Isobaric molar heat capacities of the mixture (p-cymene + ethanol) at several temperatures and atmospheric pressure

Abstract

Experimental isobaric molar heat capacities at atmospheric pressure have been determined every 10 K for the mixture {p-cymene (1) + ethanol (2)} in the temperature interval (298.6-328.4) K over the whole composition range with a Calvet type calorimeter. Densities, necessary for calculating heat capacities, have been also measured in the same conditions. Excess molar volumes have been calculated from densities. Excess molar heat capacities have been calculated from the molar heat capacities, their values being positive and increasing as the temperature rises. Excess properties are discussed in terms of intermolecular interactions. The solvation model COSMO-RS has been applied to predict the excess molar heat capacities. The model predicts fairly well the values of the excess heat capacities.

Thermophysical and volumetric study of mixtures {p-cymene + propan-1-ol} at several temperatures and atmospheric pressure. Modeling with COSMO-RS

“…328.15 K. In general terms, the excess molar volume increases as the temperature rises at a given molar fraction. This volumetric behavior is very similar to that observed for the mixture of pcymene with ethanol [2] although the values are higher for propan-1-ol. In fact, the same behavior has been reported for mixtures of several alkylbenzenes with ethanol [2] as well as for mixtures of propan-1-ol with benzene [8,15,17,21], or toluene [8,15,18,19,21], or cumene (1-methylethylbenzene) [20], or the three isomers of xylene [8,-16,21].…”

“…In general, a good agreement can be observed between both sets of data. As pointed out in a previous paper [2] for p-cymene there are noticeable deviations between our data and those of Ribeiro et al [26] which are lower than ours and also with those of Liao et al [29] which are greater than ours. An inspection of the purities of p-cymene in those papers, 0.9985 for Ribeiro et al and 0.9917 for Liao et al, show that the purity can play a role in the discrepancies as the lower the purity the higher is the density.…”

“…In this way, the excess molar volume from being sigmoidal shaped becomes positive throughout for the mixtures of propan-1-ol with benzene at 303.15 K [21], or toluene at 323.15 K [19]. Then, the volumetric behavior of the mixture of p-cymene with propan-1-ol fully agrees with that of other mixtures containing benzene or alkylbenzenes as occurred when the alkanol was ethanol [2].…”

“…In sight of this agreement, it is fair to suppose that the excess molar enthalpy for the mixture of p-cymene with propan-1-ol would be positive because it is also positive for the mixtures of propan-1-ol with benzene [5,8,10,12,13], or toluene [8,10,12,13], or the three isomers of xylene [7,8,10,11,13,14] as was also supposed on a very similar basis for the mixture of p-cymene with ethanol [2]. Then, for all of the mixtures of benzene or alkylbenzene with ethanol or propan-1-ol the prevailing thermal effect in the mixing process is the breaking of interactions in the pure compounds (especially of hydrogen bonds in the alkanol), a breaking which is not compensated by the π-OH interactions between aromatic compounds and alkanol.…”

“…The thermodynamic study of binary mixtures of short chain alkanols such as ethanol or propan-1-ol with the main component of a vegetable extract results interesting for the design of extraction processes with supercritical CO 2 as those alkanols are added as cosolvents to CO 2 for increasing the polarity of the final solvent [1]. For this reason, in an earlier paper [2] we reported values of isobaric heat capacities and densities at atmospheric pressure for the binary mixtures of p-cymene with ethanol. In this respect, it would be interesting to extend these studies to the mixture of pcymene with propan-1-ol.…”