Thermodynamics Research Center / ThermoML | Journal of Chemical Thermodynamics

ABSTRACT

The experimental data of excess molar enthalpies HE m and excess molar volumes V E m are presented for a set of 25 binary mixtures comprised of the first five methyl esters Cu 1H2u 1COOCH3 (u = 1 to 5) and five a,x-dichloroalkanes, ClCH2(CH2)v 2CH2Cl (v = 2 to 6), obtained at a temperature of 298.15 K and atmospheric pressure. Except for the mixtures with u = 1 and v = 2 to 6, which are all endothermic and with u = 5 and v = 2 to 6, which are all exothermic, the others present net endo/exothermic effects and these mixing effects evolve quasiregularly, from endothermic to exothermic, depending on the dichloroalkane present. However, the V E m are positive in most mixtures except for those corresponding to u = 4,5 and v = 5,6, which present contraction effects. These results indicate a set of specific interactions with simultaneous effects for V E m of expansion/contraction and for exothermic/endothermic HE m for this set of mixtures. The change in V E m with the chain length of the compounds is irregular. To achieve a good application of the UNIFAC model using the version of Dang and Tassios, parameters of the ester (G)/dichloride (G0) interaction were calculated again, making a distinction, during its application, dependent on the acid part of the ester u. Hence, interaction parameters are presented as a function of u, and of the dichloroalkane chain length v. The most appropriate general expression was of the type: aG=G0 1/4 uou; vP 1/4X n i1/40 ai 1ui 1 pX n i1/40 bi 1vi 1 and with this proposal good estimations of enthalpies were obtained with the UNIFAC model.