Geometrical and temperature impact on elucidation of intermolecular interactions for the binary mixtures of morpholine with aliphatic esters by thermodynamic, FTIR and DFT study

Abstract

Abstract In this investigation, the binary solutions of morpholine (MP) with tert-butyl acetate (TBA), iso-butyl acetate (IBA), butyl acetate (BA) and butyl acrylate (BAC) were prepared for the densities (ρ) and speeds of sound (u) measurements at T = (303.15, 308.15, 313.15 and 318.15) K over the entire composition range and at atmospheric pressure (P = 0.1 MPa). From these data, excess thermodynamic properties such as excess molar volume ( V m E ${V}_{m}^{E}$ ), excess isentropic compressibility ( κ S E ${\kappa }_{S}^{E}$ ) and excess speeds of sound ( u E ${u}^{E}$ ) were calculated to elucidate the strength and types of intermolecular interactions between the component molecules. Redlich-Kister (RK) equation and Prigogine–Flory–Patterson (PFP) theory was applied to correlate the excess parameters and excess volumes, respectively. Further, intermolecular free length theory and collision frequency theory were used to correlate the speed of sound data. Shifting of bands (δν), bond length and hydrogen bond strength between the atoms were calculated from the experimental FTIR and DFT theoretical studies. The systematic increasing order of the intermolecular hydrogen bond strength between the two atoms in the studied binary systems as follows: TBA > IBA > BA > BAC.