Solvent extraction of alkaline earth metals,and lithium with 1-phenyl-3-methyl-4-acylpyrazol-5-ones and trioctylphosphine oxide

The synergic extraction of magnesium, calcium, strongium, barium and lithium into cyclohexane or benzene containing 1-phenyl-3-methyl-4-acyl-pyrazol-5-one (HA) and tri-n-octylphosphine oxide (TOPO) was investigated as a function of pH, HA and TOPO concentration. The extracted species when the 4-benzoyl compound was used, were MA₂(TOPO)₂ (M = Mg, Ca, Sr), BaA₂(TOPO)₃ and LiA(TOPO)₂. When the 4-trifluoro-acetyl derivatives was used, the extracted species were the same except for SrA₂(TOPO)₃. Extraction constants for the synergic extractions were calculated.     

Adduct formation properties of mono- and bidentate phosphine oxide compounds in the liquid—liquid extraction of some divalent metals with 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone

The bidentate phosphine oxide compounds bis(diphenylphosphinyl)methane (BDPPM) and bis(diphenylphosphinyl)ethane (BDPPE) were synthesized and the liquid—liquid extraction equilibria of some divalent metal ions such as Co(II), Ni(II), Zn(II) and Cd(II) with 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (HPMBP) and the neutral phosphine oxide compounds were investigated. BDPPM was found to be much more powerful than BDPPE and the monodentate neutral ligand trioctylphosphine oxide (TOPO). The composition of the extracted species were determined by a graphical method to be M(PMBP)₂(TOPO)_s (s = 2 for Co, Ni, Cd and s = 1 for Zn), M(PMBP)₂(BDPPM) and M(PMBP)₂(BDPPE). The adduct formation constants between the acylpyrazolone chelates and the neutral ligands were determined and are discussed in terms of the molecular structure.     

Solvent extraction equilibria of bis-Hg(II) benzoylacetonate and benzoyltrifluoroacetonate complexes and their adducts with trioctylphosphine oxide

The solvent extraction equilibria of Hg(II) in 1 mol dm⁻³ (Na, H)ClO₄ with benzoylacetone and benzoyltrifluoroacetone in carbon tetrachloride containing trioctylphosphine oxide (TOPO) have been measured at 25°C. The stability constants of the complexes in the aqueous phase, the two-phase partition constants, and the adduct formation constants with TOPO of the bis-complexes have been computed from the data. It is concluded that Hg(II) forms very stable β-diketonates and the bis-complexes form stable TOPO adducts in the organic phase. However, the partition constants of the bis-complexes are much lower than those of many other metal ions and this is the reason for the poor extraction of Hg(II) with these reagents.     

Studies on mixed ligand complexes of samarium(III), europium(III) and dysprosium(III) with 1-nitroso-2-naphthol and trioctylphosphine oxide

The extraction behavior of Sm(III), Eu(III) and Dy(III) with 1-nitroso-2-naphthol (HA) and trioctylphosphine oxide (TOPO) in methyl isobutyl ketone (MIBK) from aqueous NaClO₄ solutions in the pH range 4–9 at 0.1M ionic strength has been studied. The equilibrium concentrations of Sm and Dy were measured using their short-lived neutron activation products,¹⁵⁵Sm and^165mDy, respectively. In the case of Eu, the concentrations were assayed through the^152,154Eu radiotracer. The distribution ratios of these elements were determined as a function of pH, 1-nitroso-2-naphthol and TOPO concentrations. The extractions of Sm, Eu and Dy were found to be quantitative with MIBK solutions in the pH range 5.9–7.5, 5.6–7.5 and 5.8–7.5, respectively. Quantitative extraction of Eu was also obtained between pH 5.8 and 8.8 with chloroform solutions. The results show that these lanthanides (Ln) are extracted as LnA₃ chelates with 1-nitroso-2-naphthol alone, and in the presence of TOPO as LnA₃(TOPO) and LnA₃(TOPO)₂ adducts. The extraction constants and the adduct formation constants of these complexes have been calculated.     

Estimation of rare and radioactive constitutents in samples of Indian tobacco with the aid of low-level beta-counter

The extraction of radium and barium into a mixture of 1-phenyl-3-methyl-4-benzoylpyrazol-5-one (HPy) and trioctylphosphine oxide (TOPO) in n-hexane or cyclohexane was investigated as a function of pH and TOPO concentration. It was found that the synergistic enhancement of the extraction is caused by the formation of mixed complexes of type M(Py)₂ (TOPO)₃ and the overall extraction constants of both complexes were calculated.     

Extraction separation of tervalent lanthanide metals with bis(2,4,4-trimethylpentyl)phosphinic acid

The extraction behavior of certain tervalent lanthanides (Ln) such as La, Pr, Eu, Ho and Yb, using a chloroform solution containing bis(2,4,4-trimethylpentyl)phosphinic acid (HBTMPP), either alone or combined with one of three adductants, trioctylphosphine oxide (TOPO), octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO) or methylenbis(diphenylphosphine) oxide (MBDPO), was studied. The stoichiometry, extraction constants and separation factors of these systems were determined. Lanthanide ions were found to be extracted in the presence of TOPO (B), Ln(HL₂)₃, or as the adduct complexes, Ln(HL₂)₂B. Neither CMPO nor MBDPO was found to form adducts.     

Studies on extraction of copper(II) with 1-phenyl-3-methyl-4-acyl-5-pyrazolone

The extraction of Cu(II) with 1-phenyl-3-methyl-4-acyl-5-pyrazolone (HA), in different organic solvents has been studied. The extraction mechanism of Cu(II) and the composition of the extracted species has been determined. Cu(II) was extracted as CuA₂, or in the presence of TOPO, as CuA₂TOPO. The extraction constants do not change regularly with increasing the length of acyl chain in the 1-phenyl-3-methyl-4-acyl-5-pyrazolone derivatives. The effect of the temperature on the extraction of Cu(II) has also been investigated.     

Extraction of zirconium(IV) from hydrochloric acid solutions by tri-octylamine and neutral donors

Solvent extraction of Zr(IV) from aqueous HCl solutions by mixtures of TOA and different organophosphorous bases in carbontetrachloride solvent have been found to be always higher than that by any single extractant. Synergism has been observed in the range of 2.4–9.6M HCl. Although the species extracted with neutral donor alone seems to be ZrCl₄·TOPO etc, with a mixture of extractants, however, the extracted species appears to be Q₂ZrCl₆·TOPO where Q is R₃NH. The extraction has also been found to increase with increase in the concentration of amines and neutral donors. Enhancement of extraction has been explained by the formation of a complex adduct in organic phase. Synergistic coefficients and apparent formation constants of the complex adducts have also been calculated.     

Solvent effects in the synergistic solvent extraction of Co2+

The extraction of Co²⁺ from a 0.1M ionic strength aqueous phase (Na⁺, CH₃COOH) of pH=5.1 was studied using thenoyltrifluoroacetone, HTTA, in eight different solvents and HTTA+trioctylphosphine oxide, TOPO, in the same solvents. A comparisons of the effect of solvent dielectric constants on the equilibrium constant shows a synergism as a result of the increased hydrophobic character imparted to the metal complex due to the formation of the TOPO adduct.     

First Hydrolysis Constant of Lutetium (III) by Solvent Extraction

The solvent extraction method involving diglycolic acid (dicarboxy methyl ether) as a competitive ligand to lutetium and N-tris[hydroxymethyl]methyl-2-aminoethanesulfonic acid (TES) as a buffer was used to study the hydrolysis of lutetium in 1 mol⋅dm⁻³ NaCl ionic strength at 303 K. Acid dissociation constants of H₂DG and TES were determined and the possible formation of lutetium–TES compounds was investigated. It was found that lutetium does not form compounds with TES under the experimental conditions. The solvent extraction method using ¹⁷⁷Lu as a tracer was applied and the first hydrolysis constant of lutetium was determined by means of the relationship of the equilibrium constant of the complex Lu(DG)⁺ in the absence and in the presence of hydrolysis. The value obtained was log ₁₀ β _Lu,H=−7.9±0.3.     

The solvent extraction of europium and barium with 1-aryl-3-methyl-4-aroyl-5-pyrazolones

Eleven 1-aryl-3-methyl-4-aroyl-5-pyrazolone derivatives were synthesized. Their acid dissociation constants were determined spectrophotometrically; there was a linear relationship between them and Hammett's σ values. Europium and barium ions were readily extracted into benzene and n-octyl alcohol, respectively, at very low pH.     

Synergic extraction of uranium(VI) by combination of tri-iso-octylamine and neutral donors

Synergistic effect of neutral donors like tri-butyl phosphate (TBP), triphenyl phosphine oxide (TPPO), trioctyl phosphine oxide (TOPO), and dimethyl sulphoxide (DMSO) on the extraction of uranium(VI) by tri-isooctyl amine into CCl₄ is reported. Synergistic coefficients and adduct formation constants are calculated from distribution data and correlated with relative donor abilities of added bases.     

Kinetics and mechanism of diels-alder additions of tetracyanoethylene to anthracene derivatives-III : Effect of substituents on rates and intermediate complex formation

In Diels-Alder additions of tetracyanoethylene to 1,2-, and 9-substituted anthracenes, formation constants (K) for the intermediate complexes have been separated from the global rate constant (k₂^obs). The relatively small range of values of K indicates a very small charge transfer in the complexes. The transition state for conversion of complex into adduct showed a marked degree of charge development, particularly for the 9-substituted derivatives (p = -7). Substituents in the outer rings gave good rate correlations with composite constants (σ_m⁺+σ_p⁺) with a p value of - 3. The substituent effects are discussed in terms of these and other parameters. Values for equilibrium constants for the overall addition (K_cq) are reported.     

Synergistic extraction of copper(II) from sulfate medium with capric acid and tri-n-octylphosphine oxide in chloroform

The synergistic solvent extraction of copper(II) from 0.33?mol?dm^?3 Na₂SO₄ aqueous solutions with capric acid (HL) in the absence and presence of tri-n-octylphosphine oxide (TOPO) in chloroform at 25°C has been studied. The extracted species when capric acid was used alone is CuL₂(HL)₂. In the presence of TOPO, the extracted complex is CuL₂(HL)₂(TOPO). The TOPO–HL interaction strongly influences the synergistic extraction efficiency. The extraction constants were calculated.     

Linear free energy ortho-correlations in the thiophene series. Part IX . Kinetics of esterification with diazodiphenylmethane of some 3-, 4-, and 5-substituted thiophene-2-carboxylic acids in methanol

The rate constants for the esterification of some 3-, 4-, and 5-substituted thiophene-2-carboxylic acids with diazodiphenylmethane in methanol at 25° have been measured. The reactivity of some para- and ortho-substituted benzoic acids has also been determined. Logarithmic kinetic constants for ortho-, meta-, and para-like substituted thiophene-2-carboxylic acids furnish an excellent linear free energy relationship when plotted versus Δpk_a (β 0.89, r 0.989, C.L. > 99.9%, n 18, i 0.04), thus confirming the peculiar behaviour of five-membered ring derivatives. The correlation with σ^H values offers an additional proof of the hyper-ortho character of the 2,3-relation in thiophene derivatives. para- and ortho-Substituted benzoic acids show the usual behaviour of six-membered ring derivatives.     

Prediction of ortho substituent effect in alkaline hydrolysis of phenyl esters of substituted benzoic acids in aqueous acetonitrile

The second-order rate constants k for the alkaline hydrolysis of phenyl esters of meta-, para- and ortho-substituted benzoic acids, X-C₆H₄CO₂C₆H₅, in aqueous 50.9% acetonitrile have been measured spectrophotometrically at 25°C. The log k values for meta and para derivatives correlated well with the Hammett σ_m,p substituent constants. The log k values for ortho-substituted phenyl benzoates showed good correlations with the Charton equation, containing the inductive, σ_I, resonance, σ^○ _R, and steric, E _s ^B, and Charton υ substituent constants. For ortho derivatives the predicted (log k _X)_calc values were calculated with equation (log k _ortho)_calc = (log k ^H _AN)_exp + 0.059 + 2.19σ_I + 0.304σ^○ _R + 2.79E _s ^B ? 0.0164ΔEσ_I — 0.0854ΔEσ^○ _R, where DE is the solvent electrophilicity, ΔE = E _AN — E _H20 = ?5.84 for aqueous 50.9% acetonitrile. The predicted (log k _X)_calc values for phenyl ortho-, meta- and para-substituted benzoates in aqueous 50.9% acetonitrile at 25°C precisely coincided with the experimental log k values determined in the present work. The substituent effects from the benzoyl moiety and aryl moiety were compared by correlating the log k values for the alkaline hydrolysis of phenyl esters of substituted benzoic acids, X-C₆H₄CO₂C₆H₅, in various media with the corresponding log k values for substituted phenyl benzoates, C₆H₅CO₂C₆H₄-X.     

An efficient catalyst for the synthesis of ortho-substituted biaryls by the Suzuki cross-coupling: Triphenylphosphine adduct of cyclopalladated ferrocenylimine

The air and moisture stable triphenylphosphine adduct of cyclopalladated ferrocenylimine 2 has been successfully used in palladium-catalyzed Suzuki cross-coupling for the synthesis of ortho-substituted biaryls in air. In the presence of 0.05 mol% of 2 as catalyst and 3 equivalent of CsF as base in dioxane at 100 °C, ortho-substituted biaryls were synthesized with moderate to high yields in the reactions of 2-methoxy-1-naphthylboronic acid with aryl halides, and 14 new ortho-substituted biaryls were obtained and characterized.     

Synthesis of chiral,non-racemic ferrocene derivatives by ortho-metallation and partial reductive removal of ortho-directing amino groups

Chiral, non-racemic 1,2-disubstituted ferrocenes have been prepared from monosubstituted ferrocene derivatives by amine-mediated ortho-directed reactions and subsequent partial reductive removal of the stereogenic ortho-directing group. It was found that the ortho-directing amino group of 2-substituted derivatives of N,N-dimethylaminoethyl-ferrocene and similar compounds can, after quaternisation with methyl iodide, be reductively removed with sodium borohydride to give 2-substituted methyl- or ethylferrocenes. In most cases the substituents I, Br, COOEt, P(O)Ph₂ and CN tolerate the reaction conditions used. In addition, a few examples are reported that show how the use of LiTMP allows 2-bromo- and especially 2-cyano-substituted derivatives to be further ortho-lithiated and reacted to give 1,2,3-trisubstituted ferrocenes.     

Extraction of sulfuric acid with TOPO

A study on solvent extraction of sulfuric acid by tri-octylphosphine oxide (TOPO) in n-heptane has been made. Extraction coefficients of H₂SO₄ as a function of H₂SO₄ concentration in aqueous phase, and extractant concentrations in organic phase have been studied. The composition of extracted species, equilibrium constants of extraction reaction have been evaluated. These results are important for interpreting extraction equilibrium data of uranium(VI) or other metal ions with TOPO in sulfuric acid media.     

Ortho-effects of carboxyl, sulpho and arsono groups on the protonation and dissociation constants of mono-azo and bis-azo chromotropic acid derivatives

The effect of carboxyl sulpho and arsono groups on the protonation and dissociation constants of mono-azo and bis-azo chromotropic acid derivatives has been investigated. From the value obtained for the effect of the substituents the equationortho-effect = log K_ortho-log K para has been derived. The causes of the effect are discussed