Distribution coefficients for novocaine in aliphatic alcohol (C3-C9)-solvotropic reagent-salting-out reagent-water systems

The distribution of novocaine in aliphatic alcohol (C₃-C₉)-solvotropic reagent-salting-out reagent-water systems are studied. The quantitative characteristics of extraction, distribution coefficients (D) and rate of extraction (R, %), are calculated. Relationships between the D of novocaine and the content of solvotropic reagent in the system are established, along with the composition and formation constants of the molecular complexes.     

Extraction of Nitric Acid and Np(IV) by some aliphatic ketones and alcohols

The extraction behaviour of HNO₃ and Np(IV) from aqueous nitrate solutions with some aliphatic alcohols and ketones using hexane, carbon tetrachloride, benzene and chloroform as diluents was studied. The acid concentration in the aqueous phase varied from 0.25 to 10 M and that of the extractant in the organic phase varied from 0.5 M to the undiluted fraction. In the alcohol systems, solutions of the same alcohol in the diluents CCl₄ and CHCl₃ showed similar capacity for acid extraction, and also in the same diluents, solutions of diisopropyl and diisobutyl alcohol showed similar capacity for extraction. Extraction of Np(IV) with the different ketones and alcohols used follow the same pattern as HNO₃.     

The use of the concept of solvation excesses for studying the mutual distribution of solution component particles in the H<Subscript>2</Subscript>O-KCl-NaCl and H<Subscript>2</Subscript>O-KNO<Subscript>3</Subscript>-NaNO<Subscript>3</Subscript> systems

The data on component activities and salt solubilities were analyzed to determine solvation excesses in the H₂O-KCl-NaCl and H₂O-KNO₃-NaNO₃ systems. Some rules governing the solvation of ions were discussed.     

Extraction properties of octaethyltetraamidopyrophosphate (OETAPP)

The extraction of uranium was studied in the system of 0.1 M OETAPP in CHCl₃/HCl or HNO₃. The distribution coefficients of HCl and HNO₃ were calculated as a function of OETAPP concentration. The amount of OETAPP in the aqueous phase containing HCl and HNO₃ was found from the measurements of surface tension of this phase. The distribution of HCl and HNO₃ between an organic and aqueous phase was studied as a function of the concentration in the aqueous phase of the acid in question. The solvation energy of the extracted complexes was calculated on the basis of the measured potential differences. The cohesion and adhesion energies of the studied systems are given as well.     

Application of Covington's nonstatistical distribution of solvate species theory to the preferential solvation of Tl+ in various binary solvent systems

Covington's nonstatistical distribution of solvate species theory of preferential solvation is used to analyze ²⁰⁵ Tl chemical shift data for 0.005M TlNO ₃ in nine binary solvent systems. The theory quite adequately fits the experimental data, and equilibrium constants and free energies of preferential solvation are obtained. The effect of choosing different values for the solvation number is investigated and found to be slight except for systems involving DMSO, ³ where decreasing the solvation number from 6 to 3 improves the fit to experimental data.     

Understanding the extraction mechanism,radiolytic stability and stripping behavior of thorium by ionic liquid based solvent systems: evidence of ‘ion-exchange’ and ‘solvation’ mechanism

The extraction efficiency for thorium followed the trend: Cyanex-923 > Cyanex-272 > DHOA > TBP. In case of TBP and DHOA the extraction proceeded via ‘solvation mechanism’ through Th(NO₃)₄·2L, while for Cyanex-923 and Cyanex-272 it proceeded via ‘ion exchange’ mechanism through (Th(NO₃)₂·2L)²⁺. The extraction process followed slower kinetics while change in Gibb’s energy revealed the spontaneity of the process. These ionic liquid based systems were found to be radiolytically stable, highly efficient and selective for Th. Oxalic acid was found to be suitable for almost quantitative stripping of Th from extracted ionic liquid phase.     

Extraction of iron(III) with diphenyl-2-pyridylmethane dissolved in benzene from aqueous chloride solutions

The mechanism of extraction has been investigated by partition, slope analysis and loading-ratio data. The results obtained give a picture of the mechanism of extraction of FeCl ₄ ⁻ ions in relation to the hydration and solvation of the compound extracted. The possible formula of the extracted species is (DPPM)₃H₃O⁺(H₂O)_n−FeCl ₄ ⁻ . In dilute aqueous hydrochloric acid systems the influence of the concentration of a number of salts with cations of different electrical potentials (Ze/r), on iron(III) extraction, has been studied. Splitting of the organic phases occurs at high acid and/or high salt concentrations. The phenomenon is explained on the basis of the variability of the hydration number. Investigations have been made to understand the parameters controlling the extraction of the metal and its is shown that the extraction offers a simple, fast and selective separation method of iron from solutions.     

Thermodynamics of specific interactions of pyridines in aliphatic alcohols: Gibbs energy, entropy, and degree of binding

The activity coefficients at infinite dilution (T = 298.15 K) and Gibbs energy of solvation of pyridines in aliphatic alcohols were determined. The thermodynamic functions of specific interactions in these systems were calculated.     

The Affinity of Some Lewis Bases for Hexafluoroisopropanol as a Reference Lewis Acid: An ITC/DFT Study

To figure out the possible role of 1,1,1,3,3,3-hexafluoropropan-2-ol (HFIP) as well as to provide reference thermochemical data in solution, the formation of Lewis acid-base complexes between HFIP (Lewis acid) and a series of 8 different Lewis bases (3 sulfoxides, 3 Nsp² pyridine derivatives, 1 aromatic amine, 1 cyclic aliphatic ether) was examined by isothermal titration calorimetry (ITC) experiments and static density functional theory augmented with Dispersion (DFT−D) calculations. Measured ITC association enthalpy values (ΔH_a) lie between −9.3 and −14 kcal mol⁻¹. Computations including a PCM implicit solvation model produced similar exothermicity of association of all studied systems compared to the ITC data with ΔH_a values ranging from −8.5 to −12.7 kcal mol⁻¹. An additional set of calculations combining implicit and explicit solvation by chlorobenzene of the reactants, pointed out the relatively low interference of the solvent with the HFIP-base complexation: its main effect is to slightly enhance the Gibbs energy of the HFIP-Lewis base association. It is speculated that the interactions of bulk HFIP with Lewis bases therefore may significantly intervene in catalytic processes not only via the dynamic microstructuring of the medium but also more explicitly by affecting bonds’ polarization at the Lewis bases.     

Gas-chromatographic determination of aliphatic amines in natural surface water and wastewater

A procedure was developed for the gas-chromatographic determination of aliphatic amines C₇–C₂₀ with prederivatization by N-methyl-bis(trifluoroacetamide), in the concentration range of natural surface water, to 10^?4-1 mg/L, and wastewater, to 10^?3-1 mg/L. The conditions were optimized for the extraction preconcentration of aliphatic amines with toluene from natural surface water and wastewater. The detection limit for aliphatic amines at a signal-to-noise ratio of 3: 1 was 50 ng/L.     

Influence de la solvatation preferentielle sur les dimensions des polymeres en solution dans des melanges de solvants

We have studied the dependence of the intrinsic viscosity number of polymers on the composition of binary solvents. The systems studied are: polystyrene in CCl₄/CH₃OH, C₆H₆/CH₃OH and C₆H₆/heptane and poly-2-vinylpyridine in CHCl₃/CH₃CH₂OH. We have also studied, for the same systems, preferential solvation of the polymers, using light scattering.We have observed that, near the θ point, short polystyrene chains exhibit a higher expansion than long chains. This was explained in terms of the dependence of preferential solvation on molecular weight.For the system poly-2-vinylpyridine/CH₃CH₂OH/CHCl₃, we have established the viscosity increment dependence on solvent composition. The curve describing this increment differs markedly from the theoretical curve based on G^E values (excess free energy) of the solvent mixture. However, taking into consideration the process of preferential solvation, the experimental curve can be corrected and becomes very similar in shape to the theoretical curve but there still remains a quantitative difference between the two curves.     

Separation of boric acid from radioactive wastes by liquid-liquid extraction

The extraction of boric acid from a solution modeling radioactive waste has been studied. Different aliphatic alcohols were used as extractants. Factors affecting the distribution ratio of boric acid and the behaviour of some other components of the solution under conditions of boric acid extraction were investigated. The composition of species extracted was determined from distribution data of n-hexanol and H₃BO₃.     

Reversed phase extraction chromatography using solutions of nitric acid as eluants

Approximately 40 ions have been chromatographed on thin layers of silica gel impregnated with Alamine 336-S, Alamine 336-S oxide, tri-n-octylarsine oxide, tri-n-octylphosphine oxide or tri-n-butyl phosphate, and on non-impregnated silica gel. Solutions of 0.2–15 N HNO₃ are used as eluants. R_F spectra and a number of separations are reported. The ions are classified into four groups according to their chromatographic behaviour, which is explained on the basis of anion exchange, solvation, hydrolysis and interaction with the support.Data on the extraction of HNO₃ and the co-extraction of water are reported. The behaviour of Alamine oxide and tri-n-octylarsine oxide parallels that of high-molecular-weight amines: extraction proceeds through anion exchange. Nitric acid taken up in excess of the stoichiometric amount is mainly present in the organic phase as part of the ion [O₂NO…HONO₂]⁻. On the other hand, with tri-n-octyl-phosphine oxide (TOPO) and tri-n-butyl phosphate (TBP), extraction proceeds through solvation; TOPO·HNO₃, TOPO·2HNO₃ and TBP·HNO₃ are the species present in the organic extracts.     

Extraction of tri- and tetravalent actinides with dihexyl N,N-diethylcarbamoylmethyl phosphonate (DHDECMP) and TBP from nitric acid solutions

Extraction of trivalent (Pu³⁺, Am³⁺, actinides and Eu³⁺, a representative of lanthanides) and tetravalent (Np⁴⁺ and Pu⁴⁺) actinides has been studied with dihexyl N,N-di-ethylcarbamoylmethyl phosphonate (DHDECMP) in combination with TBP in benzene from 2M nitric acid. The stoichiometries of the species extracted were found to be M(NO₃)₃·(3–n) TBP·n DHDECMP (for trivalent ions) and M(NO₃)₄·(2–n) TBP·n DHDECMP (for tetravalent ions) by the slope ratio method. The extraction constants evaluated (from the distribution data) indicate that for tetravalent ions (with solvation number two) the extraction constant increases when TBP (Kh=0.17) molecules are successively replaced by more basic DHDECMP (Kh=0.34) molecules. However, for trivalent ions (with solvation number three) when TBP molecules are totally replaced by DHDECMP molecules stereochemical factors appear and instead of increase, a substantial decrease in extraction constants is observed for Eu³⁺ and Am³⁺, a lesser decrease being observed for Pu³⁺ (larger ion).     

Studies on the separation of anions with 8-hydroxy-quinolinium ion as counterion

Distribution constants, K_D, for 8-hydroxyquinolinium-anion pairs and for a series of inorganic and organic anions are reported between aqueous acidic phases and 1-butanol and 3-methyl-1-butanol. As expected, K_D values are larger for anions with relatively large crystal radius (e.g., Cl^- < I^- < R-SO₃^-), smaller for anions containing either hydroxyl or carboxyl groups favoring solvation by water (e.g., HSO₄^-, HSeO₃^-, H₂PO₄^-, C₆H₅COO^-, CH₃COO^-) and larger in solvents with larger solubility parameters (e.g., 4-methyl-2-pentanone < 3-methyl-1-butanol < 1-butanol). Distribution constants between aqueous solutions and 8-hydroxyquinoline immobilized (chemically) on controlled-pore glass are estimated for a series of aromatic and aliphatic sulfonates. Aromatic sulfonates show substantially larger K_D values than aliphatic sulfonates. Batch equilibration data were used to design chromatographic (liquid-solid) separation of a few sulfonates.     

Liquid–liquid equilibrium of ternary systems 1-octyl-3-methylimidazolium hexafluorophosphate + aromatic + aliphatic hydrocarbons

The phase behavior of six ternary systems involving an aromatic hydrocarbon (benzene, toluene or m-xylene), an aliphatic hydrocarbon (nonane or undecane), and an ionic liquid (1-octyl-3-methylimidazolium hexafluorophosphate, [omim][PF₆]) was experimentally studied at 298.15 K and atmospheric pressure, totalizing 26 tie-lines. The main goal is to determine if [omim][PF₆] is a good solvent for the separation of the aromatic and aliphatic compounds, a common operation in the processing of reformed naphtha. All the ternary diagrams are of type 1, with high and wide two-phase regions, which show that [omim][PF₆] is a good solvent for the extraction of aromatic from aliphatic hydrocarbons. The Othmer–Tobias correlation was used for evaluation of the quality of the tie-line data, with good results. The data were correlated with the NRTL model for the activity coefficient, with estimation of new interaction energy parameters by using a modified Simplex method and a composition-based objective function. The results, expressed by root mean square deviations between experimental and calculated compositions, are very satisfactory.     

Calculation of equilibrium in anion-exchange extractive systems

Anion-exchange extractive systems based on solutions of higher quaternary ammonium salts in the presence of solvating additives, derivatives of trifluoroacetophenone, were considered. A mathematical model of the extractive system was developed and average solvation numbers and constants of solvation of ClO ₄ ^? , SCN^?, Br^?, and NO ₃ ^? ions by variously structured derivatives of trifluoroacetophenone were calculated from experimental data.     

Coordination of perchlorate ion in the secondary solvation sphere of Am3+ in the tracer concentrations in mixed system of dimethyl sulfoxide/water with 1.00M (H,Na)(Cl,ClO4)

The stability constants, β₁, of monochloride complex of Am(III) have been determined in a mixed system of dimethyl sulfoxide (DMSO) and water at 1.00 mol·dm⁻³ ionic strength using solvent extraction. The values of β₁ in mixed DMSO+H₂O solutions decrease rapidly with an increase in the mole fraction of DMSO (X _s ) in mixed solvents and become negative ones, which is not in a definition of stability constant, inX _s >0.04. The variation of β₁ inX _s ≦0.02 was accounted for by the size-variation of the primary solvation sphere around Am(III), which was present as a solventshared ion-pair, and by a little effect due to an invasion (coordination) of ClO₄ ⁻ into the secondary solvation sphere of Am³⁺. On the other hand, it was concluded that the β₁ obtained by solvent extraction inX _s >0.02 was an apparent value, because of a large effect due to an invasion (coordination) of ClO₄ ⁻ into the secondary solvation sphere of Am(III).     

Coefficients of caffeine distribution in aliphatic alcohol-ammonium sulfate-water systems

The extraction of caffeine with aliphatic alcohols C₃?CC₉ from aqueous solutions in the presence of a salting-out agent (ammonium sulfate) is studied. Quantitative characteristics of extraction are calculated: the distribution coefficients (D) and the degree of recovery (R, %). Relations are found between logD of caffeine and the length of the hydrocarbon radical in the alcohol molecule, along with certain physicochemical properties of the extragents.     

Studies on systems of salts and mixed solvents. XXXIII. On the solvation of cations (Li+, Mg2+, Al3+) in dimethylsulphoxide-water mixtures (Raman spectroscopic investigations into concentrated electrolyte solutions)

Starting from pure DMSO (DMSO-d₆) the solvent-solvent interactions detectable in the aqueous systems were investigated by means of v_SO and v_CS. On the basis of the results obtained the solvation behaviour of cations (Li⁺, Mg²⁺, Al³⁺) in DMSO (DMSO-d₆)? H₂O mixtures is discussed. In spite of the prevailing solvent-solvent interactions direct cation-DMSO (DMSO-d₆) interactions can still be proved in solutions rich in water, which suggest preferred cation solvation by the organic molecule.