A Study on Alkane + Ester + Ester Systems. Physicochemical Behavior of Binaries and Ternaries of Octane or Iso-octane with Methyl Esters (Ethanoate, Butanoate, Pentanoate)

Abstract

This work presents an experimental contribution with values of properties arising from mixing processes (enthalpies and volumes) of ternaries of octane and iso-octane (2,2,4-trimethylpentane) with methyl pentanoate or methyl butanoate and methyl ethanoate, measured at 298.15 K. Values of hE and vE of the binaries of these compounds are also obtained. In all cases, the mixtures are endothermic with expansive volumetric effects. The structural interpretation of these is analyzed in relation to the two most important effects, van der Waals forces and electrostatic interactions due to the presence of dipoles on the esters. A slightly different interpretation is made for the ester-ester binaries, which have less significant effects in the ternaries. Experimental data of binaries and ternaries are represented using the authors own model with excellent results. The UNIFAC model gives good representations of hE for the octane-ester systems, but values much higher than real ones for the ester-ester systems. The repercussion of these values in the ternary is negligible since the interaction energies in the ester-ester correspond to only around 10% of the alkane-ester.