Design, Synthesis And Performance Study Of Nitroguanidine-based Derivatives

In contrast to the traditional energetic materials, nitrogen-rich energetic compounds are ideal high energy density materials due to their superior detonation properties and higher standard molar enthalpy of formation. In addition, they can be easy to implement oxygen balance and release clean product (N2) during the decomposition process. Therefore, the synthesis of this type of energetic materials has become one of the hottest topics in this area. In this paper, some nitroguanidine-based nitrogen-rich energetic materials were designed and synthesized. Their structures, thermal behavior and energetic properties were also fully characterized and discussed.A series of nitrogen-rich energetic compounds were designed and density functional theory (DFT) calculations at the B3LYP/6-31G(d,p) theoretical level were employed to investigate the relationship between the structures and properties. Take both of the detonation properties and stabilities into consideration,1,2-dinitroguanidine, 1-amino-2-nitroguanidine and 3,7-bis(nitroimino)-2,4,6,8-tetranitro-2,4,6,8-tetraazabicyclo [3.3.0]octane were screened as the potential candidates of energetic materials.1,2-Dinitroguanidine based nitrogen-rich energetic salts were synthesized by acid-base neutralization reaction and metathesis reaction. Their structures, thermal behavior and energetic properties were also fully investigated. The results show that 1,2,3-triaminoguanidinium 1,2-dinitroguanidine salt belongs to the orthorhombic system with the space group of Pna21 and 4-amion-1,2,4-triazole 1,2-dinitroguanidine salt belongs to the monoclinic system with the space group of P21/c; all the salts fully decompose at the temperature range of 50～700℃ and sharp exothermic peaks are observed at the temperature range of 150～258℃; 3,6-diguanidine-1,2,4,5-tetrazine 1,2-dinitroguanidine salt possesses the best thermal stability while 3,6-hydrazine-1,2,4,5-tetrazine 1,2-dinitroguanidine salt has the best energetic properties.1-Amino-2-nitroguanidine based nitrogen-rich energetic salts were synthesized and their structures, thermal behavior and energetic properties were fully investigated. The results show that 1-amino-2-nitroguanidinum nitrate belongs to the triclinic system with the space group of P-1; all the salts fully decompose at the temperature range of 50～700℃ and sharp exothermic peaks are observed at the temperature range of 122～271℃; the melting point of 1-amino-2-nitroguanidinum 2,4,5-trinitroimidazole salt and 1-amino-2-nitroguanidinum 3,5-dinitroare-1,2,4-triazole salt are 142.6 and 93.8℃, respectively; 1-amino-2-nitroguanidinum 3,5-dinitroare-1,2,4-triazole salt has the highest critical temperature of thermal explosion (436.0 K) while 1-amino-2-nitroguanidinum nitrate has the best energetic properties (such as oxygen balance,0; detonation pressure,43.1 GPa; detonation velocity,9.78 km/s).Three energetic materials 7-imino-2,4,6,8-tetraazabicyclo[3.3.0]octane hydrochloride, 3,7-bis(nitroimino)-2,4,6,8-tetraazabicyclo[3.3.0]octane and 2,6-dinitro-3,7-bis(nitroimino)-2,4,6,8-tetraazabicyclo[3.3.0]octane were synthesized. The reaction mechanism and the relative properties were also studied. The results shows that 7-imino-2,4,6,8-tetraazabicyclo[3.3.0]octane hydrochloride belongs to the orthorhombic system with the space group of Pna21; all the compounds fully decompose at the temperature range of 50～700℃ without any melting point and sharp exothermic peaks at the temperature range of 142～320℃ were observed; the critical temperature of thermal explosion of them are 588.5,600.3 and 471.3 K respectively; the calculated detonation properties of 3,7-bis(nitroimino)-2,4,6,8-tetraazabicyclo[3.3.0]octane is equal to those of RDX and the detonation properties of 2,6-dinitro-3,7-bis(nitroimino)-2,4,6,8-tetraazabicyclo[3.3.0]octane is superior to those of HMX. It is demonstrate that both of the two compounds can be considered as candidates of high energy density energetic materials.The N-aminated and N-methylated reactions were investigated on 3,7-bis(nitroimino)-2,4,6,8-tetraazabicyclo[3.3.0]octane by hydroxylamine-O-sulfonicacid and iodomethane. Two important energetic intermediates were also obtained by nucleophilic substitution reaction with bromopropanone and methyl bromoacetate. The results show that 2,6-dioxopropyl-3,7-bis(nitroimino)-2,4,6,8-tetraazabicyclo[3.3.0]octane belongs to the monoclinic system with the space group of P21/c and 2,6-dimethoxycarbonyl-3,7-bis(nitroimino)-2,4,6,8-tetraazabicyclo[3.3.0]octane belongs to the monoclinic system with the space group of C2/c. Besides, the nitration reaction of the two energetic intermediates was also investigated.