Determination of the Dissociation Constants of Some Macrolide Antibiotics in Methanol–Water Binary Mixtures by UV-Spectroscopy and Correlations with the Kamlet and Taft Solvatochromic Parameters

The dissociation constants of six common human and veterinary antibiotics, namely, erythromycin, roxithromycin, tilmicosin, oleandomycin, josamycin, and spiramycin in 15?%, 25?%, 40?% and 50?% (v/v) methanol?Cwater solvent mixtures were determined by UV/pH titration and correlated with the Kamlet and Taft solvatochromic parameters, ?? ^?, ?? and ??. Kamlet and Taft??s general equation was reduced to two terms by combined factor analysis and target factor analysis in these mixtures: the independent term and polarity/polarizability ?? ^?, which are solvatochromic parameters. The influence of methanol on the dissociation constants was investigated. Further, the quasi-lattice quasi-chemical (QLQC) model of preferential solvation has been applied to quantify the preferential solvation by water of electrolytes in methanol?Cwater mixtures.     

Enthalpies of 1,4-Dioxane, 1,2-Dimethoxyethane, and Ethylacetate Solvation in the Water–1-Propanol and Water–Glycerol Binary Mixtures

The enthalpies of 1,4-dioxane, 1,2-dimethoxyethane, and ethylacetate solution in binarymixtures of water with 1-propanol and glycerol were measured at 25°C using a precise isoperibol calorimeter. The enthalpies of the solute solvation were calculated and compared with the experimental data for other solutes. The results obtained were interpreted in terms of universal and specific solute solvation using parameters of a solvent polarity. It was found that the extreme shape of the curve _solv H° vs. X for ethylacetate in the mixtures of water with 1-propanol results from peculiarities of carbotylate-group solvation and appears to be not connected with the influence of alcohol microaggregates in the mixed solvent.     

Isobaric Binary and Ternary Vapor–Liquid Equilibrium for the Mixture of n-Hexane,Methylcyclopentane and N-Methylpyrrolidone

Journal of Solution Chemistry - The vapor–liquid phase equilibrium (VLE) data for binary systems of: n-hexane?+?methylcyclopentane, n-hexane?+?N-methylpyrrolidone...     

Volumetric and Acoustic Studies of Binary Liquid Mixtures of Dipropylene Glycol Dimethyl Ether with Methyl Acetate, Ethyl Acetate and n-Butyl Acetate in the Temperature Range T = (288.15, 293.15, 298.15, 303.15, and 308.15) K

Densities and ultrasonic speeds have been measured over the whole composition range for binary liquid mixtures of dipropylene glycol dimethyl ether, CH₃(OC₃H₆)₂OCH₃, with methyl acetate, ethyl acetate, and n-butyl acetate using an Anton Paar DSA 5000 M density and speed sound analyzer at T = (288.15, 293.15, 298.15, 303.15, and 308.15) K and atmospheric pressure in order to evaluate the behavior of these binaries. From these data excess the molar volume, $ V_{m}^{\text{E}} $ , and deviation in isentropic compressibility, ?κ _S , have been calculated. These excess properties have been fitted with the Redlich–Kister type polynomial equation to get their coefficients and standard deviations which provide a base for discussing the forces operating in solutions.     

Dielectric Parameters and Hydrogen Bond Interaction Study of Binary Alcohol Mixtures

The formation of hydrogen bonds between different types of molecules in binary alcohol mixtures (methyl alcohol, ethyl alcohol, ethylene glycol, propylene glycol and glycerol) have been investigated (each system at 21 mixture concentrations) by an analysis of their dielectric parameters. The static dielectric constant ε _o, limiting high-frequency dielectric constant ε _∞, excess dielectric parameters ε _o^E and ε _∞^E, effective Kirkwood correlation factor g ^eff, and corrective Kirkwood correlation factor g _f of the binary alcohol mixtures were determined at 25 °C in order to explore hydrogen-bond interactions and the strength of molecular connectivities between unlike alcohol molecules and their dipole alignment. These results confirm that the different alcohol mixtures form hydrogen-bonded structures, which are strongly influenced by the numbers of hydroxyl groups and carbon atoms of the alcohol molecules and vary with the concentrations of the mixtures.     

A Correlation Between Solvatochromic Solvent Polarity Parameters and the Ionization Constants of Various Phenols in 1,4-Dioxane–Water Mixtures

Precise thermodynamic ionization constants K for 3-nitrophenol, 3,4-dichlorophenol, and 4-cyanophenol have been obtained in 1,4-dioxane-water mixtures (0–70% volume fraction in dioxane) at 25°C using a potentiometric method. The same information for another twelve cationic, neutral, and anionic phenols were taken from the literature. Three different methods were used to study the effects of the solvents on the ionization constants: one involves a single polarity parameter, E _T(30); the next involves the Kamlet–Taft multiparametric method; and the last involves the preferential solvation model. The pK values follow the preferential solvation model, but the parameters obtained are highly correlated. Using the data for the phenol molecule as reference, a linear correlation between ΔpK and E _T(30) has been used to develop a new method of obtaining pK values for any binary solvent composition, with only the pK in water known. The pK(s) values correlate with the molecular parameters for the dipolarity/polarizability of the solvent π* and its hydrogen-bond donor ability α. The preferential solvation parameter, f _12/1, correlates with the parameter for the hydrogen-bond donor ability of the solvent. All the phenols follow Hammett's equation and the reaction constants have been calculated for the different water–dioxane mixtures.     

Apparent Molar Volumes and Solvation Coefficients in Ternary-pseudo-binary Mixtures [（Styrene＋Ethyl Acetate or Benzene）＋（N-Methyl-2-pyrrolidone＋Ethyl Acetate or Benzene）]

Over the full range of compositions,in the ternary-pseudo-binary mixtures of x[(1-y)C6H5CH=CH2+ yCH3COOC2H5(or C6H6)]+(1-x)[(1-y)NMP+yCH3COOC2H5(or C6H6)],the apparent molar volumes of each pseudo-pure component at different y values were calculated from the density data at 298.15 K and atmospheric pressure.The results show that the four parameters cubic polynomial can correlate the apparent molar volume with the molar fraction well over the full molar fraction range.The limiting partial molar volumes and the molar volumes of each pseudo-pure component were evaluated with different methods.Based on the limiting partial molar volume and molar volume at a certain y value,a new universal coefficient termed as solvation coefficient γ was defined to describe quantitatively the solvation degree of pseudo-pure solute and the interactions of solute-solvent molecules from the macroscopical thermodynamics viewpoint.The results demonstrate the solvation coefficients decrease with the amount of the third component increasing for each pseudo-pure solute,irrespective of the pseudo-pure solvent.Then the solvation degrees of each pseudo-pure component,the specific interactions between the solute molecule and the solvent one were discussed in terms of the solvation coefficient.     

Density and Viscosity for Binary Mixtures of the Ionic Liquid 1-Butyl-3-methylimidazolium Tetrafluoroborate with 2-Propanol,N,N-Dimethylacetamide and N,N-Dimethylformamide at 293.15–323.15 K: Experimental and PC-SAFT Modeling

Journal of Solution Chemistry - For three binary mixtures composed of ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF4]) with 2-propanol, N,N?dimethylacetamide (DMA) and...     

Solubility of Potassium Acetate in Water, 2,2,2-Trifluoroethanol,Ethanol and Their Binary Mixtures at 288.15—333.15 K

The potassium acetate solutions are new potential working fluids for the closed-type reverse electrodialysis(RED) power generation system driven by thermal energy. In this paper, the solubilities of potassium acetate in water, 2,2,2-trifluoroethanol, ethanol and their binary mixtures were measured by using the laser dynamic method over the temperature range of 288.15 to 333.15 K under atmospheric pressure. The results indicate that the solubility of potassium acetate solution is influenced by both the solvent components and solution temperature evidently. Besides, it is found that the measured solubility data of the potassium acetate-water-2,2,2-trifluoroethanol solutions as per the laser dynamic method are slightly larger than that of the data obtained as per the static method. Finally, five correlation models, including the Van't Hoff model, Modified Apelblat model, Yaws model, λh model and Modified Apelblat-Jouyban-Acree model, were used to correlate the measured solubility data of those potassium acetate solutions, with the relative standard deviations within 0.23% to 1.58%.     

Aggregation Stability of SiO2, FeOOH, ZrO2, CeO2, and Natural Diamond Sols and Their Binary Mixtures: 2. The Photometric Study of Heterocoagulation of SiO2–FeOOH, SiO2–ZrO2, SiO2–CeO2, and CeO2–Natural Diamond Binary Systems in KCl Solutions

The aggregation stability of 1 : 1 and 3 : 1 (by volume) binary mixtures of two hydrophobic (SiO₂–FeOOH), one hydrophobic and one hydrophilic (SiO₂–ZrO₂, SiO₂–CeO₂), and two hydrophilic (CeO₂–natural diamond) sols was studied by photometry over a wide range of KCl concentrations at pH 6 and 3. The stability of the mixed binary sols was determined by the stability of the sol with a predominant particle number concentration. In the SiO₂–FeOOH system, the phenomenon of heteroadagulation stabilization was caused by the electrostatic factor of the stability of adsorbed SiO₂ particles and, in the SiO₂–ZrO₂ system, by the structural factor of the stability of adsorbed hydrophilic ZrO₂ particles. The stability of binary mixtures containing one or two hydrophobic components is qualitatively explained in terms of the Derjaguin theory of heterocoagulation of hydrophobic colloids. The stability of the binary system of two hydrophilic components (CeO₂–natural diamond) is determined by the structural component of the interaction energy of particles.     

Physico-chemical Properties of Binary and Ternary Mixtures of Ethyl Acetate + Ethanol + 1-Butyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide at 298.15 K and Atmospheric Pressure

Densities, viscosities and refractive indices have been measured at 298.15 K and atmospheric pressure for binary and ternary mixtures of ethanol, ethyl acetate and 1-butyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl) imide [C₄mim][NTF₂]. From these experimental properties, the corresponding excess properties have been calculated and adequately fitted with the Redlich-Kister polynomial equation. The adjustable parameters and standard deviations between experimental and calculated values are reported. Interest of this mixture is due to the possibility of using [C₄mim][NTF₂] as an entrainer in the extractive distillation of ethanol + ethyl acetate. These results are compared with previously determined experimental data for mixtures of ethyl acetate and/or ethanol with the ionic liquid 1-octyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide, [C₈mim][NTF₂].     

Viscosities for Binary Mixtures of 1-Decanol, Hexane, and Diethylamine at 10, 25, and 40°C

Experimental viscosities provide information on the structure of liquids and are required in the design of processes, which involve fluid flow, mass transfer, or heat transfer calculations. This work reports experimental viscosity data of the binary mixtures: 1-decanol + hexane, 1-decanol + diethylamine, and hexane + diethylamine at 10, 25, and 40°C and atmospheric pressure for the whole range of compositions. The viscosities of the pure liquids and their mixtures were determined using Cannon Fenske viscometers thermostated at ±0.01°C. The estimated error in the measured viscosities was less than ±0.005 mPa-s. The dynamic viscosity and the excess energy of activation for viscous flow were also calculated. The equation of Redlich–Kister was used for fitting the excess properties of the binary mixtures. The excess viscosity shows positive deviations from ideal behavior for the mixtures 1- decanol + hexane and 1-decanol + diethylamine and a small negative deviation for the binary system hexane + diethylamine. The experimental results have been also used to test some empirical and semiempirical equations adopted previously to correlate viscosity composition data.     

The enthalpies and entropies of pefloxacin dissolution in methanol, ethanol, 1-Propanol, 2-Propanol, acetone, and chloroform at 293.15–323.15 K

The solubilities of pefloxacin in methanol, ethanol, 1-propanol, 2-propanol, acetone, and chloroform have been determined from 293.15 to 323.15 K by a static equilibrium method. The experimental data were correlated with the modified Apelblat equation. The positive ??_sol H and ??_sol S for each system revealed that pefloxacin dissolution in each solvent is an entropy-driven process.     

Solid–Liquid Equilibrium for the Ternary System 2-Methyl-4-Nitroaniline + 2-Methyl-6-Nitroaniline + Ethyl Acetate: Determination and Modelling

The solid–liquid phase equilibria for the ternary system 2-methyl-4-nitroaniline + 2-methyl-6-nitroaniline + ethyl acetate was determined experimentally by the method of isothermal solution saturation at temperatures of (293.15, 303.15 and 313.15) K under the pressure of 101.2 kPa. Based on the obtained solubility data, the isothermal phase diagrams of the system were constructed. At each temperature, there are two pure solid phases formed, which correspond to pure 2-methyl-4-nitroaniline and pure 2-methyl-6-nitroaniline, which was confirmed by Schreinemakers’ wet residue method and X-ray powder diffraction. The crystallization regions of pure 2-methyl-4-nitroaniline and pure 2-methyl-6-nitroaniline increased with decreasing temperature. The crystalline region of 2-methyl-4-nitroaniline was larger than that of 2-methyl-6-nitroaniline at a fixed temperature. The solubility data were correlated with the NRTL and Wilson models. The values of the root-mean-square deviations are 5.01 × 10^?3 for the NRTL model, and 6.43 × 10^?3 for the Wilson model. The solid–liquid equilibria, phase diagrams and the thermodynamic models for the ternary system can provide the foundation for separating 2-methyl-6-nitroaniline or 2-methyl-4-nitroaniline from its mixtures.     

Ultrasonic and Volumetric Study of N–H Bond Complexes in Binary Mixtures

Experimental values of the density and ultrasonic velocity have been measured for binary mixtures of butylamine with 1-butanol and with tert-butanol at temperatures of 293.15, 303.15 and 313.15 K over the entire mole fraction range. From these data, the excess molar volumes, deviations in isentropic compressibility, excess internal pressures, and excess molar enthalpies have been calculated. All of the excess functions were fitted to Redlich-Kister polynomial relations to estimate the adjustable parameters along with the standard deviations of the fits. The variations of these excess functions with mole fraction of butylamine have been examined. The changes in these parameters with composition suggest that the interaction between butylamine and 1-butanol is strong, whereas its interaction with tert-butanol is weak. Further, the partial molar volumes and partial molar compressibilities at infinite dilution have also been evaluated since these parameters provide better insight for studying intermolecular interactions.     

Chemical Equilibrium for the Reacting System Acetic Acid–Ethanol–Ethyl Acetate–Water at 303.15 K, 313.15 K and 323.15 K

The chemical equilibrium (CE) for the quaternary reacting system ethanol–acetic acid–ethyl acetate–water was studied at 303.15, 313.15 and 323.15 K and atmospheric pressure. The CE compositions were determined by gas chromatography and nuclear magnetic resonance analytical methods. The thermodynamic constants of CE at 303.15, 313.15 and 323.15 K were calculated based on the obtained experimental data with the use of the NRTL model.     

Study of Solvent Effects on the Protonation of Functional Group of Disubstituted Anilines: Factor Analysis Applied to the Correlation between Protonation Constants and Solvatochromic Parameters in Ethanol–Water Mixtures

Summary. The stoichiometric protonation constants (log β) of some disubstituted aniline derivatives in ethanol–water mixtures (0–90% ethanol by volume) at 25.0 ± 0.1°C were firstly submitted to factor analysis in order to obtain the number factors which affect the variation of the whole data sets and, afterwards, submitted to target factor analysis to identify these factors. The influence of solvatochromic parameters in the interactions between aniline derivatives and the solvent studied was identified and quantified. The general equation of Kamlet and Taft was reduced for these mixtures to two terms using combined factor analysis (FA) and target factor analysis (TFA): the independent term and the hydrogen-bond donating ability, α (HBD), solvatochromic parameters. Further, the quasi-lattice quasi-chemical (QLQC) theory of preferential solvation has been applied to quantify the preferential solvation by water of electrolytes in ethanol–water mixtures. The effects of the substituents on the protonation constants, the additivities of these effects, and the applicability of the Hammett equation to the behavior of substituents are also discussed. Further, Hammett’s reaction constant for the protonation of disubstituted anilines has been obtained for all the solvent mixtures and correlates well with α (HBD) of the solvent.     

Preferential Solvation of Boscalid in Ethanol/Isopropanol + Ethyl Acetate Mixtures from the Inverse Kirkwood–Buff Integrals Method

The preferential solvation parameters (δx _1,3) of Boscalid in solvent mixtures of ethanol (1) + ethyl acetate (2), and isopropanol (1) + ethyl acetate (2) were derived from their available solubility data by means of the inverse Kirkwood–Buff integrals method. The values of δx _1,3 vary non-linearly with the solvent (1) proportion in the two solvent mixtures. For the ethanol (1) + ethyl acetate (2) system, the values of δx _1,3 are negative in ethanol-rich and ethyl acetate-rich mixtures, but positive in intermediate compositions; for the isopropanol (1) + ethyl acetate (2) system, the values of δx _1,3 are positive in ethyl acetate-rich mixtures and in intermediate compositions, but negative in isopropanol-rich mixtures. The δx _1,3 values are positive indicating that Boscalid is preferentially solvated by ethyl acetate. The magnitude of the preferential solvation of Boscalid by ethyl acetate is higher in isopropanol (1) + ethyl acetate (2) mixtures than in ethanol (1) + ethyl acetate (2) mixtures at 298.15, 308.15 and 313.15 K. The ethyl acetate action may be related to the disordered structure of ethanol or isopropanol molecules around the polar moieties of Boscalid, which increases the solvation, with maximum values near x ₁ = 0.40–0.45 for the two solvent mixtures.     

Excess Molar Volumes and Viscosities for Binary Mixtures of 1-Alkoxypropan-2-ols with 1-Butanol, and 2-Butanol at 298.15 K and Atmospheric Pressure

Excess molar volumes Vm^E and kinematic viscosities v have been measured as a function of composition for binary mixtures of propylene glycol monomethyl ether （1-methoxy-2-propanol）, MeOCH2CH（OH）Me, propylene glycol monoethyl ether （1-ethoxy-2-propanol）, EtOCH2CH（OH）Me, propylene glycol monopropyl ether （1-propoxy-2-propanol）, PrOCH2CH（OH）Me, propylene glycol monobutyl ether （1-butoxy-2-propanol）, BuOCH2CH（OH）Me, and propylene glycol tert-butyl ether （1-tert-butoxy-2-propanol）, t-BuOCH2CH（OH）Me with 1-butanol, and 2-butanol, at 298.15 K and atmospheric pressure. The excess molar volumes are negative across the entire range of composition for all the systems with 1-butanol, and positive for the systems 2-butanol＋ 1-methoxy-2-propanol, and ＋1-propoxy-2-propanol, negative for the systems 2-butanol＋1-butoxy-2-propanol, and change sign for the systems 2-butanol＋ 1-ethoxy-2-propanol, and ＋ 1-tert-butoxy-2-propanol. From the experimental data, the deviation in dynamic viscosity η from ∑χiηi has been calculated. Both excess molar volumes and viscosity deviations have been correlated using a Redlich-Kister type polynomial equation by the method of least-squares for the estimation of the binary coefficients and the standard errors.     

Ultrasonic Velocities,Densities, and Refractive Indices of Binary Mixtures of Polyethylene Glycol 250 Dimethyl Ether with 1-Propanol and with 1-Butanol

Measurements of the ultrasonic velocity (u), density (ρ) and refractive index (n) for binary mixtures of polyethylene glycol 250 dimethyl ether with 1-propanol and 1-butanol have been made at three temperatures (T=293, 303 and 31 K) over the entire composition range in order to investigate the nature of intermolecular interactions between the components of these liquid mixtures. Various excess thermodynamic properties such as the excess ultrasonic velocity (Δu), deviation in isentropic compressibility (Δk _S ), excess intermolecular free length (L_f^E)(L_{\mathrm{f}}^{\mathrm{E}}), excess acoustic impedance (Z ^E), excess pseudo-Grüneisen parameter (Γ ^E), and molar refraction deviation (ΔR _m) were calculated using experimental values of the ultrasonic velocity, density and refractive index and were then represented with the Redlich-Kister polynomial equation. The observed excess deviation parameter values were explained on the basis of the strength of intermolecular interactions between the components of the mixtures. Estimations of the refractive index and ultrasonic velocity have also been made using various empirical relations and are discussed in terms of the average percentage deviations (APD).