arXiv subjects

Isaías García de la Fuente

Publications and source records attributed to Isaías García de la Fuente.

At least 37 records · Page 2Linked to original sources

arXiv2024

Thermodynamics of amide + amine mixtures. 3. Relative permittivities of N,N-dimethylformamide + N-propylpropan-1-amine, + N-butylbutan-1-amine, + butan-1-amine, or + hexan-1-amine systems at several temperatures

Relative permittivities at 1 MHz, $\varepsilon_{\text{r}}$, and at (293.15-303.15) K, are reported for the binary systems N,N-dimethylformamide (DMF) + N-propylpropan-1-amine (DPA), + N-butylbutan-1-amine (DBA), + butan-1-amine (BA) or + hexan-1-amine (HxA). The values of the excess relative permittivities, $\varepsilon_{\text{r}}^{\text{E}}$, have also been determined for these solutions. The measurements were realized by means of a precision impedance analyser 4294A, to which a 16452A cell connected using a 16048G test lead, all of them from Agilent. The $\varepsilon_{\text{r}}^{\text{E}}$ values are large and negative, and diminish when the size of the amine increases along a homologous series, which has been ascribed mainly to the rupture of interactions between like molecules along mixing. Calculations on excess molar orientational polarizabilities support this conclusion, indicating a dominant contribution to $\varepsilon_{\text{r}}^{\text{E}}$ from the orientational polarizability of the molecules in the mixture. The analysis of excess relative Kirkwood correlation factors shows that the correlation between dipoles is effectively decreased along the mixing process.

physics.chem-ph↗

arXiv2024

Thermodynamics of chlorobenzene, or bromobenzene, or 1-chloronaphthalene or 1,2,4-trichlorobenzene + alkane mixtures

The systems C$_6$H$_5$Cl, or C$_6$H$_5$Br, or 1-chloronaphthalene, or 1,2,4-trichlorobenzene, or 1-methylnaphthalene, or 1,2,4-trimethylbenzene + alkane have been investigated by means of the their excess molar properties, including, when the needed data are available, those at constant volume, internal energies ($U_{V\text{m}}^{\text{E}}$) and heat capacities ($C_{V\text{m}}^{\text{E}}$), and using the DISQUAC, and Flory models, and the concentration-concentration structure factor formalism. The position of the mixtures within the $G_{\text{m}}^{\text{E}}$ (excess molar Gibbs energy) vs. $H_{\text{m}}^{\text{E}}$ (excess molar enthalpy) diagram has been also determined. Interactions between C$_6$H$_5$X molecules become stronger in the sequence X = H $\approx$ F $\approx$ Cl < Br. These interactions are weaker than those between 1-chloronaphtahlene or 1,2,4-trichlorobenzene molecules. It is shown that the considered systems have some common features: dispersive interactions are dominant, structural effects for solutions with shorter n-alkanes are large and $U_{V\text{m}}^{\text{E}}$ decreases when the number ($n$) of C atoms of the alkane increases. This variation is held when an n-alkane is replaced by a branched alkane with the same $n$ in systems with C$_6$H$_5$Cl or 1-chloronaphthalene. This suggests that larger alkanes are poorer breakers of the interactions between aromatic halogenated compounds. Viscosity and $C_{V\text{m}}^{\text{E}}$ data support this conclusion. The parabolic dependence of $C_{V\text{m}}^{\text{E}}$ with $n$ indicates that the short orientational order of long n-alkanes is destroyed. Aromaticity and proximity effects are discussed.

physics.chem-ph↗

arXiv2024

Thermodynamics of mixtures containing a fluorinated benzene and a hydrocarbon

Fluorobenzene, or 1,4-difluorobenzene or hexafluorobenzene + alkane mixtures and hexafluorobenzene + benzene, or + toluene, or + 1,4-dimethylbenzene systems have been studied using thermodynamic properties from the literature and through the application of the DISQUAC and UNIFAC (Dortmund) models and the concentration-concentration structure factor ($S_{\text{CC}}(0)$). Interaction parameters for the contacts F/alkane and F/aromatic have been determined for DISQUAC, and they have been taken from the literature for UNIFAC. Both models predict double azeotropy for the C$_6$F$_6$ + C$_6$H$_6$ system, although in different temperature ranges. Excess molar enthalpies ($H_{\text{m}}^{\text{E}}$) of the fluorobenzene, or 1,4-difluorobenzene + n-alkane systems are positive and are accurately described by the models using interaction parameters independent of the n-alkane, discarding Patterson's effect in such mixtures. DISQUAC calculations confirm that conclusion for C$_6$F$_6$ + n-alkane mixtures. DISQUAC provides better results than UNIFAC on excess molar isobaric heat capacities ($C_{p\text{m}}^{\text{E}}$) of solutions involving n-alkanes, or on $H_{\text{m}}^{\text{E}}$ of C$_6$F$_6$ + aromatic hydrocarbon systems. For mixtures with a given n-alkane, the relative variation of excess molar internal energies at constant volume ($U_{V\text{m}}^{\text{E}}$) and $H_{\text{m}}^{\text{E}}$ and with the fluorohydrocarbons is different, due to structural effects. C$_6$F$_6$ + aromatic hydrocarbon mixtures are characterized by interactions between unlike molecules, as seen from their negative $H_{\text{m}}^{\text{E}}$ values. The $S_{\text{CC}}(0)$ formalism reveals that homocoordination is more important in C$_6$F$_6$ + n-alkane mixtures than in the corresponding systems with C$_6$H$_5$F, and that heterocoordination is dominant in the solutions of C$_6$F$_6$ with an aromatic hydrocarbon.

physics.chem-ph↗

arXiv2024

Thermodynamics of mixtures with strongly negative deviations from Raoult's law. XV. Permittivities and refractive indices for 1-alkanol + n-hexylamine systems at (293.15-303.15) K. Application of the Kirkwood-Fröhlich model

Relative permittivities at 1 MHz, $\varepsilon_{\text{r}}$, and refractive indices at the sodium D-line, $n_{\text{D}}$, are reported at 0.1 MPa and at (293.15-303.15) K for the binary systems 1-alkanol + n-hexylamine (HxA). Also, their corresponding excess functions are calculated and correlated. Positive values of the excess permittivities, $\varepsilon_{\text{r}}^{\text{E}}$, are encountered for the methanol system, whereas the remaining mixtures show negative values. This reveals that interactions between unlike molecules contribute positively to $\varepsilon_{\text{r}}^{\text{E}}$. This contribution is dominant for the methanol mixture, while those arising from the breaking of interactions between like molecules are prevalent for the remaining mixtures. At $ϕ_1$ (volume fraction) = 0.5, $\varepsilon_{\text{r}}^{\text{E}}$ changes in the order: methanol > 1-propanol > 1-butanol > 1-pentanol < 1-heptanol. Similar variation with the chain length of the 1-alkanol is observed for mixtures such as 1-alkanol + heptane, or + cyclohexylamine, and can be explained in terms of the lower and weaker self-association of longer 1-alkanols. The effect of the replacement of HxA by cyclohexylamine, or by aniline, is also shown. Calculations on molar refractions indicate that dispersive interactions in the systems under study increase with the length of the 1-alkanol. The mixtures are studied by means of the application of the Kirkwood-Fröhlich model, and the Kirkwood correlation factors, including the corresponding excess values, are reported.

physics.chem-ph↗

arXiv2024

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, $n_{\text{D}}$, have been reported at (293-303.15) K for the N,N-dimethylacetamide (DMA) + CH$_3$CO(CH$_2$)$_{u-1}$CH$_3$ ($u$ = 1, 2, 3) systems, and at 298.15 K for the mixture with $u$ = 5. These data have been used to compute excess molar volumes, $V_{\text{m}}^{\text{E}}$, excess adiabatic compressibilities, $κ_S^{\text{E}}$, and excess speeds of sound $c^{\text{E}}$. Negative $V_{\text{m}}^{\text{E}}$ values indicate the existence of structural effects and interactions between unlike molecules. From excess molar enthalpies, $H_{\text{m}}^{\text{E}}$, 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 to $H_{\text{m}}^{\text{E}}$ and are more relevant in mixtures containing NMP. The application of the Flory's model reveals that the random mixing hypothesis is valid to a large extent for DMF solutions, while NMP systems are characterized by rather strong orientational effects. From values of molar refraction and of the product $P_{\text{int}} V_{\text{m}}$ (where $P_{\text{int}}$ is the internal pressure and $V_{\text{m}}$ 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.

physics.chem-ph↗

arXiv2024

Orientational effects in alkanone, alkanal or dialkyl carbonate + alkane mixtures and in alkanone + alkanone or + dialkyl carbonate systems

Interactions and structure of alkanone, or alkanal or dialkyl carbonate + alkane mixtures, or of 2-alkanone+ 2-alkanone, or of ketone + dialkyl carbonate systems have been investigated by means of a set of thermodynamic properties and by the application of the Flory model. The properties considered are excess molar quantities: enthalpies, $H_{\text{m}}^{\text{E}}$, volumes, $V_{\text{m}}^{\text{E}}$, or isobaric heat capacities, $C_{p \text{m}}^{\text{E}}$, and liquid-liquid equilibria. Experimental data show that alkane mixtures are characterized by rather strong dipolar interactions. In the case of systems containing ketones with the same number of C atoms and a given alkane, dipolar interactions become weaker in the sequence: aromatic > cyclic > linear. In addition, the mentioned interactions become also weaker in the order: dialkyl carbonate > linear alkanone > linear alkanal. This is an important result, as carbonates show lower effective dipole moments than the other compounds, and it suggests that the group size may be relevant when evaluating thermodynamic properties of liquid mixtures. Results on $H_{\text{m}}^{\text{E}}$ from the Flory model show that orientational effects (i.e., non-random mixing) are rather similar for systems with linear, cyclic or aromatic ketones or alkanals and alkanes. In contrast, orientational effects become weaker in dialkyl carbonate + alkane mixtures. The behaviour of 2-alkanone + 2-alkanone systems and of mixtures of longer 2-alkanones or cyclohexanone with dialkyl carbonate is close to random mixing. Larger orientational effects are encountered in solutions of carbonates and shorter 2-alkanones.

physics.chem-ph↗

arXiv2024

Orientational and steric effects in linear alkanoates + N-Alkane mixtures

The CH$_3$(CH$_2$)$_u$COO(CH$_3$)$_v$CH$_3$ + n-alkane mixtures have been investigated on the basis of an experimental database containing effective dipole moments of esters, and excess molar functions of the systems: enthalpies ($H_{\text{m}}^{\text{E}}$), volumes ($V_{\text{m}}^{\text{E}}$), isobaric heat capacities ($C_{p\text{m}}^{\text{E}}$) and isochoric internal energies ($U_{V\text{m}}^{\text{E}}$) and by means of the application of the Flory model and the Kirkwood-Buff formalism. The situation of the mixtures within the $G_{\text{m}}^{\text{E}}$ (excess molar Gibbs energy) vs. $H_{\text{m}}^{\text{E}}$ diagram has also been briefly considered. Results indicate that dispersive interactions are dominant and that steric effects can explain some differences between solutions containing heptane and isomeric esters. Proximity and orientational effects are also discussed in diester + hexane mixtures. In the case of systems with a given alkane and different isomeric polar compounds, orientational effects become weaker in the order: n-alkanone > dialkyl carbonate > n-alkanoate. Results from the Kirkwood-Buff formalism indicate that the number of ester-ester interactions decreases in systems with alkyl ethanoates when the alkyl size increases and that preferential solvation between polar molecules decreases as follows: dialkyl carbonate > n-alkanone > n-alkanoate.

physics.chem-ph↗

arXiv2024

Density and speed of sound of (iodobenzene + n-alkane) liquid mixtures at $T$ = (288.15 to 308.15) K. Application of the Prigogine-Flory-Patterson model

(Iodobenzene + n-alkane) liquid mixtures have been studied experimentally, in terms of densities and speeds of sound at a pressure $p$ = 0.1 MPa and in the temperature range $T$ = (288.15 to 308.15) K, and theoretically, by the application of the Prigogine-Flory-Patterson (PFP) model. The n-alkanes considered are n-heptane, n-decane, n-dodecane, and n-tetradecane. Excess molar volumes ($V_{\text{m}}^{\text{E}}$) and excess isentropic compressibilities ($κ_S^{\text{E}}$) have been calculated and correlated by Redlich-Kister polynomials. ${(\partial{V_{\text{m}}^{\text{E}}}/\partial T)}_p$ curves at the same (p,T) conditions have been obtained from correlated $V_{\text{m}}^{\text{E}}$ values. From these experimental results and the knowledge of the excess molar enthalpies and volumes of mixtures containing fluorobenzene, chlorobenzene or bromobenzene with n-alkanes, we have inferred: (i) the presence of structural effects, especially important for the n-heptane mixture and less relevant for volumetric properties as the length of the n-alkane increases; and (ii) that the interactional effects on $V_{\text{m}}^{\text{E}}$ do not vary appreciably with the length of the n-alkane, so the observed $V_{\text{m}}^{\text{E}}$ variation is fundamentally determined by the corresponding variation of the contribution from structural effects. The application of the PFP model supports this interpretation, providing free volume contributions to $V_{\text{m}}^{\text{E}}$ that vary parallelly to $V_{\text{m}}^{\text{E}}$ with the length of the n-alkane, and interactional contributions that rest approximately constant independently of the n-alkane size.

physics.chem-ph↗

arXiv2024

Thermodynamics of 2-alkanol + polar organic solvent mixtures. I. Systems with ketones, ethers or organic carbonates

The mixtures 2-propanol or 2-butanol + n-alkanone, or + acetophenone or + linear monoether, or + cyclic ether, or + linear organic carbonate, or + propylene carbonate have been investigated using thermodynamic data, and in terms of the Flory theory, and the Kirkwood-Buff integrals. The data considered are: excess molar enthalpies ($H_{\text{m}}^{\text{E}}$), volumes, entropies, and the temperature dependence of $H_{\text{m}}^{\text{E}}$. The enthalpy of the 2-alkanol-solvent interactions have been determined, and the different contributions to $H_{\text{m}}^{\text{E}}$ are discussed. It is shown that $H_{\text{m}}^{\text{E}}$ values of the 2-alkanol (fixed) + n-alkanone, or + linear carbonate mixtures change in the same manner that for n-alkanone, or linear carbonate + n-alkane (fixed) systems. In contrast, $H_{\text{m}}^{\text{E}}$ values of 2-alkanol (fixed) + linear monoether or + n-alkane mixtures change similarly. This set of results suggests that solvent-solvent interactions are determinant in systems with n-alkanone or linear carbonate, while interactions between alcohol molecules are determinant in mixtures with linear monoethers. According to the Flory model, orientational effects in systems with a given 2-alkanol become weaker in the sequence: linear monoether > linear organic carbonate > n-alkanone, and are stronger in solutions with a cyclic monoether than in those with cyclic diethers, and in systems with acetophenone or propylene carbonate than in the mixtures with the corresponding linear solvents. Results obtained from the Kirkwood-Buff integrals are consistent with these findings. The application of Flory model reveals that orientational effects are similar in systems with 1- or 2-alkanols, with the exception of solutions with linear monoethers, where such effects are stronger in mixtures containing 1-alkanols.

physics.chem-ph↗

arXiv2024

Viscosities of iodobenzene + n-alkane mixtures at (288.15-308.15) K. Measurements and results from models

Kinematic viscosities were measured for iodobenzene + n-alkane mixtures at (288.15-308.15) K and atmospheric pressure. Using our previous density data, dynamic viscosities ($η$), deviations in absolute viscosity ($Δη$) and quantities of viscous flow were determined. The McAllister, Grunberg-Nissan and Fang-He correlation equations and Bloomfield-Dewan's model (with residual Gibbs energies calculated using DISQUAC with interaction parameters available in the literature) were applied to iodobenzene, or 1-chloronaphthalene, or 1,2,4-trichlorobenzene, or methyl benzoate or benzene or cyclohexane + n-alkane systems. The dependence of $U_{\text{m,}V}^{\text{E}}$ (isochoric molar excess internal energy) and $Δη$ with $n$ (the number of C atoms of the n-alkane) shows that the fluidization loss of mixtures containing iodobenzene, 1,2,4-trichlorobenzene, or 1-chloronaphthalene when $n$ increases is due to a decrease upon mixing of the number of broken interactions between like molecules. The breaking of correlations of molecular orientations characteristic of longer n-alkanes may explain the decreased negative $Δη$ values of benzene mixtures with $n$ =14,16. The replacement, in this type of systems of benzene by cyclohexane leads to increased positive $Δη$ values, probably due to the different shape of cyclohexane. On the other hand, binary mixtures formed by one of the aromatic polar compounds mentioned above and a short n-alkane show large structural effects and large negative $Δη$ values. From the application of the models, it seems that dispersive interactions are dominant and that size effects are not relevant on $η$ values. The free volume model provides good results for most of the systems considered. Results improve when, within Bloomfield-Dewan's theory, the contribution to $η$ of the absolute reaction rate model is also considered.

physics.chem-ph↗

arXiv2024

Liquid-Liquid Equilibria for Systems Containing 4-Phenylbutan-2-one or Benzyl Ethanoate and Selected Alkanes

Liquid-liquid equilibrium (LLE) phase diagrams have been determined, by means of the critical opalescence method with a laser scattering technique, for the mixtures 4-phenylbutan-2-one + CH$_3$(CH$_2$)$_n$CH$_3$ ($n = 10,12,14$) and for benzyl ethanoate + CH$_3$(CH$_2$)$_n$CH$_3$ ($n = 12,14$). The systems are characterized by having an upper critical solution temperature (UCST), which increases with n. The corresponding LLE curves show a rather horizontal top and become skewed toward higher mole fractions of the polar compound when n is increased. Calorimetric and LLE measurements show that, for mixtures with molecules with a given functional group, interactions between aromatic molecules are stronger than those between homomorphic linear molecules (aromaticity effect). This has been ascribed to proximity effects arising from the presence of the polar group and the aromatic ring within the same molecule. Proximity effects become weaker in the sequence 1-phenylpropan-2-one > 4-phenylbutan-2-one > 1-phenylethanone and are more important in benzyl ethanoate than in ethyl benzoate molecules. Values of the critical compositions and temperatures calculated with the DISQUAC group contribution model are in good agreement with the experimental results. Accordingly, the shape of the LLE curves is also correctly described by DISQUAC.

physics.chem-ph↗

arXiv2024

Thermodynamics of Amide + Amine Mixtures. 2. Volumetric, Speed of Sound and Refractive Index Data for N,N-Dimethylacetamide +N-Propylpropan-1-Amine, +N-Butylbutan-1-Amine, +Butan-1-Amine, or +Hexan-1-Amine Systems at Several Temperatures

Data on density, $ρ$, speed of sound, $c$, and refractive index, $n_{\text{D}}$, of binary systems containing N,N-dimethylacetamide (DMA) + N-propylpropan-1-amine (DPA) or + butan-1-amine (BA) at 293.15 K, 298.15 K and 303.15 K, and + N-butylbutan-1-amine (DBA) or + hexan-1-amine (HxA) at 298.15 K are reported. A densimeter and sound analyzer Anton Paar DSA 5000 has been used for the measurement of $ρ$ and $c$, whereas $n_{\text{D}}$ values have been obtained by means of a refractometer RFM970 from Bellingham+Stanley. Also, values of excess molar volumes, $V_{\text{m}}^{\text{E}}$, excess isentropic compressibilities, $κ_S^{\text{E}}$, excess speeds of sound, $c^{\text{E}}$, excess isobaric thermal expansion coefficients, $α_p^{\text{E}}$, and of excess refractive indices, $n_{\text{D}}^{\text{E}}$, have been determined from these data. The investigated systems are characterized by amide-amine interactions and structural effects, as it is shown by their negative or low positive $V_{\text{m}}^{\text{E}}$ values and by the results from the application of the Prigogine-Flory-Patterson (PFP) model. The breaking of amine-amine interactions is more relevant in systems containing linear primary amines than in those with linear secondary amines, and the $V_{\text{m}}^{\text{E}}$ values are lower for the latter systems. Molar refraction has been used to evaluate the dispersive interactions in the mixtures under study, yielding the result that DPA and HxA systems present similar dispersive interactions and mainly differ in their dipolar character. Steric hindrance of the amide group in DMA leads to weaker amide-amine interactions than in the corresponding N,N-dimethylformamide (DMF) + amine systems.

physics.chem-ph↗

arXiv2024

Thermodynamics of amide + ketone mixtures. 1. Volumetric, speed of sound and refractive index data for N,N-dimethylformamide + 2-alkanone systems at several temperatures

Densities, $ρ$, speeds of sound, $c$, and refractive indices, $n_{\text{D}}$, have been measured for the systems N,N-dimethylformamide (DMF) + propanone, + 2-butanone, or + 2-pentanone in the temperature ($T$) range from 293.15 to 303.15 K and at 298.15 K for the DMF + 2-heptanone mixture. Due to the high volatility of acetone, the corresponding $n_{\text{D}}$ measurements were developed at 293.15 K and 298.15 K. The direct experimental data were used to determine the excess molar volumes, $V_{\text{m}}^{\text{E}}$, and the excess refractive indices, $n_{\text{D}}^{\text{E}}$, at the working $T$. Values of the excess functions at 298.15 K, for the speed of sound, $c^{\text{E}}$, the isentropic compressibility, $κ_S^{\text{E}}$ and for the excess thermal expansion coefficient, $α_p^{\text{E}}$, were also calculated. The investigated systems are characterized by strong amide-ketone interactions, which become weaker when the alkanone size is increased. This is supported by negative $V_{\text{m}}^{\text{E}}$ values; by the dependence on $T$ and pressure of $V_{\text{m}}^{\text{E}}$, and by positive $P_{\text{int}}^{\text{E}}$ (excess internal pressure) values. Analysis of the systems in terms of the Rao's constant indicates that there is no complex formation. In addition, negative $V_{\text{m}}^{\text{E}}$ values also reveal the existence of structural effects, which largely contribute to the excess molar enthalpy, $H_{\text{m}}^{\text{E}}$. $V_{\text{m}}^{\text{E}}$ and $H_{\text{m}}^{\text{E}}$ values increase with the chain length of the 2-alkanone. It allows to conclude that the relative $V_{\text{m}}^{\text{E}}$ variation with the ketone size is closely related to that of the interactional contribution to this excess function. Molar refraction values, $R_{\text{m}}$, show that dispersive interactions become more relevant for the systems including longer 2-alkanones.

physics.chem-ph↗

arXiv2024

Thermodynamics of Amide + Amine Mixtures. 1. Volumetric, Speed of Sound, and Refractive Index Data for N,N-Dimethylformamide +N-Propylpropan-1-amine, +N-Butylbutan-1-amine, +Butan-1-amine, or +Hexan-1-amine Systems at Several Temperatures

Values of density ($ρ$), speed of sound ($c$) and refractive index ($n_{\text{D}}$) for N,N-dimethylformamide (DMF) + N-propylpropan-1-amine (DPA) or + butan-1-amine (BA) mixtures at (293.15-303.15) K, and for DMF + N-butylbutan-1-amine (DBA) or hexan-1-amine (HxA) mixtures at 298.15 K are reported. $ρ$ and $c$ measurements were conducted using a vibrating-tube densimeter and sound analyzer, Anton Paar model DSA5000; $n_{\text{D}}$ values were obtained by means of a RFM970 refractometer from Bellingham+Stanley. The experimental $ρ$, $c$ and $n_{\text{D}}$ values have been used to determine excess molar volumes, $V_{\text{m}}^{\text{E}}$, excess adiabatic compressibilities, $κ_S^{\text{E}}$, excess speeds of sound, $c^{\text{E}}$, excess thermal expansion coefficients, $α_p^{\text{E}}$, and excess refractive indices, $n_{\text{D}}^{\text{E}}$. This set of data shows the existence of interactions between unlike molecules and of structural effects in the mixtures under study. $V_{\text{m}}^{\text{E}}$ values of solutions including linear secondary amines are lower than those of mixtures with linear primary amines. In fact, the contribution to $V_{\text{m}}^{\text{E}}$ from the breaking of amine-amine interactions is larger for the latter systems. Calculations on Rao's constant point out that there is no complex formation between the mixture components. Dispersive interactions have been analyzed by means of the molar refraction. It is shown that solutions with DPA or HxA are characterized by similar dispersive interactions and that they mainly differ in dipolar interactions.

physics.chem-ph↗

arXiv2024

Thermodynamics of mixtures containing a very strongly polar compound. 11. 1-Alkanol + alkanenitrile systems

1-Alkanol + alkanenitrile systems have been studied by means of the DISQUAC, ERAS and UNIFAC (Dortmund) models. DISQUAC and ERAS parameters for the alkanol/nitrile interactions are reported. DISQUAC describes a whole set of thermodynamic properties: phase equilibria, vapour-liquid (VLE), liquid-liquid (LLE) and solid-liquid (SLE) equilibria, molar excess functions, Gibbs energies, $G_{\text{m}}^{\text{E}}$, and enthalpies, $H_{\text{m}}^{\text{E}}$, and partial excess molar enthalpies at infinite dilution, $H_{\text{mi}}^{\text{E,}\infty }$ using the same set of interaction parameters for each solution. The dependence on the molecular structure of the interaction parameters is similar to that observed in other previous applications to mixtures formed by 1-alkanols and a strongly polar compound, in such way that the quasichemical interchange coefficients can be kept constant from 1-propanol. However, methanol and ethanol solutions behave differently. From the analysis of experimental data for $H_{\text{m}}^{\text{E}}$, $TS_{\text{m}}^{\text{E}}(=H_{\text{m}}^{\text{E}}-G_{\text{m}}^{\text{E}})$, and molar excess volumes, $V_{\text{m}}^{\text{E}}$, it is concluded that the studied systems are characterized by dipolar interactions and strong structural effects. The former are more relevant in acetonitrile solutions. Association effects are more important in butanenitrile mixtures. DISQUAC improves $H_{\text{m}}^{\text{E}}$ results from the ERAS model. ERAS results on $H_{\text{m}}^{\text{E}}$ for systems containing acetonitrile are also improved by UNIFAC. This remarks the importance of dipolar interactions in the investigated mixtures. ERAS describes the variation of $V_{\text{m}}^{\text{E}}$(${{x}_{1}}$=0.5) with the 1-alkanol size for mixtures with a given nitrile, but the concentration dependence of this excess function is poorly represented.

physics.chem-ph↗

arXiv2024

Thermodynamics of ketone + amine mixtures: Part II. Volumetric and speed of sound data at (293.15, 298.15 and 303.15) K for 2-propanone + dipropylamine, + dibutylamine or + triethylamine systems

Densities, $ρ$ , and speeds of sound, $u$, of 2-propanone + dipropylamine,+ dibutylamine or + triethylamine systems have been measured at (293.15, 298.15 and 303.15) K and atmospheric pressure using a vibrating tube densimeter and sound analyser Anton Paar model DSA-5000. The $ρ$ and $u$ values were used to calculate excess molar volumes, $V^{E}$, and the excess functions at 298.15 K for the thermal expansion coefficient, $α_{p}^{E}$, and for the isentropic compressibility, $κ_{S}^{E}$ at 298.15 K. $V^{E}$, $κ_{S}^{E}$ and $α_{p}^{E}$ are positive magnitudes. When replacing dipropylamine by dibutylamine or triethylamine in the studied mixtures, the excess functions increase. This may be ascribed to the interactions between unlike molecules are more important in the former solutions. From the comparison with similar data obtained for 2-propanone + aniline, + N-methylaniline, or + pyridine systems, it is concluded that interactions between unlike molecules are stronger in mixtures containing aromatic amines. Free volume effects are present in solutions with dipropyl or dibutylamine as the $V^{E}$ curves are shifted towards higher mole fractions of 2-propanone.

physics.chem-ph↗

arXiv2024

Dielectric and refractive index measurements for the systems 1-pentanol + octane, or + dibutyl ether or for dibutyl ether + octane at different temperatures

Relative permittivities, $\varepsilon_{r}$, and refractive indixes, $n_{D}$, have been measured at (288.15-308.15) K and (293.15-303.15) K, respectively, for the mixtures 1-pentanol + octane, or + dibutyl ether and dibutyl ether + octane. These data have been used, together with density measurements available in the literature, to determine the correlation factor, $g_{K}$, for the studied systems according to the Kirkwood-Fröhlich equations. Results show that the existence of cyclic species of 1-pentanol are predominant at low concentrations of this alkanol when is mixed with octane. These species are broken in large extent by the more active molecules of oxaalkane in the dibutyl ether mixtures, which is in agreement with calorimetric data. The dibutyl ether + octane system does not show meaningful structure. These conclusions are confirmed by values of the molar polarization and by the temperature dependence of $\varepsilon_{r}$. The empirical expressions of Lorentz-Lorenz, Wiener, Heller, Gladstone-Dale and Newton correlate well the $n_{D}$ data.

physics.chem-ph↗

arXiv2024

Dielectric and refractive index measurements for the systems 1-pentanol + 2,5,8,11,14-pentaoxapentadecane, or for 2,5,8,11,14-pentaoxapentadecane + octane at (293.15-303.15) K

Relative permittivities, $\varepsilon_{r}$, and refractive indices, $n_{D}$, have been measured at (293.15-303.15) K, for the mixtures 1-pentanol + 2,5,8,11,14-pentaoxapentadecane (TEGDME) or TEGDME + octane. These data have been used, together with density measurements available in the literature, to calculate the correlation factors, $g_{K}$, according to the Kirkwood-Fröhlich equations. The curves of the deviations of from the ideal behaviour, $Δ\varepsilon_{r}$, of the 1-pentanol + TEGDME system are shifted to high mole fractions of the alcohol, and show a rather large minimum. The shape of the $Δ\varepsilon_{r}$ curves of methanol + TEGDME or + polyethylene glycol dimethyl ether 250 (PEG-250) mixtures is similar. This reveals that polyethers can break the alcohol self-association even at high alkanol concentrations. The higher $Δ\varepsilon_{r}$ values of the methanol solutions are ascribed to large self-association of this alcohol. The $Δ\varepsilon_{r}$ curves of the 1-pentanol + dibutyl ether (DBE) system are nearly symmetrical, and the $Δ\varepsilon_{r}$ values are higher than those of the corresponding TEGDME mixture. This indicates that effects related to the alcohol self-association are much more relevant in the DBE system. These findings are supported by $g_{K}$ and molar polarization data. Values of molar refraction of 1-pentanol systems reveal that dispersion forces become more important in the sequence: octane < DBE < TEGDME. Such forces are also more relevant in the 1-pentanol + TEGDME system than in the methanol + TEGDME solution. The comparison of $\varepsilon_{r}$ and $g_{K}$ data for TEGDME or DBE + octane mixtures shows than the polyether is a more structured liquid.

physics.chem-ph↗