Niko Fischer

N-Rich Salts of 2-Methyl-5-nitraminotetrazole: Secondary Explosives with Low Sensitivities†

2-Methyl-5-nitraminotetrazole (1) was formed by nitration of 2-methyl-5-aminotetrazole. 2-Methyl-5-aminotetrazole was obtained by an improved synthesis starting from sodium 5-aminotetrazolate, which is methylated with dimethyl sulfate in dimethyl formamide giving 2-methyl-5-aminotetrazole in 29% yield. Nitrogen-rich salts such as guanidinium (2), 1-aminoguanidinium (3), 1,3-diamino-guanidinium (4), 1,3,5-triamino-guanidinium (5), azidoformamidinium (6), hydrazinium (7), diaminouronium 2-methyl-5-nitraminotetrazolate (8), as well as an urea adduct (9), were prepared by facile deprotonation or metathesis reactions. Diaminourea was synthesized by hydrazinolysis of dimethyl carbonate with hydrazine hydrate. All compounds were fully characterized by vibrational spectroscopy (IR and Raman), multinuclear NMR spectroscopy, elemental analysis, and differential scanning calorimetry (DSC) measurements. The crystal structures of 2-6, 8, and 9 could be determined using single crystal X-ray diffraction. The heats of formation of 2-9 were calculated using the atomization method based on CBS-4M enthalpies. With these values and the experimental (X-ray) densities several detonation parameters such as the detonation pressure, velocity, energy, and temperature were computed using the EXPLO5 code. In addition, the sensitivities toward impact, friction, and electrical discharge were tested using the BAM drop hammer, BAM friction tester, as well as a small scale electrical discharge device.

Sensitivities of some imidazole-1-sulfonyl azide salts.

Imidazole-1-sulfonyl azide hydrochloride, an inexpensive and effective diazotransfer reagent, was recently found to be impact sensitive. To identify safer-to-handle forms of this reagent, several different salts of imidazole-1-sulfonyl azide were prepared, and their sensitivity to heat, impact, friction, and electrostatic discharge was quantitatively determined. A number of these salts exhibited improved properties and can be considered safer than the aforementioned hydrochloride. The solid-state structures of the chloride and less sensitive hydrogen sulfate were determined by single-crystal X-ray diffraction in an effort to provide some insight into the different properties of the materials.

Transition metal complexes of 3-amino-1-nitroguanidine as laser ignitible primary explosives: structures and properties.

3-Amino-1-nitroguanidine (ANQ, 2) was synthesized via hydrazinolysis of nitroguanidine. By dissolving 2 in solutions containing transition metal salts, several complexes M(2+)(ANQ)2X2(H2O)y with M(2+) = Co, Ni, Cu, Zn as well as M(ANQ)2X(H2O)y with M = Ag could be isolated. In these cases, nitrate as well as perchlorate and chloride served as the respective anions X. Additionally, the ANQ complexes of Co, Ni, and Ag with dinitramide as the anion were synthesized from ANQ and silver dinitramide and by reacting the cobalt and nickel ANQ perchlorate complexes with ammonium dinitramide. The crystal structures of all described complexes were determined by low temperature single-crystal X-ray diffraction. Additionally, they were characterized using IR spectroscopy and elemental analysis. The decomposition temperatures were determined by differential scanning calorimetry and the sensitivities toward impact and friction were assessed using a BAM drophammer and a BAM friction tester (BAM = Bundesanstalt für Materialforschung und -prüfung). Additionally, the sensitivity toward electrostatic discharge was determined on a small-scale ESD device. The potential use of the nitrate, dinitramide and perchlorate containing species as primary explosives was investigated in a laser ignition test.

1-Amino-3-nitroguanidine (ANQ) in High-performance Ionic Energetic Materials

1-Amino-3-nitroguanidine (ANQ, 2) was synthesized via hydrazinolysis of nitroguanidine (1). An appropriate Lewis structure of ANQ is drawn based on VB calculations. Due to its basicity, it can be protonated by strong mineral acids or acidic heterocycles. In order to synthesize new energetic materials the nitrate (3) and perchlorate (4) salts of 1-amino-3-nitroguanidine were synthesized by protonation of 2 with 40% nitric acid and 60% perchloric acid, respectively. 5-Nitrimino-1,4H-tetrazole obtained by reacting 5-amino-1H-tetrazole with 100% HNO3 was used to synthesize the nitriminotetrazolate salt 5. Furthermore, the dinitramide salt 6 of 1-amino-3-nitroguanidine was synthesized by metathesis reaction of silver dinitramide and 1-amino-3-nitroguanidinium chloride. The dinitroguanidinate salt 7 was synthesized by protonation of 2 with 1,3-dinitroguanidine, which was prepared from nitroguanidine in anhydrous nitric acid/N2O5. All compounds were fully characterized by singlecrystal X-ray diffraction, vibrational spectroscopy (IR and Raman), multinuclear NMR spectroscopy, mass spectrometry, elemental analysis, and DSC measurements. The heats of formation of 2 - 7 were calculated using the atomization method based on CBS-4M enthalpies. With these values and the experimental (X-ray) densities several detonation parameters such as the detonation pressure, velocity, energy, and temperature were computed using the EXPLO5 code. In addition, the sensitivities towards impact, friction and electrical discharge were tested using the BAM drophammer, friction tester as well as a small-scale electrical discharge device. A Koenen test with 1-amino-3-nitroguanidinium nitrate (3) was carried out in order to evaluate its explosive performance and shipping classification. Graphical Abstract 1-Amino-3-nitroguanidine (ANQ) in High-performance Ionic Energetic Materials

Calcium 5-Nitriminotetrazolate—A Green Replacement for Lead Azide in Priming Charges

The new energetic material calcium 5-nitriminotetrazolate (1) is presented. A facile preparative route in combination with an outstanding thermal as well as long-term stability, easy initiation, and low sensitivity make 1 an auspicious green alternative filler in priming charges.