EXPERIMENTAL VALUES AND ANALYSIS OF MIXING HEATS OF THE BINARY-MIXTURES FORMED BY ALKYL BENZOATES AND N-ALKANES

H-E values for 28 binary mixtures of four alkyl (methyl, ethyl, propyl , and butyl) benzoates and seven odd n-alkanes (from pentane to heptad ecane) were determined experimentally at 298.15 K. Data plots (x,H-E) revealed the endothermicity of the mixtures. For a given eater the end othermic effects increased regularly with n-alkane chain length and de creased regularly with the length of the alkylated chain of benzoate. The experimental values were analysed using two versions of the UNIFAC group contribution model. Using the new data, values were calculated for the specific interactions of the characteristic carboxyl group, CO O, on the benzoates with other groups in the mixing process for these mixtures, namely, CH2/COO and ACH/COO. Using the new values the model produced good H-E estimates, with an overall mean error of less than 5 %.