Entire Solvent Composition Range Research Articles

VOLUMETRIC AND VISCOMETRIC DETERMINATION OF BINARY LIQUID MIXTURES OF 2-ETHOXYETHANOL AND AMYL ACETATE AT TEMPERATURES OF (298.15 AND 303.15) K

Densities and viscosities have been determined at temperatures of (298.15 and 303.15) K for binary liquid mixtures of 2-ethoxyethanol with amyl acetate over the entire range of solvent composition. From the experimentally determined values, excess molar volume, VE, excess viscosity, ηE and excess Gibbs free energy of activation of viscous flow, G*E have been calculated. These calculated excess thermodynamic functions were fitted to Redlich-Kister polynomial equation to obtain the fitting coefficients and standard deviations. The values of excess molar volume, VE were negative and that of the excess viscosities, ηE were found to be positive, while excess Gibbs free energy of activation of viscous flow, ΔG*E were negative over the whole range of solvent composition for the binary systems at the studied temperatures. The behavior of these excess functions with composition of the mixtures have been discussed in respect of molecular interactions between the components of liquid systems. The mixture viscosities were correlated using empirical relations like Grunberg-Nissan, Frenkel, Hind, Wijk and Kendall-Monroe model equations. Comparison of these interaction parameters have been engaged to explain the intermolecular interactions between the alkoxy alcohol and the ester.

Volumetric Behaviour of Binary Mixtures of Diethyl Ether + (C1 – C4) Alkoxyethanols at Different Temperatures

Densities of pure liquids and binary mixtures of diethyl ether (DEE) with 2-alkoxyethanols (2- methoxyethanol, 2-ethoxyethanol and 2-butoxyethanol) have been determined over the entire range of solvent compositions at (293.15, 298.15 and 303.15) K. Excess molar volumes (VM E ) have been calculated from the density data and were fitted into the Redlich-Kister type polynomial equation to obtain the fitting parameters Ai. The values of excess molar volumes, vm E were negative in regions of low diethyl ether (DEE) composition and small positive values were observed in regions of high diethyl ether (DEE) compositions in all the systems studied. VM E values were also found to decrease with increase in temperature and increase in chain length of the 2-alkoxyethanols. The above trends were attributed to the combined effects of disruption and formation of hydrogen bonds between like molecules of 2- alkoxyethanols and unlike molecules of diethyl ether (DEE), respectively.

Conductometric investigations of surfactant behavior in aqueous polar aprotic organic additives

Micellar properties of sodiumdodecyl sulfate (SDS) and cetyltrimethylammonium bromide (CTAB) in aqueous polar aprotic additives viz., dimethylsulfoxide (DMSO), dimethylformamide (DMF), acetonitrile (AN) and 1,4-dioxane were determined between 25 and 45°C. The critical micelle concentration (CMC) determined using electrical conductivity measurements have been used to evaluate thermodynamic properties of micellization. By detailed experiments, it was observed that the DMSO and DMF have an inhibitory effect on micellization of the targeted surfactants, i.e. SDS and CTAB in aqueous solutions over the entire solvent composition range from 0.67–5.94mol% by weight. The addition of dioxane and AN initially increase CMC of CTAB and then it decreases gradually with further increase in the concentration of dioxane and AN. A contrary trend is observed in the micellar behavior of SDS in the presence of dioxane and AN. The changes in standard enthalpy and entropy of micellization values are found to be consistent with the observed behavior of the two surfactants in the presence of these additives. Near constant counter-ion binding values are indicative of the fact that no structural transition of the micelles of the two surfactants takes place in the range of the composition studied.

Understanding the enhanced solubility of 1,3-benzenedicarboxylic acid in polar binary solvents of (acetone + water) at various temperatures

Understanding solid dissolution in polar binary solvents showing maximum or minimum solubility phenomenon is essential for the design and operation of anti-solvent crystallization process. Solubilities of 1,3-benzenedicarboxylic acid in binary solvents of acetone with water are measured from 278.15 to 323.15K using the static equilibrium method, covering the entire range of solvent composition. The solubility always increases with increasing temperature, while, at fixed temperature, a maximum solubility is observed in mixed solvents of certain composition. The experimental temperature-dependent solubility data of 1,3-benzenedicarboxylic acid in cosolvents of different compositions are correlated using the Apelblat model with an average relative deviation (ARD) of 0.18%. Calculations of the derived thermodynamic functions show that the dissolution of 1,3-benzenedicarboxylic acid in the solvent mixtures is endothermic and mainly driven by the enthalpy change. The Simplified Modified Wilson (SMW) model is adopted to reproduce the isothermal solubility data over the entire acetone composition with an overall ARD of 1.41%, with which the maximum mole fraction solubility and the corresponding solvent composition at different temperatures are determined, and are subsequently used to estimate the solubility parameter of 1,3-benzenedicarboxylic acid.

Ultrasonic Velocity and Compressibility Studies of Tetraalkylammonium Salts in Acetonitrile + Methanol Binary Mixtures at 298.15 K

Abstract The ultrasonic velocities (u) and densities (ρ) of tetraalkylammonium perchlorates (R4NClO4, where R = Methyl, Ethyl, Propyl or Butyl) and tetrabutylammonium tetraphenylborate (Bu4NPh4B) solutions have been measured at different salt concentrations in the range (30–500) × 10−4 mol kg –1 in binary mixtures of acetonitrile (AN) with methanol (MeOH) containing 0, 20, 40, 60, 80 and 100 mol % methanol at 298.15 K. The isentropic compressibilities (K s ) and apparent molal isentropic compressibilities (K s,φ ) of different salts in the solvent mixtures have been calculated. Limiting apparent molal isentropic compressibilities (K o s,φ ) for various salts have been evaluated and split into contributions of individual ions i.e., into (K o s,φ )± values. The variation of (K o s,φ )± values with solvent composition shows that Bu4N+ and Ph4B+ have very large positive (K o s,φ )± values which show strong solvophobic interactions in AN and in AN + MeOH mixtures over the entire solvent composition range. These positive values indicate some special type of interactions with the solvent molecules, which increase with the increase of MeOH composition. ClO4 – shows much weaker solvation in AN + MeOH mixtures by having some interaction with AN in the AN rich region of the mixtures. The negative values of Me4N+ and Et4N+ ions show strong structural effects which arise due to solute-solvent interactions in MeOH rich region of mixtures.

Compressibility Studies of Some Copper(I), Silver(I), and Tetrabutylammonium Salts in Acetonitrile + Adiponitrile Binary Mixtures

Ultrasonic velocities and densities of some copper(I), silver(I), and tetrabutylammonium salts have been measured in the concentration range of (0.002 to 0.28) m in binary mixtures of acetonitrile (AN) + adiponitrile (ADN) containing 1.0, 0.9, 0.8, 0.7, 0.6, and 0.5 mol fraction of AN at 298.15 K. The isentropic compressibility (κs) and apparent molal isentropic compressibility (κs,ϕ) in various solvent systems have been calculated by using ultrasonic velocity (u) and partial molal volume (Vϕ) data, respectively. Limiting apparent molal isentropic compressibilities (κs,ϕo) for various salts have been evaluated from κs,ϕ versus m1/2 plots and split into the contributions of individual ions (κs,ϕo)±. The (κs,ϕo)± values for copper(I) and silver(I) ions are found to be negative over the entire solvent composition range which indicates strong solvation of these ions. The (κs,ϕo)± values becoming more and more negative with an increase in the ADN composition shows that the extent of solvation increases with an increase in ADN composition. The large and positive (κs,ϕo)± values for Bu4N+ and Ph4B− indicate some special type of interaction with the solvent molecules, which increases with the increase of ADN composition in the mixture.

Enthalpies of Transfer of Tetraalkylammonium Bromides and CsBr from water to Aqueous DMF at 298.15 K

Enthalpies of transfer of tetraalkylammonium bromides and CsBr from water to aqueous DMF mixtures are reported and analyzed in terms of a new solvation theory. It was found that a previous equation could not reproduce these data over the whole range of solvent compositions. Using a new solvation theory to model the enthalpies of transfer shows excellent agreement between experimental and calculated values over the entire range of solvent compositions. The analyses show that tetrapropylammonium bromide, Pr4NBr, and tetrapentylammonium bromide, Pen4NBr, are preferentially solvated by water; in contrast tetrabutylammonium bromide, Bu4NBr, is preferentially solvated by DMF. The solvation of tetramethylammonium bromide, Me4NBr, and cesium bromide, CsBr, is random. The extent to which the tetraalkylammonium bromides disrupt solvent–solvent bonds increases systematically in going from Me4NBr to Pen4NBr.

A new equation to reproduce the enthalpies of transfer of formamide, N-methylformamide and N, N-dimethylformamide from water to aqueous methanol mixtures at 298 K

The enthalpies of transfer of formamide (Form) N-methylformamide (NMF) and N, N-dimethylformamide (DMF) from water to aqueous methanol mixtures are reported and analysed in terms of the new solvation theory. It was found that a previous equation could not reproduce these data over the whole range of solvent compositions. Using the new solvation theory to reproduce the enthalpies of transfer shows excellent agreement between the experimental and calculated data over the entire range of solvent compositions. The analyses show that the solvation of DMF is random in the aqueous methanol mixtures while Form and NMF are preferentially solvated by methanol. It is also found that the interaction of the solutes is stronger with methanol than with water.

Enthalpies of solution of urea in water-methanol mixtures at 298.15 K

The standard enthalpies of solution of urea in water-methanol mixtures were determined over the entire range of solvent compositions at 298.15 K. A comparison of the results obtained with the published data on mixtures of water with ethanol and n-propanol revealed a differentiating effect of the alcohol concentration on the enthalpy of solution of urea. Only for water-methanol solutions, an increase in the alkanol content in the mixture (0.6 mole fractions < x2 < 1.0 mole fractions) caused an increase in the degree of solvation of urea.

Determination of solvatochromic solvent parameters for the characterization of gas-expanded liquids

Solvatochromic shifts of six probe indicators {4-nitroaniline, 4-nitroanisole, 4-nitrophenol, N, N-dimethyl-4-nitroaniline, 4-(2,4,6-triphenylpyridinium)-2,6-diphenylphenoxide and 2,6-dichloro-4-(2,4,6-triphenyl-1-pyridinio)phenolate} have been measured in binary mixtures of carbon dioxide with acetone and methanol at 35 and 40 °C over the entire range of solvent composition. The indicators were used to specify the solvatochromic solvent parameters ( E T(30), α, β, and π*), which were calculated from the solvatochromic shifts of the maximum absorbance peak ( ν max ) observed by means of UV–vis spectroscopy.

Isentropic compressibilities of some copper(I), sodium(I) and tetraalkylammonium salts evaluated from ultrasonic velocity measurements in acetonitrile + N,N-dimethylformamide mixtures at 298.15 K

Ultrasonic velocity (u) and density (p) of tetrabutylammonium tetraphenylborate (Bu 4 NBPh 4 ), tetrabutylammonium perchlorate (Bu 4 NClO 4 ), copper(I) perchlorate tetraacetonitrile (CuClO 4 .4CH 3 CN), sodium perchlorate (NaClO 4 ) and sodium tetraphenylborate (NaBPh 4 ) have been measured at different salt concentrations in the concentration range 0.02-0.6 mol kg - 1 in binary mixtures of acetonitrile (AN) with N,N-dimethylformamide (DMF) containing 0, 10, 20, 40, 60, 75, 80, 90 and 100 mol % DMF. The isentropic compressibility (K s ) and apparent molal isentropic compressibility (K s , Φ ) of the salts in various solvent mixtures have been calculated. Limiting apparent molal isentropic compressibilities (K o s,Φ) for various salts have been evaluated and split into contributions of individual ions i.e. into (K o s,Φ) ′ values. The variation of (K o s,Φ) ′ values with solvent composition shows that Na + has very large negative (K o s,Φ) ′ values which show strong solvation of Na + in AN + DMF mixtures over the entire solvent composition range and the solvation of Na + by DMF is relatively stronger than that with AN. Cu + also shows strong but relatively less solvation as compared to Na + in AN + DMF mixtures over the entire solvent composition range. The solvation of Cu + by AN is relatively stronger than with DMF. ClO - 4 shows much weaker solvation in AN+DMF mixtures by having some interaction with AN in the AN rich region of the mixture.

Compressibility studies of some copper (I) and tetraalkylammonium salts in binary mixtures of triethylphosphite with acetronitrile, benzonitrile and pyridine at 298.15 K

Ultrasonic velocity (u) and density (ϱ) of tetrabenzonitrile copper (I) perchlorate (CuClO 44C 6H 5CN), tetrabutylammonium tetraphenylborate (Bu 4NBPh 4) and tetrabutylammonium perchlorate (Bu 4NClO 4) have been measured at different salt concentrations in the concentration range 0.002–0.28 mol kg −1 in binary mixtures of triethylphosphite (TEP) with acetonitrile (AN), benzonitrile (BN) and pyridine (PY) containing 0, 20, 40, 60 and 80 mol % TEP. The isentropic compressibility (K s) and apparent molal isentropic compressibility (K s,ø) in various solvent systems have been calculated. Limiting apparent molal isentropic compressibilities (K 0 s,φ for various salts have been evaluated and split into contributions of individual ions i.e. into (K 0 s,φ) ± values. The variation of (K 0 s,φ) ± values with solvent composition shows that Cu + indicates strong solvation in AN + TEP, BN + TEP and PY + TEP mixtures over the entire solvent composition range and the solvation with TEP is relatively stronger than that with AN, BN and PY. ClO 4 − is better solvated in AN + TEP mixture by having some interaction with AN but is poorly solvated in BN + TEP and PY + TEP mixtures. Both Bu 4N + and Ph 4B − show some interaction with TEP in the TEP-rich region of all the solvent systems.

Micellization of ionic surfactants in aqueous-rich region of organic solvants: A conductometric study of micellization behaviour of sodium dodecylsulfate in aqueous-rich region of 1-BuOH, 2-BuOH, t-BuOH at different temperatures

The critical micelle concentration (cmc) of sodium dodecyl sulfate (SDS) is determined in aqueous-rich region of 1-butanol (1-BuOH), 2-butanol (2-BuOH) and tertiary-butanol (t-BuOH) at 25, 35 and 45°C from conductance measurements. In the range of alcohol mole fraction, x 2, 0< x 2<0.008 the cmc decreased by a function of x 2 in the order: 1-BuOH>2-BuOH>t-BuOH. Though not very significant, a relatively weak effect of temperature was observed in increasing the cmc in this narrow composition range. As the concentration of these additives was increased, cmcs levered off and the effect of temperature tends to be insignificant. Thermodynamic parameters of micellization, enthalpy (Δ H m 0), entropy (Δ S m 0) and free energy (Δ G m 0) were determined from temperature dependence of cmc. The solvent composition dependence of these thermodynamic parameters is determined in terms of the effect of additives on micellizaffon of SDS. It is observed that both Δ H m 0 and Δ S m 0 bear out not only the observed order of decrease in cmc, but also account reasonably the effects produced by differences in alkyl chain configuration for these isomeric alcohols. In all cases Δ G m 0<0, and remained practically constant over the entire solvent composition range studied. It is suggested that due to different structural consequences of intermolecular interactions both enthalpy and entropy must differ in a mutually compensating manner so that Δ G m 0 is not significantly affected.

Solvation of fluoride ions 4. Gibbs energies of transfer from water to aqueous dimethylsulphoxide, propanone and 2-methylpropan-2-ol mixtures

Solubility data are reported at 298.15K for LiF, NaF and, to a lesser extent, KF in aqueous mixtures of dimethylsulphoxide (DMSO), propanone, (acetone, AC) and 2-methylpropan-2-ol (tertiary butanol, t-BuOH) over virtually the entire solvent composition range. These data have been combined wherever possible with appropriate literature data to give standard Gibbs energies of transfer of the fluoride ion, Δt,G0(F−), from water to the aqueous-organic mixtures on the basis of the TATB assumption. Consistent with the poor acceptor properties of the cosolvents cf. H2O all three systems show highly positive values of Δt,G0(F−). However, both DMSO and t-BuOH systems show some interesting anomalies as a function of solvent composition.

Kinetics of dissociation of tris‐2,2′‐bipyridyl‐iron(II) cation in aqueous acetic acid solutions

AbstractThe kinetics of dissociation of tris‐2,2′‐bipyridyl‐iron(II) complex ion have been examined in aqueous acetic acid solutions. The reaction is first order in the complex ion; the dependence of rate on H+ is somewhat like that observed in aqueous solutions approaching a limiting value at higher H+ concentrations. The influence of solvent composition on the reaction rate under acid‐dependent and acid‐independent conditions shows an initial retardation by acetic acid. The argument of ion‐pair formation based on decrease of dielectric constant proposed to explain the kinetics in other aqueous solvent media was found useless to explain the behavior in acetic acid solutions. Other solvent parameters also did not provide satisfactory correlation with the kinetic results, thus, indicating the operation of more complex microscopic solute‐solvent and solvent‐solvent interactions. While solvent effects play some part in the rate process, the rate of reaction would tend to zero in the absence of H2O and H+. This interesting observation proved useful in proposing a reaction mechanism that is consistent with the rate behavior over the entire range of solvent composition. The activity of water in the reaction medium is controlled by the content of acetic acid which can effect the structure of water through operation of hydrophobic forces and formation of hydrates. While acetic acid cannot possibly fulfill the role of water in occupying the vacated coordination position, the anomalous rise in rate even under some water deficient conditions seems to be related to the coordinating ability of HSO4− derived from H2SO4 present in the solution.

Ion solvation in lithium battery electrolyte solutions. 1. Apparent molar volumes

Apparent molar volumes, Vφ{symbol}(MX), of seven electrolytes (NaClO4, NaCF3SO3, NaBPh4, LiClO4, LiAsF6, Ph4AsCF3SO3 and KCF3SO3) have been determined by vibrating-tube densimetry in nonaqueous solvent mixtures of propylene carbonate (PC) with acetonitrile (AN), dimethoxyethane (DME) and tetrahydrofuran (THF). Vφ{symbol}(MX) was measured at an electrolyte concentration of 0.05M over the entire solvent composition range wherever possible. Ionic apparent molar volumes of transfer, ΔtV φ(ion), were obtained via the tetraphenylarsonium tetraphenylborate (TATB) assumption. ΔtV φ(ion) from PC to the mixed solvents are generally strongly negative for both cations and anions consistent with the greater compressibilities and lower dielectric constants of the cosolvents. In PC/AN mixtures cations and anions have similar values of ΔtV φ(ion) but in PC/DME and PC/THF mixtures they differ considerably. Cationic volumes show the expected dependence on ion-size but the differences among the anion volumes are much greater than expected at high cosolvent compositions. These effects are discussed in terms of preferential solvation and other solvent interactions. The implications of these findings for lithium batteries are briefly discussed.

Heats of transfer of cobalt(ii) perchlorate from pure to mixed solvents

Heats of solution of solid solvates Co(ClO 4) 2·6L (L denotes the solvent molecule) in mixtures of water with N, NV-dimethylformamide (DMF). N,N-dimethylacetamide (DMA), and dimethylsulphoxide (DMSO), as well as in DMA-DMSO mixtures, were measured over the entire range of solvent compositions. These data together with separately obtained differential heats of solution of solvent L in all the above mixtures enabled the determination of heats of transfer of CO(ClO 4) 2 from the pure to the mixed solvents. Visible absorption spectra of ternary solutions of CO(ClO 4) 2 in mixed solvents were also measured. The results were discussed in terms of possible ion-solvent and solvent-solvent interactions occuring in the systems investigated.

Preferential solvation of ions in mixed solvents—III. Conductance studies of some 1:1 electrolytes in N,N-dimethylformamide + methanol mixtures at 25°C.

Equivalent conductances of Bu 4NNO 3,AgNO 3 and KI in methanol (MeOH) and those of Bu 4NBPh 4,Bu 4NNO 3, Bu 4NI, Agno 3 and KI in several N,N-dimethylformamide + methanol (DMF + MeOH) mixtures over the entire solvent composition range have been measured at 25°C.The conductance data in all the cases have been analysed by the Shedlovsky method.Evaluation of limiting ion conductances (λ 0 i) and hence the solvated radii ( r i) of ions in DMF + MeOH mixtures shows a homoselective preferential solvation of Bu 4NBPh 4, Bu 4NNO 3 and Bu 4NI with the cation Bu 4N + and the anions Ph 4B −, NO − 3 and I − all being selectively solvated by MeOH. AgNO 3 and KI, on the other hand, are heteroselectively preferentially solvated with Ag + and K + being preferentially solvated by DMF and NO − 3 and I − preferentially solvated by MeOH.

Excess Free Energy Approach to the Estimation of Solubility in Mixed Solvent Systems I: Theory

□ An approach is developed by which the solubility of an organic compound in mixed solvents may be estimated. In this approach, an expression for the excess Gibbs free energy of mixing for multicomponent solvent systems was used to obtain parameters characteristic of the interaction between the solvents. A fairly simple equation which predicts the solubility of a solute in a binary solvent system over the entire solvent composition range was then derived. The equation may be partitioned into terms that contain (a) pure solvent solubilities, (b) solvent-solvent interaction contributions, and (c) contributions from the solute-mixed solvent interactions. The required data are the molar volume of the solute, the pure solvent solubilities, and, theoretically, one experimentally determined solubility in a solvent mixture. The equation can be easily extended for systems with three or more solvents.

Conductance of Some High Valence Type Electrolytes in Mixed Solvents. II. Conductance of Pentaamminenitrocobalt(III) and Tris(1,10-phenanthroline)iron(II) Sulfates in Water–Ethylene Glycol Mixtures at 25 °C

Abstract Conductance data are reported for dilute solutions of pentaamminenitrocobalt(III) sulfate, [Co(NO2)(NH3)5]SO4, and tris(1,10-phenanthroline)iron(II) sulfate, [Fe(phen)3]SO4 in water–ethylene glycol mixed solvents at 25 °C. The conductance data were analyzed in terms of the 1957 Fuoss-Onsager and Fuoss-Hsia equations. While the application of the 1957 Fuoss-Onsager equation to [Fe(phen)3]SO4 data suggested a complete dissociation of the salt over the entire range of solvent compositions, the Fuoss-Hsia equation fitted the data better and yielded KA values which are in accord with the ion association theories. [Co(NO2)(NH3)5]SO4 had a higher association constant in the range of solvent composition studied (0 to 40% ethylene glycol) than the predictions of the ion association theories.