Intradiffusion, Density, and Viscosity Studies in Binary Liquid Systems of Acetylacetone + Alkanols at 303.15 K

Intradiffusion coefficients of acetylacetone (AcAc) and methanol/ethanol/1-propanol/1-butanol were measured in binary liquid mixtures over the whole concentration range at 303.15 K by the 1H diffusion-order spectroscopy (DOSY) nuclear magnetic resonance (NMR) method based pulse field gradient (PFG). The solvent effect on the enol-keto tautomeric equilibrium as well as differences in intradiffusion coefficients (D) between two tautomers were also studied. The experimental results show that from methanol to 1-butanol, the differences in D between the enol and keto tautomer vary from 5 % to 26 % at different concentrations of AcAc. The densities and viscosities of binary liquid mixtures of AcAc with the above four alkanols have also been determined at 303.15 K and employed to calculate the excess molar volumes and deviations in viscosity over the entire range of mole fractions. Isotherms of V E as a function of mole fraction of AcAc show positive deviations in methanol and ethanol but negative deviations in 1-propanol and 1-butanol, whereas all isotherms of Δη as a function of mole fraction of AcAc record negative deviations. The V E and Δη are fitted to a Redich–Kister type equation. The measured results are interpreted in terms of molecular interactions in the solutions.