Thermodynamic study of (alkyl esters plus alpha,omega-alkyl dihalides) V. H-m(E) and V-m(E) for 25 binary mixtures {xC(u-1)H(2u-1)CO(2)CH(3) + (1-x)alpha,omega-ClCH2(CH2)(v-2)CH2Cl}, where u=1 to 5, alpha=1 and v = omega=2 to 6

Abstract

The experimental data of excess molar enthalpies HmE and excess molar volumes VmE 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 α,ω-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 VmE 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 VmE of expansion/contraction and for exothermic/endothermic HmE for this set of mixtures. The change in VmE 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 (G′) 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 / G′ = φ (u, v) = underover(∑, i = 0, n) ai - 1 ui - 1 + underover(∑, i = 0, n) bi - 1 vi - 1and with this proposal good estimations of enthalpies were obtained with the UNIFAC model. © 2006 Elsevier Ltd. All rights reserved.