PHYSICOCHEMICAL PROPERTIES OF DIMETHYL-SULFOXIDE METHANOL LIQUID-MIXTURES - EXPERIMENTAL AND SEMIEMPIRICAL QUANTUM-CHEMICAL STUDIES

The H-1 NMR spectra of liquid binary mixtures of dimethyl sulfoxide (D MSO) and methanol (MeOH), were recorded at 298 K over almost the whole range of the mixed solvent compositions. From these data were found t he Values of the spectral parameter, Delta delta(DMSO-MeOH). The densi ties (d(12)) and viscosities (eta(12)) of the mixed solvent were measu red at 298.15 K, as well as the relative permittivities (epsilon(12)) at 293.15, 298.15, 303.15 and 308.15 K. From all these data, the molar volumes (V-12) and their deviations from ideality were calculated. Ad ditionally, the temperature coefficients of relative permittivity, alp ha(12) were found. These structural parameters of functions of concent ration suggest the formation of stable DMSO-MeOH and DMSO-2 MeOH type complexes. The semiempirical quantum chemical (MOPAC package) method w as applied to optimize the geometry, energy and hydrogen-bond lengths of dimers and trimers formed by molecules of dimethyl sulfoxide and me thanol, and these conclusions wholly support the conclusions drawn fro m the physicochemical studies.