Gas-phase standard enthalpy of formation of 3,5-dimethyl-4-nitroisoxazole determined by semi-micro-combustion calorimetry and thermal analysis

Abstract

The present paper reports the determination of the standard (p° = 0.1 MPa) molar enthalpy of formation in gas phase at T = 298.15 K of 3,5-dimethyl-4-nitroisoxazole, which was derived from the enthalpy of combustion in solid state and the sublimation enthalpy. The combustion enthalpy was derived from the respective combustion energy value, which was obtained from combustion calorimetry using a static bomb combustion calorimeter in oxygen atmosphere at T = 298.15 K. The sublimation enthalpy was obtained at the same temperature by using thermogravimetry experiments in isothermal regime. The purity and the constant pressure heat capacity of the compound were determined by using differential scanning calorimetry, priori to carry out the combustion experiments. The value obtained of formation enthalpy of compound in gas phase presents high precision and low uncertainty.