Effects of nitric acid concentration for nitration of fused [1,2,5]oxadiazolo[3,4-d]pyrimidine-5,7-diamine

Nitration reactions are very often used for the selective synthesis of novel, high performing nitramine-based materials. Now nitration reactions of the fused 5,7-diamino pyrimidine derivative 1, under different nitric acid concentrations were examined. Concentrated nitric acid gave selectively N-(5-amino-4,5-dihydro-[1,2,5]oxadiazolo[3,4-d]pyrimidin-7-yl)nitramide, 2, while the fused ring nitrate salt, 4, and ring open nitrate salt, 3 were obtained using low concentrations of nitric acid (< 70%). In addition, the cesium salt of the fused nitramine derivative 5 was synthesized. All new compounds were isolated in high yields and comprehensively characterized by NMR, FTIR spectroscopy, and elemental analyses. The molecular structures of 2, 3, and 5 were analyzed by single X-ray crystallographic data. These compounds have high calculated heats of formation and high crystal densities. Detonation properties for compounds 2 and 3 were calculated using EXPLO5 software. Fused ring compound 2 (v(D), 8549 m s(-1); P, 29.62 GPa), and nitrate salt, 3 (v(D), 8392 m s(-1); P, 29.37 GPa) have superior detonation properties compared with TNT (v(D), 7303 m s(-1); P, 21.30 GPa). In addition, electrostatic potentials, two-dimensional (2D)-fingerprints, and Hirshfeld surface analysis were used to predict the sensitive properties of compounds 2 and 3. The experimental sensitives suggest possible applications with insensitive energetic applications.

Automated summary

The nitration reactions of fused 5,7-diamino pyrimidine derivative and the synthesis of new compounds were studied in this research. The selectivity of the products was found to be influenced by the concentration of nitric acid used. Through experiments and various analyses, the structures and properties of the compounds were determined, and two of them were found to have excellent detonation properties. Additionally, the sensitivity of the compounds was predicted, suggesting potential applications in insensitive energetic materials.