Molecular interaction studies in hydrogen bonded polar binary mixtures

The molecular interactions between the polar systems of propan-1-ol (1PN) with alkyl benzoates (methyl benzoate and ethyl benzoate) for various mole fractions at different temperatures are studied by determining the dielectric permittivity in radio, microwave and optic frequency regions, respectively. Dipole moment, excess dipole moment, excess Helmholtz free energy, excess permittivity, relaxation time, excess inverse relaxation time and excess thermodynamical values are calculated using experimental data. Hamiltonian quantum mechanical calculations are performed on both pure and equimolar binary systems of 1PN with alkyl benzoates for the measurement of dipole moment from the ab initio Hartree–Fock and density functional theory (B3LYP) methods with 6-31?+?G* and 6-311?+?G** basis sets using Spartan 08 modelling software and these theoretical values are in good agreement with the experimental values.     

Investigations on Binary Mixtures of Propan-2-ol with Methyl Benzoate and Ethyl Benzoate

The molecular interactions between the polar systems propan-2-ol with alkyl benzoates (methyl benzoate and ethyl benzoate), for various mole fractions and different temperatures, were studied by determining the dielectric permittivity using a LF impedance analyzer and Abbe’s refractometer in the static and optical frequency regions, respectively. The effective Kirkwood correlation factor, corrective Kirkwood correlation factor, dipole moment, excess dipole moment, and excess Helmholtz free energy were calculated using the experimental data. Hamiltonian quantum mechanical calculations (ab initio and semiempirical) were performed using PC Spartan and Argus lab Modeling software for both pure and equimolar binary systems of propan-2-ol with alkyl benzoates.     

Dielectric and Thermodynamic Studies on the Hydrogen Bonded Binary System of Isopropyl Alcohol and Aniline

The molecular interactions between the polar systems isopropyl alcohol (IPA) and aniline for various mole fractions at different temperatures were studied by determining the dielectric permittivity using an HP-LF impedance analyzer at radio frequencies, the plunger method in the microwave frequency range and Abbe’s refractometer in optical region. Kirkwood effective correlation factors, corrective Kirkwood correlation factors, excess permittivities, Bruggeman parameters, excess Helmholtz free energy, relaxation time, dipole moment and excessive dipole moment were calculated using the experimental data. Optimized geometries were calculated using Spartan Modeling software for both pure and equimolar systems of isopropyl alcohol and aniline for Hamiltonian quantum mechanical calculations. Conformational analysis of the formation of hydrogen bond between the two systems is supported by the FT-IR spectra.     

Static permittivities of ethanol mixtures with isomers of propanol and butanol at temperatures from 288.15 to 308.15 K

The relative permittivities of five binary mixtures of ethanol with propan-2-ol, butan-1-ol, butan-2-ol, 2-methylpropan-1-ol and 2-methylpropan-2-ol are reported for twenty-one mole fractions over the entire concentration range at 288.15, 293.15, 298.15, 303.15 and308.15 K. The excess static permittivity, the permittivity temperature coefficient (?lnε _r/?T) and its excess values were calculated. The excess parameters were fitted to the Redlich–Kister polynomial equation. The results were used in the analysis of hydrogen-bond inter molecular interactions occurring in the alcoholic binary mixtures having different natures of their constituents with varying carbon chain lengths.     

Thermodynamic and acoustical properties of mixtures <Emphasis Type="Italic">p</Emphasis>-anisaldehyde—alkanols (C<Subscript>1</Subscript>–C<Subscript>4</Subscript>)—2-methyl-1-propanol at 303.15 K

The density, viscosity and speed of sound of pure p-anisaldehyde and some alkanols, for example, methanol, ethanol, propan-1-ol, propan-2-ol, butan-1-ol, butan-2-ol, 2-methylpropan-1-ol, and the binary mixtures of p-anisaldehyde with these alkanols were measured over the entire composition range at 303.15 K. From the experimental data, various thermodynamic parameters such as excess molar volume (V^E), excess Gibbs free energy of activation (ΔG*^E), and deviation parameters like viscosity (Δη), speed of sound (Δu), isentropic compressibility (Δκ_s), are calculated. The excess as well as deviation parameters are fitted to Redlich—Kister equation. Additionally, the viscosity data for the systems has been used to correlate the application of empirical relation given by Grunberg and Nissan, Katti and Chaudhari, and Hind et al. The results are discussed in terms of specific interactions present in the mixtures.     

Structure and molecular interactions in {ethanol + (propan-1-ol/propan-2-ol)} mixtures at 303.15 K

In view of industrial importance of binary {ethyl alcohol + (propan-1-ol/propan-2-ol)} mixtures, the densities (ρ) and refractive indices (n _D ) of these alkanols mixtures were measured for different compositions at 303.15 K. Molar volumes (V _m) and excess molar volumes (V ^E) of these binary mixtures were calculated from experimental density data of pure solvents and solvents mixtures. The measured refractive index and density data was used to calculate specific refractions (R _D ), molar refractions (R _M) and apparent molar refractions (R _{φ, i} ) of binary mixtures. From mole fraction dependence of apparent molar refractions, the limiting apparent molar refractions (R _{φ, i} ^○ ) of propan-1-ol and propan-2-ol have been determined. The graphical values of R _{φ, i} ^○ for propan-1-ol and propan-2-ol were found to be 9.5664 and 7.405 cm³ mol^?1 respectively. Structural changes, geometrical fittings and molecular interactions in binary mixtures of these alkanols have been discussed.     

Topological investigations of the molecular species and molecular interactions that characterize pyrrolidin-2-one + lower alkanol mixtures

Molar excess volumes, V^E, molar excess enthalpies, H^E, and speeds of sound data, u, of pyrrolidin-2-one (i) + ethanol or propan-1-ol or propan-2-ol or butan-1-ol (j) binary mixtures have been determined over entire composition range at 308.15 K. The observed speeds of sound data have been utilized to predict excess isentropic compressibilities, of the investigated binary mixtures. The observed excess thermodynamic properties V^E, H^E and have been analyzed in terms of Graph theory. The analysis of V^E data by the Graph theory suggests that pyrrolidin-2-one exists mainly as a mixture of cyclic and open dimer; ethanol as a mixture of dimer and trimer; butan-1-ol and propan-2-ol as mixture of monomer and dimer and propan-1-ol as a dimer in the pure state, and their mixtures contain 1:1 molecular complex. The IR studies lend additional credence to the nature and extent of interactions for the proposed molecular entities in the mixtures. Also, it has been observed that V^E, H^E and values predicted by the Graph theory compare well to with their corresponding experimental values.     

Relative permittivity data of binary mixtures containing 2-butanol, 2-butanone,and cyclohexane

Relative permittivity measurements were made on binary mixtures of (2-butanol + 2-butanone) and (2-butanol or 2-butanone + cyclohexane) for various concentrations at T = (298.2, 308.2, and 318.2) K. Some experimental results are compared with those obtained from theoretical calculations and interpreted in terms of homo- and heterogeneous interactions and structural effects. The molecular dipole moments were determined using Guggenheim–Debye method within the temperature range of (298.2 to 318.2) K. The variations of effective dipole moment and correlation factor, g, with the mole fraction in these materials were investigated using Kirkwood–Frohlich equation. The pure compounds showed a negative and small temperature coefficient of effective dipole moment. In order to obtain valuable information about heterogeneous interaction (interactions between the unlike molecules), the Kirkwood correlation factor, the Bruggeman dielectric factor and the excess permittivity were calculated. In order to predict the permittivity data of polar–apolar binary mixtures, five mixing rules were applied.     

Dielectric data of binary mixtures of 1,2-butanediol with 2-ethyl-1-hexanol and 1,4-dioxane at T = (298.2, 308.2, and 318.2) K

Relative permittivity measurements were made on binary mixtures of (1,2-butanediol + 2-ethyl-1-hexanol) and (1,2-butanediol + 1,4-dioxane) for various concentrations at T = (298.2, 308.2, and 318.2) K. The molecular dipole moments were determined using Guggenheim–Debye method in the temperature range of (298.2 to 318.2) K. The variations of effective dipole moment and correlation factor, g, with the mole fraction in these materials were investigated using Kirkwood–Frohlich equation. The pure compounds showed a negative and small temperature coefficient of effective dipole moment. In order to obtain valuable information about heterogeneous interaction (interactions between the unlike molecules), the Kirkwood correlation factor, the Bruggeman dielectric factor and the excess permittivity were calculated. In addition, in order to predict the permittivity data of polar-apolar binary mixtures, five mixing rules were applied.     

Excess molar enthalpies of formamide + some alkan-1-ols (C1-C6) and their correlations at 298.15 K

Excess molar enthalpies, H^E for the binary systems formamide+methanol, + ethanol, + propan-1-ol, + butan-1-ol, + pentan-1-ol, and + hexan-1-ol have been measured at 298.15 K and atmospheric pressure with a Paar 1455 solution calorimeter. All the system present endothermic events and showed maximum positive H^E values around 0.40-0.50 mole fraction of formamide. The H^E values increases in the order: methanol<ethanol<propan-1-ol<butan-1-ol<pentan-1-ol<hexan-1-ol. Experimental showed insolubility of hexan-1-ol in formamide around x≅0.5 mole fraction of formamide. The excess enthalpies of the above mentioned binary systems, were used to discuss interaction between the alkan-1-ols and formamide molecules. The results are interpreted to gain insight into the changes in molecular association equilibria and structural effects in these systems through O···HO hydrogen bonding. The experimental data have been correlated using Redlich-Kister polynomials. In this research work, the thermodynamics models were also tested: NRTL, Wilson models and their parameters were calculated. The correlation of excess enthalpy data in the systems using NRTL model provides good results.     

Densities, viscosities, and ultrasonic velocity studies of binary mixtures of trichloromethane with methanol, ethanol, propan-1-ol, and butan-1-ol at T = (298.15 and 308.15) K

Densities, viscosities, and ultrasonic velocities of binary mixtures of trichloromethane with methanol, ethanol, propan-1-ol, and butan-1-ol have been measured over the entire range of composition, at (298.15 and 308.15) K and at atmospheric pressure. From the experimental values of density, viscosity, and ultrasonic velocity, the excess molar volumes (V^E), deviations in viscosity (Δη), and deviations in isentropic compressibility (Δκ_s) have been calculated. The excess molar volumes, deviations in viscosity and deviations in isentropic compressibility have been fitted to the Redlich-Kister polynomial equation. The Jouyban-Acree model is used to correlate the experimental values of density, viscosity, and ultrasonic velocity.     

Studies of solvation in homogeneous and heterogeneous media by electronic spectroscopic method

Solvation characteristics in homogenous (pure and mixed binary solvents) and heterogeneous media (aqueous micelles, beta- and gamma-cyclodextrine solutions) have been studied by monitoring the emission characteristics of a newly synthesised dye. The longest wavelength absorption and emission band of the dye arise due to transition between S(0) and S(1) state. The maximum energy of electronic transition involving intramolecular charge transfer is found to be dependent on both the hydrogen-bond donating ability and the polarity-polarisability in pure solvent. The dipole moment in the S(1) state, as determined by solvatochromic procedure, agrees well with the value obtained by theoretical calculation at the AM1 level. Preferential solvation of the dye by alcohols has been found to occur in ethanol+water, propan-1-ol+water, propan-2-ol+water binary mixtures. In aqueous micellar media the dye molecule is located at the water-micelle interface. The binding constant for the dye-micelle interaction has also been determined. The results have been compared with those for a structurally related symmetrical ketocyanine dye.     

Study of intermolecular interactions through dielectric properties of the mixtures consisting of 1,4-butanediol,primary amyl alcohols and 1,4-dioxane at various temperatures

This paper presents relative permittivities, excess permittivities, effective dipole moments, and excess Kirkwood correlation factors of binary mixtures of 1,4-butanediol with two primary pentanol isomers [1-pentanol (amyl alcohol) + 3-methyl-1-butanol (isoamyl alcohol)] from T = (298.15 to 318.15) K at p = 101.3 kPa over the entire composition range. Experimental permittivity values for polar–non-polar binary systems of (1,4-dioxane + amyl alcohol or isoamyl alcohol) were also obtained as a function of composition at the same range of temperatures. The experimental permittivity data were fitted using Redlich–Kister equation to evaluate the adjustable parameters and the standard errors. From the experimental data, the excess parameters were calculated. In this work, variations of effective dipole moment and correlation factor were investigated using Kirkwood−Frohlich equation. The experimental data of measurements were used in the analysis of the homo- and hetero interactions occurring in these binary solutions.     

Densities, Viscosities, Speeds of Sound, FT-IR and 1H-NMR Studies of Binary Mixtures of n-Butyl Acetate with Ethanol, Propan-1-ol, Butan-1-ol and Pentan-1-ol at?298.15, 303.15, 308.15 and 313.15?K

Densities, viscosities and speeds of sound of binary mixtures of ethanol, propan-1-ol, butan-1-ol and pentane-1-ol with n-butyl acetate have been measured over the entire range of composition at temperatures of 298.15, 303.15, 308.15 and 313.15 K and atmospheric pressure. From the experimental densities, viscosities and speeds of sound, the excess molar volumes V ^E, deviations in viscosity ????, and deviations in isentropic compressibility ???? _S have been calculated. The excess molar volumes and deviations in isentropic compressibility are positive for all the binary systems studied over the whole composition, while deviations in viscosities are negative for all of the binary mixtures. The excess molar volumes, deviations in viscosity, and deviations in isentropic compressibility have been fitted to a Redlich?CKister type polynomial equation. FTIR and ¹H-NMR studies of these mixtures are also reported.     

Dipole moments of Flourobenzene and its Mesogenic Derivative in 1,4-Dioxane and 1-Butanol Solutions

Experimental data from dielectric investigations of solutions of flourobenzene (FB) and its mesogenic derivative (1-fluoro-4-(4-pentylcyclohexyl) benzene (FPCHB) in 1,4-dioxane are reported for various mole fractions and temperatures. The molecular dipole moments were determined using the Guggenheim-Debye method in the temperature range of 298.2 to 318.2 K. Both fluorinated compounds show a positive and small temperature coefficient for the effective dipole moment. Variations of the effective dipole moment and correlation factor, g, with mole fraction in these mixtures were investigated using the Kirkwood-Frohlich equation. Dielectric measurements were also carried out on binary mixtures of FPCHB with 1-butanol for various concentrations at 318.2 K. The Kirkwood correlation factor, the Bruggeman factor, and the excess permittivity were determined.     

Thermodynamic,Dielectric and Conformational Studies on Hydrogen Bonded Binary Mixtures of Propan-1-ol with Methyl Benzoate and Ethyl Benzoate

Dielectric relaxation studies of propan-1-ol with alkyl benzoates (methyl benzoate and ethyl benzoate) have been carried out, for various mole fractions, at different temperatures using a LF impedance analyzer, Plunger method, and an Abbe’s refractometer in the radio, microwave and optical frequency regions, respectively. Kirkwood’s effective correlation factor, the corrective Kirkwood correlation factor, Bruggeman parameter, relaxation time, excess inverse relaxation time and thermodynamic parameters were calculated using the experimental data. Conformational analysis of the formation of hydrogen bonds in the equi-molar binary mixtures of propan-1-ol with alkyl benzoates is supported by experimental and theoretical FT-IR values.     

Excess molar enthalpies of R-fenchone + propan-1-ol or +propan-2-ol. Modeling with COSMO-RS and UNIFAC

In this paper, experimental excess molar enthalpies for the binary mixtures of R-fenchone with propan-1-ol or propan-2-ol, at four temperatures (283.15, 298.15, 313.15 and 328.15) K and atmospheric pressure are reported over the entire composition range. They have been fitted to the Redlich–Kister equation at each temperature. Excess molar enthalpies are positive in all cases, being greater for the mixture with propan-2-ol than for the mixture with propan-1-ol. These positive values of the excess enthalpy suggest the predominance of the effect due to hydrogen bond breaking over the interaction between dissimilar molecules in the mixture. Finally UNIFAC (Dortmund) method and the Quantum Continuum Method COSMO-RS have been used to predict the excess molar enthalpies. Better predictions are obtained in the case of UNIFAC model.     

Excess Molar Volumes, Excess Molar Enthalpies and Excess Isentropic Compressibilities of 1-Methyl Pyrrolidin-2-one with Water and Propanols

Excess molar volumes V ^E, excess molar enthalpies H ^E, and speeds of sound u for 1-methyl pyrrolidin-2-one (1) + water or propan-1-ol or propan-2-ol (2) binary mixtures have been measured over the entire composition range (at 308.15 K) using a dilatometer, calorimeter and interferometer. Speeds of sound data, u, of (1 + 2) binary mixtures have been utilized to determine excess isentropic compressibilities, $ \kappa_{S}^{\text{E}} $ . The observed V ^E, H ^E and $ \kappa_{S}^{\text{E}} $ data have been analyzed in terms of (1) Graph theory (which involves the topology of the constituents of mixture), and (2) the Prigogine–Flory–Patterson theory. Analysis of V ^E data in terms of Graph theory suggests that 1-methyl pyrrolidin-2-one, water, propan-1-ol, and propan-2-ol exist as associated molecular entities. IR studies lend additional support to the proposed molecular entities in (1 + 2) mixtures. It has been observed that V ^E, H ^E and $ \kappa_{S}^{\text{E}} $ values predicted by Graph theory compare well with their corresponding experimental values.     

Heteromolecular structures in aqueous solutions of dimethylformamide and tetrahydrofuran,according to molecular dynamics data

The complex dielectric permittivity of aqueous solutions of tetrahydrofuran and dimethylformamide in wide ranges of temperature (220–300 K) and pressure (0.1–12 MPa) is studied by means of molecular dynamics. The autocorrelation functions of the dipole moments of molecules are calculated. Dielectric permittivity spectra are obtained. The dielectric relaxation times are determined as functions of the tetrahydrofuran and dimethylformamide concentrations in the indicated binary mixtures. The dielectric relaxation frequency shifts toward low frequencies in the range of tetrahydrofuran and dimethylformamide concentrations x ≤ 0.5 molar fraction, due to the formation of heteromolecular structures with hydrogen bonds. This is confirmed by the negative values of the excess dielectric permittivities of binary solutions at x ～ 0.3–0.4 molar fraction.     

Investigation of ultrasonic speeds of sound and excess parameters in binary liquid mixtures of N-alkanes with octan-2-ol using different empirical theories at 298.15 K

Ultrasonic velocity, density and percentage deviation in velocity were measured for mixtures of n-alkanes, namely, n-octane, n-decane, n-dodecane and n-tetradecane with octan-2-ol at 298 K. The experimental sound velocity data were compared by using three theoretical relations, namely, Nomoto relation, Vandael ideal mixing relation and Schaaffs collision factor theory to predict which one of them agrees the experimental data. It was observed that Nomoto relation was the best suited method in all the four binary systems. Hence, in the real time applications which are using the above said components can be handled without experimental expenses. The experimental data were used to calculate the interaction parameter (α), adiabatic compressibility (β), intermolecular free length (L_f), excess velocity (U^E), excess impedance (Z^E) and excess volume (V^E) which were discussed to identify the molecular interactions in terms of non-ideality in the binary liquid mixtures. It was observed that the increase of mole fraction of octan-2-ol with different n-alkanes dipole–induced dipole interactions were supported.