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With the isothermal dissolution equilibrium method, the solid-liquid phase equilibrium for 5-amino-3-methyl-1-phenylpyrazole in ten organic solvents including methanol, ethanol, n -propanol, isopropanol, 2-butanone, acetonitrile, n -butanol, toluene, 1,4-dioxane and isobutanol was established over a temperature range from (283.15 to 318.15) K at atmospheric pressure (101.1 kPa), and the solubility of 5-amino-3-methyl-1-phenylpyrazole in these solvents were determined by a high-performance liquid chromatography (HPLC). The mole fraction solubility of 5-amino-3-methyl-1-phenylpyrazole in the solvents increased with increasing temperature within the temperature range studied, and obeyed the following sequence from high to low in different solvents: 1,4-dioxane > acetonitrile > methanol > isobutanol > ethanol > n -propanol > isopropanol > 2-butanone > toluene > cyclohexane. The obtained solubility values of 5-amino-3-methyl-1-phenylpyrazole were correlated with the modified Apelblat equation, λh equation, Wilson model and NRTL model. The maximum values of root-mean-square deviation ( RMSD ) and relative average deviation ( RAD ) were 4.95 × 10 − 4 and 0.62%, respectively. In total, the four thermodynamic models were all acceptable for describing the solubility behavior of 5-amino-3-methyl-1-phenylpyrazole in these solvents. Furthermore, the mixing Gibbs energy, mixing enthalpy, mixing entropy, activity coefficient at infinitesimal concentration and reduced excess enthalpy were obtained with Wilson model. The results demonstrated that the dissolution process of 5-amino-3-methyl-1-phenylpyrazole was spontaneous and favorable in the ten organic solvents. Moreover, the solute–solvent intermolecular interaction was roughly estimated based on the values of activity coefficients. The determined solubility data and thermodynamic models in this work would be helpful to optimize the purification procedure of 5-amino-3-methyl-1-phenylpyrazole. [ABSTRACT FROM AUTHOR]

Abstract: The solubility of ornidazole in different solvents (methanol, ethanol, 1-propanol, 1-butanol, isopropyl alcohol and ethyl acetate) has been determined using a gravimetric method over different temperature ranges (298.15K to 328.15K) at one atmospheric pressure. Further, various thermodynamic parameters have been evaluated from these solubility data. [Copyright &y& Elsevier]

Abstract: The fluorescence quenching studies of carboxamide namely (E)-N-(3-Chlorophenyl)-2-(3,4-dimethoxybenzylideneamino)-4,5,6,7-tetrahydrobenzo[b]thiophene-3-carboxamide [ENCDTTC] by aniline and carbon tetrachloride in six different solvents namely toluene, cyclohexane, n-hexane, n-heptane, n-decane and n-pentane have been carried out at room temperature with a view to understand the quenching mechanisms. The Stern–Volmer (S–V) plots have been found to be nonlinear with a positive deviation for all the solvents studied. In order to interpret these results we have invoked the ground state complex formation and sphere of action static quenching models. Using these models various quenching rate parameters have been determined. The magnitudes of these parameters suggest that sphere of action static quenching model agrees well with the experimental results. Hence the positive deviation is attributed to the static and dynamic quenching. Further, with the use of Finite Sink approximation model, it was possible to check these bimolecular reactions as diffusion-limited and to estimate independently distance parameter R′ and mutual diffusion coefficient D. Finally an effort has been made to correlate the values of R′ and D with the values of the encounter distance R and the mutual coefficient D determined using the Edward''s empirical relation and Stokes Einstein relation. [Copyright &y& Elsevier]

Abstract: Tetrafluoroborate-containing ionic liquids allow for a room temperature gelation of dimethylsulfoxide, which contains an organogelator at below the minimum gelation concentration. The gel formation has no effect on the mobility of ions, as the conductivity values of ionic liquid-DMSO gels are virtually identical to those of ionic liquid-DMSO solutions. [ABSTRACT FROM AUTHOR]

Abstract: Molar volume, viscosity and conductance of lithium chloride (LiCl), sodium chloride (NaCl) and potassium chloride (KCl) in 0.01m aqueous ascorbic acid have been calculated from density, viscosity and conductance data at temperatures 303.15, 308.15, 313.15 and 318.15K. The solute–solvent interactions for LiCl, NaCl and KCl have been inferred from ϕ v o, B-coefficient of Jones–Dole equation and Λ m o values. The structure making/breaking behavior of LiCl, NaCl and KCl is inferred from the sign of [∂2 ϕ v o/∂T2]p, dB/dT and temperature coefficient of Walden product i.e. d(Λ m o η o)/dT values. It has been found from molar volume, viscosity and conductance studies that LiCl, NaCl and KCl behaves as structure-breaker in 0.01m aqueous ascorbic acid solution. The energy of activation for LiCl, NaCl and KCl is calculated from conductance and viscosity data and it has found that E Λ is less than E η . [Copyright &y& Elsevier]

Abstract: Clegg–Pitzer–Brimblecombe ion-interaction semi-empirical approach was rarely exploited for modeling electrolyte, particularly, in mixed solvent systems. Indeed, a review of the literature shows that the use of an exact and complete form of this model (PSC) was only limited to the works of two research groups for the investigation of electrolyte in mixed solvent systems. In this work, we have used both Pitzer and PSC ion-interaction theoretical approaches for modeling the non-ideal behavior of HCl in the ternary HCl+methanol+water electrolyte system. The modeling purposes were achieved based on the experimental determination of the mean molal activity coefficients for HCl in this ternary system by using the potentiometric data of a galvanic cell containing a pH glass membrane and Ag/AgCl electrodes. The measurements were performed over the electrolyte molality ranging from 0.01 up to 5.75mol/kg in mixed methanol (x%)+water (100− x%) solvent, with solvent mass fraction percents: x%=10, 20, 30, 40 and 50%, at 298.15±0.05K. [Copyright &y& Elsevier]

Abstract: The molar transition energy (E T) polarity values of 1-(p-dimethylaminophenyl)-2-nitroethylene were collected in mixed solvent systems comprising a formamide [N,N-dimethylformamide (DMF), N-methylformamide (NMF) and formamide (FA)] and a hydroxylic (water, methanol, ethanol, propan-1-ol, propan-2-ol, butan-1-ol, and 2-methylpropan-2-ol) solvent. Mixed systems containing DMF with the other formamides (NMF and FA) and NMF with FA were also studied. Each solvent system was analyzed in terms of both solute–solvent and solvent–solvent interactions. These latter interactions were responsible for the synergism observed in some mixtures. All data were successfully fitted to a model based on solvent exchange equilibria and the results suggest that both hydrogen bonding and solvophobic interactions contribute to the formation of the solvent complexes responsible for the observed synergistic effects in the PS of the dye. [Copyright &y& Elsevier]

Abstract: A LFE (Linear Free Energy) analysis of kinetic data for different organic reactions in various organic aqueous solutions was carried out. The rate constants of these reactions were compared with those for the solvolysis of tert-butyl chloride in the same solvents in terms of the LFE Relationships, and linear plots were observed in a wide range of the co-solvent content. This similarity points to a common nature of the solvent effect in these reactions in variety of water–organic mixtures, regardless of largely different reaction mechanisms. We explain these results by the prevalence of hydrophobic stabilization of the initial state of these reactions in water-rich solvent mixtures. Recently the same conclusion was also made on the basis of investigations into sonication effects in kinetics of organic reactions. A considerable contribution of hydrophobic effects to the Y scale by Grunwald and Winstein was deduced. [Copyright &y& Elsevier]

Abstract: The paper aims to pay tribute to scientific achievements of Nikolai Izmailov (1907–1961) to the solution chemistry. In the forties–fifties, Izmailov proposed the most detailed scheme of dissociation of electrolytes in solutions and considered the problem of the differentiating influence of non-aqueous solvents on the acids strength. He also generalized the concept of an unified acidity scale in different solvents, proposed several new methods for estimating Gibbs energy of ion solvation, and contributed a lot to the theory of physico-chemical analysis. Beginning from the thirties, Izmailov investigated the possibility to apply various indicator electrodes, especially glass electrodes, in organic solvents. [Copyright &y& Elsevier]

Abstract: The specific conductance of ammonium formate, ammonium benzoate, sodium formate and sodium benzoate in (10%, 20% and 30% (W/W)) methanol–water, ethanol–water and glycerol–water mixtures at different temperatures (293, 298, 303 and 308 K) was measured. The molar conductance (Λ), limiting molar conductance (Λ 0), limiting ionic conductance (λ 0), association constants (K A), the activation energy of the transport process (E a), Walden product (Λ 0 η 0), hydrodynamic radii (1/r s + +1/r s −)−1, transfer numbers of the studied ions (t), standard thermodynamic parameters of association (ΔG A, ΔH A and ΔS A) were calculated and discussed. The results show that, the molar conductance and the limiting molar conductance values were decreased as the relative permittivity of the solvent decreased while, the association constant increased. Also the results show that the molar conductance, the limiting molar conductance and the association constant values were increased as the temperature increased indicating that the association process is an endothermic one. [Copyright &y& Elsevier]

Abstract: The Kirkwood–Buff integrals and the volume-corrected preferential solvation parameters for the first solvation shell are reported for binary mixtures of 1,4-dioxane with many organic solvents. They are calculated from reported thermodynamic data at the temperatures for which these data are available. The co-solvents include n-hexane, n-heptane, c-hexane, methyl-c-hexane, benzene, toluene, ethylbenzene, methanol, ethanol, 1-propanol, 2-propanol, c-pentanol, 1,2-ethanediol, acetic acid, dichloromethane, chloroform, tetrachloromethane, 1,2-dichloroethane, 1,2-dibromoethane, trichloroethene, tetrachloroethene, bromochlorotrifluoroethane (halothane), hexafluorobenzene, acetonitrile, triethylamine, piperidine, formamide, N,N-dimethylformamide, dimethyl sulfoxide, and tetramethylene sulfone (sulfolane). The derived preferential solvation parameters of these mixtures are discussed in terms of the interactions that take place. [Copyright &y& Elsevier]

Abstract: It is shown that the conductivities of LiBF4, LiPF6, LiN(SO2CF3)2 (LiTFSI), NaPF6, KPF are abnormally high in two diamine solvents: ethylenediamine (EDA) and 1,3-diaminopropane (1,3 DAP). This is particularly evident for KPF6, κ MAX(EDA)=35 mS cm− 1 and κ MAX(1,3 DAP)=17.4 mS cm− 1. Compared to three other organic solvents having the same viscosity, η ≅1.6 cP, but higher relative permittivity, NMF ε =186.9, NMP ε =32, γ-Bu ε =39.1, the maxima of conductibility of EDA and 1,2 DAP, which have a low relative permittivity, ε ≅13–11, are largely superior or equal to those of NMF, NMP, γ-Bu. For KPF6, κ MAX(NMF)=15.4mS cm− 1, κ MAX(NMP)=7.8 mS cm− 1 and κ MAX(γ-BL)=10.8 mS cm− 1. We assume that this is due to a non-Stokesian conductivity mechanism. [Copyright &y& Elsevier]

Abstract: Enthalpies of solution (Δ solnHθ) of fullerene[60] in benzene, toluene, bromobenzene, 1,2-dichlorobenzene and nitrobenzene have been measured in a Precision Solution Calorimeter at 298 K, by using the ampoule breaking technique. The dissolution of C60 in these aromatic organic solvents was observed to be exothermic, with exception of benzene and nitrobenzene, in which the enthalpy is close to zero. From the experimental values of Δ solnHθ and solubility data of C60 from the literature, Δ solnGθ and Δ solnSθ were calculated. We attempted to correlate (Δ solnHθ) of C60 in these solvents with the solubility, Hildebrand''s solubility parameter and polarizability parameter. Thermodynamic data suggest that the process of dissolution of C60 in the studied aromatic solvents is entropically controlled. [Copyright &y& Elsevier]

Abstract: The Abraham general solvation model is used to calculate the numerical values of the solute descriptors for 3-nitrobenzoic acid from experimental solubilities in organic solvents. The mathematical correlations take the form ofwhere CS and CW refer to the solute solubility in the organic solvent and water, respectively; CG is a gas-phase concentration; R2 is the solute excess molar refraction; Vx is McGowan volume of the solute; Σα2H and Σβ2H are measures of the solute hydrogen-bond acidity and hydrogen-bond basicity; π2H denotes the solute dipolarity/polarizability descriptor; and L(16) is the solute gas-phase dimensionless Ostwald partition coefficient into hexadecane at 298 K. The remaining symbols in the above expressions are known solvent coefficients, which have been determined previously for a large number of gas/solvent and water/solvent systems. We estimate R2 as 0.9900 and calculate Vx as 1.1059, and then solve a total of 48 equations to yield π2H=1.1800, Σα2H=0.7300, Σβ2H=0.5200 and log L(16)=5.6011. These descriptors reproduce the experimental data with a standard deviation of only 0.082 log units. [Copyright &y& Elsevier]