Thermochemical properties of oxepane

Abstract

In this work, the vapor pressures of oxepane (CAS 592-90-5) have been determined for the first time within the temperature range 276.2–303.2 K using the transpiration method. The enthalpy of vaporization of hexamethylene oxide was evaluated from the experimental vapor pressure data measured by using this method. Values of the enthalpies of combustion and formation have been determined for the first time by combustion calorimetry in a static bomb. A conformational analysis of oxepane in the gas has been performed using methods of molecular mechanics and ab initio computations; the structure of the most stable conformer has been identified. The enthalpy of formation of oxepane in the gaseous state was calculated with the composite G4 method. The thermodynamic functions of oxepane in the ideal gas state over wide temperature range (298.15–1500 K) have been evaluated. Values of the strain energies in a series of cyclic and heterocyclic compounds have been estimated.