Thermodynamic properties of (a butyl ester plus an n-alkane).: XIII.: HmE and VmE for {xCH3(CH2)u-1CO2(CH2)3CH3+(1-x) CH3(CH2)2v+1CH3}, where u=1 to 3 and v=1 to 7

In the framework of a series of studies carried out by our research team, the excess molar enthalpies H-m(E) and excess molar volumes V-m(E) for 21 binary mixtures composed of one of three butyl esters (ethanoate, propanoate, and butanoate) and one of seven odd n-alkanes (pentane to heptadecane) were determined experimentally at T = 298.15 K. Experimentation showed the mixing processes for these systems to be endothermic, with the H-m(E) values varying quasi-linearly with n-alkane chain length; there is also a regular variation in the V-m(E) values, though the mixtures of the three butyl esters with pentane presented contraction effects with values of V-m(E) that were more negative than expected. The most probable molecular interactions taking place in (ester + n-alkane) systems are discussed. Comparison of the experimental results with certain theoretical group-contribution models showed that differences in the estimates increased with increasing molar mass of the mixture components, indicating a need to improve modeling by adapting the models so that they more closely reflect the special circumstances that affect the behaviour of the mixtures in question. (C) 2000 Academic Press.