Molecular interactions in methanoate/alkanol solutions. Computation of mixing properties and characterization by FTIR/ATR spectroscopy

Abstract

New experimental data of mixing properties (vE and hE), measured at 298.15 K and atmospheric pressure, are presented for a set of binaries formed by alkyl (methyl to pentyl) methanoates with the first four alkanols (methanol to butanol). The experimental data are represented adequately with a polynomial equation that permits a more detailed analysis of the structural behaviour of the solutions formed. The numerical values of vE and hE are the net result of several effects (positive and negative) due to inter- and/or intramolecular interactions explained by FTIR/ATR spectroscopy, which affect the modelling used. In a predictive context, two versions of the UNIFAC group contribution model were used, introducing in one of them the specificities of the associative effects, both for the methanoates and the alkanols. In both versions, it was necessary to recalculate OH/HCOO interaction parameters, which finally produced acceptable values of hE. To estimate the volumetric and energetic behaviour together, a combined model, EOS/gE, constituted by Soave-Redlich-Kwong/UNIFAC, was used and the results obtained are acceptable.