Number Of Solvents Research Articles

Ultrasonic study of vanadium myristate in liquor ammonia

The ultrasonic velocity of vanadium myristate confirms that there is a significant interaction between the solute-solvent molecules in dilute solutions and the carboxylate molecules do not aggregate appreciably in dilute solutions. The value of Critical Micelle Concentration (CMC) for vanadium myristate is in agreement with those obtained from other physical parameters. The effects of concentration and chain length of soap on ultrasonic velocity and the various acoustic parameters (adiabatic compressibility, specific acoustic impedance, intermolecular free length, apparent molar compressibility, apparent volume, molar sound velocity, molar sound compressibility and solvation number) have been investigated.

Palladium Recovery by Reactive Precipitation using a Cyanex 301‐Based Stable Emulsion

Cyanex 301®, di(2,4,4‐trimethylpentyl) dithiophosphinic acid, has been combined with gelatin and alginate to prepare a stable emulsion that can be used for the reactive precipitation of palladium (metal reaction with the sulfur functional group of Cyanex 301). The ionotropic gelation of alginate leads to material precipitation. The process has been successfully tested for Pd binding from 0.1–5 M HCl solutions. The maximum binding capacity was found to be close to 350 mg Pd g−1 Cyanex 301. A 1∶1 stoichiometric relation between Cyanex 301 and Pd has been identified. Extractant dependency plots showed that the ligand in the Pd‐Cyanex 301 complex can also have a solvation number higher than one. Palladium uptake is not significantly affected by the presence of competing metals such as Cu, Ni, Zn, or Pt. Quantitative stripping of Pd from the precipitated bio‐polymer could not be achieved.

Synergism in the extraction of ascorbic and nicotinic acids by binary solvent mixtures

The distribution coefficients of ascorbic and nicotinic acids in systems aqueous salt solution-binary mixture of hydrophilic solvents were determined. Butanol, ethyl acetate, and butyl acetate were used as hydrophilic solvents and sodium chloride and sulfate as salting out agents. The synergistic effect was interpreted and the synergistic coefficients, complex formation constants, and solvation numbers calculated.

Solvation shell dynamics studied by molecular dynamics simulation in relation to the translational and rotational dynamics of supercritical water and benzene

The solvation shell dynamics of supercritical water is analyzed by molecular dynamics simulation with emphasis on its relationship to the translational and rotational dynamics. The relaxation times of the solvation number (tau S), the velocity autocorrelation function (tau D), the angular momentum correlation function (tau J), and the second-order reorientational correlation function (tau 2R) are studied at a supercritical temperature of 400 degrees C over a wide density region of 0.01-1.5 g cm(-3). The relaxation times are decomposed into those conditioned by the solvation number n, and the effect of the short-ranged structure is examined in terms of its probability Pn of occurrence. In the low to medium-density range of 0.01-0.4 g cm(-3), the time scales of water dynamics are in the following sequence: tau D>tau S approximately or > tau J approximately or > tau 2R. This means that the rotation in supercritical water is of the "in-shell" type while the translational diffusion is not. The comparison to supercritical benzene is also performed and the effect of hydrogen bonding is examined. The water diffusion is not of the in-shell type up to the ambient density of 1.0 g cm(-3), which corresponds to the absence of the transition from the collision to the Brownian picture, whereas such transition is present in the case of benzene. The absence of the transition in water comes from the fast reorganization of the hydrogen bonds and the enhanced mobility of the solvation shell in supercritical conditions.

Gold(III) extraction by 1,3-Bis(2′-acetoxymethylthiobutyl-3′-thiobutylpropyl)-6-methyluracyl from hydrochloric acid solutions

Gold(III) extraction by 1,3-bis(2′-acetoxymethylthiobutyl-3′-thiobutylpropyl)-6-methyluracyl from 0.5 M HCl solutions to chloroform is studied. The reagent has a high efficiency, separates gold(III) ions from the sum of nonprecious and ferrous metals, and can be repeatedly used after stripping. The extraction mechanism is solvation, with Au-S coordination bonds formed with all sulfur atoms of the reagent; the solvation number changes from 1 to 0.25 with increasing gold(III) aqueous concentration.

Vibrational spectroscopic and density functional theory studies on ion solvation and ion association of lithium tetrafluoroborate in N, N-dimethylcarbamoyl chloride-based solvents

Solvation and association interactions in solutions of LiBF 4/DMCC (DMCC for N, N-dimethylcarbamoyl chloride) and LiBF 4/DMCC–DME (DME for 1,2-dimethoxyethane) have been studied as a function of concentration of lithium tetrafluoroborate by infrared and Raman spectroscopy. Strong interactions between Li + and solvent molecules or BF 4 − anions are observed. The apparent solvation numbers of Li + in LiBF 4/DMCC solutions were deduced. Band-fitting to the B–F stretching band of BF 4 − anion permits detailed assess of the ion pairing. Based on the calculations of density function theory, optimal structures of Li +(DMCC) n ( n = 1–3) were suggested. It is found that the lithium ion was preferentially solvated by DME in DMCC–DME binary solvents. This finding is supported by quantum chemistry calculations.

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 ClO4−, SCN−, Br−, and NO3− ions by variously structured derivatives of trifluoroacetophenone were calculated from experimental data.

Measurement of solubilities for rhodium complexes and phosphine ligands in supercritical carbon dioxide

The solubilities of phosphine ligands and rhodium (Rh) complexes in supercritical carbon dioxide were measured with Fourier transform infrared (FT-IR) spectroscopy at 320 and 333 K and several pressures. Triphenylphosphine (TPP) and tris( p-trifluoromethylphenyl)-phosphine (TTFMPP) were selected as ligands for the Rh complex. The solubilities of the fluorinated ligands and complexes were compared with those of the non-fluorinated compounds. The solubilities of ligand increased up to 10 times by the fluorination. It was found that the solubilities of Rh complexes were enhanced up to 30 times by introducing trifluoromethyl group to the ligand. The experimental data was correlated by the Chrastil equation. The correlated results were in good agreement with the experimental data. Furthermore, the solvation numbers of carbon dioxide around the ligands and Rh complexes were obtained from the slope of the Chrastil equation. The solvation number for the fluorinated compounds was about two and five times higher than those of the non-fluorinated ligand and complex, respectively.

Thermodynamic studies of some 1,2,4-triazole derivatives in DMF and THF solutions at 308.15 K

Some new 1,2,4-triazole derivatives have been synthesized and characterized by TLC, IR, NMR and mass spectra. Densities, viscosities and ultrasonic velocities of these compounds have been measured over the wide composition range at 308.15 K in dimethyl formamide (DMF) and tetrahydro furan (THF). From these data, various acoustical and thermodynamic parameters (C.V. Suryanarayana, J. Kuppuswamy. J. Acoust. Soc. Ind., 4, 75 (1976); H. Erying, M.S. John, Significance of Liquid Structures, Wiley, New York (1969); G.K. Johri, R.C. Misra. Acustica, 56, 66 (1989)) were evaluated. Some of these parameters are isentropic compressibility (κs), intermolecular free length (L f), relaxation strength (r), relative association (R A), Rao's molar constant (R m), van der Waal's constant (b), molar compressibility (W), internal pressure (π), free volume (V f), solvation number (S n) etc. The behavior of solutions of these compounds in DMF and THF are explained from the evaluated parameters.

Solvation of potassium and tetra- n-butylammonium iodides in methanol from acoustic and positron annihilation measurements

The positron annihilation and acoustic methods were applied to investigate solvation of potassium iodide, and tetra- n-butylammonium iodide in methanol. The acoustic results show that the influence of KI on the structure of liquid is stronger but shorter in their range than that of (C 4H 9) 4NI, although the solvation numbers are lower for KI. The solvation numbers of ions (five for K +, seven for (C 4H 9) 4N + and two for I −) are deduced. The positron annihilation suggests that the effect of KI on liquid methanol structure is stronger but shorter in range, leading to formation of small but more compressed solvates.

Effect of temperature on ultrasonic velocity and thermodynamic parameters of bisphenol- C-formaldehyde-acrylate resin solutions

The density, viscosity and ultrasonic velocity (2 MHz) of pure solvents: ethanol, MEK and DMF, and BCFA solutions (0.5–4 wt%) were investigated at three different temperatures: 30, 35 and 40 °C. Various acoustical parameters such as isentropic compressibility ( κ s), internal pressure ( π), free volume ( V f), free path length ( L f) and solvation number ( S n) were determined and correlated with concentration ( C). Fairly good to excellent linear relationships are observed at three temperatures. The linear decrease of κ s, π and L f with C and linear increase with temperature; and linear increase of V f with C and T in DMF system, nonlinear increase with C and T in EtOH system and nonlinear decrease with C and increase with T in MEK system indicated strong molecular interactions in the solutions and solvophilic nature of BCFA, which is further supported by positive values of solvation number. The observed solvation trend is EtOH > MEK > DMF.

FT-Raman spectroscopic and density functional theory studies on ion preferential solvation and ion association of lithium tetrafluoroborate in 4-methoxymethyl ethylene carbonate-based mixed solvents

Ion preferential solvation and association interactions of lithium tetrafluoroborate (LiBF 4) in binary solvents MEC/DMC (MEC for 4-methoxymethyl ethylene carbonate and DMC for dimethyl carbonate) and MEC/AN (AN for acetonitrile), respectively, have been studied by FT-Raman spectroscopy for different solvent compositions. Intermolecular interactions are present between MEC and DMC or AN. The individual solvation numbers of lithium cation in different environment were deduced. It is found that the lithium ion was preferentially solvated by MEC in all the binary solvents. The ion pairing process is greatly promoted by the increasing molar fractions of DMC and AN in the ternary electrolytes. Some of these findings are supported by quantum chemistry calculation.

Medium effects on the fluorescence spectra of tertiary aliphatic amines in mixed solvents and supercritical fluids

Emission spectra of some tertiary amines were measured in cyclohexane (CH)–tetrahydrofuran (THF) mixtures and in supercritical fluids of CHF 3. The emission bands of these amines were found to show large successive red shifts with increasing concentration of polar solvent molecules. This finding was rationalized by considering the consecutive solvation of the polar molecules around the Rydberg excited state of the amine. In order to estimate the degree of solvation, the wavenumbers of the emission maxima were plotted as functions of the THF and CHF 3 concentrations. The changes in solvation number with increasing THF and CHF 3 concentrations were obtained from the spectral shifts by applying a calculation for the stepwise solvation model.

Solvation Number and Conformation of N, N-Dimethylacrylamide and N, N-Dimethylpropionamide in the Coordination Sphere of the Cobalt(II) Ion in Solution Studied by FT-IR and FT-Raman Spectroscopy

The solvation number and conformation of N,N-dimethylacrylamide (DMAA) in the coordination sphere of the cobalt(II) ion in solution were studied, and compared with those of N,N-dimethylpropionamide (DMPA) by means of FT-Raman and FT-IR spectroscopy. Both solvents are present as either the planar cis or nonplanar staggered conformer in equilibrium, and the former is more stable in the bulk. As these solvents solvate the metal ion through the carbonyl O atom of the acryl (DMAA) or propionyl (DMPA) group, the solvation structure around the metal ion is highly congested to reduce the solvation number and/or to lead to a conformational geometry change of solvent. It turns out that the solvation number of the cobalt(II) ion is 4 for both DMAA and DMPA at 298 K, and that DMPA changes its conformation upon solvation, whereas DMAA hardly changes. The enthalpy of conformational change DeltaH degrees for DMPA is 5 kJ mol(-1) in the bulk, and is -9 kJ mol(-1) in the coordination sphere of the cobalt(II) ion. On the other hand, the DeltaH degrees value for DMAA is 9 kJ mol(-1) in the bulk.

Physical chemistry of lithium hexafluoroarsenate in tetrahydrofuran

The density, the propagation rate of ultrasound, the electroconductivity, and the viscosity of lithium hexafluoroarsenate solutions in tetrahydrofuran, which are perspective liquid-phase components for the creation of novel polymer electrolytes for chemical lithium power sources, are determined. The ionic association is investigated on the basis of the Lee-Wheaton model. The determination of the solvation numbers in the region of concentrations that are in reality applied in the lithium power sources is conducted on the basis of the method of isoentropy compression. It is shown that the phenomenon of anomalous electroconductivity of the system under test may be connected with an ionotropic electroconduction mechanism.

Preferential hydration of lysozyme in water/glycerol mixtures: A small-angle neutron scattering study

In solution small-angle neutron scattering has been used to study the solvation properties of lysozyme dissolved in water/glycerol mixtures. To detect the characteristics of the protein-solvent interface, 35 different experimental conditions (i.e., protein concentration, water/glycerol fraction in the solvent, content of deuterated compounds) have been considered and a suitable software has been developed to fit simultaneously the whole set of scattering data. The average composition of the solvent in the close vicinity of the protein surface at each experimental condition has been derived. In all the investigated conditions, glycerol resulted especially excluded from the protein surface, confirming that lysozyme is preferentially hydrated. By considering a thermodynamic hydration model based on an equilibrium exchange between water and glycerol from the solvation layer to the bulk, the preferential binding coefficient and the excess solvation number have been estimated. Results were compared with data previously derived for ribonuclease A in the same mixed solvent: even if the investigated solvent compositions were very different, the agreement between data is noticeable, suggesting that a unique mechanism presides over the preferential hydration process. Moreover, the curve describing the excess solvation number as a function of the solvent composition shows the occurrence of a region of maximal hydration, which probably accounts for the changes in protein stability detected in the presence of cosolvents.

Solvation of the Electrolytic Components of Seawater

A new modification of the adiabatic compressibility method of investigating solvation in solutions is presented and applied to the analysis of the following structurally-related characteristics of hydrated complexes of seawater electrolytes (NaCl, KCl, MgCl2, CaCl2, Na2SO4, MgSO4) at different concentrations (0.1 to 5.0 mol⋅kg−1) and temperatures (278.15 to 308.15 K): solvation numbers (h) and their dependences on concentration, volumes of stoichiometric mixtures of ions without their hydration shells (V2h), compressibilities (β1h) and molar volumes of water in their solvation shells (V1h), their dependences on concentration and temperature, etc.

Observation of Three Behaviors in Confined Liquid Water within a Nanopool Hosting Proton-Transfer Reactions

In this contribution, we report on studies of rotational and diffusional dynamics of 7-hydroxyquinoline (7HQ) within a reverse micelle (RM) containing different amounts of water. Analyzed in terms of the wobbling-in-a-cone model, the data reveal structural and dynamical properties of the nanopool. We clearly observed three regions in the behavior of confined water molecules within the RM hosting a double proton-transfer reaction between the probe and water. This observation remarkably reproduces the change of calculated water density within this life-mimicking medium. The number of water molecules per AOT head in the transition regions changes from 2 to 5, the latter being very near to the full solvation number (6) of the RM heads. Moreover, the H-bonds breaking and making within the RM to give new structures of the probe strongly affect the environment fluidization in different extents, reflected in different relaxation times of these structures; however, they are of similar sizes. We discuss the role of RM confinement and the proton-transfer dynamics on the behavior of water and their relationships to the packing of water molecules in the studied range of concentrations.

Vibrational Spectroscopic Study on Ion Solvation and Association of Lithium Perchlorate in 4‐Methoxymethyl‐ethylene Carbonate

AbstractSolvation interaction and ion association in solutions of lithium perchlorate/4‐methoxymethyl‐ethylene carbonate (MEC) have been studied by using Infrared and Raman spectra as a function of concentration of lithium perchlorate. The splitting of ring deformation band and ring ether asymmetric stretching band, and the change of carbonyl stretching band suggest that there should be a strong interaction between Li+ and the solvent molecules, and the site of solvation should be the oxygen atom of carbonyl group. The apparent solvation number of Li+ was calculated by using band fitting technique. The solvation number was decreased from 3.3 to 1.1 with increasing the concentration of LiClO4/MEC solutions. On the other hand, the band fitting for the ClO−4 band revealed the presence of contact ion pair, and free ClO−4 anion in the concentrated solutions.

Experimental and computational studies on the solvation of lithium tetrafluorobrate in dimethyl sulfoxide

AbstractSolvation structures of the lithium cation and tetrafluorobrate anion in dimethyl sulfoxide (DMSO) were investigated by Raman spectroscopy and ab initio calculations at various salt concentrations. The SO and CS stretching bands were used to monitor the structural change of the solvation shell. It has been shown that the solvation number of Li+, calculated by the changes in intensities of the CS asymmetric and symmetric stretching bands, is consistent with the value predicted by ab initio calculations. The wavenumber shift of the CH stretching band is suggested to be the result of the anion solvation and the dissociation of the associated DMSO molecules. Copyright © 2007 John Wiley & Sons, Ltd.