Vapour pressure and enthalpy of sublimation of 1,3,5,7-tetranitro-1,3,5,7-tetra-azacyclo-octane (HMX)

The vapour pressure of 1, 3, 5, 7-tetranitro-1, 3, 5, 7-tetra-azacyclo-octane (HMX) has been measured in the temperature range 188 to 213°C by the Knudsen effusion method, and the enthalpy of sublimation over this range calculated to be 38.7 kcal mol–1. Similar measurements on anthracene have been made which confirm literature values.A marked dependence of the vapour pressure, but not of its temperature variation, on the size of the effusion orifice has been observed.