Preface

103

The data available in the literature for the molar excess Gibbs energies GE, azeotropes, molar excess enthalpies HE, activity coefficients γi∞, and partial molar excess enthalpies HiE,∞, at infinite dilution, and molar excess heat capacities CpE, of n‐alkan‐1‐ol (1) + n‐alkane (2) mixtures are examined on the basis of the DISQUAC group contribution model. Being available the interaction parameters for systems containing methanol or ethanol, we report the interchange coefficients from propanol to hexadecanol: Cah.1DISand Cah,1QUAC (1 = 1,2 or 3). For the dispersive coefficients: Cah,1DIS increase with the size of the n‐alkan‐1‐ol; Cah,3DIS decrease as far as propanol, and then increase regularly, an opposite behaviour is encountered for Cah,3DIS the quasichemical coefficients: Cah,1.DIS and Cah,3.DIS are constant, and Cah,3CUAC varies in a similar way to the maximum of the HE of the mixtures under study; from decanol, they are constant. The model describes consistently the molar excess functions for the systems investigated, even the CpE and, qualitatively, the temperature dependence of this magnitude. Partial molar excess quantities at infinite dilution are reasonably well represented. Larger differences are obtained for H1E,∞.

Section: Introductionmentioning

confidence: 99%

A Characterization of the Aliphatic/Hydroxyl Interactions using a Group Contribution Model (Disquac)

González

Fuente

Cobos

et al. 1991

103

“…If it is acknowledged that the model is not universal or flexible enough to describe new systems or properties, usually new relationships with greater number of parameters are incorporated. It may be observed while tracing the way from the quasichemical theory [2] to the DISQUAC model [3], and from the original UNIFAC to its modified version [l]. This process, although explicable, deprives the group contribution models of their predictive character and transforms them gradually into specific correlation equations.…”

Section: Introductionmentioning

confidence: 99%

Solid‐liquid equilibria in n‐alkanol+n‐alkane systems. Prediction by several group‐contribution theories

Hofman

Barbés

Casanova

1998

Several, widely used, group contribution models have been used to predict solid-liquid equilibria for n-alco-hol+n-alkane binary mixtures. They are: modified W A C [l], DISQUAC [2, 31, Nitta-Chao [4] and the Hole Model (HM) (51. Also a recently reported group contribution model (AssODis) including association [6]has been taken into account. The results have been compared with experimental data &r:

“…by (a, h = I) Muiioz Embid[5], (a, h = Br) Kehiaian[4], (a, h = C1) Kehiaian[3] and (a, h = F) ArtalPI.The interchange parameters of the aliphatic-halogen (a, h) contacts being known, the representation of GE and H: of n-monohaloalkane + n-monohaloalkane mixtures requires only the adjustment of the (h, h') contact parameters. Based on our previous experience with other contacts of polar-polar or polar-polarizable compounds, it was…”

mentioning

confidence: 99%

Molar excess enthalpies of n‐monohaloalkanes + n‐monohaloalkanes mixtures. Estimation of DISQUAC interchange energy parameters

Artal

Embid

Otı́n

et al. 1996

Molar excess enthalpies, H Em, at 298.15 K and atmospheric pressure were determined for six binary liquid mixtures [x{iodethane or 1‐iodobutane or bromoethane or 1‐bromobutane or 1‐chloropropane or 1‐chloropentane} + (1 ‐ x) 1‐fluoropentane]. These experimental results along with the data available in the literature on molar excess Gibbs energies, G Em, activity coefficients at infinite dilution, In γ ∞i, and molar excess enthalpies, H Em, for n‐monohaloalkane + n‐monohaloalkane mixtures, are examined on the basis of the DISQUAC group‐contribution model. The interchange energies of the contacts between two different halogen atoms are entirely dispersive and were determined in this work. The model reproduces reasonably well most of the experimental data. For a given n‐monohaloalkane, mixed with the other n‐monohaloalkanes, it can be seen that the values of the dispersive interchange energies coefficients of the Gibbs energy, C dishh',1, and enthalpy, C dishh',2, the contact between the two different halogen atoms, X and Y, and the experimental equimolar values of the excess thermodynamic properties G Em(x1 = 0.5), and H Em(x1 = 0.5), have the same trend as the gas‐phase electric dipole moment, p, of the molecule X‐Y. The same trend is also observed for the difference in the electric polarizability, Δα, between the halogen atoms X and Y.