Effects of temperature on nitration of sulfamates

Ammonium dinitramide (ADN) has attracted great interest as a potential oxidizer for next generation rocket propellants. It is a halogen-free alternative to ammonium perchlorate, which is currently in wide used as a solid propellant oxidizer. However, in ADN synthesis, N-nitration is necessary to form the N-(NO2)2 group. Using a reaction calorimeter, the thermal behavior of nitration of sulfamates (K, Na, and NH4) using a mixture of acids (HNO3/H2SO4 and HNO3/AcOH) as the nitration agent was examined. The heat of decomposition of potassium sulfamate at −10 °C was greater than that at 20 °C. The heat of decomposition decreased in the following order: K salt>Na salt>NH4 salt in HNO3/H2SO4. The dipole moments of the sulfamates were calculated, and the results revealed that the electronic states of nitrogen were different. Thus, the dipole moments of sulfamates affect the decomposition heat of sulfamates. The heat of decomposition in HNO3/AcOH was larger than that in HNO3/H2SO4.