Study of molecular interactions in solutions of azomethines of sulfamethoxazole in N,N-dymethylformamide and tetrahydrofuran

Density, ultrasonic velocity and viscosity of azomethines containing sulfamethoxazole nucleus have been measured in N,N-dimethylformamide and tetrahydrofuran solutions over a wide concentration range at temperature 308.15 K. From these experimental data, acoustical parameters such as intermolecular free path length, isentropic compressibility and relaxation strength have been evaluated, that help understanding the molecular interactions occurring in these solutions. Furthermore, compressibility solvation number, the apparent molar compressibility and apparent molar volume of the solutions have been determined and discussed.     

Ultrasonic and ir investigations of N–H bond complexes

Complex formation of 1?:?1 mixtures of naphthols, viz. (α-naphthol and β-naphthol) with triethylamine in benzene have been studied at a frequency of 2?MHz in the concentration range of 0.010–0.090 and at varying temperatures of 30, 40 and 50°C. Using the measured ultrasonic velocity, the thermoacoustical parameters such as adiabatic compressibility, intermolecular free length, molar sound velocity, molar compressibility and acoustic impedance have been calculated. The ultrasonic velocity shows a maxima and adiabatic compressibility shows a corresponding minima as a function of concentration for these mixtures. These, in turn, are used to study the solute–solute interaction and the possibility of complex formation between unlike molecules of naphthols and triethylamine through intermolecular hydrogen bonding. The hydrogen bond is formed between hydrogen atom of naphthols and nitrogen atom of triethylamine molecule. The result obtained using infrared spectroscopy for both the systems also supports the existence of complex formation through intermolecular hydrogen bonding.     

Ultrasonic and IR study of molecular association process through hydrogen bonding in ternary liquid mixtures

Complex formation in ternary liquid mixtures of heterocyclic compounds, viz. pyridine and quinoline with phenol in benzene has been studied through ultrasonic velocity measurements (at 2 MHz) in the concentration range of 0.010–0.090 at varying temperatures of 35, 45 and 55 °C. The ultrasonic velocity and density data are used to estimate adiabatic compressibility, intermolecular free length, molar sound velocity, molar compressibility and specific acoustic impedance. These acoustical parameters, in turn, are used to study the solute–solute interactions in these systems. The ultrasonic velocity shows a maxima and adiabatic compressibility a corresponding minima as a function of concentration for these mixtures. The results indicate the possible occurrence of complex formation between unlike molecules through intermolecular hydrogen bonding between the nitrogen atom of pyridine and quinoline molecules and the hydrogen atom of phenol molecule. Further, the excess values of adiabatic compressibility and intermolecular free length have also been evaluated and discussed in relation to complex formation. The infrared spectra of both the systems, pyridine–phenol and quinoline–phenol, have been also recorded for various concentrations at room temperature (35 °C) and found to be useful for understanding the presence of N⋯HO bond complexes and the strength of molecular association at specific concentrations.     

Acoustic and volumetric studies of uracil in aqueous urea solution at different temperatures

Volumetric, viscometric and ultrasonic studies of uracil in an aqueous urea solution in varying concentration of 2, 3 and 5?M have been carried out at 298, 308 and 318?K. The uracil concentration in the aqueous urea solution varies from 0.05% to 0.4%. Density (ρ), viscosity (η) and sound speed (u) have been measured. The experimental data are used for computing various thermodynamic and acoustic parameters, namely apparent molar volume, isentropic compressibility, apparent isentropic compressibility, relative association, intermolecular free length, acoustic impedance, viscous relaxation time, hydration number, Gibb's free energy, classical absorption coefficient of the solution and viscosity data have been further analysed in the light of Masson's equation and Jones–Dole's equations, respectively. The results have been discussed in terms of solute–solute and solute–solvent interaction and the structural changes of the solutes in solutions. The effect of variation of temperature on these interactions has also been investigated.     

Acoustical parameters of toluene + chloroform + cyclohexane mixtures at 303.15, 308.15, and 313.15 K

Ultrasonic velocity, density and viscosity of the ternary mixture of toluene + chloroform + cyclohexane, were measured at 303.15, 308.15, and 313.15 K. The thermodynamically parameters such as adiabatic compressibility (??), intermolecular free length (L _f), free volume (V _f), internal pressure (?? _i ), acoustic impedance (Z), molar sound velocity (R), and molar compressibility (W) have been obtained from the experimental data for all the mixtures, with a view to investigate the exact nature of molecular interaction. Adiabatic compressibility and intermolecular free length decrease with increase in concentration and temperature. The other parameters show almost increasing concentration of solutes. These parameters have been further used to interpret the molecular interaction part of the solute and solvent in the mixtures.     

Ultrasonic study on binary mixture containing dimethylformamide and methanol over the entire miscibility range (0 < x < 1) at temperatures 303–323 K

The experimental density and speed of ultrasound measurements in connection with literature data have been measured for pure N,N-dimethylformamide (DMF), methanol and their binary mixtures over the whole miscibility range at different temperatures 303, 308, 313, 318 and 323 K. These parameters were used to determine the adiabatic compressibility, intermolecular free length, molar compressibility, molar sound velocity, acoustic impedance, relaxation strength and their excess values. The variation of these parameters with composition of mixture indicates the nature and extent of interaction between unlike molecules. The non-ideal behavior of the system studied was explained on the basis of the dipole-induced dipole interactions and hydrogen bonding. The complex formation through intermolecular hydrogen bonding was confirmed from the recorded FTIR spectra. Available thermal energy breaks the bonds between the associated molecules into their respective monomers on increasing the temperature.     

Thermo-elastic and thermodynamic properties of light and heavy crude oil

Three different experiments, viz., ultrasound interferometry, differential scanning calorimetry, and density measurements were carried out over a wide range of temperature varying from 20°C to 70°C in light, heavy, and a mixture of light and heavy crude oil samples which differ considerably in its American Petroleum Institute gravity. The properties of the mixture have been discussed in terms of its deviation from the ideal values of mixing. The directly measured quantities such as the compression wave velocity, the specific heat at constant pressure, and the density were used to evaluate the temperature dependence of adiabatic compressibility, coefficient of volume expansion and the acoustic impedance. A correlation between thermo-elastic and thermodynamic functions of crude oils has been investigated. In particular, the ratio of the specific heats has been determined by making use of the thermo-elastic functions, which was further used to estimate the specific heat at constant volume. The values of the isothermal compressibility and the coefficient of volume expansion are used to evaluate the pressure–temperature dependence of crude oil conforming to in-situ reservoir conditions.     

Effect of simple electrolytes on the thermodynamic properties of room temperature ionic liquids in aqueous solutions

Density, sound velocity and conductivity measurements are carried out on 1-heptyl-3-methylimidazolium bromide ([C₇mim][Br]) in pure water and in aqueous solutions of sodium di-hydrogen citrate, di-sodium hydrogen citrate and tri-sodium citrate over a range of temperatures at atmospheric pressure. The experimental density and sound velocity data are used to calculate the apparent molar volume and isentropic compressibility as a function of temperature and concentration. The effects of temperature and charge on the anion of sodium citrate salts on the apparent molar volume and isentropic compressibility of [C₇mim][Br] are studied. It was found that both of the apparent molar volume and isentropic compressibility of [C₇mim][Br] in aqueous sodium citrate solutions are larger than those in pure water and increase by increasing temperature. The effects of temperature and charge on the anion of sodium citrate salts on the conductivity behavior of the investigated IL solutions are also studied.     

Acoustical study on ternary mixture of dimethyl acetamide (DMAC) in diethyl ether and isobutyl methyl ketone at different frequencies

The experimental density (ρ) and the velocity (U) for ternary mixture of dimethyl acetamide diethyl ether and isobutyl methyl ketone at different frequencies (2, 4, 6 and 8 MH_Z) have been measured at a constant temperature of 308 K. These data have been used to compute acoustic impedance (Z), adiabatic compressibility (K _s), intermolecular free length (L_f ), molar volume (V_m ), molar sound velocity (R), molar compressibility (B), available volume (V _a), Lennard-Jones potential repulsive term exponent (n), relative association (R _A), interaction parameter (X) and excess values of some of the above parameters for entire range of mole fraction and are interpreted to explain molecular interaction occurring in the liquid mixture.     

Acoustical studies of some derivatives of 1,5-benzodiazepines formamide and tetrahydrofuran solutions at 298.15 K

Some derivatives of 1,5-benzodiazepines have been synthesized and characterized by TLC, IR, NMR, and Mass Spectral data. The ultrasonic velocity, density and viscosity of these synthesized compounds have been measured in dimethyl formamide and tetrahydrofuran at 298.15 K. From these experimental data, various acoustical parameters such as isentropic compressibility, intermolecular free path length, molar compressibility, Rao’s molar sound function, relaxation strength, internal pressure, free volume etc., have been calculated which helps in understanding the molecular interactions occurring in these solutions.     

Investigations of Molecular Interactions in the Binary Mixtures of 1-Butyl-3-methylimidazolium bis(Trifluoromethanesulfonyl) Amide and 2-Propoxyethanol from <Emphasis Type="Italic">T</Emphasis> = (298.15 to 323.15) K at Atmospheric Pressure

Density and speed of sound values of pure and binary mixtures of 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl) amide ([Bmim][NTf₂]) and 2-propoxyethanol (2-PR) were determined over the whole composition range as a function of temperature from 298.15 to 323.15 K) under atmospheric pressure. Heat capacity values of the pure compounds were also measured. The experimental values were used to calculate excess molar volume, excess isentropic compressibility, excess intermolecular free length and excess speed of sound values. The excess values were fitted with the Redlich–Kister polynomial equation to estimate the binary coefficients and standard deviation between the experimental and calculated values. The partial molar volumes at infinite dilutions were also calculated. The trends of variation of these properties were interpreted in light of the solute–solvent interactions occurring in the system. Further, the molecular interactions in the binary system were analyzed using experimental FT-IR spectra recorded at room temperature.     

Study of Molecular Interactions in Binary Mixtures of Aniline with Carboxylic Acids at 293.15 K, 303.15 K and 313.15 K

Ultrasonic velocity, density, refractive index and viscosity of binary mixtures of aniline with acetic acid (AA) and propionic acid (PA) have been measured at 293.15, 303.15 and 313.15 K over the entire composition range. Further, the specific heat ratio, heat capacity, effective Debye temperature and pseudo-Gruensisen parameter and non-linearity parameter have been evaluated using ultrasonic absorption data. The deviation in isentropic compressibility, excess molar volume, excess intermolecular free length, deviation in molar refraction, deviation in viscosity, relaxation time, enthalpy, entropy and Gibbs energy of activation have been calculated from the experimental data and fitted with the Redlich-Kister polynomial equation. A comparative study has also been made between experimental and theoretically calculated values of densities using the HBT and Rackett density models. Mixing rules for the prediction of refractive index, e.g. Lorentz-Lorenz (L-L), Eykmen (Eyk), Weiner (W), Heller (H), Gladstone-Dale (G-D), Arago-Biot (A-B) and Newton (N) have been applied to these binary mixtures.     

Study of molecular interactions in binary mixtures of formamide with 2-methoxyethanol and 2-ethoxyethanol at varying temperatures

The thermophysical properties of binary mixtures of formamide with 2-methoxyethanol and 2-ethoxyethanol have been investigated in this article. Densities, refractive index, ultrasonic velocity and viscosity for the two binary mixtures viz. formamide with 2-methoxyethanol and 2-ethoxyethanol have been measured over the entire composition range at 293, 303 and 313 K and at atmospheric pressure. The excess molar volume, the molar refraction deviation, excess Gibb's free energy of activation for viscous flow, excess isentropic compressibility, deviation in viscosity, excess free volume and excess molar enthalpy have been computed using experimental data. These excess parameters have been correlated with Redlich–Kister polynomial equation. The results have been interpreted on the basis of strength of intermolecular interaction occurring in these mixtures. Densities, refractive index and ultrasonic velocity were correlated with second-order polynomial equation. The molar volume and excess partial molar volume at infinite dilution have also been calculated for both the mixtures.     

Partial molar volumes and partial molar adiabatic compressibilities of a short chain perfluorosurfactant: Sodium heptafluorobutyrate in aqueous solutions at different temperatures

Density and ultrasound measurements of sodium heptafluorobutyrate in aqueous solutions at T = (283.15, 288.15, 293.15, 298.15, 303.15, 308.15, 313.15, 318.15, and 323.15) K have been obtained. From these results partial molar volumes and isentropic partial molar adiabatic compressibilities were calculated. Deviations from the Debye-Hückel limiting law provide evidence for limited association at lower concentrations. The change of the partial molar volume and isentropic partial molar adiabatic compressibility upon aggregation was calculated. Variations of the change of partial molar volumes and isentropic partial molar adiabatic compressibility upon aggregation are discussed in terms of temperature.     

Intermolecular interactions in dioxane-water solutions of substituted coumarins according to ultrasonic data

Density, ultrasonic velocity of pure dioxane (Dx) and ligands, 4,6-dimethyl-7-hydroxycoumarin (L₁), 6-ethyl-7-hydroxy-4-methylcoumarin (L₂), and 3-chloro-7-hydroxy-4-methylcoumarin (L₃) in different percent of Dx-water mixture have been investigated at 303.15 K. Acoustical parameters such as adiabatic compressibility (β), intermolecular free length (L _f ), acoustical impedance (Z), relative association (R _A ), apparent molar compressibility (Φ_β), and apparent molar volume (Φ _V ) have also been evaluated from the experimental data of density and ultrasonic velocity. An excellent correlation between a given parameters is observed at all percent of dioxane-water and the result suggests nature of intermolecular interactions between the components.     

Thermodynamic and transport properties of (1,2-ethanediol + 1-nonanol) at temperatures from (298.15 to 313.15) K

Densities and kinematic viscosities have been measured for (1,2-ethanediol + 1-nonanol) over the temperature range from (298.15 to 313.15) K. The speeds of sound in those mixtures within the temperature range from (293.15 to 313.15) K have been measured as well. Using the measurement results, the molar volumes, isentropic compressibility coefficients, molar isentropic compressibilities, and the corresponding excess and deviation values (excess molar volumes, excess isentropic compressibility coefficients, excess molar isentropic compressibilities, differently defined deviations of the speed of sound, and dynamic viscosity deviations) were calculated. The excess Gibbs free energies estimated by the use of the UNIQUAC model are also reported. The excess molar volumes and Gibbs free energies are positive, whereas the compressibility excesses are s-shaped. The excess and deviation values are expressed by Redlich–Kister polynomials and discussed in terms of variations of the structure of the system caused by the participation of two different alcohol molecules in the dynamic intermolecular association process through hydrogen bonding. The effect of temperature is discussed. The predictive abilities of the McAllister equation for viscosities of the mixtures under test have also been examined.     

Studies on acoustic behavior of praseodymium soaps

The CMC and various acoustic parameters of praseodymium soaps in 1-pentanol have been determined by ultrasonic velocity measurements. The results show that the ultrasonic velocity, specific acoustic impedance, apparent molal compressibility, and molar sound velocity increase while adiabatic compressibility and intermolecular free length decrease with increasing concentration and chain length of soap.     

Molecular interaction studies in ternary liquid mixture of dimethylacetamide using ultrasonic technique at 308 K

The experimental density (ρ) and ultrasonic velocity (U) for ternary mixture containing dimethylacetamide (DMAC), acetone and diethyl ether at frequencies 2, 4, 6 and 8 MHz have been measured at temperature 308 K. These data are used to compute adiabatic compressibility (K_s), intermolecular free length (L_f), acoustic Impedance (Z), molar volume (V_m), molar sound velocity (R), molar compressibility (B), available volume (V_a), Lennard-Jones potential repulsive term exponent (n), relative association (R_A), interaction parameter (χ) and some excess thermo acoustic parameters for whole range of concentration of DMAC and are interpreted to elucidate molecular interaction occurring in the liquid mixture.     

Studies on thermo-acoustic parameters of poly(ethylene glycol)- 400 at different temperatures

The ultrasonic velocity and density have been measured at different temperatures between 299 and 363 K for the pure liquid sample, poly(ethylene glycol) with average molecular mass 400 g mol^?1 (PEG 400). From these, isentropic compressibility (β), intermolecular free length (L _f), acoustic impedance (Z), molar volume (V _m), Schaff’s available volume V _a(s), molar sound velocity (R _a), and molar compressibility (W) have been evaluated. The variations of these parameters with the temperature of the sample have been studied. Data so obtained are employed to compute other thermodynamic parameters. Variations in various parameters with respect to temperature are discussed in the light of the results obtained.