Solvatochromic Measurement of KAT Parameters and Modeling Preferential Solvation in Green Potential Binary Mixtures of N-Formylmorpholine with Water, Alcohols, and Ethyl Acetate

Kamlet–Abboud–Taft (KAT) solvatochromic parameters (α, β, and π*), as well as the Reichardt’s polarity scale (ET(30)), were measured from ultraviolet–visible (UV–vis) absorption spectral shift of three indicator solutes namely 4-nitroaniline, N,N-dimethyl-p-nitroaniline, and the betaine dye 4-(2,4,6-triphenylpyridinium-1-yl)-2,6-diphenylphenolate. These measurements were done within the whole mole fraction range of the binary mixture of green solvents N-formylmorpholine with water, ethanol, 1-propanol, 2-propanol, 1-butanol, and ethyl acetate at room temperature (298.15 ± 0.1 K). The Redlich–Kister model was employed to demonstrate the effect of solvent composition on the solvatochromic parameters obtained in the mixtures understudy. The data of ET obtained for the indicator dyes in different mole fractions (0.0–1.0) of the binary mixtures were analyzed to investigate their preferential solvation in terms of both the solute–solvent and the solvent–solvent interactions. The solvent exchange model was successfully utilized to calculate preferential solvation parameters. It was found that the solvation shell of the dyes is mainly affected by the solvent–solvent interactions, and all studied systems showed the nonideal behavior.