Thermodynamics of liquid mixtures containing methyl methylthiomethyl sulfoxide: XVI. Excess enthalpies of some alkylbenzenes+methyl methylthiomethyl sulfoxide and alkylbenzenes+dimethyl sulfoxide at 298.15 K

Abstract

Excess enthalpies of binary mixtures between one of the alkylbenzenes (ethylbenzene, n-propylbenzene, n-butylbenzene, n-pentylbenzene, n-hexylbenzene, n-heptylbenzene and n-octylbenzene) and methyl methylthiomethyl sulfoxide (MMTSO) or dimethyl sulfoxide (DMSO) have been determined at 298.15 K. For all the mixtures, changes in enthalpy are positive over the whole range of mole fractions. Linear relationships are obtained between the limiting excess partial molar enthalpies H E,∞ 1 and H E,∞ 2 and ( α 2 μ 2 1+ α 1 μ 2 2) V −1 1 V −1 2, where α and μ are the polarizabilities and electric dipole moments of the alkylbenzenes(1) and the sulfoxides(2), respectively, and V the molar volumes of 1 or 2. Phase separations are observed for the binary mixtures containing alkylbenzenes higher than n-butylbenzene. Mutual solubilities determined are decreased with increase of sizes of alkyl radicals. In homogeneous regions, all the molar excess enthalpies are increased with increase of the size of alkyl radicals.