Density, speed of sound, refractive index and relative permittivity of methanol, propan-1-ol or pentan-1-ol + benzylamine liquid mixtures. Application of the Kirkwood-Fröhlich model

Producción CientíficaDensities (P), speeds of sound (c), relative permittivities at 1 MHz (er) and refractive indices at the sodium D-line (nD) at T = (293.15 K to 303.15 K) and p = 0.1 MPa are reported for binary liquid mixtures alkan-1- ol + benzylamine. Methanol, propan-1-ol and pentan-1-ol are the alkan-1-ols studied in this work. The values of the excess molar volume (VE m), excess isentropic compressibility (jE S ), excess speed of sound (cE), excess refractive index (nE D), excess relative permittivity (eE r ) and its temperature derivative ð@eE r =@TÞp are calculated, and they are adjusted to Redlich-Kister polynomials. The VE m values are negative, indicating a predominance of the solvation between unlike molecules and structural effects. eE r values indicate a positive contribution from the creation of (alkan-1-ol)-benzylamine interactions, and the pos- itive value for the methanol mixture emphasises the importance of solvation. Calculations on excess molar refractions point out to weaker dispersive interactions than in the ideal mixture, which may be explained by the mentioned solvation effects. The Kirkwood-Fröhlich model has been applied to the mix- tures, and the Kirkwood correlation factors suggest an important relative weight, especially in the metha- nol system, of linear-like molecules in the solutions, which is in accordance with the positive contribution of the formed multimers to eE r due to their good effective response to the electric field.Junta de Castilla y León, ( Consejería de Educación - Apoyo a GIR, BDNS: 425389) Project VA100G19Ministerio de Educación, Cultura y Deporte ( grant FPU15/05456

Thermodynamics of amide + amine mixtures. 4. Relative permittivities of N,N-dimethylacetamide + N-propylpropan-1-amine, + N-butylbutan-1-amine, + butan-1-amine, or + hexan-1-amine systems and of N,N-dimethylformamide + aniline mixture at several temperatures. Characterization of amine + amide systems using ERAS

Producción CientíficaRelative permittivities at 1 MHz and at (293.15-303.15) K are reported for the binary systems N,N-dimethylacetamide (DMA) + N-propylpropan-1-amine (DPA), + N-butylbutan-1-amine (DBA), + butan-1-amine (BA) or + hexan-1-amine (HxA) and for N,N-dimethylformamide (DMF) + aniline. The excess permittivities are large and negative for systems with DMA, whereas they are large and positive for the aniline mixture. From the analysis of these excess permittivity data and of measurements previously reported, it is concluded: (i) the main contribution to the excess permittivity in systems with linear amines arises from the breaking of interactions between like molecules; (ii) in the DMF + aniline mixture, interactions between unlike molecules contribute positively to the excess permittivity, and such a contribution is dominant; (iii) longer linear amines are better breakers of the amide-amide interactions; (iv) interactions between unlike molecules are more easily formed when shorter linear amines, or DMF, participate. These findings are confirmed by a general study conducted in terms of excess values of molar orientational and induced polarizabilities and of the relative Kirkwood correlation factors for systems and components. The ERAS model is also applied to amide + amine mixtures. ERAS represents rather accurately the excess enthalpies and volumes of the mentioned systems. The variation of the cross-association equilibrium constants, determined using ERAS, with the molecular structure is in agreement with that observed for the excess permittivity.The authors gratefully acknowledge the financial support received from the Consejería de Educación y Cultura of Junta de Castilla y León, under Project BU034U16. F. Hevia and A. Cobos are grateful to Ministerio de Educación, Cultura y Deporte for the grants FPU14/04104 and FPU15/05456 respectively

Thermodynamics of amide + amine mixtures. 5. Excess molar enthalpies of N,N-dimethylformamide or N,N-dimethylacetamide + N-propylpropan-1-amine, + N-butylbutan-1-amine, + butan-1-amine, or + hexan-1-amine systems at 298.15 K. Application of the ERAS model

Producción CientíficaExcess molar enthalpies, HEm, 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 HEm 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 HEm 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 HEm 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 (VEm), 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 HEm and VEm. The application of the model suggests that, in the systems under study, solvation effects are of minor importance and that physical interactions are dominant.Consejería de Educación, Junta de Castilla y León: Project VA100G19 (Apoyo a GIR, BDNS: 425389)Ministerio de Educación, Cultura y Deporte (MECD): Grant FPU14/04104Ministerio de Educación, Cultura y Deporte (MECD): Complementary Grants EST16/00824 and EST17/0029

Thermodynamics of mixtures with strongly negative deviations from Raoult's law. XVII. Permittivities and refractive indices for alkan-1-ol + N,N-diethylethanamine systems at (293.15–303.15) K. Application of the Kirkwood-Fröhlich model

Producción CientíficaRelative permittivities at 1 MHz, epsilon(r), at 0.1 MPa and (293.15–303.15) K and refractive indices, nD, at similar conditions have been measured for the alkan-1-ol (methanol, propan-1-ol, butan-1-ol, pentan-1-ol or heptan-1-ol) + N,N-diethylethanamine (TEA) systems. Positive values of the excess permittivities, epsilon(r)E, are encountered for the methanol system at high alcohol concentrations. The remaining mixtures are characterized by negative epsilon(r)E values over the whole composition range. At fi1 (volume fraction) = 0.5, epsilon(r)E changes in the order: methanol > propan-1-ol > butan-1-ol < pentan-1-ol < heptan-1-ol. Mixtures formed by alkan-1-ol and an isomeric amine, hexan-1-amine (HxA) or N-propylpropan-1-amine (DPA) or cyclohexylamine, behave similarly. This has been explained in terms of the lower and weaker self-association of longer alkan-1-ols. From the permittivity data, it is shown that: (i) (alkan-1-ol)-TEA interactions contribute positively to epsilon(r)E; (ii) TEA is an effective breaker of the network of the alkan-1-ols; (iii) structural effects, which are very important for the volumetric and calorimetric data of alkan-1-ol + TEA systems, are also relevant when evaluating dielectric data. This is confirmed by the comparison of epsilon(r)E measurements for alkan-1-ol + aliphatic amine mixtures; (iv) the aromaticity effect (i.e., the replacement of TEA by pyridine in systems with a given alkan-1-ol) leads to an increase of the mixture polarization. Calculations conducted in the framework of the Kirkwood-Fröhlich model are consistent with the previous statements.Consejería de Educación, Junta de Castilla y León: Project VA100G19 (Apoyo a GIR, BDNS: 425389)Ministerio de Educación, Cultura y Deporte (MECD): Grants FPU14/04104 and FPU15/0545