Thermodynamic properties of binary mixtures containing oxaalkanes: Part V. Monoethers, acetals, polyethers, cyclic mono- and di-ethers+benzene

A flow microcalorimeter has been used to determine excess enthalpies, H (E), at 298.15 K of binary mixtures of dipentylether, dihexylether, 1,2-dimethoxyethane and 1,2-diethoxyethane (1)+benzene (2). These data along with the data available in the literature on H (E), molar excess Gibbs energies, G (E) and liquid-vapour equilibria (LVE) of non-cyclic monoethers, acetals, polyethers and of cyclic mono- and di-ethers+benzene are examined on the basis of the DISQUAC group contribution model. Using a set of adjusted interchange energies parameters, structure dependent, the model provides a fairly consistent description of the thermodynamic properties as a function of concentration. The interaction parameters, dispersive and quasichemical, depend on the intramolecular environment of the O atom. There is clear evidence for the steric and inductive effects exerted by the alkyl groups adjacent to the O atom, for -O-C-O- proximity effect and for a ring strain effect. The steric effect results in a regular decrease of the dispersive interaction parameters of the oxygen/benzene (e,b) contact; The proximity effect of the O atoms produces a regular decrease and the ring strain a regular increase of the dispersive interaction parameters; the quasi-chemical remain constant.