Densities and thermochemical properties of dimethylsulfone in dimethylsulfoxide and dimethylsulfoxide/water equimolar mixture

摘要

In this paper the densities and enthalpies of solution of dimethylsulfone (DMSO2) in dimethylsulfoxide (DMSO) and DMSO/water equimolar mixture have been measured over available concentration range (up to about 1 mol kg ~(- 1)). Densities of solutions and apparent molar volumes were determined over the 293.15-323.15 K temperature range. In DMSO2-DMSO-water system the strongest interaction between DMSO and water molecules leads to the increase of partial molar volumes for DMSO2. It was shown that the competitive intermolecular interactions are responsible for the observed phenomena. Solution enthalpies of DMSO2 in the above mentioned solvents and the enthalpies of transfer of DMSO2 from water to DMSO and DMSO/water mixture have been calculated. The obtained results confirm that the endothermal process of sulfone crystalline lattice decomposition predominates during the dissolution of sulfones. With the transfer of DMSO2 from water to DMSO and mixed solvent the endothermic increase of transfer enthalpies takes place.