Description of Thermodynamic Behavior of the Systems Formed by Alkyl Ethanoates with 1-Chloroalkanes Using the COSMO-RS Methodology Contributing with New Experimental Information

Abstract

For this work, V m E and H m E have been measured at a temperature of 298.15 K and at atmospheric pressure for a set of binary mixtures composed of seven alkyl ethanoates (from methyl to octyl, except heptyl) and six 1-chloroalkanes (C 4 to C 9 ). Of the 42 binary mixtures, measurements have only been made for systems for which the excess quantities have not been published previously. Except for the octyl ethanoate +1-chlorobutane system, with V m E < 0, and hexyl ethanoate+1-chlorobutane, with V m E ≈ 0, the mixtures present expansive effects. In the case of the enthalpies, methyl ethanoate+1-chloroalkane mixtures are all endothermic and evolve toward H m E < 0 as the alkanolic part of the ethanoate increases, and mixtures of octyl ethanoate+1chloroalkane are all totally exothermic. The COSMO-RS model, based on quantum chemical calculations, has been used to explain the behavior of these mixtures, which estimate the enthalpic effects as a result of the inter/intramolecular interactions of the two types of ester/chloroalkane molecules. The results obtained with the COSMO-RS give a good qualitative prediction with an explanation of the different effects that determine the behavior of these mixtures, especially the influence, in both the pure substance and the mixture, of the increased chain length in both types of compound. Application of two different versions of the UNIFAC method gives acceptable results, although with the original version of Dang and Tassios 10 it was necessary to determine new parameters using the experimental database of this work.

Thermodynamic study of (alkyl esters+α,ω-alkyl dihalides) VI. and for 20 binary mixtures {xCu−1H2u−1CO2(CH2)3CH3+(1−x)α,ω-BrCH2(CH2)v−2CH2Br}, where u=1 to 5, α=1, and v=ω=2 to 6

“…Previous studies have demonstrated a difference between the values of H E m in the mixtures of mono-and dihalides with a second compound of the same class, as verified in the (ester + monochloroalkane) [13], which also occurred for derivatives of bromide that we will demonstrate in a future work on monobromides. The differences in H E m , with higher values in mixtures with the monohalides, Cl or Br, are associated with increased acidity of the hydrogens after adding a Cl or Br atom to the compound.…”

Thermodynamic study of (alkyl esters+α,ω-alkyl dihalides) VII. and for 20 binary mixtures {xCu−1H2u−1CO2C3H7+(1−x)α,ω-ClCH2(CH2)v−2CH2Cl}, where u=1 to 4, α=1 and v=ω=2 to 6. An analysis of behavior using the COSMO-RS methodology

“…Adequate estimations are observed for the 1,2-dichloroethane, but the predictions tend to diverge as the length of the dichloroalkane chain increases. In order to obtain a better prediction of the H E m for the mixtures selected, as described previously for halogenated compounds [8,20], the COSMO-RS parameters must be fine-tuned. As a result, the original values for the van der Waals interactions s(Cl, Cl) = À39.60 kJ/mol/nm 2 and s(Cl, H) = À26.06 kJ/mol/nm 2 , presented in the literature cited previously, have been replaced, respectively, by À45.54 and À36.48 kJ/mol/nm 2 .…”

“…In a first step, as indicated in a previous paper [8], the molecular geometries of the components of the mixtures were optimized using the Guassian03 quantum-chemistry software [17] to the calculus level B3LYP/6-311++G ** . This is later used to generate files which contain the information required to apply the continuous solvation COSMO model to the BVP86/TZVP/DGA1 level.…”

“…10.007 interactions that define the behavior of a system are required [7]. Since the experimentation carried out in a previous work [8] showed that, initially, the COSMO-RS methodology [6] provided satisfactory estimations of H E m in the binary mixtures of alkyl ethanoates + monochloroalkanes, we decided to use this methodology to estimate the H E m of mixtures of propyl esters with the dichloroalkanes selected for this work. The behavior of the excess properties of these mixtures will be studied in terms of the different intermolecular interactions -electrostatic, hydrogen bond, and van der Waals -described by the COSMO-RS methodology.…”

Mechanistic understanding of the behavior of diuron in the adsorption from water onto activated carbon

“…Phenomena related to the adsorption of organic solutes on AC have been shown to depend on the structural and physico-chemical properties of both adsorbate and adsorbent, which determine the contribution of polar, Van de Waals and hydrogen bonding interactions to the adsorption potential [1]. COSMO-RS has shown general suitability for calculating thermodynamic properties of fluid mixtures from electronic information of individual molecules [13], such as Gibbs free energies and equilibrium constants of reaction [14], L-L equilibrium data as solubility [15] and partition coefficients [16], excess enthalpy [17] and pK a values [18]. In addition, COSMO-RS has been successfully applied to predict adsorption equilibrium data from aqueous solutions [19][20][21][22].…”