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
Graphical abstract
Highlights
► ɛr and nD have been measured at (293.15–303.15) K for 1-pentanol + TEGDME or TEGDME + n-C8. ► Correlation factors have been calculated according to the Kirkwood–Fröhlich equations. ► Polyethers can break alcohol self-association at high alkanol concentrations. ► Effects due to alcohol self-association are much relevant in systems with monoethers. ► Conclusions are supported by gK and molar polarization data.
Introduction
1-Alkanol + ether mixtures are of high interest from both practical and theoretical points of view. For example, mixtures containing oxygenated compounds, such as ethers and/or alkanols are of great importance because they are increasingly used as additives to gasoline owing to their octane-enhancing and pollution-reducing properties [1], [2]. Polyethers are important solvents in many chemical reactions such as Grignard reduction, or alkylation or organo-metallic reactions [3]. On the other hand, in a series of recent articles [4], [5], [6], [7], we have shown some crucial features of 1-alkanol + ether systems. A short summary follows. (i) Effects related to self-association of 1-alkanols are determinant when considering the thermodynamic properties of mixtures with linear monoethers. (ii) Such effects are weakened if a linear monoether is replaced by a cyclic monoether, in such way that, from 1-hexanol, 1-alkanol + tetrahydrofuran, or +tetrahydropyran mixtures show a structure close to that of random mixing. (iii) The replacement of a linear monoether by a linear polyether also leads to a weakening of the mentioned effects relative to self-association of 1-alkanols, while dipolar interactions are increased. These results have been obtained from measurements on phase equilibria, molar excess enthalpies, molar excess heat capacities at constant pressure or from volumetric measurements and from the application of different theories such ERAS [8], DISQUAC [9], Flory [10], or the Kirkwood–Buff integrals formalism [11]. The investigation of the mixture structure can be also carried out on the basis of ɛr, and nD, data. These magnitudes together with density data make possible the determination of the Kirkwood's correlation factor, gK [12], [13], [14], [15], which provides useful information on the mixture structure. As a part of a general systematic study in which liquid solutions are investigated using gK, we report here ɛr and nD measurements for the mixtures 1-pentanol + TEGDME, or TEGDME + octane at (293.15–303.15) K. Previously, we have investigated 1-pentanol + DBE, or +octane mixtures, or the DBE + octane system [16]. ɛr and nD data at different temperatures for the methanol + TEGDME, or +PEG-250 systems [17], [18], [19], or for glyme + alkane mixtures [20], [21], [22] are available in the literature.
Section snippets
Materials
1-Pentanol, octane and TEGDME were supplied by Fluka, and used without further purification. Their purity in mass fractions was ≥0.99; ≥0.99 and ≥0.98, respectively. Values of the physical properties of pure compounds, density, ρ (measured with an Anton Paar DMA 602 vibrating-tube densimeter (uncertainty 5 g cm−3), thermostated within ±0.01 K); ɛr, and nD are listed in Table 1. They are in good agreement with the literature values (Table 1).
Apparatus and procedures
Binary mixtures were prepared by mass in small flasks of
Results
Table 2 lists, in the temperature range (293.15–303.15) K, values of ɛr and of deviations of this magnitude from the ideal state, Δɛr, vs. x1, the mole fraction of the first component for 1-pentanol + TEGDME or for TEGDME + octane systems. For an ideal mixture at the same temperature and pressure than the system under study, the values are calculated from the equation [22]:where ϕi = xiVi/Vid. Deviations from the ideal behaviour are calculated from the expression:
Discussion
Inspection of the Δɛr curves allows state some interesting features. (i) The curves of the 1-pentanol + TEGDME system are skewed to high x1 values, and show a rather large minimum (Fig. 1). This indicates that the polyether is a very active breaker of the alcohol structure, in such way that the total number of parallel aligned effective dipoles of 1-pentanol, that contribute to the dielectric polarization of the system, decreases upon mixing [26]. A similar behaviour is observed for methanol +
Conclusions
The properties ɛr and nD have been measured at (293.15–303.15) K for the systems 1-pentanol + TEGDME, or TEGMDE + octane. Values of Δɛr and gK for 1-alkanol + TEGDME, or +PEG-250 show that polyethers can break the alcohol structure even at high alcohol concentrations, and that DBE is a less active compound when breaking the alcohol self-association. This is supported by Pm values and by the temperature dependence of ɛr. Rm values of 1-pentanol systems reveal that dispersion forces become more
Acknowledgements
The authors gratefully acknowledge the financial support received from the Ministerio de Ciencia e Innovación, under the Project FIS2010-16957. V.A. acknowledges the grant financed jointly by the Junta de Castilla y León and Fondo Social Europeo.
References (60)
- et al.
Thermodynamics of 1-alkanol + cyclic ether mixtures
Fluid Phase Equilib.
(2006) - et al.
Application of the Kirkwood–Buff formalismo to CH3(CH2)n−1OH + polyether mixtures for n = 1, 2, 3
Thermochim. Acta
(2011) - et al.
Dielectric constants and apparent dipole moments of (butan-1-ol or butan-2-ol + cyclohexane) at 298.15 and 318.15 K and of (2-methylpropan-2-ol + cyclohexane) at 299.15 and 318.15 K
J. Chem. Thermodyn.
(1988) - et al.
Dielectric and refractive index measurements for the systems 1-pentanol + octane, or +dibutyl ether or for dibutyl ether + octane at different temperatures
Thermochim. Acta
(2012) - et al.
Relative permittivity increments for the binary mixture (methanol + polyethylene glycol dimethyl ether 250) at several temperatures from 283.15 K to 323.15 K
J. Chem. Thermodyn.
(2002) - et al.
Relative permittivity increments for {xCH3OH + (1 − x) CH3OCH2(CH2OCH2)3CH2OCH3} from T = 283.15 K to 323.15 K
J. Chem. Thermodyn.
(2001) - et al.
Changes of refractive index on mixing for the binary mixtures {xCH3OH + (1 − x) CH3OCH2(CH2OCH2)3CH2 OCH3} and {xCH3OH + (1 − x) CH3OCH2(CH2OCH2)nCH2OCH3} (n = 3–9) at temperatures from 293.15 K to 333.15 K
J. Chem. Thermodyn.
(1998) - et al.
Permittivity and density of the systems (monoglyme, diglyme, triglyme or tetraglyme + n-heptane) at several temperatures
J. Chem. Thermodyn.
(2011) - et al.
On the permittivity of the systems {tetraglyme + (n-nonane or n-dodecane)} at various temperatures
J. Chem. Thermodyn.
(2006) - et al.
Study of static permittivity and hydrogen bonded structures in amide-alcohol mixed solvents
Thermochim. Acta
(2010)
Densities and viscosities of the binary mixtures of interest for absortion refrigeration systems and heat pumps
Fluid Phase Equilib.
Speeds of sound, densities, isentropic compressibilities of the system (methanol + polyethylene glycol dimethyl ether 250) at temperatures from 293.15 to 333.15 K
J. Chem. Thermodyn.
Molar excess enthalpies at T = 298.15 K for (1-alkanol + dibutylether) systems
J. Chem. Thermodyn.
Heat capacities of {xCnH2n+1OH + (1 − x) C7H16} for n = 1 to 6 at 298.15 K
J. Chem. Thermodyn.
Thermochemical behaviour of mixtures of n-alcohol + aliphatic ether: heat capacities and volumes at 298.15 K
Thermochim. Acta
Thermodynamics of liquid mixtures containing a very strongly polar compound. Part 6. DISQUAC characterization of N,N-dialkylamides
Fluid Phase Equilib.
Liquid density of 1-pentanol at pressures up to 140 Ma and from 293.15 to 403.15 K
Fluid Phase Equilib.
Analysis of temperature dependence of some physical properties of (n-nonane + tetraethylene glycol dimethyl ether)
J. Chem. Thermodyn.
Volumetric properties of methylcyclohexane with n-alkanes (C5–C10) at 293.15, 298.15 and 303.15 K. Comparison with Prigogine–Flory–Patterson theory
J. Mol. Liq.
Physical properties of {anisole + n-alkanes} at temperatures between (293.15 and 303.15 K)
J. Chem. Thermodyn.
Methyl ether (MTBE) scores well as high-octane gasoline component
Oil Gas J.
Diesel emissions improvements through the use of biodiesel or oxygenated components
Fuel
Glyme–lithium salt behaviour
J. Phys. Chem. B
Thermodynamics of (1-alkanol + linear monoether) systems
J. Chem. Thermodyn.
Application of the Flory theory and of the Kirkwood–Buff formalism to the study of orientational effects in 1-alkanol + linear o cyclic monoether mixtures
Ind. Eng. Chem. Res.
A new theoretical approach for predicting excess properties of alkanol/alkane mixtures
Ber. Bunsenges. Phys. Chem.
Thermodynamics of binary liquid organic mixtures
Pure Appl. Chem.
Statistical thermodynamics of liquid mixtures
J. Am. Chem. Soc.
The statistical mechanical theory of solutions
J. Chem. Phys.
Apparent dipole moments of 1-alkanols in cyclohexane and n-heptane, and excess molar volumes of (1-alkanol + cyclohexane, or n-heptane) at 298.15 K
J. Solut. Chem.
Cited by (13)
Dielectric study of primary alkanediols (C<inf>3</inf>, C<inf>4</inf>, C<inf>5</inf>) with 1-pentanol isomers
2017, Journal of Molecular LiquidsDielectric study of H-bonded interactions in amyl alcohols with ketones and DMSO at T = 298.15 K
2017, Journal of Chemical ThermodynamicsStudy of intermolecular interactions through dielectric properties of the mixtures consisting of 1,4-butanediol, primary amyl alcohols and 1,4-dioxane at various temperatures
2015, Journal of Chemical ThermodynamicsCitation Excerpt :The stated purity of the alcohols was checked using density and refractive index measurements at 298.15 K. The measured refractive index and density data of the chemicals used in this study along with the literature values [31–33] are given in table 1. A three-terminal cylindrical cell with 27 pF of empty capacitance was used for the capacitance measurements.