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Dive into the research topics where Isaías García de la Fuente is active.

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Featured researches published by Isaías García de la Fuente.


Physical Chemistry Chemical Physics | 2001

Thermodynamics of mixtures containing alkoxyethanols. Part XV. DISQUAC characterization of systems of alkoxyethanols with n-alkanes or cyclohexane

Juan Antonio González; José Carlos Cobos; Francisco Javier Carmona; Isaías García de la Fuente; Venkat R. Bhethanabotla; Scott W. Campbell

Binary mixtures of alkoxyethanols, CH3–(CH2)n–O–(CH2CH2O)mOH, and n-alkanes or cyclohexane are characterized in terms of DISQUAC. The corresponding dispersive (DIS) and quasichemical (QUAC) interchange coefficients, Ceh,lDIS/QUAC, for the (e,h) contacts (type e, –O–; type h, –OH) are given. In comparison with the values for 1-alkanol + monooxalkane systems, the proximity effects in CH3–(CH2)n–O–CH2–CH2–OH + n-alkane mixtures lead to an increase in the Ceh,lDIS and Ceh,lQUAC (l = 1,2) coefficients and to a decrease in Ceh,2DIS. For other hydroxyethers (3-methoxypropanol, 4-methoxybutanol), the Ceh,lQUAC (l = 1,2) coefficients approach those of 1-alkanol + monooxalkane mixtures with increasing separation between the –O– and OH– groups. However, the Ceh,2DIS coefficient is still lower than in alcoholic solutions, indicating that proximity effects in the framework of DISQUAC remain. DISQUAC yields a consistent description of the vapor–liquid equilibria, VLE, and of liquid–liquid equilibria, LLE. Good results are obtained for azeotropic data. The coordinates of the critical points are represented over a reasonable range of composition and temperature. Excess molar enthalpies HmE and the excess molar heat capacity at constant pressure, CpmE, are well reproduced. The typical large deviations for properties at infinite dilution, excess molar partial enthalpies, HmE,∞, and natural logarithms of activity coefficients, ln γi∞, of the associated compound are found. Thermodynamic properties of alkoxyethanol + alkane mixtures are determined by the self-association of the polar compound ia both inter- and intramolecular H-bonds, as well as by dipole–dipole interactions between alkoxyethanol molecules. These interactions are analyzed in terms of the effective dipole moments () and are more important than in 1-alkanol + alkane mixtures. The dipole–dipole interactions in systems with alkoxyethanols decrease along a homologous series, and are enhanced by the presence of two ether atoms. Intramolecular H-bonds are more relevant than the intermolecular H-bonds and become weakened with the separation between the –O– and –OH groups of the hydroxyethers.


Thermochimica Acta | 1993

Calorimetric and phase equilibrium data for linear carbonates + hydrocarbons or + CCl4 mixtures. Comparison with DISQUAC predictions

Juan Antonio González; Isaías García de la Fuente; José Carlos Cobos; Carlos Casanova; Henry V. Kehiaian

Abstract The disquac interaction parameters for the linear organic carbonate—alkane, carbonate—cyclohexane, carbonate—benzene or —toluene, and carbonate—CCl 4 contacts are revised on the basis of new experimental data on vapor—liquid equilibria for dimethyl or diethyl carbonate + n -alkane mixtures. The new parameters differ slightly from the previous ones. The main conclusions remain valid. The quasichemical interchange coefficients for carbonate—alkane or —cyclohexane contacts, and the purely dispersive interchange coefficients for carbonate—benzene or —toluene and carbonate—CCl 4 contacts, show a relatively weak steric effect. The model provides a fairly consistent description of low pressure fluid phase equilibria (vapor—liquid, liquid—liquid and solid—liquid) and related excess functions (Gibbs energy and enthalpy) using the same set of parameters.


Fluid Phase Equilibria | 1992

Characterization of the alkanol/alkanol contacts and prediction of excess functions of ternary systems of two n-alkan-1-ols and one n-alkane using DISQUAC

Juan Antonio González; Isaías García de la Fuente; José Carlos Cobos; Carlos Casanova

Abstract Gonzalez, J.A., Garcia de la Fuente, I., Cobos, J.C. and Casanova, C., 1992. Characterization of the alkanol/alkanol contacts and prediction of excess functions of ternary systems of two n-alkan-1-ols and one n-alkane using DISQUAC. Fluid Phase Equilibria, 78: 61-80. The data available in the literature on the molar excess Gibbs energies GE, molar excess enthalpies HE, and activity coefficients at infinite dilution γ∞i, for mixtures of two n-alkan-1-ols are examined on the basis of the DISQUAC group contribution model. Using the available interaction parameters for the hydroxyl/aliphatic contacts, the interchange coefficients for the hydroxyl/hydroxyl contacts CDISh1h2,l (l = 1, 2, 3)were fitted. One set of GE ternary data and 21 sets of HE ternary data for n-alkan-1-ol(1)+ n-alkan-1-ol(2) + n-alkane(3) systems are also investigated in the framework of this model. The relative standard deviations for the excess enthalpies are less than 0.1 for most of the mixtures.


Thermochimica Acta | 1996

disquac analysis of binary liquid organic mixtures containing cyclic or linear alkanols and cycloalkanes or n-alkanes

Juan Antonio González; Isaías García de la Fuente; José Carlos Cobos

Abstract Literature data for cycloalkanol + cycloalkane or n-alkane mixtures are critically reviewed and characterized in terms of the disquac model incorporating intramolecular effects related to the inclusion of a functional group, OH, in an aliphatic ring. Although the interaction parameters follow similar rules to those encountered for other heterocycles (amines, ethers, ketones), some differences are found, e.g., the quasichemical coefficients are independent not only (as usual) of the alkane, but also of the cycloalkanol. It is shown that for such systems steric effects are less important than ring strain. A treatment of 1-alkanols + cycloalkanes (except C6H12) mixtures using the interaction parameters determined previously for cyclohexane is included.


Fluid Phase Equilibria | 1998

Thermodynamic properties of n-alkoxyethanols + organic solvents mixtures. VIII. Liquid-liquid equilibria of systems containing 2-methoxyethanol and alkanes (C6H12 and CH3-(CH2)u-CH3, u = 3,4,6,8)

Miguel Angel Rubio; Juan Antonio González; Isaías García de la Fuente; José Carlos Cobos

Abstract Liquid–liquid equilibria (LLE) data are reported for 2-methoxyethanol+n-pentane, +n-hexane, +n-octane, +n-decane, or +cyclohexane mixtures at atmospheric pressure, between 281 K and the upper critical solutions temperatures (UCST). The coexistence curves were determined visually. These curves are rather symmetrical, with the asymmetry increasing with the size of the n-alkane. The UCSTs increase almost linearly with the number of the carbon atoms of the n-alkane. The system with cyclohexane shows the lower UCST. The (x,T) data were fitted to the equation T=Tc+k|y−yc|m where y=γx1/{1+x1(γ−1)} and yc=γx1c/{1+x1c(γ−1)}. Tc and x1c are the coordinates of the critical points fitted together with k, m and γ using a Marquardt algorithm. The critical exponents of the order parameter for the mixtures studied are calculated. Its mean value is 0.363.


Thermochimica Acta | 1994

Application of DISQUAC to binary liquid organic mixtures containing 1-alkanols and CCl4

Juan Antonio González; Isaías García de la Fuente; José Carlos Cobos; Carlos Casanova

Abstract The data available in the literature on vapour—liquid equilibria (VLE), molar excess Gibbs energies G E , molar excess enthalpies H E , activity coefficients γ, ∞ i and partial molar excess enthalpies H E,∞ i at infinite dilution of 1-alkanol(1)+tetrachloromethane(2) mixtures are examined on the basis of the disquac group contribution model. The components of the mixtures are characterized by three types of surface groups: hydroxyl (OH group), alkane (CH 3 or CH 2 groups), and tetrachloromethane (CCl 4 group). The alkane/CCl 4 and alkane/hydroxyl interaction parameters are available in the literature. The parameters for the hydroxyl/CCl 4 interactions are reported in this work. The model provides a good description of the VLE and of the related G E data. For the H E data, surprising larger discrepancies are encountered for systems containing 1-propanol or 1-butanol. The temperature dependence of the H E values is fairly well represented. Predictions for the natural logarithms of the activity coefficients at infinite dilution and on H E,∞ i are similar to those for other 1-alkanol(1) + organic solvent(2) mixtures.


Journal of the Chemical Society, Faraday Transactions | 1997

Thermodynamics of mixtures with strongly negative deviation from Raoult's law Part 1Application of the DISQUAC model to mixtures of alkan-1-ols and propanal or linear alkanones and trichloromethane

Juan Antonio González; Isaías García de la Fuente; and Jose Carlos Cobos

Thermodynamic properties: vapour–liquid equilibria (VLE), molar excess Gibbs energies, GE, molar excess enthalpies, HE, or the mole fraction structure factors, Scc(0), of systems containing alkan-1-ols and propanal, or linear alkanones and CHCl3, i.e. strongly associated mixtures which show compound formation, are studied in the framework of the DISQUAC (dispersive quasichemical) model. Interaction parameters for the contacts OH–CO (in propanal) and Cl (in CHCl3)–CO (in alkanones) are reported. For alkan-1-ol–propanal systems, DISQUAC gives better results for VLE than other models previously applied, such as lattice fluid(LF), lattice fluid associated solution (LFAS), extended real associated solution (ERAS), or the universal quasichemical (UNIQUAC) association theory. For HE, only the latter improves results meaningfully but DISQUAC gives good agreement for Scc(0). It is shown that heterocoordination is an esssential characteristic of this class of systems. For linear alkanones with CHCl3, DISQUAC consistently describes GE and HE. Only the symmetry of the GE curve of the propan-2-one–CHCl3 mixtures is not entirely satisfactory. The calculated Scc(0) also shows that heterocoordination plays an important role in these mixtures. As a trend, heterocoordination seems to be represented by large and negative enthalpic parameters for the selected contacts.The ability of DISQUAC to predict VLE and HE for the complex ternary systems propan-2-one–butan-2-one–CHCl3 and methanol–propan-2-one–CHCl3 is examined. Previously, the highly non-ideal mixture methanol–CHCl3 was studied with the necessity for interaction parameters for the OH–Cl contact. DISQUAC accurately describes the VLE of this system, and reproduces reasonably the S-shaped HE. Scc(0) shows that this system is characterized by homocoordination. For the ternary mixtures considered, DISQUAC yields good results for VLE at different temperatures but HE values are only qualitative.


Fluid Phase Equilibria | 1994

Thermodynamics of mixtures containing linear monocarboxylic acids. I. DISQUAC predictions on molar excess Gibbs energies, molar excess enthalpies and solid-liquid equilibria for mixtures of linear monocarboxylic acids with organic solvents

Juan Antonio González; Isaías García de la Fuente; José Carlos Cobos; Carlos Casanova

Mixtures of linear monocarboxylic acids and n-alkanes, cyclohexane, benzene or tetrachloromethane are studied in the framework of DISQUAC. The model gives a fairly good representation of the molar excess Gibbs energy GE and of solid-liquid equilibria. Larger differences from experimental data are found when predicting the molar excess enthalpy HE; these are probably due to errors in the measured data. A method to improve DISQUAC results by fitting geometrical parameters of the ethanoic acid is also described briefly.


Thermochimica Acta | 1999

DISQUAC predictions on thermodynamic properties of ternary and higher multicomponent mixtures. I. Results for total pressure measurements at isothermal conditions of ternary systems

Juan Antonio González; Javier Carmona; Isaías García de la Fuente; José Carlos Cobos

Abstract The ability of DISQUAC to represent vapor-liquid equilibria, VLE, particularly pressures for sets of ( x 1 , x 2 ) values at a given temperature, of ternary mixtures is investigated. Results are obtained using binary interaction parameters only, that is, ternary interactions are neglected. At this end, a set of 39 ternary systems and of 98 related binaries is analyzed. The ternary mixtures treated are of widely different classes. They may be formed by only hydrocarbons; by one or two polar, but not self-associated, compounds and hydrocarbons; or by one or two alcohols and organic solvents, such as hydrocarbons, CCl 4 or polar components. Deviations for ternary and binary systems are similar. The mean relative standard deviation in pressure is 0.020 for the former, and 0.017 for the latter. This means that good predictions on VLE of ternary mixtures can be obtained, taking into account binary interactions only. Moreover, DISQUAC results are practically independent of the system considered, and are valid over a wide range of temperature. Poorer predictions are obtained for those solutions with a binary showing a miscibility gap. It is also noteworthy that, in most of the cases, the interaction parameters needed are already available in the literature. Only for a few binary systems considered, the VLE data are correlated to obtain interchange coefficients which are later used to predict VLE of the related ternary. For the binary mixtures, DISQUAC predicts correctly: the coordinates of azeotropes and excess Gibbs energies, G E . A comparison between DISQUAC results and those obtained using different association models is also presented. DISQUAC and the UNIQUAC association theory yield similar predictions for ternary systems containing two alcohols and one n -alkane.


Physics and Chemistry of Liquids | 2003

Thermodynamics of mixtures containing a very strongly polar compound: IV – application of the DISQUAC, UNIFAC and ERAS models to DMSO+ organic solvent systems

Juan Antonio González; S. Villa; N. Riesco; Isaías García de la Fuente; José Carlos Cobos

Binary mixtures of dimethylsulfoxide (DMSO) with alkane, benzene, toluene 1-alkanol, or 1-alkyne have been investigated in terms of DISQUAC. The corresponding interaction parameters are reported. ERAS parameters for 1-alkanol + DMSO mixtures are also given. ERAS calculations were developed considering DMSO as a not self-associated compound. DISQUAC represents fairly well a complete set of thermodynamic properties: molar excess enthalpies, molar excess Gibbs energies, vapor–liquid equilibria, natural logarithms of activity coefficients at infinite dilution, or partial molar excess enthalpies at infinite dilution. DISQUAC improves UNIFAC calculations for H E . Both models yield similar results for VLE. In addition, DISQUAC also improves, ERAS results for 1-alkanol + DMSO mixtures. This may be due to ERAS cannot represent the strong dipole–dipole interactions present in such solutions.

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Ismael Mozo

University of Valladolid

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Iván Alonso

University of Valladolid

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Fernando Hevia

University of Valladolid

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Luis F. Sanz

University of Valladolid

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Ana Cobos

University of Valladolid

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