study is revealed. Preferable types of interactions of stationary phases containing crown compounds with organic compounds of different classes are discussed. It is concluded that phases of the mixed type based on crown ethers are promising for improving the selectivity and efficiency of gas-chromatographic separation     

Allylation of phenoxides by crown ethers and their polymers

Allylation of sodium phenoxide in the presence of crown ethers produces a high ratio of O/O + C allylation when conducted in water, phenol, benzene, or diethyl ether. The striking increase in the product ratios is attributed to specific complexation of the crown ethers that facilitate the dissociation of the ion pair aggregate of the sodioderivative in benzene or diethyl ether. The crown ethers may act as a phase transfer catalyst when the reaction is run in water. Furthermore, the O/O + C ratios of the allylation strongly depend on the kind of crown ethers used. To examine their effect the allylation of sodium phenoxide was studied with various crown ethers, such as 18-crown-6, benzo-18-crown-6, benzo-15-crown-5, poly(vinylmonobenzo-15-crown-5), and poly(vinylmono-benzo-18-crown-6), as catalysts. It was found that among these crown ethers poly(vinylmono-benzo-15-crown-5) was the most effective catalyst.     

Complexes of sodium and lithium borohydrides with macrocyclic polyethers

A method for the synthesis of complexes of sodium and lithium borohydrides with crown ethers is proposed. The complexes of sodium borohydride with benzo-15-crown-5, 4′-aminobenzo-15-crown-5, dibenzo-18-crown-6, and diaza-18-crown-6 and the complexes of lithium borohydride with benzo-15-crown-5 and dibenzo-18-crown-6 are synthesized. These complexes can be used for the preparation of hydrogen in their reactions with methanol. The complex formation does not affect the purity of hydrogen formed.     

Nitration of Benzo Crown Ethers with Potassium Nitrate in Polyphosphoric Acid

A general method for the nitration of benzo crown ethers with potassium nitrate in polyphosphoric acid has been developed. Mono- and dinitro derivatives of benzo-12-crown-4, benzo-15-crown-5, dibenzo-18-crown-6, and dibenzo-24-crown-8 have been prepared. The role of complex formation in the regioselective tendency for the nitration of dibenzo-18-crown-6 has been demonstrated.     

Thermochemical behaviour of crown ethers in the mixtures of water with organic solvents: Part VII. Enthalpy of solution of 15-crown-5 and benzo-15-crown-5 in the mixtures of water with acetone at 298.15 K

Enthalpy of solution of crown ethers (15-crown-5 and benzo-15-crown-5) in water-acetone mixtures have been measured within the whole range of mole fraction at 298.15 K. The obtained data have been compared with those of the solution enthalpy of both crown ethers in the mixtures of water with dimethyl sulfoxide. The replacement of SO group with CO in the molecule of the organic solvent brings about an increase in the exothermic effect of the solution of 15-crown-5 and benzo-15-crown-5 ethers, especially in the mixtures with a medium water content. The observed effect is connected with the preferential solvation of the molecules of both crown ethers by acetone molecules in the water-acetone mixtures. The process of preferential solvation of 15-crown-5 and benzo-15-crown-5 ethers does not take place in the water-dimethyl sulfoxide mixture.     

4′-N-烷基(芳基)-氨甲基苯并-18-冠醚-6及高聚物支载和硅胶支载冠醚的合成

本文报道新冠醚4′-N-烷基-和4′-N-芳基-氨甲基苯并-18-冠醚-6及聚苯乙烯珠体和硅胶支载冠醚的合成。后二者均可用作相转移催化剂。聚苯乙烯珠体支载的苯并-18-冠醚-6催化溴辛烷与氰化钾、氰化钠、或醋酸钾的取代反应时,活性较上述高聚物支载的苯并-15-冠醚-5为高。     

Effect of crown ethers on the solvent extraction and separation of lanthanide(III) ions with 4-benzoyl-3-methyl-1-phenyl-2-pyrazolin-5-one

Synergistic solvent extraction of 14 lanthanides with mixtures of 4-benzoyl-3-methyl-1-phenyl-2-pyrazolin-5-one (HP) and the crown ethers (S), 18-crown-6, benzo-18-crown-6 or dibenzo-18-crown-6 from an aqueous chloride medium with the constant ionic strength of 0.1 mol dm⁻³ was investigated using benzene as a diluent. The composition of the species extracted was determined as LnP3 · S. The addition of a crown ether to the chelating extractant produced rather significant synergistic effects. On basis of experimental data, values of equilibrium constants, synergistic coefficients, and separation factors were calculated.     

酚醛冠醚共缩聚物的合成与性能

用2,6-二羟甲基-4-苯基苯酚分别与二苯并-18-冠-6(2B18C6)、二苯并-24-冠-8(2B24C8)、二苯并-30冠-10(2B30C10)、苯并-15-冠-5(B15C5)、苯并-18-冠-6(B18C6)缩聚合成了五种酚醛型冠醚共聚物。我们用聚冠醚的氯仿溶液萃取苦味酸碱金属盐水溶液,研究了它们对金属离子的络合性能。结果表明,聚冠醚(PB15C5)和(PB18C6)的萃取能力和选择性显著优于相应的单冠醚。     

冠醚共缩聚物的合成与性能

双冠醚化合物对某些金属离子比单冠醚具有更好的络合性能和选择性,它们合成、应用研究越来越受到人们的重视,本工作采用2,6-二羟甲基对甲氧基苯酚为缩合剂与芳香族冠醚缩聚,得到一系列具有双冠醚结构特征的新酚醛型聚苯并冠醚(简称聚冠醚),聚冠醚合成容易,并呈现了比相应单冠醚更优越的络合萃取能力和富集效率。     

腙型双冠醚对碱金属的配位性能

本文报道了五个腙型双冠醚的合成。电导测定结果表明含苯并-15-冠-5单元的双冠醚与四苯基硼酸钾、铷、铯,含苯并-18-冠-6单元的双冠醚与四苯基硼酸铯生成2:1夹心型配合物(冠醚单元:金属离子)。并用这些双冠醚的氯仿溶液萃取苦味酸碱金属盐水溶液,测定了萃取百分率和计算了萃取平衡常数,结果表明腙型双冠醚的萃取能力及选择性优于相应的单冠醚。     

Separation of rhenium by extraction with crown ethers and flow-injection extraction—spectrophotometric determination with Brilliant Green

The extraction behavior of perrhenate with crown ethers was studied and methods for the separation and determination of rhenium were developed. The distribution ratio of perrhenate with dicyclohexano-18-crown-6 (DC18C6) increases with increases in the dielectric constant of organic solvents and in the potassium ion concentration of aqueous solution. The molar ratios of crown ether to KReO₄ in the extracted species are probably 1:1 for DC18C6, dibenzo-18-crown-6 and 18-crown-6 and 2:1 for benzo-15-crown-5 and 15-crown-5. Microgram amounts of rhenium were satisfactorily separated from large amounts of molbdenum(VI) by extraction with DC18C6 in 1,2-dichloroethane from 2 M potassium hydroxide solution containing tartrate and by back-extraction with sodium phosphate buffer solution after the addition of a twofold volume of hexane to the organic phase. Rhenium was determined by the flow-injection extraction-photometric method with Brilliant Green. Rhenium was satisfactory determined in molybdenite and other ore samples.     

Thermodynamics of Amino Acid Methyl Ester Hydrochlorides—Crown Ether Complexes in Methanol at 25°C

Stability constants, free energies, and enthalpies and entropies of the complexation of L-alanine methyl ester hydrochloride (L-Ala-HCl), L-phenylalanine methyl ester hydrochloride (L-Phe-HCl), and valine methyl ester hydrochloride (L-Val-HCl) with 15-crown-5 (15C5), benzo-15-crown-5 (B15C5), 18-crown-6 (18C6), benzo-18-crown-6 (B18C6), dicyclohexano-18-crown-6 (DC18C6), and dicyclohexano-24-crown-8 (DC24C8) in methanol are reported for 20°C. No significant variation in the stability constants and free energies of complexation is observed, indicating that the various crown ethers are poorly selective in binding the amino acids. However, the nature of the crown ether and the amino acid and their pattern of substitution cause a remarkable variation in the enthalpies and entropies of complexation. This indicates a strong enthalpy–entropy compensation effect. The enthalpy–entropy compensation effect for the crown ether complexes of the amino acid methyl ester hydrochlorides reported herein is compared with that of the crown ethers complexes of the amino alcohols and the free amino acid. It is found that the enthalpy–entropy compensation effect holds equally for the three classes of complexes.     

Voltammetric determination of copper at chemically modified electrodes based on crown ethers

The feasibility of fabricating copper-sensitive chemically modified electrodes (CMEs) for trace analysis in aqueous and in 40% (v/v) ethanol-water media was investigated. Carbon paste electrodes modified with crown ethers were constructed by mixing the crown ethers into a graphite powder-paraffin oil matrix. The electrodes so formed were able to bind Cu(II) ions chemically and gave better voltammetric responses than the unmodified ones. The crown ethers studied and compared were 15-crown-5, benzo-15-crown-5 and dibenzo-18-crown-6. With a 3% benzo-15-crown-5 CME, Cu(II) could be quantified at sub-ppm levels by differential pulse voltammetry with a detection limit of 0.05 ppm. By differential pulse anodic stripping voltammetry Cu(II) could be quantified over the range I to 100 ppb. Interference from metal ions like Ni(II), Co(II), Mn(II), Fe(II), etc. have also been studied. The method was successfully applied to artificial as well as commercial samples of alcoholic beverages.     

Formation Constants of Complexes of Monovalent Cations with Benzocrown Ethers in Nitromethane

The complexation reactions between the macrocyclic polyethers dibenzo-18-crown-6, benzo-18-crown-6, benzo-15-crown-5 and polyethers bearing a stilbene unit with alkali metal and silver cations have been studied conductometrically in nitromethane. The formation constants of 1 : 1 and 1 : 2 (metal : ligand) complexes were determined and found to decrease with increasing cation diameter. The stability of the stilbene crown – metal cation complexes is lower than for complexes of other investigated crown ethers with analogous cations. There seem to be some effects of double bond-silver ion interactions.     

含嘧啶环的双冠醚（Ⅱ）

由4，6－二氯－5－硝基嘧啶、2，4－二氯－5－硝基－6－甲基嘧啶分别与4′-氨基苯并冠醚反应合成了6种以嘧啶环为桥链的新双冠醚，其中分别含有苯并－12－冠－4（Al,Bl)、苯并－15－冠－5（A2，B2）和苯并－18－冠－6（A3，B3）单元。用这些双冠 氯仿溶液绎碱金属苦味酸盐水溶液进行了萃取，计算了萃取平衡常数Kc。结果表明双冠醚（A1，B1）、（A2，B2）和（A3，B3）分别对钠、钾和铯具有较高的萃取能力，其选择性显著优于相应的单冠醚。     

Effect of rigid fragments in the macrocycle on the adaptation of crown ethers to alkali-metal ions

Complexation selectivity curves were obtained by theoretical conformational analysis and penalty functions in terms of the conformational factors in the following crown ethers: 15-crown-5; benzo-15-crown-5: 18-crown-6; benzo-18-crown-6; dibenzo-18-crown-6; cyclohexano-18-crown-6. In the last case the effect of cis—trans isomerism in the bridging bonds on the selectivity of complexation with the ligand was investigated. Analysis of the selectivity curves shows that the introduction of aromatic fragments into the macrocycle reduces its adaptive capabilities. The complexation selectivity of the ligands from the selectivity curves is compared with the experimental stability series of the crown ether complexes with alkali metals.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 26, No. 3, pp. 355–360, May–June, 1990.     

Solvent extraction of alkaline earth metal picrates with poly- and bis(crown ether)s

Summary Solvent extraction of alkaline earth metal picrates with poly- and bis(crown ether)s containing benzo-15-crown-5- and benzo-18-crown-6 moieties was carried out in a water-chloroform system. The poly- and bis(crown ether)s showed larger extractability for the metal picrates than the corresponding monocyclic crown ethers. Especially, poly- and bis(benzo-15-crown-5), and bis(benzo-18-crown-6) were found to have relatively high extractability and selectivity for Ba²⁺ and Sr²⁺, respectively.

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Lösungsmittelextraktion von Erdalkalipikraten mit Hilfe von Poly- und Bis-Kronenethern

Zusammenfassung Poly- und Bis-Kronenether mit Benzo-15-krone-5- und Benzo-18-krone-6-Einheiten wurden zur Extraktion von Erdalkalipikraten im Wasser-Chloroform-System verwendet. Die genannten Ether zeigten eine bessere Extraktionsfähigkeit für die Pikrate als die entsprechenden monocyclischen Kronenether. Im Falle von Ba²⁺ und Sr²⁺ ergab sich eine besonders gute Extrahierbarkeit und Selektivität mit Poly- und Bis(benzo-15-krone-5)- und Bis(benzo-18-krone-6)-Ethern.