The mixtures CH3(CH2)(u-1)COO(CH2)(v-1)CH3 (u = 5-13, v = 1,2; u = 1,2,3; v = 3,4; u = 1,2,4, v = 5) + n-alkane have been investigated on the basis of excess molar functions, enthalpy (H-m(E)), volume (V-m(E)), isobaric heat capacity (C-pm(E)), and isochoric internal energy (U-Vm(E)), and viscosity data, and by means of different models (Flory, Grunberg-Nissan and Bloomfield-Dewan). Solutions are characterized by weak orientational effects. Large structural effects are encountered in a number of systems, such as those containing pentane. The variation with the ester size of the difference between the standard enthalpy of vaporization at 298.15 K of an ester and that of the homomorphic alkane along an homologous series formed by methyl or ethyl n-alkanoates reveals the existence of structural changes in longer n-alkanoates, which lead to stronger interactions between them. A similar result is obtained from values of cohesive energy density. The variation of V-m(E) values of the corresponding heptane mixtures supports this statement. The observed decrease of H-m(E) for systems with a given n-alkane (heptane, e.g.) seems to be more related to the COO group is more sterically hindered than to interactional effects. The U-Vm(E) (n) function (n is the number of C atoms in the n-alkane) shows a minimum for systems with esters characterized by (u >= 4, v = 1); (u >= 7, v = 2), or (u >= 1, v = 4,5). A similar dependence of U-Vm(E) (n) was encountered for n-alkane mixtures involving cyclic molecules (cyclohexane, benzene). This result suggests that certain n-alkanoates, in an alkane medium, can form quasi-cyclic structures. Viscosity data are well described by means of free volume effects only. For systems with butyl ethanoate or methyl decanoate, the variation of Delta eta(n) (deviation of dynamic viscosity) is consistent with that of U-Vm(E)(n), which supports the existence of the mentioned cyclic structures in these esters. The Flory model provides poor results on H-m(E) for systems characterized by large structural effects. Results are improved when the model is applied to U-Vm(E) data.

Excess molar enthalpies, H_m^E, 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, V_m^E, at the same conditions have been also determined using a densimeter Anton Paar model DSA 5000 for the benzylamine + heptane mixture. The H_m^E 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 |V_m^E| values are low, indicating the existence of large structural effects. H_m^E 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 V_m^E 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 H_m^E and with the alcohol size. The different contributions to H_m^E have been evaluated. The systems have been studied using the DISQUAC and ERAS models. ERAS describes correctly the V_m^E function. DISQUAC largely improves ERAS results on H_m^E 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.

(Iodobenzene + n-alkane) liquid mixtures have been studied experimentally, in terms of densities (rho) and speeds of sound (c), 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. rho and c measurements have been performed at a pressure p = 0.1 MPa and in the temperature range T = (288.15 to 308.15) K. Excess molar volumes (VEm) and excess isentropic compressibilities (kappa ES) have been calculated and correlated by Redlich-Kister polynomials. (dVEm/dT)p curves at the same (p, T) conditions have been obtained from correlated VEm values. The mixtures are characterized by the following features: (i) VEm increases with the number of carbon atoms of the n-alkane (n), being negative for n = 7, small and S-shaped with positive and negative values for n = 10, and positive for n = 12 and n = 14; (ii) kappa ES and (dVEm/dT)p are negative, increase with n and are very close to zero for n = 14. From these experimental results and the knowledge of the excess molar enthalpies of mixtures containing fluorobenzene, chlorobenzene or bromobenzene with n-alkanes, we have inferred the presence of structural effects, especially important for n = 7 and less relevant for volumetric properties as n increases. The VEm obtained are compared with those of other (halogenated benzene + n-alkane) liquid mixtures existing in the literature, namely systems with fluorobenzene, chlorobenzene, and bromobenzene. From this comparison and the analysis of the isobaric thermal expansion coefficients of the pure compounds, it is inferred that the interactional effects on VEm do not vary appreciably with the length of the n-alkane, so the observed VEm variation is fundamentally determined by the corresponding variation of the contribution from structural effects. Moreover, the application of the PFP model supports this interpretation, providing free volume contributions to VEm that vary parallelly to VEm with the length of the n-alkane, and interactional contributions that rest approximately constant independently of the n- alkane size.

Excess molar enthalpies, H_m^E, over the whole composition range have been determined for the liquid mixtures N,N-dimethylformamide (DMF) or N,N-dimethylacetamide (DMA) + butan-1-amine (BA), or + hexan-1-amine (HxA), or + N-propylpropan-1-amine (DPA), or N-butylbutan-1-amine (DBA) at 298.15 K and at 0.1 MPa using a BT2.15 calorimeter from Setaram adapted to work in dynamic mode at constant temperature and pressure. All the H_m^E values are positive, indicating that interactions between like molecules are predominant. The replacement of DMF by DMA in systems with a given amine leads to lower H_m^E results, which have been ascribed to stronger amide-amide interactions in DMF mixtures. The replacement of HxA by DPA in systems with a given amide leads to slightly higher H_m^E values, as interactions between unlike molecules are weaker for the latter. Structural effects in the investigated solutions are also present, since the corresponding excess molar volumes (V_m^E), previously determined, are negative or slightly positive. The systems have been characterized in terms of the ERAS model reporting the interaction parameters. The model correctly describes both H_m^E and V_m^E. The application of the model suggests that, in the systems under study, solvation effects are of minor importance and that physical interactions are dominant.

Kinematic viscosities were measured for iodobenzene + n-alkane mixtures at (288.15-308.15) K and atmospheric pressure. The corresponding dynamic viscosities (ri) were also determined using density data previously obtained in our laboratory. This set of data was employed to calculate Delta ri (deviations in absolute viscosity) and quantities of viscous flow. In addition, the correlation equations: McAllister, Grunberg-Nissan, Fang-He, and the Bloomfield-Dewan's model were applied to the systems: iodobenzene, or 1-chloronaphthalene, or 1,2,4-trichlorobenzene, or methyl benzoate or benzene or cyclohexane + n-alkane. It is remarkable that, within the Bloomfield-Dewan's model, residual Gibbs energies were calculated using DISQUAC with interaction parameters available in the literature. From the dependence of UEVm (isochoric molar excess internal energy) and Delta ri with n (the number of C atoms of the n-alkane), it is shown that the loss of fluidization of mixtures containing iodobenzene, 1,2,4-trichlorobenzene, or 1-chloronaphthalene when n increases can be ascribed 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 Delta ri values of benzene mixtures with n = 14,16. The replacement, in this type of systems, of benzene by cyclohexane, leads to increased positive Delta ri values, probably due to the different shape of cyclohexane. On the other hand, binary mixtures formed by an aromatic polar compound mentioned above and a short n-alkane show large structural effects and large negative Delta ri values. From the application of the models, it seems that dispersive interactions are dominant and that size effects are not relevant on ri values. The free volume model provides good results for most of the systems considered, since deviations are less than 6% for 20 mixtures from the 29 solutions under study, and only 4 systems show deviations higher than 10%, with a maximum deviation of 15%. Results improve when, within the BloomfieldDewan's theory, the contribution to ri of the absolute reaction rate model is also considered.

The CH3(CH2)uCOO(CH2)vCH3 + 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 (HmE), volumes (VmE), isobaric heat capacities (CpmE) and isochoric internal energies (UVmE) and by means of the application of the Flory model and the Kirkwood-Buff formalism. The situation of the mixtures within theGmE(excess molar Gibbs energy) vs. HmEdiagram 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.

A differential scanning calorimetric technique has been used to obtain solid–liquid equilibrium temperatures for the mixtures naphthalene or biphenyl + 1-tetradecanol, or + 1-hexadecanol. All the systems show a simple eutectic point, whose final composition was determined by means of the Tamman’s plots using the needed values of the eutectic heat and of the heat of melting, which are also reported. DISQUAC interaction parameters for the OH/aromatic contacts in the selected systems are given. The present experimental SLE phase diagrams are similarly described by DISQUAC and UNIFAC (Dortmund) models. However, the comparison of DISQUAC and UNIFAC results for systems involving naphthalene and shorter 1-alkanols (methanol + 1-octanol) reveals that the temperature dependence of the interaction parameters is more suitable in DISQUAC. The systems are also investigated in terms of the concentration-concentration structure factor. It is shown that the positive deviations from the Raoult’s law of the studied solutions become weaker when the homocoordination decreases.

The systems C6H5Cl, or C6H5Br, 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-Vm(E)) and heat capacities (C-Vm(E)), and using the DISQUAC, and Flory models, and the concentration-concentration structure factor formalism. The position of the mixtures within the G(m)(E) (excess molar Gibbs energy) vs. H-m(E) (excess molar enthalpy) diagram has been also determined. Interactions between C6H5X molecules become stronger in the sequence X = H approximate to F approximate to 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-Vm(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 C6H5Cl or 1-chloronaphthalene. This suggests that larger alkanes are poorer breakers of the interactions between aromatic halogenated compounds. Viscosity and C-Vm(E) data support this conclusion. The parabolic dependence of C-Vm(E) with n indicates that the short orientational order of long n-alkanes is destroyed. Aromacity and proximity effects are discussed. (C) 2022 Elsevier B.V. All rights reserved.

Excess molar enthalpies, H-m(E), have been measured using a Tian-Calvet microcalorimeter for the systems CH3(CH2)(u-1)OH (u = 1,2,3,4,7,10) + cyclohexylamine at 298.15 K and 0.1 MPa. The H-m(E) values are large and negative, indicating the existence of strong interactions between unlike molecules, which is consistent with the also large and negative excess molar volumes, V-m(E) of these solutions, previously measured by us. The contribution from the equation of state term to H-m(E) has been evaluated for the 1-alkanol + cyclo hexylamine, or + 1-hexylamine, or + aniline mixtures, and the corresponding excess molar internal energies at constant volumes, U-m,V(E), determined. It is shown that such contribution is particularly important for the methanol + aniline system, in such way that the excess functions H-m(E) and U-m,V(E) have different sign at x(1) = 0.5. The DISQUAC and ERAS models have been applied to the cyclohexylamine systems, and the interaction parameters reported. DISQUAC improves ERAS results on H-m(E). The latter model describes correctly the V-m(E) curves. The variation of H-m(E) of CH3(CH2)(u-1)OH + cyclohexylamine, or + 1-hexylamine, or + aniline mixtures with u along a homologous series with a given amine, or with the amine in mixtures with a given 1-alkanol is discussed in terms of the different interactional contributions to H-m(E). (C) 2021 Elsevier Ltd.

Densities (rho) and speeds of sound (c) at a temperature T = 298.15 K, relative permittivities at 1 MHz (epsilon(tau)) and refractive indices at the sodium D-line (n(D)) at T (293.15 K to 303.15K), all of them at a pressure p = 0.1 MPa, are reported for binary liquid mixtures alkan-1-ol -- aniline. The alkan-l-ols considered are methanol, propan-1-ol and pentan-1-ol. Also, the values of the excess molar volume (V-m(E)), excess isentropic compressibility (K-S(E)), excess speed of sound (C-E), excess refractive index (n(D)(E)). excess relative permittivity (epsilon(E)(tau)) and its temperature derivative (partial derivative epsilon(E)(r)/partial derivative T)(p), are calculated and fitted to Redlich-Kister polynomials. The agreement among the reported data and other literature sources is analysed by comparing V-m(E), n(D)(E), epsilon(E)(tau) and the deviation of c from mole-fraction linearity (Delta c). The positive excess molar internal energies at constant volume (U-m(E), V) show the dominance of the breaking of interactions between like molecules in the energy balance on mixing, particularly the breaking of strong dipolar interactions between aniline molecules. This contribution is also dominant for the epsilon(E)(tau) values, as they are negative and decrease with the length of the alkan- 1 -ol chain. Calculations on the concentration-concentration structure factor are consistent with these statements, revealing homocoordination in the studied systems. The V-m(E) are negative, which together with the positive U-m,V(E) indicate the existence of important structural effects in the studied mixtures. The application of the Kirkwood-Frohlich model shows that the average relative orientation of neighbouring dipoles is similar in the mixtures methanol + aniline or + pyridine, in spite of the different character of the predominant interactions in the latter mixture (heterocoordination). (C) 2020 Elsevier B.V. All rights reserved.

Fluorobenzene, or 1,4-difluorobenzene or hexafluorobenzene + alkane mixtures and hexafluorobenzene + benzene, or + toluene, or + 1,4-dimethylbenzene systems have been investigated using thermodynamic properties from the literature and through the application of the DISQUAC and UNIFAC (Dortmund) models and the concentration-concentration structure factor (S-CC(0)) formalism. DISQUAC interaction parameters for the contacts F/alkane and F/aromatic have been determined. UNIFAC interaction parameters available in the literature for these contacts have been used along calculations. Both models predict double azeotropy for the C6F6 + C6H6 system, although in different temperature ranges. TheH(m)(E) values 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. This means that no Patterson's effect exists in such mixtures. DISQUAC calculations allow state that such conclusion is still valid for C6F6 + n-alkane mixtures. DISQUAC provides better results than UNIFAC on C-pm(E) of solutions involving n-alkanes, or on H-m(E) of C6F6 + aromatic hydrocarbon systems. Mixtures with alkanes are characterized by interactions between like molecules, which are mainly of dispersive type, which is supported, e.g, by the negative C-pm(E) values of these systems. It is shown that structural effects can contribute largely to H-m(E). This is investigated in terms of the excess molar internal energy at constant volume, U-Vm(E), whose values are determined for the investigated solutions. For mixtures with a given n-alkane, the relative variation of H-m(E) and U-Vm(E) with the fluorohydrocarbons is different.HE mvalues change in the sequence C6F6 > 1,4-C6H4F2 > C6H6 > C6H5F, while U-Vm(E) changes in the order: 1,4-C6H4F2 > C6H6 approximate to C6H5F > C6F6. C6F6 + aromatic hydrocarbon mixtures are characterized by interactions between unlike molecules as it is demonstrated by their negative H-m(E) values. The application of the S-CC(0) formalism reveals that homocoordination is more important in C6F6 + n-alkane mixtures than in the corresponding systems with C6H5F, and that heterocoordination is dominant in the solutions of C6F6 with an aromatic hydrocarbon. (C) 2021 Elsevier B.V. All rights reserved.

Densities, $$\rho$$, and kinematic viscosities, $$\nu$$, have been determined at atmospheric pressure and at 293.15–303.15 K for binary mixtures formed by methanol and one linear polyether of the type CH3–O–(CH2CH2O)n–CH3 (n = 2, 3, 4). Measurements on $$\rho$$ and $$\nu$$ were carried out, respectively, using an Anton Paar DMA 602 vibrating-tube densimeter and an Ubbelohde viscosimeter. The $$\rho$$ values were used to compute excess molar volumes, $$V_{{\text{m}}}^{{\text{E}}}$$, and, together with the $$\nu$$ results, dynamic viscosities ($$\eta$$). Deviations from linear dependence on mole fraction for viscosity, $$\Delta \eta$$, are also provided. Different semi-empirical equations have been employed to correlate viscosity data. Particularly, the equations used are the: Grunberg–Nissan, Hind, Frenkel, Katti–Chaudhri, McAllister and Heric. Calculations show that better results are obtained from the Hind equation. The $$V_{{\text{m}}}^{{\text{E}}}$$ values are large and negative and contrast with the positive excess molar enthalpies, $$H_{{\text{m}}}^{{\text{E}}}$$, available in the literature, for these systems. This indicates that structural effects are dominant. The $$\Delta \eta$$ results are positive and correlate well with the difference in volumes of the mixture compounds, confirming the importance of structural effects. The temperature dependences of $$\eta$$ and of the molar volume have been used to calculate enthalpies, entropies and Gibbs energies, $$\Delta G^{*}$$, of viscous flow. It is demonstrated that $$\Delta G^{*}$$ is essentially determined by enthalpic effects. Methanol + CH3–O–(CH2CH2O)n–CH3 mixtures have been treated in the framework of the ERAS model. Results for $$H_{{\text{m}}}^{{\text{E}}}$$ are acceptable, while the composition dependence of the $$V_{{\text{m}}}^{{\text{E}}}$$ curves is poorly represented. This has been ascribed to the existence of strong dipolar and structural effects in the present solutions.

Systems of the type linear primary or secondary amine + cyclohexane, or + polar compound (namely, linear or cyclic monoether, + 1,4-dioxane, + N,N-dialkylamide, or + ethanitrile) have been investigated using literature data, and by means of DISQUAC. Interaction parameters for the contacts amine/ether, amine/amide and amine/nitrile are provided. For a given contact, the QUAC interchange coefficients remain practically constant along each homologous series. A similar trend has been encountered in other many previous studies. DISQUAC correctly describes excess molar enthalpies, HmE, and vapour-liquid and solid-liquid equilibria of the studied mixtures and improves calculations on HmE from the UNIFAC (Dortmund) model. The experimental data have been used to determine the enthalpy of the interactions between unlike molecules, which are stronger in systems with N,N-dialkylamides or ethanenitrile than in mixtures with ethers. On the other hand, it is shown that HmE values of amine + C6H12 mixtures are closely related to the amine self-association, and that interactions between molecules of the polar compounds are determinant on HmE results of the mixtures amine + fixed polar compound or of the systems fixed amine + polar compound (no linear monoether). Structural effects are relevant in the di-n-butylamine + linear ether systems. The application of the Flory model reveals that orientational effects are rather weak in the investigated solutions. This is in agreement with previous studies on this type of mixtures using the ERAS model.

Mixtures formed by 1-alkanol and one strongly polar compound, nitromethane (NM), ethanenitrile (EtN), dimethyl sulfoxide (DMSO, sulfolane (SULF), nitrobenzene (NTBz) or benzonitrile (BzCN), have been investigated on the basis of a set of thermophysical data, which includes: excess molar functions, enthalpies, H-m(E), Gibbs energies, G(m)(E), entropies, TSmE, isobaric heat capacities, C-pm(E), volumes, V-m(E); liquid-liquid equilibria (LLE), excess permittivies and deviations from the linearity of dynamic viscosities. In addition, calculations have been conducted to determine the Kirkwood-Buff integrals and the Kirkwood correlations factors, g(K), of the investigated mixtures. In the former case, DISQUAC has been employed for modeling the needed vapour-liquid equilibria data. Many systems under consideration are characterized by dipolar interactions between like molecules and have positive values of H-m(E), C-pm(E) and TSmE. On the other hand, alkanol-solvent interactions, for mixtures with a fixed 1-alkanol, become weakened in the sequence: DMSO approximate to SULF > EtN > NM > BzCN > NTBz. In systems with a given solvent, such interactions become also weaker when the chain length of the 1-alkanol is increased. Interestingly, the considered mixtures also show strong structural effects. Results on Kirkwood-Buff integrals reveal that nitriles are more preferred than nitroalkanes around a central alcohol molecule. Calculations on g(K) show that, in terms of the mixture polarization, the systems are rather unstructured, and that this trend becomes more important when the 1-alkanol size increases in solutions with a given solvent. (C) 2019 Elsevier B.V. All rights reserved.

Liquid-liquid equilibria (LLE) phase diagrams have been determined for the systems: 2-ethoxy-benzenamine +octane, or +decane, or +dodecane, or +tetradecane and for 4-ethoxy-benzenamine +heptane, or +octane. The experimental method used is based on the observation, by mean of a laser scattering technique, of the turbidity produced on cooling when a second phase takes place. All the mixtures show an upper critical solution temperature, which increases with the alkane size. Dipolar interactions between like molecules become stronger in the sequence: 2-ethoxy-benzenamine < aniline <4-ethoxy-benzenamine. Data available in the literature suggest that this relative variation is also valid for alkane mixtures containing other substituted anilines or phenols, characterized by having a second polar group. The dependence of the UCST values with the molecular structure of the polar aromatic compound involved is shortly discussed in terms of intramolecular and steric effects. (C) 2018 Elsevier B.V. All rights reserved.

Excess molar enthalpies, H-m(E) , over the whole composition range have been determined for the liquid mixtures N,N-dimethylformamide (DMF) or N,N-dimethylacetamide (DMA) + butan-1-amine (BA), or + hexan-1-amine (HxA), or + N-propylpropan-1-amine (DPA), or N-butylbutan-1-amine (DBA) at 298.15 K and at 0.1 MPa using a BT2.15 calorimeter from Setaram adapted to work in dynamic mode at constant temperature and pressure. All the H-m(E) values are positive, indicating that interactions between like molecules are predominant. The replacement of DMF by DMA in systems with a given amine leads to lower H-m(E) results, which have been ascribed to stronger amide-amide interactions in DMF mixtures. The replacement of HxA by DPA in systems with a given amide leads to slightly higher 4 values, as interactions between unlike molecules are weaker for the latter. Structural effects in the investigated solutions are also present, since the corresponding excess molar volumes (V-m(E)), previously determined, are negative or slightly positive. The systems have been characterized in terms of the ERAS model reporting the interaction parameters. The model correctly describes both H-m(E) and V-m(E) The application of the model suggests that, in the systems under study, solvation effects are of minor importance and that physical interactions are dominant. (C) 2019 Elsevier B.V. All rights reserved.

The liquid-liquid equilibrium (LLE) curves for 2-phenylethan-1-ol (2-phenylethanol, 2PhEtOH) + octane, + decane, + dodecane, + tetradecane or + 2,2,4-trimethylpentane have been determined by a method of turbidimetry using a laser scattering technique. Experimental results reveal that the systems are characterized by an upper critical solution temperature (UCST), which increases linearly with the number of C atoms of the n-alkane. In addition, the LLE curves have a rather horizontal top and become skewed to higher mole fractions of the n-alkane, when its size increases. For a given n-alkane, UCST decreases as follows: phenol > phenylmethanol > 2-PhEtOH, indicating that dipolar interactions decrease in the same sequence. This has been ascribed to a weakening in the same order of the proximity effects between the phenyl and OH groups of the aromatic alkanols. DISQUAC interaction parameters for OH/aliphatic and OH/aromatic contacts in the investigated systems are reported. Phenol, or phenylmethanol or 2-PhEtOH, + n-alkane mixtures only differ by the first dispersive Gibbs energy interaction parameter for the (OH/aliphatic) contact.

Relative permittivities at 1 MHz, εr, 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, εrE, 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 εrE 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 εrE 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.

Interactions and structure of organic carbonate + alkane, and 1-alkanol + organic carbonate mixtures have been investigated by means of a set of molar excess functions, enthalpies (H-m(E)), volumes (V-m(E)), isobaric heat capacities, (C-pm(E)) or entropies; and considering internal pressure (P-int); liquid-liquid equilibria or permittivity data. In addition, the mentioned systems have been studied using the Flory model and the concentration-concentration structure factorS(cc)(0), formalism. The mixtures under consideration are characterized by dipolar interactions and by homocoordination (that is, by interactions between like molecules). In systems with a given solvent, dipolar interactions are weakened in the order: propylene carbonate (PC) > dimethyl carbonate (DMC) > diethyl carbonate (DEC). Comparison of mixtures containing DMC or DEC with those involving 2-propanone or 3-pentanone shows that dipolar interactions are not determined merely by values of the dipole moment, but they also depend on the size group. The enthalpies of the alkanol-carbonate interactions have been evaluated from calorimetric data. They are stronger in DMC solutions, and become weaker when the alcohol size increases in mixtures with a given carbonate. Application of the Flory model to 43 systems of the type 1-alkanol + carbonate provides a mean relative standard deviation for H-m(E) equal to 0.107. Results reveal that orientational effects decrease in the order DEC > PC > DMC. Orientational effects are particularly relevant in methanol or ethanol + DEC mixtures. Interestingly, the mentioned effects are weaker in 1-alkanol + DMC mixtures than in DMC + alkane systems. A similar trend is observed in DEC solutions when the considered alcohol is longer than ethanol. (C) 2017 Elsevier B.V. All rights reserved.