Phase Equilibria and Thermodynamic Properties of Some Branched Alkyl Ethers

Abstract

The low-temperature heat capacity and thermodynamic properties of the solid-to-solid transition and fusion of di-isobutyl ether (DIBE) were determined by adiabatic calorimetry in the temperature range from (8 to 373) K. The saturation vapor pressure of DIBE was determined by a comparative ebulliometry over the moderate pressure range from (10.8 to 99.6) kPa. A density of liquid DIBE was measured in the temperature interval from (298 to 313) K using a quartz pycnometer. The normal boiling temperature, Tn.b., the enthalpy of vaporization at T = 298.15 K and Tn.b., and the ideal gas thermodynamic functions (changes of the entropy, enthalpy, and Gibbs energy) at T = 298.15 K were derived. Appropriate thermodynamic functions over a wide temperature range from (150 to 1000) K and the standard enthalpy of formation at T = 298.15 K were computed by the methods of statistical thermodynamics (ST) and the density functional theory (DFT) on the level B3LYP/6-31G(d,p). The experimental data on the vapor pressure of DI...