Exploring the Mechanism of Ammonium Dinitramide Synthesis through DFT Calculations

Ammonium dinitramide (ADN) has emerged as a promising substitute for ammonium perchlorate (AP) in solid rocket propellants due to its favorable energetic properties and absence of halogens. However, a comprehensive understanding of its synthesis mechanism has not been thoroughly achieved. In this sense, this study explores various submechanisms governing the synthesis of ADN in the gas phase and under the influence of an implicit solvent (PCM). Density Functional Theory (DFT) was employed to determine the thermochemical properties of all stationary states on the ground-state potential energy surface related to the elementary reactions involved in the nitration process. Five different pathways were described for the gas phase reaction and three different pathways with implicit solvent, all of which were accessible. Two of the five pathways (the same two pathways found with PCM) appear to be preferential, forming nitramide more easily and favoring the formation of dinitramidic acid (HDN), which will later react with ammonia to form ADN.