Physicochemical properties of dimethyl sulfoxide–methanol liquid mixtures. Experimental and semiempirical quantum chemical studies

Abstract

The ¹H NMR spectra of liquid binary mixtures of dimethyl sulfoxide (DMSO) and methanol (MeOH), were recorded at 298 K over almost the whole range of the mixed solvent compositions. From these data were found the values of the spectral parameter, Δδ(DMSO–MeOH). The densities (d₁₂) and viscosities (η₁₂) of the mixed solvent were measured at 298.15 K, as well as the relative permittivities (ε₁₂) at 293.15, 298.15, 303.15 and 308.15 K. From all these data, the molar volumes (V₁₂) and their deviations from ideality were calculated. Additionally, the temperature coefficients of relative permittivity, α₁₂, were found. These structural parameters of functions of concentration suggest the formation of stable DMSO–MeOH and DMSO–2 MeOH type complexes. The semiempirical quantum chemical (MOPAC package) method was applied to optimize the geometry, energy and hydrogen-bond lengths of dimers and trimers formed by molecules of dimethyl sulfoxide and methanol, and these conclusions wholly support the conclusions drawn from the physicochemical studies.