Ultrasonic measurements and other allied parameters of praseodymium and neodymium palmitates in mixed organic solvents

Ultrasonic measurements on praseodymium and neodymium palmitates were made in a mixture of 60% benzene and 40% dimethyl sulfoxide (V/V), to determine the critical micelle concentration (CMC), soap-solvent interaction, and various acoustic and thermodynamic parameters. The values of the CMC increase with the increase in the size of the cation in the soap molecules. The ultrasonic velocity, specific acoustic impedance, apparent molar compressibility, apparent molar volume and relative association increase while the adiabatic compressibility, intermolecular free length, solvation number, molar sound velocity and available volume decrease with increasing soap concentration.     

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.     

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.     

Molecular Interactions in Binary Mixtures of Benzene with 1-Alkanols(C5,C7,C8) at 35℃:An Ultrasonic Study

Densities and ultrasonic speeds have been measured in binary mixtures of benzene with 1‐pentanol, 1‐heptanol and 1‐octanol, and in the pure components, as a function of composition at 35 °C. The isentropic compressibility, intermolecular free length, relative association, acoustic impedance, isothermal compressibility, thermal expansion coefficient, deviations in isentropic compressibility, excess free length, excess volume, deviations in ultrasonic speed, excess acoustic impedance, apparent molar compressibility, apparent molar volume, partial molar volume of 1‐alkanol in benzene have been calculated from the experimental data of densities and ultrasonic speeds. The variation of these parameters with composition indicates weak interaction between the component molecules and this interaction decreases in the order: 1‐pentanol > l‐heptanol> 1‐octanol. Further, theoretical values of ultrasonic speeds were evaluated using free length theory, collision factor theory, Nomoto's relation and Van Dæl‐Vangeel ideal mixing relation. The relative merits of these theories and relations were discussed for these systems.     

Acoustic,excess thermodynamical,molecular interaction and anti-microbial activity studies on binary liquid mixtures of geranyl acetate and benzyl benzoate in the temperature range of 303.15K–318.15K

The binary organic liquid mixture of geranyl acetate + benzyl benzoate was taken at different mole fractions and various temperatures 303.15K, 308.15K, 313.15K and 318.15K and measured their density, ultrasonic sound velocity and viscosity. Data from experiments were used to calculate variations in binary systems at different temperatures regarding excess acoustic parameters. Variations in ultrasonic velocity, intermolecular free length, and adiabatic compressibility were among these. To estimate the coefficients and standard errors for the excess/deviation functions, multi-parametric non-linear regression analysis was used to fit a Redlich-Kister polynomial with the calculated excess/deviation functions. Changes in these properties with temperature and composition have been investigated in the molecular interactions between the molecules of the binary mixtures. FTIR spectra also support the results. Furthermore, liquid mixtures and individual compounds were studied for their antibacterial activity.     

Acoustic and Thermodynamic Properties of Binary Liquid Mixtures of Benzaldehyde in Hexane and Cyclohexane

Densities and ultrasonic speeds of binary mixtures of benzaldehyde with n-hexane and cyclohexane at 30 °C were measured over the entire composition range. From these experimental data, the adiabatic compressibility (K _S ), intermolecular free length (L _f), acoustic impedance (Z), relative association (R _a) and relaxation strength (r) were calculated. Also, the excess adiabatic compressibility (K _S ^E), intermolecular free length (L _f^E), acoustic impedance (Z ^E), and ultrasonic velocity (U ^E) were calculated. The observed variation of these parameters helps in understanding the nature of interactions in these mixtures. Further, theoretical values of the ultrasonic speed were evaluated using theories and empirical relations. The relative merits of these theories and relations were discussed.     

Thermo-physical properties of the binary mixture of benzaldehyde with bromobenzene at 303.15, 308.15, and 313.15?K

The values of density, viscosity, and ultrasonic velocity for the binary liquid mixture of benzaldehyde with bromobenzene have been measured over the entire range of composition at 303.15, 308.15, and 313.15?K. These values have been used to calculate the excess molar volume (V ^E), deviation in viscosity (????), deviation in velocity (?U), deviation in isentropic compressibility (??? _s), excess internal pressure (???), excess intermolecular free length (?L _f), and excess acoustic impedance (?Z). McAllister??s three-body-interaction model is used for correlating kinematic viscosity of binary mixtures. The excess values were correlated using the Redlich?CKister polynomial equation to obtain their coefficients and standard deviations. The thermo-physical properties (density, viscosity, and ultrasonic velocity) under the study were fitted to the Jouyban?CAcree model.     

Thermodynamic properties of pure liquids within a generalized version of the hole theory

A generalized hole theory for computing the thermodynamic and acoustic properties of liquids and liquid mixtures has been developed. Ultrasonic velocity, isothermal compressibility and thermal expansivity of different pure liquids at 293.15 and 298.15?K are evaluated by using hole theory. The calculated values of ultrasonic velocities, isothermal compressibilities, and thermal expansivities are compared with the experimental findings. A fairly good agreement between experimental and calculated values is observed.     

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.     

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.     

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.     

Isentropic compressibilities of (amide + water) mixtures: A comparative study

The density and ultrasonic velocity of aqueous solutions of formamide (FA), N-methylformamide (NMF), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMA), pyrrolidin-2-one (PYR), N-methyl-2-pyrrolidinone (NMP), and their pure phases have been measured at 298.15 K and atmospheric pressure. Densities and ultrasonic velocities in pure amides have been also measured at the temperature range 288.15 K to 308.15 K for the computation of their thermal expansivities. Isentropic compressibility, intermolecular free length, relative association, apparent molar compressibility, as well as the excess quantities, ultrasonic velocity, isentropic compressibility, intermolecular free length, have been evaluated and fitted to the Redlich–Kister type equation. The deviation from ideal mixing law in ultrasonic velocity is positive while the deviations in isentropic compressibility and intermolecular free length are negative for all (amide + water) mixtures. This behavior reveals the nature and the magnitude of intermolecular interactions between the amide–water molecules. The sequence of superimposed curves of various ultrasonic parameters vs. the amide mole fraction is related to the strength of interactions between the unlike molecules and the role of –CH₃ substitution in amides. The comparison of ultrasonic to volumetric properties reveals differences on the position of the extrema and their relation with the degree of substitution while the interpretation of these differences is discussed. Two different approaches on the computation of excess functions, applied in this work, brought out a difference in the magnitude of deviations and a partial reversion to the sequence of amides curves suggesting a different estimation in terms of deviations from ideal mixing law and therefore of the relative molecular interactions.     

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.     

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 measurements and other allied parameters of yttrium soaps in mixed organic solvents

The ultrasonic measurements of yttrium soaps were made in a mixture of 70% benzene and 30% dimethylsulfoxide (v/v) to determine the critical micelle concentration, soap-solvent interaction and various acoustic and thermodynamic parameters. The values of the CMC decrease with increasing chainlength of fatty acid constituent of the soap molecule and are in agreement with the values obtained from other micellar properties. The various acoustic parameters (intermolecular free-length, adiabatic compressibility, apparent molar compressibility, specific acoustic impedance, apparent molar volume, molar sound velocity, solvation number, available volume and relative association) for yttrium soaps (myristate, palmitate, stearate and oleate) have been evaluated by ultrasonic velocity measurements.

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Ultraschallmessungen und damit verknüpfte Parameter von Yttrium-Seifen in gemischten organischen Lösungsmitteln

Zusammenfassung Es wurden Ultraschallmessungen von Yttrium-Seifen in einer Mischung 70% Benzol und 30% Dimethylsulfoxid (v/v) durchgeführt, um die kritische Micellenkonzentration, Seifen-Solvens-Wechselwirkung und verschiedene akustische und thermodynamische Parameter zu bestimmen. Die CMC-Werte fallen mit steigender Kettenlänge der Fettsäurekomponente des Seifenmoleküls und sind damit in Übereinstimmung mit den aus anderen micellaren Eigenschaften bestimmten Werten. Verschiedene akustische Parameter (intermolekulare freie Länge, adiabatische Kompressibilität, effektive molare Kompressibilität, spezifische akkustische Impedanz, effektives molares Volumen, molare Schallgeschwindigkeit, Solvatationszahl, verfügbares Volumen und relative Assoziation) der Yttrium-Seifen (Myristat, Palmitat, Stearat und Oleat) wurden aus den Ultraschallmessungen ermittelt.

     

Volumetric and ultrasonic studies of the system (water + polypropylene glycol 400) at temperatures from (283.15 to 313.15) K

Ultrasonic velocity and density of aqueous solutions of polypropylene glycol have been measured experimentally over the whole range of composition at temperatures T = (283.15 to 313.15) K and atmospheric pressure. From these experimental data, the excess specific volumes, isentropic compressibility, increments of the ultrasonic velocity, and the isentropic compressibility have been determined for each composition. The results have been interpreted in light of polymer–solvent and polymer–polymer interactions. Also, the excess specific volumes, the increments of the ultrasonic velocity, and the isentropic compressibility were fitted to a variable-degree polynomial equation.     

Ultrasound velocity and density studies in some refined and unrefined edible oils

Density and ultrasonic velocity at a frequency of 3?MHz and in the temperature range 298–333?K are measured in some of the refined and unrefined edible oils, namely coconut oil, castor oil, sunflower oil, kardi (safflower oil) and groundnut oil, which are predominantly used in south India. Velocity has been observed to be decreasing with temperature nonlinearly in some oils in the temperature range studied. This is in agreement with others' observations made in different oils and fats. Velocity change with temperature is attributed to change in intermolecular distance with temperature and the nature of variation depends on the internal molecular dynamics. Density of all the oils has been found to be decreasing with temperature. Various physical parameters such as specific volume, molar sound velocity, adiabatic compressibility, molar compressibility and intermolecular free length have been estimated using measured data on velocity and density.     

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.     

Ultrasonic Study of Basic α‐Amino Acids in Different Acetate Salt Solutions at Different Temperatures

The ultrasonic velocity (U), has been measured for three α‐amino acids, namely L‐lysine monohydrochloride, L‐arginine and L‐histidine in solutions (1 mol/L aqueous) of sodium acetate (SA), potassium acetate (PA) and calcium acetate (CA) at different temperatures (303.15, 308.15, 313.15, 318.15 and 323.15 K). With the help of these results various ultrasonic derived parameters, viz. isentropic compressibility (κ_s), change in isentropic compressibility (Δκ_s), relative change in isentropic compressibility (Δκ_r), specific acoustic impedance (Z), relative association (RA), and apparent molal compressibility (?) have been estimated. The results have been interpreted in the light of intermolecular interactions between solute and solvent.