Benzofuroxan-Based Energetic Materials with Alternating Nitro and Hydroxyl Groups: Synthesis, Characterization, and Energetic Properties

Due to its good stability, density and oxygen balance, the benzofuroxan fused ring framework has attracted particular attention in the field of high energy density materials. The planar structure of the benzofuroxan facilitates the straightforward derivatization with explosophores and contributes to molecular stability. In this work, a benzofuroxan scaffold was utilized to develop a highly dense energetic material, namely 5,7-dihydroxy-4,6-dinitrobenzo[c][1,2,5]oxadiazole 1-oxide (DHDNBF). The successive inclusion of explosophores like nitro (-NO2) and oxidative functionality like hydroxyl (-OH) on benzofuroxan resulted in an impressive density (rho=1.91 g cm-3) and a positive oxygen balance (6.20 %) in DHDNBF (2). Furthermore, the hydroxy groups on DHDNBF enable the formation of dicationic energetic salts 3-7, contributing to additional modifications in the overall performance. Energetic salts 3, 4, and 5 exhibit significantly higher densities ranging from 1.84 (5) to 1.87 (3) g cm-3 and possess a favorable oxygen balance approaching zero or equal to zero. A marked improvement in thermal stabilities was observed in all the energetic salts (3-7) compared to their neutral counterparts, DHDNBF. Energetic salts 4 (Dv=8459 m s-1, P=32.10 GPa) and 5 (Dv=8539 m s-1, P=30.37 GPa) possess good energetic performance, comparable to that of well-known explosives such as LLM-105 (Dv=8560 m s-1, P=33.4 GPa). Overall, the favorable characteristics of energetic salts 4 and 5 make them potential candidates for use as benzofuroxan-based secondary and primary explosives, respectively, in various military and civilian applications.