Spectral Study of Intermolecular Interactions in Some Sulfolane/Alcoholic Binary Mixtures Using Solvatochromic Measurements

Solvatochromic parameters including the Kamlet–Abboud–Taft parameters (α, β, and π*: KAT parameters) and Reichardt’s polarity scale (ET(30)) were measured spectroscopically over the whole mole fraction range of binary mixtures of sulfolane and some alcohols (methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, iso-butanol, tert-butanol) at 303.15 K. These parameters were obtained based on UV–Vis absorbance of some solvatochromic probes. The spectral changes of these indicators were interpreted in terms of specific and nonspecific dye–solvent interactions. The parameter ET(30) was obtained from electronic absorbance of the betaine dye within the mixtures. Absorbance band shifts of N,N-dimethyl-4-nitroaniline and 4-nitroaniline in concert with absorbance changes of Reichardt’s betaine dye were used to obtain dipolarity/polarizability (π*), hydrogen-bond donating (HBD) acidity (α) and hydrogen-bond accepting (HBA) basicity (β) of the mixtures. The Redlich–Kister equation was applied to the experimental data for different empirical solvatochromic parameters to demonstrate the effect of solvent composition on these parameters in the mixtures.