4, 4′,5, 5′‐Tetranitro‐2, 2′‐bisimidazole (TNBI) was synthesized by nitration of bisimidazole (BI) and recrystallized from acetone to form a crystalline acetone adduct. Its ammonium salt (1) was obtained by the reaction with gaseous ammonia. In order to explore new explosives or propellants several energetic nitrogen‐rich 2:1 salts such as the hydroxylammonium (3), guanidinium (4), aminoguanidinium (5), diaminoguanidinium (6) and triaminoguanidinium 7 4, 4′,5, 5′‐tetranitro‐2, 2′‐bisimidazolate were prepared by facile metathesis reactions. In addition, methylated 1, 1′‐dimethyl‐4, 4′,5, 5′‐tetranitro‐2, 2′‐bisimidazole (Me2TNBI, 8) was synthesized by the reaction of 2 and dimethyl sulfate. Metal salts of TNBI can also be easily synthesized by using the corresponding metal bases. This was proven by the synthesis of pyrotechnically relevant dipotassium 4, 4′,5, 5′‐tetranitro‐2, 2′‐bisimidazolate (2), which is a brilliant burning component e.g. in near‐infrared flares. All compounds were characterized by single crystal X‐ray diffraction, NMR and vibrational spectroscopy, elemental analysis and DSC. The sensitivities were determined by BAM methods (drophammer and friction tester). The heats of formation were calculated using CBS‐4M electronic enthalpies and the atomization method. With these values and mostly the X‐ray densities different detonation parameters were computed by the EXPLO5 computer code. Due to the great thermal stability and calculated energetic properties, especially guanidinium salt 4 could be served as a HNS replacement.
4‐Amino‐3,5‐dinitroaniline (3) was synthesized by fluorine/amine exchange of 4‐fluoro‐3,5‐dinitroaniline in ethanol. 4‐Diazo‐2,6‐dinitrophenol (Iso‐DDNP, 4) was obtained after nitration in HNO3 (100 %) and acetic anhydrid. 4‐Amino‐2,3,5‐trinitrophenol (7) was obtained by nitration of N‐(4‐acetoxyphenyl)acetamide and deprotection of the amine. Further nitration resulted in 6‐diazo‐3‐hydroxy‐2,4‐dinitrophenol (8). The thermal stability and sensitivity of 4 and 8 toward impact and friction was compared to commercially used DDNP (2‐diazo‐4,6‐dinitrophenol). All target compounds were characterized by single‐crystal X‐ray diffraction, NMR and elemental analysis and DSC. The sensitivities were determined by BAM methods (drophammer and friction tester). The heats of formation were calculated by using CBS‐4M electronic enthalpies and the atomization method. Various detonation parameters such as detonation velocity and pressure were computed by using the EXPLO5 computer code V6.01.
Several 3,6-disubstituted 1,2,4,5-tetrazines were synthesized by nucleophilic substitution using 3,6-bis-(3,5-dimethyl-pyrazol-1-yl)-1,2,4,5-tetrazine and 3,6-dichloro-1,2,4,5-tetrazine as electrophiles. All new compounds were characterized by 1 H NMR, 13 C NMR and vibrational spectroscopy, mass spectrometry and elemental analysis (C,H,N). For analysis of the thermostability, differential scanning calorimetry (DSC) was used. Especially, the symmetrically bis-3,5-diamino-1,2,4-triazolyl-substituted derivative shows a very high thermal stability up to 370 • C. Therefore its energetic properties were determined and compared with thoses of hexanitrostilbene (HNS). The crystal structures of 3,6-bishydrazino-1,2,4,5-tetrazine, 3,6-dichloro-1,2,4,5-tetrazine and 3-amino-6-(3,5-diamino-1,2,4-triazol-1-yl)-1,2,4,5-tetrazine dihydrate have been determined by low-temperature X-ray diffraction.
Abstract2‐Nitrimino‐5,6‐dinitrobenzimidazole (1) was synthesized by nitration of 2‐aminobenzimidazole at ambient temperature in good yield. In order to explore new insensitive explosives four energetic nitrogen‐rich 1 : 1 salts such as the guanidinium (1a), aminoguanidinium (1b), triaminoguanidinium (1c) and hydroxylammonium (1d) were synthesized either by facile acid/base or in situ metathesis reaction. In addition 2‐nitrobenzimidazole (2) was synthesized by the reaction of 2‐aminobenzimidazole using potassium hyperoxide in THF. Different nitration methods were tested to obtain a theoretically 2,4,5,6,7‐pentanitrobenzimidazole but only the already known 4,5,6,7‐tetranitrobenzimidazol‐2‐one (3) could be isolated. All synthesized compounds were characterized especially by low temperature X‐ray diffraction, CHN elemental analysis and 1H and 13C NMR spectroscopy. The heat of formation of all new synthesized compounds was calculated using CBS‐4M electronic enthalpies in combination with the atomization method to calculate their detonation parameters with the EXPLO 5 V5.05 computer code.
The diazophenols 3-amino-6-diazo-2,4-dinitrophenol (4) and 3-chloro-6-diazo-2,5-dinitrophenol (8) were synthesized and comprehensively characterized. The regio-selectivity of nitration reactions with N,NЈ-(1,4-phenylene)dimethanesulfonamide (1) and N,NЈ-(1,4phenylene)diacetamide (6) was investigated in detail. The purity of the products was confirmed via low temperature X-ray diffraction, multinuclear NMR spectroscopy, and elemental analysis. Moreover, the * Prof. Dr. T. M. Klapötke
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