Damon A. Parrish

3,4,5-Trinitropyrazole-Based Energetic Salts

High-density energetic salts that are comprised of nitrogen-rich cations and the 3,4,5-trinitropyrazolate anion were synthesized in high yield by neutralization or metathesis reactions. The resulting salts were fully characterized by (1)H, (13)C NMR, and IR spectroscopy; differential scanning calorimetry; and elemental analysis. Additionally, the structures of the 3,5-diaminotriazolium and triaminoguanidinium 3,4,5-trinitropyrazolates were confirmed by single-crystal X-ray diffraction. Based on the measured densities and calculated heats of formation, the detonation performances (pressure: 23.74-31.89 GPa; velocity: 7586-8543 ms(-1); Cheetah 5.0) of the 3,4,5-trinitropyrazolate salts are comparable with 1,3,5-triamino-2,4,6-trinitrobenzene (TATB; 31.15 GPa and 8114 ms(-1)). Impact sensitivities were determined to be no less than 35 J by hammer tests, which places these salts in the insensitive class.

Energetic Salts with π-Stacking and Hydrogen-Bonding Interactions Lead the Way to Future Energetic Materials

Among energetic materials, there are two significant challenges facing researchers: 1) to develop ionic CHNO explosives with higher densities than their parent nonionic molecules and (2) to achieve a fine balance between high detonation performance and low sensitivity. We report a surprising energetic salt, hydroxylammonium 3-dinitromethanide-1,2,4-triazolone, that exhibits exceptional properties, viz., higher density, superior detonation performance, and improved thermal, impact, and friction stabilities, then those of its precursor, 3-dinitromethyl-1,2,4-triazolone. The solid-state structure features of the new energetic salt were investigated with X-ray diffraction which showed π-stacking and hydrogen-bonding interactions that contribute to closer packing and higher density. According to the experimental results and theoretical analysis, the newly designed energetic salt also gives rise to a workable compromise in high detonation properties and desirable stabilities. These findings will enhance the future prospects for rational energetic materials design and commence a new chapter in this field.

Nitrocyanamide‐Based Ionic Liquids and Their Potential Applications as Hypergolic Fuels

Nitrocyanamide ionic liquids with substituted imidazolium, guanidinium, and tetrazolium cations have been synthesized and fully characterized. Aminoguanidinium nitrocyanamide (7) crystallizes in the triclinic system P1. The results obtained from theoretical calculations based on 7 are consistent with the single-crystal structure data. These ionic liquids exhibit desirable physicochemical properties, such as low melting points and good thermal stabilities. Furthermore, they are all impact insensitive materials. Their energetic performances, including heats of formation, detonation pressures, and detonation velocities, were studied by a combination of theoretical and empirical calculations. The ionic liquids 1-4 have large liquid ranges and low viscosities. They were shown to be promising candidates as hypergolic ionic liquids through the combustion tests with 100% HNO(3).

Energetic multifunctionalized nitraminopyrazoles and their ionic derivatives: ternary hydrogen-bond induced high energy density materials.

Diverse functionalization was introduced into the pyrazole framework giving rise to a new family of ternary hydrogen-bond induced high energy density materials. By incorporating extended cationic interactions, nitramine-based ionic derivatives exhibit good energetic performance and enhanced molecular stability. Performance parameters including heats of formation and detonation properties were calculated by using Gaussian 03 and EXPLO5 v6.01 programs, respectively. It is noteworthy to find that 5-nitramino-3,4-dinitropyrazole, 4, has a remarkable measured density of 1.97 g cm(-3) at 298 K, which is consistent with its crystal density (2.032 g cm(-3), 150 K), and ranks highest among azole-based CHNO compounds. Energetic evaluation indicates that, in addition to the molecular compound 4, some ionic derivatives, 9, 11, 12, 17, 19, and 22, also have high densities (1.83-1.97 g cm(-3)), excellent detonation pressures and velocities (P, 35.6-41.6 GPa; vD, 8880-9430 m s(-1)), as well as acceptable impact and friction sensitivities (IS, 4-30 J; FS, 40-240 N). These attractive features highlight the application potential of nitramino hydrogen-bonded interactions in the design of advanced energetic materials.

Derivatives of 5-nitro-1,2,3-2H-triazole – high performance energetic materials

The energetic derivatives of 5-nitro-1,2,3-2H-triazole, which include 2-(methyl or amino)-4-(nitramino, azido, or nitro)-5-nitro-1,2,3-2H-triazoles, were prepared in moderate yields, and confirmed with NMR and IR spectroscopy, and elemental analysis. Their key properties, viz., melting and decomposition temperatures, densities, detonation pressures and velocities, and impact sensitivities, were measured or calculated. Among the new derivatives, 2-amino-4,5-dinitro-1,2,3-2H-triazole exhibits properties (Tm, 94 °C; Td, 190 °C; ρ, 1.83 g cm−3; P, 36.2 Gpa, vD, 8843 m s−1, IS, 24 J), comparable with RDX (Tm, 205 °C; Td, 230 °C; ρ, 1.80 g cm−3; P, 35.0 Gpa, vD, 8762 m s−1, IS, 7.5 J), and may have potential as a high-performance energetic material.

3‐Azido‐N‐nitro‐1H‐1,2,4‐triazol‐5‐amine‐Based Energetic Salts

Twelve energetic nitrogen-rich salts based on 3-azido-N-nitro-1H-1,2,4-triazol-5-amine were prepared and fully characterized by (1)H, (13)C NMR, and IR spectroscopy, differential scanning calorimetry (DSC), and elemental analysis. The crystal structures of the neutral compound 3-azido-N-nitro-1H-1,2,4-triazole-5-amine (1) and its triaminoguanidinium salt (13) were determined by single-crystal X-ray diffraction. The density of 1 and its twelve salts ranged from 1.57 to 1.79 g  cm(-3), and the heat of formation was calculated with the Gaussian 03 suite of programs. Compounds 1-13 exhibit promising detonation performances (pressure: 25.3-39.3 GPa; velocity: 8159-9409 m s(-1); EXPLO 5.05). Impact sensitivities were also determined by hammer tests and resulted ranging from 2.5 J (very sensitive) to >40 J (insensitive).

Energetic Salts Based on 3,5-Bis(dinitromethyl)-1,2,4-triazole Monoanion and Dianion: Controllable Preparation, Characterization, and High Performance

Molecular modification of known explosives is considered to be an efficient route to design new energetic materials. A new family of energetic salts based on the 3,5-bis(dinitromethyl)-1,2,4-triazole monoanion and dianion were controllably synthesized by using 1-diamino-2,2-dinitroethene as a precursor. X-ray structure determination of monohydrazinium 3,5-bis(dinitromethyl)-1,2,4-triazolate (5) and monoammonium (6) and diammonium 3,5-bis(dinitromethyl)-1,2,4-triazolate hydrate (8·H2O) further confirmed the structures of these anions. In addition, as supported by X-ray data, in the monoanion system, the roving proton on the ring nitrogen rather than on the gem-dinitro carbon results in extensive hydrogen-bonding interactions and higher packing coefficients. Interestingly, 5 and 6 possess the highest calculated crystal densities, 1.965 and 1.957 g cm(-3) at 150 K, for hydrazinium and ammonium energetic salts, respectively. Energetic evaluation indicates that 5 (detonation velocity vD = 9086 m s(-1); detonation pressure P = 38.7 GPa) and 6 (vD, 9271 m s(-1); P = 41.0 GPa) exhibit great detonation properties, superior to those of current highly explosive benchmarks, such as 1,3,5-trinitroperhydro-1,3,5-triazine (RDX) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX).

4-Amino-3,5-dinitropyrazolate salts—highly insensitive energetic materials†

Energetic salts based on the 4-amino-3,5-dinitropyrazolate anion and selected nitrogen-rich cations were prepared in high yield by neutralization or metathesis reactions. Their key properties of the resulting energetic salts, such as melting point, thermal stability (169–303 °C), density (1.54–1.84 g cm−3), impact sensitivity (>60 J), heat of formation, and detonation pressure (20.99–32.55 GPa) and velocity (7712–8751 m s−1), were measured or calculated. As highly insensitive energetic materials, salts 9 (32.55 GPa, 8743 m s−1) and 11 (28.85 GPa, 8751 m s−1) are comparable with 1,3,5-triamino-2,4,6-trinitrobenzene (TATB, 31.15 GPa and 8114 m s−1).

Synthesis and properties of 3,4,5-trinitropyrazole-1-ol and its energetic salts

3,4,5-Trinitropyrazole-1-ol and its nitrogen-rich salts were synthesized and well characterized by 1H, 13C NMR (some with 15N NMR), and IR spectroscopy, and by elemental analysis. Additionally, the structures of the ammonium and triazolium 3,4,5-trinitropyrazole-olates were confirmed by single-crystal X-ray diffraction. With respect to measured or calculated properties, such as thermal stability (Td, 118–186 °C), density (1.72–1.90 g cm−3), detonation performance (P, 28.77–36.40 GPa; vD, 8175–8676 m s−1), and impact sensitivity (1–40 J), 3,4,5-trinitropyrazole-1-ol and its salts have the potential to be useful energetic materials.

Energetic 1,5-diamino-4H-tetrazolium nitro-substituted azolates

1,5-Diaminotetrazole (DAT) is a fascinating component in the construction of high-energy-density materials because of its extremely high nitrogen content (∼84%). Three DAT nitro-substituted azolate salts were synthesized and fully characterized by IR, NMR, elemental analysis, thermal stability, phase behavior, and density. 1,5-Diamino-4H-tetrazolium 5-nitrotetrazolate salt (2) crystallizes in the orthorhombic system Pbca. The detonation pressure (P) values calculated for these salts range from 28.05 to 29.88 GPa, and the detonation velocities (D) from 8343 to 8655 m s−1, which make them competitive energetic materials. Each of the compounds has an oxygen balance approaching zero (−23.8 to −33.5%). Their impact sensitivities were determined. The salts were compared using natural bond orbital (NBO) analysis of the nitro-substituted azolate anions. These CHNO-explosives, DAT nitro-substituted azolate salts, are potential green energetic materials which are obtained via a straightforward synthetic route.