Molecular interaction study of the diisopropyl ether-propionic acid mixture by spectroscopic and dielectric studies.

FTIR and 13C NMR spectral studies have been carried out on diisopropyl ether-propionic acid binary mixture to probe the molecular interactions and stoichiometry of complexation. Density functional theory (DFT) calculations of vibrational frequencies of pure acid and ether-acid binary mixtures have also been performed. In addition, Kirkwood-correlation factors, excess permittivity and excess free energy of mixing have been obtained at various concentrations and at four different temperatures from the dielectric measurements. Excess permittivity is found to have positive deviation and excess free energy deviates negatively from ideal behaviour.