Measurements and Analysis of Excess Enthalpies of Ester + n‐Alkane Using the UNIFAC Model

Berichte der Bunsengesellschaft/Physical Chemistry Chemical Physics 02/1991; 95(2):128 - 135. DOI: 10.1002/bbpc.19910950205


We present new experimental data of the excess molar enthalpies at 298.15 K for eighteen different binary mixtures of nine methyl alkanoates (ethanoate to decanoate) with n-heptane and n-undecane. The results show that all the systems are endothermic, hE values increase with the length of the n-alkane and decrease with the length of the methyl ester. The data have been analysed with a version of the UNIFAC model, and the parameters corresponding to the CH2/COOC interaction have been recalculated using a larger base of experimental data. New values for the CH2/COO interaction parameters have been obtained.

1 Follower
4 Reads
  • [Show abstract] [Hide abstract]
    ABSTRACT: Ortega, J. and Legido, J.L., 1993. Revision of interaction parameters for estimating the enthalpies of mixtures of benzyl ethanoate + n-alkanes or 1-chloroalkanes using the UNIFAC model with presentation of new experimental data. Fluid Phase Equilibria, 86: 251-273A theoretical and experimental study of the mixing enthalpies at 298.15 K and atmospheric pressure for binary systems composed of benzyl ethanoate and twelve n-alkanes (from C6 to C17), and benzyl ethanoate and five 1-chloroalkanes (from C4 to C8) is presented. The results showed that all the systems were endothermal and that the hevalues increased in a quasi-linear fashion with the number of -CH2- groups in both the n-alkane and the 1-chloroalkane. The data were analyzed using two versions of the UNIFAC group-contribution model, establishing new values for the aromatic/ester and aromatic/chloride interactions. The aromatic groups were represented as ACH and ACCH2, the ester group as CF3COO, and the chloride group as Cl and CCl. Using the new interaction pair values in the calculations produced overall improvements of the order of 50% in the predictions compared with those of the original model. In no case did the error in the he estimates calculated with these new values exceed 6%.
    Fluid Phase Equilibria 07/1993; 86:251–273. DOI:10.1016/0378-3812(93)87180-9 · 2.20 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The original UNIFAC model and two of its modifications have been fitted to binary molar excess enthalpy (HE) data to correlate and predict binary excess enthalpy HE in systems containing esters and n-alkanes.The results show that the version of Rupp et al. (Ind. Eng. Chem. Process Des. Dev., 23 (1984) 391) and the UNIFAC model with tripled values of surface area parameters (UNIFAC(3Q)) are preferable to the original UNIFAC model. Both versions produce mean deviations of HE better than 7% for all the systems containing methanoates, ethanoates, the other alkanoates and benzoates studied.
    Thermochimica Acta 07/1994; 240(1):207-213. DOI:10.1016/0040-6031(94)87042-X · 2.18 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: HE values for 28 binary mixtures of four alkyl (methyl, ethyl, propyl, and butyl) benzoates and seven odd n-alkanes (from pentane to heptadecane) were determined experimentally at 298.15 K. Data plots (x,HE) revealed the endothermicity of the mixtures. For a given ester the endothermic effects increased regularly with n-alkane chain length and decreased regularly with the length of the alkylated chain of benzoate. The experimental values were analysed using two versions of the UNIFAC group contribution model. Using the new data, values were calculated for the specific interactions of the characteristic carboxyl group, COO, on the benzoates with other groups in the mixing process for these mixtures, namely, CH2COO and ACHCOO. Using the new values the model produced good HE estimates, with an overall mean error of less than 5%.
    Fluid Phase Equilibria 07/1995; 108(1):121-133. DOI:10.1016/0378-3812(95)02704-I · 2.20 Impact Factor
Show more