(604a) Improvements in the Synthesis of Guanidinium Azotetrazolate (GUzT)

Guanidinium azotetrazolate (GuZT) is a high-nitrogen material with potential application as a burning rate modifier in gun propellants and ingredient for explosives. Beyond its explosive properties and burning rate modification effects in formulation, it appeals to the energetics industry because of its straightforward synthesis and relative insensitivity to friction and impact. To date, it has been manufactured at Indian Head at scales of up to 50 gallons, and preparations for synthesis at twice that scale are underway. In preparation for this endeavor, experiments were performed to determine the optimum operating parameters for maximizing yield and purity for the 100-gallon scale process. First, the reaction concentration was increased by over twofold to maximize the quantity of reacting materials in the reactor at one time. This strategy reduced the labor cost/kg by more than 50%. Early laboratory synthesis required the addition of solid guanidine hydrochloride (GuHCl) to a solution of sodium hydroxide and sodium azotetrazolate (NaZT). This process worked well to yield pure GuZT product. However, as the scaling process progressed, the sensitivity of GUZT to impact increased significantly. Changing the GuHCl from a solid feed to a solution resulted in the impact sensitivity returning to its less sensitive values. It was suspected that the GuHCl was included in the GUZT crystal lattice during the addition and subsequent reaction. Feeding the reactant as a solution allowed the reaction to take place in solution, yielding purer insoluble GUZT product. Next, a series of experiments was performed to optimize the yield and purity of the GuZT product. Factors of interest included temperature at filtration, ratio of reactants, and reaction temperature. Real-time crystallization data was also collected with an eye toward solving potential crystal morphology challenges. This series of experiments was completed, in addition to experiments used to determine the washing parameters of the final product. These efforts yielded factors significantly influencing the measured responses, which are implemented at the 100-gallon scale. Efficacy of the study is reported.