VmE Values Research Articles

Physicochemical properties, theoretical modelling and molecular interaction analysis in ternary liquid mixtures containing 1-propanol, 1,3-diaminopropane and ethyl acetate at temperature 298.15–318.15 K

In the present report, density (ρ), viscosity (η), speed of sound (u) and refractive index (nD) of ternary liquid mixture containing 1-propanol (1P) (1) + 1,3-diaminopropane (1,3-DAP) (2) + ethyl acetate (EAc) (3) were measured at five different temperatures (T = 298.15 to 318.15 K) and at 0.1 MPa pressure. Data of ρ, η, u and nD were used to compute the excess molar volume, VmE, deviation in viscosity, Δη, deviation in ultrasonic speed, Δu, excess isentropic compressibility, ksE, excess free volume, VfE, excess intermolecular free length, LfE, excess available volume, VaE, and deviation in refractive index, ΔnD, and these computed physicochemical properties were fitted to Singh equation. The VmE data were fitted to the Nagata and Cibulka equations. Further, Kohler model, Tsao-Smith model, Radojkovic model, Jacob-Fitzner model and Rastogi model were used to calculate the VmE values. The speed of sound data was analyzed by various correlations such as Van Dael, Nomato, Impedance dependence, Schaaff’s collision factor theory (CFT) and Jacobson’s free length theory (JFLT). Various correlations like Heller, Arago-Biot, Lorentz-Lorenz, Erying, Newton, Gladstone-Dale, and Weiner were used to correlate nD data.

Experimental analysis of volumetric, acoustic, viscometric and optical properties of water with 1-amino-2-propanol, 1,2-diaminopropane and 1,3-diaminopropane at T=298.15 -318.15 K: Molecular Modelling by Graph, PFP and IR spectroscopy investigations

BackgroundLiquid mixtures are used as a solvent in most of the natural systems and chemical processes. Therefore, the physicochemical properties of liquid mixtures at different compositions and at different temperatures have a significant role in the optimization of chemical processes. The present report involves the analysis of the thermophysical properties of water (1) and amines (2). MethodsDensity, ρ, dynamic viscosity, η, refractive index, nD, and speed of sound, u, data were measured for binary mixtures of water (1) and amines (1A2P (1-amino-2-propanol), 1,2-DAP (1,2-diaminopropane) and 1,3-DAP (1,3-diaminopropane) (2) at five different temperatures (T = 298.15 to 318.15 K) and at 0.1 MPa pressure. Based on experimental data, the excess molar volume, VmE, deviation in dynamic viscosity, Δη, excess Gibbs free energy of activation, G*E, deviation in refractive index, ΔnD, excess ultrasonic speed, uE, excess isentropic compressibility, KsE, deviation in free volume, ΔVf, excess available volume, VaE, and excess intermolecular free length, LfE, were calculated and these evaluated properties were fitted to Redlich-Kister polynomial (R.K.). The VmE data was analyzed by Prigogine-Flory-Patterson (PFP) theory. The dynamic viscosity, η, values were studied by different correlations. The VmE and Δη data were also analyzed by Graph theoretical approach (GTA). Raman and FT-IR spectroscopic studies give important information about the intermolecular interactions present between unlike molecules water (1) and amines (2) which is also recognized by GTA. Significant findingsThe value of VmE and KsE values were found negative over the whole composition range, and it follow the sequence as: 1,2-DAP > 1,3-DAP > 1A2P with water at equimolar composition. GTA and PFP well supported the VmE data. GTA studies help in investigating the specific intermolecular interactions between unlike components. Further, Graph theory studies predicted OH—–NH interaction is dominant interaction among all interactions which were also supported by Raman and FTIR spectroscopic studies.

Thermodynamic and molecular simulation analysis of molecular interactions between methyl 2–hydroxyisobutyrate + water or n–alkanol (C1–C2) mixtures

Methyl 2–hydroxyisobutyrate (HBM) is essential as a photoresist thinner in semiconductor fabrication. In this study, we examined the density and viscosity of HBM combined with water or alkanol (C1–C2) at a pressure of 0.1 MPa and temperatures ranging from 288.15 K to 323.15 K. Based on experimental data, we calculated the excess molar volume, as well as apparent, partial, and excess partial molar volumes, and deviations in viscosity. These derived thermodynamic properties were then modeled using the Redlich-Kister (RK) polynomial equation. The VmE values of HBM + water mixtures are more negative compared to HBM + alkanol mixtures because of the stronger H–bonding interactions in HBM–water than in HBM–alkanol. With increasing temperature, the VmEbecome more negative, whereas the Δη values lower with a temperature rise. The values for excess molar volume and deviation in viscosity were analyzed through a graph theoretical method. Additionally, the excess free energy of activation was determined from the viscosity data. FTIR spectral analysis validated the findings related to intermolecular interactions and the graph theoretical method. Lastly, molecular dynamics simulations shed light on the intermolecular interaction energies and their differences in the studied binary systems.

Study of Excess Molar Volumes of the Binary Mixture of 1-Hexanol and Benzene at 303.15 K Temperature

The densities, ρ of pure 1-Hexanol, Benzene and their binary mixture covering the whole composition range have been measured at 303.15 K temperature. Excess molar volumes VmE, partial molar volumes, Vi have been calculated from the ρ data. To obtain correlation coefficients and standard deviations VmE was fitted to Redlich–Kister type function in terms of mole fraction. In the whole range of composition the values of VmE were found to be positive. The positive values of VmE were shown due to depolymerization of the network structures and disrupt their H-bonding and resulting into volume expansion.

Molecular interaction in the binary mixtures of tetrahydrofuran and 1,4-dioxane with methanol. New UNIFAC-VISCO interaction parameters for cyclic ethers

Densities (ρ), viscosities (η), and refractive indices (nD) have been measured for binary organic systems of methanol (MeOH) with tetrahydrofuran (THF) and 1,4-dioxane (DXN) over the entire range of composition, and at different temperatures between 298.15 and 318.15 K. From the data of ρ, η, and nD, properties such as excess molar volume, VmE, thermal expansivity, α, excess thermal expansivity, αE, deviation in viscosity, Δη, free energy for the activation of viscous flow, ΔG≠, and its excess, ΔG≠E, and deviation in refractive index, ΔnD, were derived. Measured ρ, η, and nD were correlated with the concentration-dependent polynomial equations, and their excess properties were fitted with Redlich-Kister type equations. Temperature-dependent Jouyban-Acree model was also used to correlate the experimental ρ and η. Negative values of VmE and Δη, and ΔG≠E lead to reveal that the effect of cross hydrogen bonding plays a significant role in both the systems of THF + MeOH and DXN + MeOH. Finally, six new pairs of group–group interaction parameters, αnm, were determined for these cyclic ethers, which can be utilized in extending further the applicability of UNIFAC-VISCO model.

Physicochemical and acoustic characterization of binary mixtures of tetraalkylammonium bromide: PEG based DES and water

In modern green chemistry, Deep eutectic solvents (DESs) have gain appreciable recognition as an analogues of ionic liquids (ILs) due to inexpensive and easy to handle preparation method. DESs exhibit similar physiochemical properties to ILs and considered as a suitable alternative to volatile organic solvents. In present study, DESs were formulated by complexing HBA: Tetraethylammonium bromide and Tetrapropylammonium bromide and HBD: Polyethylene glycol of average molecular weight (200/400/600) in 1:2 M ratio. The densities (ρ), speeds of sound (u) of pure DESs and their binary mixtures with H2O were collected as a function of DES concentration and temperature. The excess molar properties: VmE and Ks,mE were calculated using these data and fitted to the Redlich-Kister equation to estimate standard deviation between the experimental and calculated values of excess molar properties. The trends of variation in calculated values of VmE and Ks,mE were interpreted in light of temperature and DES: H2O interactions occurring within the binary mixtures. The PFPT (Prigogine-Flory-Patterson Theory) and ERAS (Extended Real Associated Solution Model) were applied to evaluate the validity of theories to predict VmE for presently studied binary mixtures.

Volumetric, Optical, and Spectroscopic Study of Molecular Interactions for Binary Liquid Mixtures of Gamma-Valerolactone with 2-Alkoxyethanols

Physical parameters such as densities, ρ, and refractive indices, nD, of pure gamma-valerolactone/2-alkoxyethanols and their binaries have been determined over the whole composition range at different temperatures (298.15, 303.15, 308.15, and 313.15 K) and pressure = 0.1 MPa. From the experimental results, excess properties such as excess molar volumes, VmE, deviations in refractive indices, ΔϕnD, and deviations in molar refractions, ΔϕRM, have been calculated. The predicted data were fitted to the Redlich–Kister-type polynomial equation to derive the binary interaction parameters and recognize standard deviations between experimental and calculated values of the liquid solutions. Furthermore, the partial molar volumes, V¯m,1, V¯m,2, and excess partial molar volumes, V¯m,1E, V¯m,2E, were also computed. The Prigogine–Flory–Patterson theory and Graph theory were employed to correlate experimental VmE values. The departure of real mixtures from ideal behavior was interpreted in terms of strength and nature of molecular interactions. Furthermore, Fourier-transform infrared spectroscopy studies of the investigated solution along with pure components were also reported to obtain a better insight into intermolecular interactions between unlike molecules. In our study, positive values of VmE and negative values of ΔϕnD were observed, which suggests weak dispersion forces between dissimilar molecules.

Thermodynamics of mixtures containing amines. XVII. [formula omitted] and [formula omitted] measurements for benzylamine + heptane or + 1-alkanol mixtures at 298.15 K. Application of the DISQUAC and ERAS models

Excess molar enthalpies, HmE, at 298.15 K and 0.1 MPa have been measured by means of a Tian-Calvet microcalorimeter for the systems benzylamine (phenylmethanamine) + heptane, or + methanol, or + 1-propanol, or + 1-pentanol, or + 1-heptanol, or + 1-decanol. In addition, excess molar volumes, VmE, at the same conditions have been also determined using a densimeter Anton Paar model DSA 5000 for the benzylamine + heptane mixture. The HmE of this solution is large and positive since at 298.15 K the system temperature is close to its upper critical solution temperature. Thus, systems with n-alkanes show positive deviations from the Raoult's law. The measured |VmE| values are low, indicating the existence of large structural effects. HmE values of mixtures involving 1-alkanols are large and negative. That is, interactions between unlike molecules are dominant and the systems are characterized by negative deviations from Raoult's law. It is shown that the enthalpy of the hydrogen bonding between molecules of 1-alkanol and benzyalmine are more negative than those between 1-alkanol molecules. The VmE values of the systems with 1-alkanols are also large and negative, and are determined mainly by interactional effects since they increase in line with HmE and with the alcohol size. The different contributions to HmE have been evaluated. The systems have been studied using the DISQUAC and ERAS models. ERAS describes correctly the VmE function. DISQUAC largely improves ERAS results on HmE or on excess molar heat capacities at constant pressure for the mixtures with 1-alkanols, which underlines that physical interactions are very relevant in such solutions.

Excess molar enthalpies, excess molar volumes and refractive index of binary liquids mixtures of 2,2′-aminodiethanol with propan-2-ol, butan-1-ol and butan-2-ol at various temperatures and ambient pressure (81.5 kPa)

Excess molar enthalpies, HmE , excess molar volumes, VmE , and refractive index deviations, ΔnD , over the whole composition range have been determined for binary liquid mixtures of 2,2′-aminodiethanol (DEA) + propan-2-ol, or + butan-1-ol, or + butan-2-ol at, T = (303.15) K for excess molar enthalpy, T = (303.15 to 343.15) K for excess molar volume, T = (298.15) K for refractive index and at ambient pressure (81.5 kPa).All the HmE values were positive, indicating that interactions between like molecules are stronger than unlike molecules. All the VmE values were negative, show that the total volume of the mixture before mixing is higher than the total volume of mixture after mixing. Refractive index deviations values were positive; represent mixture after mixing is denser than pure components. Excess or derived properties have been correlated using the Redlich–Kister polynomial equation. The obtained results were qualitatively interpreted in terms of steric hindrance and molecular interactions between the mixing components.

Density, viscosity, surface tension, excess property and alkyl chain length for 1,4-butanediol (1) + 1,2-propanediamine (2) mixtures

The density (ρ), viscosity (η), and surface tension (γ) of 1,4-butanediol (BDO) (1) + 1,2-propanediamine (PDA) (2) binary system were measured under local atmospheric pressure (88.8 kPa) and at T = (293.15 to 318.15) K. The excess properties of the BDO (1) + PDA (2) binary system were calculated by the basic density and viscosity data. The values of VmE, Δη, and ΔG*E values were fitted with the Redlich-Kister (R-K) equation and evaluated the standard deviations (σ) between the experimental and theoretical values. Meanwhile, UV-Vis, FTIR, FLS and 1H-NMR were used to infer that the form of intermolecular hydrogen bond was -CH2O-H···N(H2)-. In addition, the influence of alkyl chain on the physicochemical properties of the mixture, such as excess molar volume and viscosity deviation, was studied.

Investigation on thermophysical properties of binary systems of [C4mim][NTf2] with cyclic ethers: Application of PFP and ERAS theories

Room temperature ionic liquids (RTILs) have been researched as a novel substitute for volatile organic solvents since their inception two decades ago. The high viscosity and cost of pure ILs are major constrains for their industrial application which can be overcome by the addition of small amount of organic solvent. The introduction of organic solvents in pure ILs makes noticeable alteration in thermophysical properties of pure IL through variations in the molecular interactions. This manuscript deals with the excess molar volumes VmE, excess molar isentropic compressibilities Ks,mE and logarithm of viscosities lnηm for binary systems of 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C4mim][NTf2]) with two cyclic ethers: tetrahydrofuran (THF) and 1,4 dioxane (DIO), at entire mole fraction range of IL and temperature between 298.15 K to 323.15 K. The VmE, Ks,mE and lnηm were calculated from the experimental values of densities, ρ, speeds of sound, u, and viscosities, η, respectively. The Redlich-Kister polynomial equation was utilized to obtain fitting parameters for VmE, Ks,mE and lnηm. The values of VmE, Ks,mEand lnηm were negative. The negative deviation from ideality was ascribed to efficient packing and presence of strong-ion dipole interactions in the binary systems. The negative deviation was more pronounced in binary system of [C4mim][NTf2] + THF than [C4mim][NTf2] + DIO. The values of lnηm decrease with rise in the temperature for both systems. The Prigogine-Flory-Patterson (PFP) theory and Extended Real Association Solution Model (ERAS) were employed to correlate experimental VmE.

Experimental and theoretical excess molar properties of aqueous choline chloride based deep eutectic solvents

Deep eutectic solvents (DESs), an alternative to ionic liquids and conventional molecular organic solvents have attracted scientific attention because of their unique physico-chemical properties that can be tuned judiciously. These physico-chemical properties are altered if water, the most eco-friendly solvent is present as an impurity or as a cosolvent. The peculiar effect of water on the thermodynamic properties of DESs composed of choline chloride (CH) as an hydrogen bond acceptor (HBA) and ethylene glycol (EG), glycerol (GLY) and 1,4-butanediol (BD) as hydrogen bond donors (HBD) in the ratio of 1:2 are reported here. Densities of the aqueous solutions of CH:EG, CH:GLY and CH:BD were measured over the entire range of composition and temperature ranges from 293.15 K to 323.15 K at atmospheric pressure. Intermolecular interactions responsible for the negative excess molar volumes VmE for all the mixtures studied have been discussed. The non-ideal behavior of the studied mixtures have been evaluated through comparing the values of VmE with the Prigogine−Flory−Patterson (PFP) theory and extended real associated solution model (ERAS). These results will be further utilized in industrial processes as well as in the thermodynamic modeling of DES based systems.

Batch investigation on volumetric, acoustic and calorimetric properties for binary mixtures of aniline + (diethanolamine, triethanolamine, butylamine and hexylamine) from experimental and theoretical point of view

Density and speed of sound for binary systems of diethanolamine (DEA), triethanolamine (TEA), butylamine (BUT) and hexylamine (HEX) in aniline (ANL) were measured at temperature ranges of (303.15–318.15) K. From the measured experimental data, excess molar volume, VmE and deviation in isentropic compressibility, ∆kS were calculated. Excess molar enthalpy HmE was also calculated for the above mentioned systems at 303.15 K only. The values of VmE and HmE were negative for all systems in the whole composition range. The results were analyzed to discuss the effect of the alkyl chain length, the orientation and number of the OH groups and the structural deformation of the molecules in the face of unlike molecules. The values of VmE, ∆kS and HmE were correlated by Redlich ̶ Kister polynomial equation. The obtained values were used to evaluate the nature and type of intermolecular interaction in multicomponent mixtures. The experimental excess molar enthalpy data have been correlated with two thermodynamics models Wilson and NRTL. Theoretical calculations were also performed using the ab initio method to validate the data in which the associated molecular interactions were compared and discussed. The agreement between theoretical and experimental data was acceptable for all studied systems.

Theoretical and experimental study of 1-butyl-3-methylimidazolium nitrate with 1-pentanol, 1-hexanol and 1-heptanol: COSMO-RS and structure factor

In this paper, some thermodynamic and structural properties of the binary mixtures containing [Bmim][NO3] and 1-alkanols (1-pentanol, 1-hexanol, and 1-heptanol) was studied using theoretical and experimental methods. Density and viscosity for the mixtures above were measured at temperatures (293.15 K to 323.15 K), and values of excess molar volumes, VmE and viscosity deviations Δη were calculated. For binary mixtures of [Bmim][NO3] with 1-octanol, 1-nonanol, and 1-decanol a miscibility gap was observed in the mole fraction regions between 0.1 and 0.9. Findings indicate that strong interactions occur in the binary solutions containing short-range 1-alkanol, and increasing the length of the alcohol causes the weakening of the intermolecular interactions. To obtain more information about the molecular structure of aforesaid mixtures, the conductor-like screening model for real solutions (COSMO-RS) method was applied, and the D parameter, the concentration-concentration structure factor, Scc(0), and the chemical short-range order parameter α′, were calculated for the binary mixtures.

Physicochemical and thermodynamic properties of pyrrolidinium-based ionic liquids and their binary mixtures with carboxylic acids

Two oxopyrrolidinium-based ionic liquids (ILs) with different functional groups namely, epoxypropane and dihydroxy propane in cation, were synthesized in this work. Propanoic acid and butanoic acid were mixed with the synthesized ILs to create a series of binary liquid mixtures with various mole fractions. The physicochemical properties of density (ρ) and speed of sound (u) of the binary systems were measured in the range of 0.1–1.0 mol fraction at temperatures from 293.15 to 313.15 K at a 5 K interval under atmospheric pressure (p = 101 kPa). Based on these experimental data, the excess molar volume, (VmE), isentropic compressibility, (ks), deviation in isentropic compressibility (∆ks) and intermolecular free length (Lf) were then calculated. Furthermore, the interactions such as H-bond, ionic interaction, dipole-dipole interactions and weak van der Waals interactions among the IL and carboxylic acid were inferred through the experimental and derived data. These interactions appear to play a major role in determining the potential usefulness of these IL-acid binary systems. The negative values of VmE and ∆ks may be indicative of strong interactions between IL and acid. A long carbon chain of acid appears to enhance the interaction strength that could be attributed to the increase in viscosity of systems due to the longer alkyl chain and big size of acid. The derived thermodynamic properties, including VmE, ∆ks and Lf were fitted in Redlich-Kister polynomial equation and standard deviation.

Acoustic and volumetric study of renewable oxygenated fuel additives at (298.15–323.15) K: Isomeric butanediols with ethylbutyrate

Today biofuels are emerging in an exponentially manner in order to replace the fossil fuels. Biofuels are composed of several organic compounds containing wide variety of functional groups. The interactions existing among these compounds play a significant role in the efficiency of the biofuels. In this paper, the authors presented the new findings related to interactions existing in ethylbutyrate and α, ω-alkanediols in pure state as well as in their mixtures. Densities and speeds of sound at various temperatures (298.15–323.15) K and at ambient pressure 0.1 MPa have been measured for these mixtures. From experimental data, the excess properties such as excess molar volume, VmE, excess isentropic compressibility, κsE, excess molar isentropic compressibility, Ks,mE, excess speed of sound, uE, and excess isobaric thermal expansion, αpE, of the investigated mixtures were calculated. All the excess parameter values were fitted using the Redlich-Kister polynomial smoothing equation. The results were analysed in terms of molecular interactions. The partial molar volumes, V¯m,1 and V¯m,2, partial molar isentropic compressibilities, K¯s,m,1 and K¯s,m,2, excess partial molar volumes, V¯m,1E and V¯m,2E and excess partial molar isentropic compressibilities, K¯s,m,1E and K¯s,m,2E over whole composition range; the excess partial molar quantities of the components at infinite dilution have been calculated. The variations of these parameters with change in composition and temperature have been discussed in terms of intermolecular interactions prevailing in these mixtures. The VmE values for these mixtures were also calculated by using Prigogine–Flory–Patterson (PFP) theory and the results were compared with experimental findings.

Molecular interactions in the binary mixtures of some monoalkanolamines with acetonitrile between 303.15 and 323.15

Densities, ρ, and refractive indices, nD for the binary systems of acetonitrile (ACN) + monoethanolamine (MEA), + monomethylethanolamine (MMEA), and + monoethylethanolamine (MEEA) have been measured in the whole range of composition and at different temperatures from T = (303.15 to 323.15) K for ρ, and at T = 303.15 for nD. Excess molar volumes, VmE, partial molar volumes, V¯i, thermal expansivities, α, and excess thermal expansivities, αE, were calculated from the experimental ρ. From measured nD at 303.15 K deviations in refractive index, ΔnD, and excess molar refractions, RmE, for these mixtures have also been evaluated. Values of VmE, αE, and RmE were found to be almost negative within the studied range of temperature. For each system the values of ρ, α, and nD were correlated to appropriate polynomials, whereas those of VmE, αE, ΔnD, and RmE were fitted to the Redlich-Kister type equations. Moreover, temperature dependent Jouyban-Acree model also showed satisfactory correlation with experimental ρ values for all the systems. Though intermolecular interactions of various types are to influence the variation patterns of VmE, V¯i, αE, and RmEvs. composition for these systems, it has been suggested that those due to cross H-bonding and interstitial accommodation effect have to play the significant roles.

Volumetric and acoustic properties of fuel additive oxygenate with hydrocarbons

Densities and speed of sound for the binary mixture of diisopropyl ether (DIPE) (1)+toluene, n-octane (2) and toluene (1)+n-hexane, n-heptane, n-octane (2) and n-hexane, n-heptane (1)+n-octane (2) were measured from 298.15K to 318.15K. The measured data were used to calculate excess molar volume VmE, deviation in ultrasonic speed Δu, excess isentropic compressibility KsE, excess intermolecular free length LfE and excess available volume VaE. For theoretical interpretation of VmE values, Prigogine-Flory-Patterson theory and Graph theory were applied at 298.15K. Ultrasonic speed data were predicted at 298.15K using various empirical correlations like Nomoto, Van Dael, Impedance dependence and also by Schaaff's collision factor theory. The temperature effect on KsE and VmE was also discussed. The results were analyzed in the light of unlike interactions, packing effect, cohesion forces and change in orientation order.

Thermodynamic and acoustic properties of binary mixtures of diisopropyl ether, benzene and alkanes at 298.15, 308.15 and 318.15 K: Prigogine-Flory-Patterson theory and graph theory

Densities and speed of sound for the binary mixtures of diisopropyl ether (1) + n‑hexane, n‑heptane, benzene (2) and benzene (1) + n‑hexane, n‑heptane, n‑octane (2) and n‑hexane (1) + n‑heptane (2) were measured from 298.15 K to 318.15 K. The measured data were used to calculate excess molar volume VmE, deviation in ultrasonic speed Δu, isentropic compressibility KsE, excess intermolecular free length LfE and excess available volume VaE. All the derived properties were fitted to Redlich-Kister equation. For theoretical interpretation of VmE values, Prigogine-Flory-Patterson theory and Graph theory were used at 298.15 K. Various empirical correlations like Nomoto, Van-Dael and impedance dependence relation were applied to predict the experimental ultrasonic speed data. Schaaff's collision factor theory was used for prediction of experimental ultrasonic speed data at 298.15 K. The excess intermolecular length (LfE) was calculated from Jacobson free length theory at 298.15 K. The effect of temperature for KsE and VmE was also discussed in terms of intermolecular interactions.

Thermodynamics of amide + ketone mixtures. 2. Volumetric, speed of sound and refractive index data for N,N-dimethylacetamide + 2-alkanone systems at several temperatures. Application of Flory's model to tertiary amide + n-alkanone systems

Data on density, ρ, speed of sound, c, and refractive index, nD, have been reported at (293–303.15) K for the N,N-dimethylacetamide (DMA)+CH3CO(CH2)u−1CH3 (u=1, 2, 3) systems, and at 298.15K for the mixture with u=5. These data have been used to compute excess molar volumes, VmE, excess adiabatic compressibilities, κSE, and excess speeds of sound cE. Negative VmE values indicate the existence of structural effects and interactions between unlike molecules. From molar excess enthalpies, HmE, available in the literature for N,N-dimethylformamide (DMF), or N-methylpyrrolidone (NMP)+n-alkanone systems, it is shown: (i) amide-ketone interactions are stronger in DMF systems than in those with NMP; (ii) they become weaker when u increases in mixtures with a given amide. Structural effects largely contribute toHmE and are more relevant in mixtures containing NMP. The application of the Flory's model reveals that the random mixing hypothesis is valid in large extent for DMF solutions, while NMP systems are characterized by rather strong orientational effects. From values of molar refraction and of the product PintVm (where Pint is the internal pressure and Vm the molar volume), it is concluded that dispersive interactions increase with u, or when DMF is replaced by DMA in mixtures with a fixed ketone.