Effect of phenyl substituent on the dimerization of copper(II)-carboxylate in solvent extraction of copper(II) with phenylacetic acid

The effects of the phenyl substituent on the dimerization of copper(II) carboxylate in the solvent extraction of copper(II) with phenylacetic acid using benzene and 1-octanol as a solvent were investigated, at 25 degrees and at the aqueous ionic strength of 0.1M (NaClO(4)). The dimerization of copper(II) phenylacetate has been found to be written as: 2CuA(2)Cu(2)A(4) in 1-octanol, and 2CuA(2)(HA)(2)Cu(2)A(4)(HA)(2) + (HA)(2) in benzene, with the dimerization constants, log K = 2.24 and log K = 4.19, respectively. It was proved that the phenyl group inhibits the formation of the dimeric copper(II) phenylacetate, and its effect is partially shielded by a methylene substituent.     

Influence of the solvent on the extraction of copper(II) from nitrate medium using salicylideneaniline

Different solvents including cyclohexane, dichloromethane, chloroform, toluene, 1-octanol, and methyl isobutyl ketone (MIBK) have been evaluated in extracting copper(II) from nitrate medium by salicylideneaniline. Extracted species differs from solvent to solvent: CuL₂ in cyclohexane, toluene, 1-octanol, and methyl isobutyl ketone. However, in dichloromethane or chloroform, there are two complexes of the type CuL₂ and CuL₂(HL). The extraction constants and percentage of extraction (%E) are calculated for different solvents. Solvent played an important role in recovering copper(II) from the aqueous solution, thus affecting the extraction equilibrium and extraction efficiency. The nonpolar solvent showed better performance than the polar solvent. The maximum extraction efficiency was 85.75% at pH?=?4.5, which was from cyclohexane.     

The effect of diluents on extraction of copper(II) with di(2-ethylhexyl)phosphoric acid

The liquid–liquid extraction of copper(II) from sulfate medium with di(2-ethylhexyl)phosphoric acid (D2EHPA, HL) at 25°C is studied with the following parameters: pH, concentration of the extractant, and the nature of diluent. The effect of the diluent using polar and nonpolar solvents in the extraction of copper(II) is discussed. The extracted copper(II) species were CuL₂ in 1-octanol and methyl isobutyl ketone and CuL₂ · 2HL in toluene, carbon tetrachloride, and cyclohexane. The extraction constants are evaluated for different diluents.     

The simultaneous spectrophotometric determination of iron and of copper using I,IO-phenanthroline

The use of n-octanol as extracting solvent has been employed in a new procedure whereby 1, 10-phenanthroline provides a simultaneous separation and spectrophotometric determination of both iron and copper when present together. The method depends upon the extraction of the Cu(I) complex into the water-immiscible alcohol phase leaving the Fe(II) complex in the aqueous phase. The separation of the two phase system in one extraction to give a quantitative partition of copper and iron is a feature of the method. The Cu(I) complex with 1, 10-phenanthroline was previously thought to be inoperative using any known water-immiscible organic solvent. The corresponding use of 2,2'-dipyridine as a substitute for 1, 10-phenan-throline was investigated and found to be inadequate. The new procedure is the first disclosure that the ferroin functional group may serve as a Cu(I) specific in substitution for the cuproine functional group of such ligands as cuproine⁵, neo-cuproine8 and bathocuproine7. The new procedure has been demonstrated to give a high degree of precision and at the same time providing simplicity in manipulation.     

Solvent effect on ion-pair extraction of 2-(2-pyridylazo)-1-naphthol-4-sulfonate anion with solvated hydroxonium ion using alcohols and 1-octanol/octane mixed solvents.

Extraction of 2-(2-pyridylazo)-1-naphthol-4-sulfonate anion with solvated hydroxonium ion was carried out using 14 kinds of alcohols and 1-octanol/octane mixed solvents as a solvent at 25 degrees C. Alcohols are 1-pentanol, 1-hexanol, 1-heptanol, 2-heptanol, 3-heptanol, 4-heptanol, 1-octanol, 2-octanol, 3-octanol, 1-nonanol, 2-nonanol, 3-nonanol, 5-nonanol and 1-decanol. Among them, 1-octanol was found to be extremely high in extractability for 2-(2-pyridylazo)-1-naphthol-4-sulfonate anion with hydroxonium cation. The extraction equilibrium for the systems using 1-octanol/octane mixed solvents was analyzed in detail in order to examine the extraction mechanism for these extraction systems. 2-(2-Pyridylazo)-1-naphthol-4-sulfonate anion was found to be extracted with the hydroxonium ion solvated by three 1-octanol molecules as an ion-pair. The extraction and partition constants of the ion-pair of 2-(2-pyridylazo)-1-naphthol-4-sulfonate anion with solvated hydroxonium ion were estimated in the 1-octanol/octane mixed solvent systems.     

Two-phase potentiometric metal extraction titrations of silver(I), copper(II) and cadmium(II) using some cation-exchangers as extractants

The use of two-phase potentiometric metal extraction titrations to study solvent extraction equilibria is described. The method provides a highly reproducible and convenient manner by which to determine extraction behaviour. The system was tested on a number of acidic extractants, namely D2EHPA, Ionquest 801, Cyanex 272, naphthenic acid and Versatic 10 acid. The extraction from an aqueous nitrate medium of silver(I), copper(II) and cadmium(II) was studied. The potentiometric data were used to obtain extraction curves and elucidate the nature of the extracted complexes by slope analysis and non-linear least squares treatment. In general, the following extraction order was obtained: D2EHPA > Ionquest 801 > Cyanex 272 and naphthenic > Versatic 10 for copper(II) and cadmium(II). Organophosphorus acids were shown to form complexes of the nature of Cu(HA(2))(2) with copper(II) and carboxylic acids formed dimeric complexes (CuA(2)(HA))(2). With cadmium octahedral complexes of the form CdA(2)(HA)(4) occurred. The extraction of silver(I) by Versatic 10 gave a dimeric complex (AgA(HA))(2). HA denotes the extractant in the acid form.     

Extraction of copper(II) carboxylates with chloroform under substoichiometric conditions

The features are considered of binding carboxylic acids (HR) as dimeric solvated copper(II) complexes at the copper(II) extraction with chloroform under substoichiometric conditions, with excess of the metal ion in the aqueous phase. The fundamental difference in the optimization of the quantitative extraction of copper(II) in the form of any carboxylate with a maximum ratio of Cu:R and the total binding with carboxylic acids to form the copper complex of the minimum stoichiometry was noted. It was found that quantitative binding of HR occurred at the extraction of mixed-ligand acetate-carboxylate copper(II) complexes without control over the aqueous phase acidity when acetic acid medium or copper(II) acetate was used, but not copper chloride, nitrate, perchlorate, or sulfate. The possibility of determination by extraction-photometric method by the color of the Cu(II) complex was shown that was suitable only to those carboxylic acids, whose logarithm of the partition coefficient in the water-chloroform mixture was higher than three.     

Effects of solvation on partition and dimerization of benzoic acid in mixed solvent systems

The partition of benzoic acid between 0.1M perchloric acid solution and two kinds of mixed solvents has been carried out at 25 degrees C. The partition and dimerization constants of benzoic acid have been determined in the 1-octanol-benzene and 2-octanone-benzene systems. In both the mixed solvent systems, with increasing content of 1-octanol and 2-octanone in each mixed solvent, the partition constant of benzoic acid has been found to increase, and the dimerization constant of benzoic acid in each organic phase to decrease. These phenomena are attributable to solvation of monomeric benzoic acid by 1-octanol and 2-octanone molecules in each mixed solvent.     

Benzothiazole-2-aldehyde-2-quinolylhydrazone as a reagent for the extractive spectrophotometric determination of copper (II)

Benzothiazole-2-aldehyde-2-quinolylhydrazone (BTAQH) was used for the spectrophotometric determination of trace amounts of copper(II) after the extraction process. Copper(II) reacts with BTAQH at pH 8.3–12.6 to form a water-insoluble 1:2 complex, which can be extracted with many kinds of organic solvent. The extracted species with benzene has an absorption maximum at 523 nm and obeyed Beer's law over the range 0.09 to 0.75 ppm of copper. The molar absorptivity is 7.50 × 10⁴M^?1 cm^?1 at 523 nm. The spectral properties of the copper(II) complexes with some tridentate hydrazones containing benzothiazole ring as a functional group were also discussed.     

Suspended droplet solvent microextraction-flame atomic absorption spectrometry (SDSME-FAAS) determination of trace amounts of copper in river and sea water samples

A simple and sensitive suspended droplet solvent microextraction (SDSME) method is proposed for the preconcentration and determination of copper by flame atomic absorption spectrometry (FAAS). The analytical procedure is based upon the formation of a complex between Cu(II) and 1-phenyl-1,2-propandione-2-oxime-thiosemicarbazone (PPDOT) as a complexing agent. After extraction of the complex by 1-octanol, copper concentration in the solvent drop was determined by FAAS. The effect of different parameters such as pH, PPDOT concentration, kind of buffer, kind and volume of organic solvent, volume of aqueous phase, extraction time, stirring rate of sample solution, temperature, and ionic strength were investigated. The effect of foreign ions on the determination was also studied. Under the optimized chemical and instrumental conditions, a linear calibration curve was achieved in the range of 0.0050–0.26 mg/L, with the limit of detection of 3 μg/L and the enrichment factor of 52.6. This method can be applied successfully to the determination of copper in water samples.     

A study of the complexation and extraction of Cu(II) sulfate and Ni(II) sulfate by N3O2-donor macrocycles

Comparative solvent extraction (water/chloroform) studies of Ni(II) and Cu(II) employing a dinonyl-substituted N3O2-donor macrocycle (L2) as extractant have been undertaken from sulfate, chloride, nitrate and acetate-containing aqueous media. Contrary to expectations, efficient extraction of both metal sulfates was observed, the degree of extraction being comparable (or slightly enhanced) relative to that observed for each of the other anionic systems. X-Ray diffraction studies of [NiL1(H2O)3]SO4 x 4H2O and [CuL1(H2O)]SO4 x 6.67 H2O (where L1 is the unsubstituted derivative of L2) show that each complex occurs as a hydrogen-bonded 'cluster', with the sulfate anions involved in hydrogen bonded networks that incorporate ligand amine protons and water molecules; in the copper complex, which adopts a dimeric arrangement, simultaneous sulfate binding to a copper site is also present. In each complex the macrocyclic ligand fails to coordinate via its ether oxygen donors but instead is arranged so that the metal ion and sulfate anions are somewhat shielded hydrophobically from the exterior of the complex cluster assembly.     

Investigation of aggregation in solvent extraction of lanthanides by acidic extractants (organo-phosphorus and naphthenic acid)

Three acidic extractants (Ⅰ) di(2-ethylhexyl) phosphoric acid (HDEHP),(Ⅱ) 2-ethylhexyl phos-phonic acid mono-2-ethylhexyl ester (KEHPEHE) and (Ⅲ) naphthenic acid were employed in preparing the samples for the characterization of the coordination structure of lanthanlde-extractant complexes and the physicochemical nature of aggregates formed in the organic diluent of the solvent extraction systems.Photo correlation spectroscopy (PCS) re-suits on the aggregates formed by the partially saponified HDEHP in n -heptane showed that the hydrodynamic radius of the aggregates was comparable to the molecular dimensions of HDEHP.The addition of 2-octanol into the diluent,by which the mixed solvent was formed,increased the dimensions of the corresponding aggregates.Aggregates formed from the ianthamde ions and HDEHP in the organic phase of the extraction systems were found very unstable.In the case of naphthenic acid,PCS data showed the formation of w/o microemulsion from the saponified naphthenic acid in the mix     

Efficacy of natural oils and conventional chemicals in the physical extraction of 4-hydroxybenzoic acid from aqueous solution

4-hydroxybenzoic acid (4-HBA) is a phenolcarboxylic acid and a valuable chemical with various pharmacological properties and a wide range of industrial applications. The present work is envisioned to retrieve 4-HBA from aqueous solution through physical extraction using natural oils (mustard oil, sunflower oil and soyabean oil) and chemicals (MIBK and 1-octanol) as solvent. The experimental evaluation of extraction equilibrium using aforesaid solvents is reported in the form of distribution coefficient (K_D), extraction efficiency (E_P %), partition coefficient (P) and dimerization constant (D). The results were analysed using several physicochemical aspects of the solvents utilized, such as the solvent polarity parameter, dielectric constant, and dipole moment. Further, the comparison of these extraction results was made with the results of our previous study which was with the solvents sesame oil, canola oil, benzene, toluene and p-ether. The results may be arranged in the increasing order with respect to average K_D and average E_P % for natural oils as canola oil (0.23, 18.85%) < mustard oil (0.25, 20.45%) < sunflower oil (0.27, 21.00%) < soyabean oil (0.34, 25.06%) < sesame oil (0.49, 33.24%) and for chemicals as benzene (0.08, 7.5%) < toluene (0.09, 8.25%) < p-ether (0.09, 8.32%) < MIBK (2.55, 71.41%) < 1-octanol (5.01, 83.01%).     

Effervescence assisted dispersive liquid–liquid microextraction with extractant removal by magnetic nanoparticles

In this article, effervescence assisted dispersive liquid–liquid microextraction with extractant removal by magnetic nanoparticles is presented for the first time. The extraction technique makes use of a mixture of 1-octanol and bare Fe₃O₄ magnetic nanoparticles (MNPs) in acetic acid. This mixture is injected into the sample, which is previously fortified with carbonate, and as a consequence of the effervescence reaction, CO₂ bubbles are generated making possible the easy dispersion of the extraction solvent. In addition, the MNPs facilitates the recovery of the 1-octanol after the extraction thanks to the interaction between hydroxyl groups present at the surface of the MNPs and the alcohol functional group of the solvent. The extraction mode has been optimized and characterized using the determination of six herbicides in water samples as model analytical problem. The enrichment factors obtained for the analytes were in the range 21–185. These values permit the determination of the target analytes at the low microgram per liter range with good precision (relative standard deviations lower than 11.7%) using gas chromatography (GC) coupled to mass spectrometry (MS) as analytical technique.     

Preferable solvatation of decane and benzene in 1-octanol-N,N-dimethylformamide mixed solvent

Heat effects of the dissolution of decane and benzene in a model system of 1-octanol (OctOH)-N,N-dimethylformamide are measured at 298 and 318 K using a variable temperature calorimeter with an isotermic shell. The state of hydrocarbon molecules in the mixed solvent is studied using an extended coordination model and is compared to earlier data for ethyl acetate (EtOAc), DMF, OctOH, and tetramethyl hematoporphyrin (TMHP). It is shown that the polar carboxylic groups of porphyrin are preferably solvated by amide molecules due to stronger interaction with DMF, while nonpolar aliphatic groups are solvated by alcohol molecules. We conclude that a solvate shell of aromatic benzene is strongly enriched with DMF over the range of compositions, suggesting that the weakening of the preferable solvatation of porphyrin relative to EtOAc is due primarily to the influence of nonpolar substituents.     

Selective stripping voltammetric determinations employing cells for electrolysis with simultaneous ion-exchange or solvent extraction

Cells have been designed for stripping-voltammetry analyses employing graphite working electrodes and mercury film electrodes on a graphite support, permitting ion-exchange or solvent extraction separation simultaneously with the pre-electrolysis. The ion-exchange separation was tested on the determination of mercury in the presence of excess of copper(II), lead and cadmium and on the determination of bismuth in the presence of excess of copper(II). The solvent extraction separation was tested on the determination of mercury(II) in the presence of copper(II), lead and cadmium and the determination of copper(II) in the presence of bismuth. Very good results were obtained by using ion-exchange, where the sensitivity and precision of the determination are comparable with those obtained in the determinations without separation, the separation efficiency being very high, limited virtually only by the capacity of the ion-exchanger used. The solvent extraction separations yielded poorer results: the sensitivity of the determination is decreased substantially, the separation efficiency is not very high and difficulties arise from the adsorption of the organic phase on the electrode surface.     

Dimeric molecular association of dimethyl sulfoxide in solutions of nonpolar liquids

Although many vibrational spectroscopic studies using infrared (IR) absorption and Raman scattering (RS) techniques revealed that dimethyl sulfoxide (DMSO) forms intermolecular dimeric associations in the pure liquid state and in solutions, the results of a number of dielectric relaxation studies did not clearly show the presence of such dimers. Recently, we found the presence of dimeric DMSO associations in not only the pure liquid but also in solutions of nonpolar solvents, such as tetrachloromethane (CCl(4)) and benzene (Bz), using dielectric relaxation (DR) techniques, which ranged from 50 MHz to 50 GHz at 25 °C. The dimeric DMSO associations cause a slow dielectric relaxation process with a relaxation time of ca. 23 ps for solutions in CCl(4) (ca. 17 ps in Bz) due to the dissociation into monomeric DMSO molecules, while the other fast relaxation is caused by monomeric DMSO molecules with a relaxation time of ca. 5.0 ps (ca. 5.5 ps in Bz) at 25 °C. A comparison of DR and vibrational spectroscopic data for DMSO solutions demonstrated that the concentration dependence of the relative magnitude of the slow and fast DR strength corresponds well to the two IR and RS bands assigned to the vibrational stretching modes of the sulfoxide groups (S═O) of the dimeric associations and the monomeric DMSO molecules, respectively. Moreover, the concentrations of the dimeric associations ([DIM]) and monomeric DMSO molecules ([MON]) were governed by a chemical equilibrium and an equilibrium constant (K(d) = [DIM](2)[MON](-1)) that was markedly dependent on the concentration of DMSO and the solvent species (K(d) = 2.5 ± 0.5 M(-1) and 0.7 ± 0.1 M(-1) in dilute CCl(4) and Bz solutions, respectively, and dramatically increased to 20-40 M(-1) in pure DMSO at 25 °C).     

Ion-pair liquid-liquid-liquid microextraction of nerve agent degradation products followed by capillary electrophoresis with contactless conductivity detection

The four nerve agent degradation products methylphosphonic acid (MPA), ethyl methylphosphonic acid (EMPA), isopropyl methylphosphonic acid (IMPA) and cyclohexyl methylphosphonic acid (CMPA) have been successfully extracted from aqueous sample solution by ion-pair liquid-liquid-liquid microextraction. In this procedure, the target analytes in the sample solution were converted into their ion-pair complexes with tri-n-butyl amine and then extracted by an organic solvent (1-octanol) layer on top of the sample solution. Simultaneously, the analytes were back-extracted into a drop of an aqueous acceptor solution which was suspended in the organic phase at a microsyringe needle tip. The factors influential to extraction: type of organic solvent, type of ion-pair reagent and its concentration, pH values of sample solution and acceptor aqueous phase, stirring rate and extraction time were investigated in detail. After extraction, the drop of the acceptor solution was withdrawn into the syringe and injected into a capillary electrophoresis system for analysis. Using contactless conductivity detection, direct quantification of these compounds is possible. Moreover, large-volume sample injection was employed for further preconcentration. Improvements in the limits of detection between 2.5 and 4 orders of magnitude could be achieved and concentrations at the ng/mL level can be determined. This newly established approach was successfully applied to a spiked river water sample.