Experimental, DFT Study and Molecular Dynamics Simulation of the Structural and Thermodynamic Properties of the Binary Mixtures of Morpholine and Isobutanol

Alcohols are widely used in industry and medical sciences and are used as solvents. Isobutanol is considered as a leading candidate for the replacement of current fossil fuels. Due to global environmental problems and fuel crises, isobutanol is expected to be produced in biotechnological process, which fulfills the demands of green and sustainable energy production[1]. Isobutanol is used as a solvent in the pharmaceutical industry [1].Amino acids, aminoethers and their compounds in the industry are very important. Morpholine is used as a cheap solvent in the industry [2]. In this work, thermodynamic properties of binary mixtures of morpholine and isobutanol were measured over the entire composition range at temperatures T = (293.15 to 313.15) K and at atmospheric pressure. From the experimental data, the excess molar volumes were calculated. In the gas phase and using the density functional theory (DFT), the most stable geometric structures of morpholine … morpholine, morpholine … isobutanol, and isobutanol … isobutanol have been investigated. In addition, quantum theory of atoms in molecules (AIM) were applied to analyzed hydrogen bonding (H-bonding) interactions. In the liquid phase, the molecular dynamics (MD) simulation technique was employed to calculate the densities, radial distribution functions (RDFs), combined distribution function (CDF) and mean square displacement (MSD) of the mixtures with different mole fractions at 298.15 K and at 1 atm. For these mixtures, by molecular dynamics simulation and quantum calculations, the hydrogen bonding (H-bonding) interactions were investigated too.