A theoretical and experimental study of the thermal decomposition of nitroguanidine(NQ)has been carried out. Various thermolysis channels were studied by quantum chemistry methods at the CCSD(or DLPNO-CCSD)level using the aug-cc-pVDZ basis set. It is shown that the lowest activation enthalpies(170—180kJ/mol)are characteristic of the reactions of NO2 abstraction from the initial NQ and the reaction channel with the transfer of oxygen from the nitro group to carbon in the limiting stage. Additionally, the thermolysis of NQ was studied experimentally in a nonisothermal mode with heating rates from 1 to 10K/min. In these experiments, the weight loss of the sample, thermal effects, and mass spectra of the products were recorded. An analysis of the experimental data confirmed the results of a theoretical study of the mechanism of thermal decomposition of NQ. The main thermolysis products are N2O, HNCO, NH3, and NO2, which fully corresponds to quantum chemical calculations.
A family of ethylene-bridged energetic compounds containing 4-amino-3,5-dinitropyrazolated moiety and diverse explosophore groups were designed and synthesized by using 4-bromo-3,5-dinitropyrazole as raw material. The structures were characterized by NMR and single crystal X-ray diffraction. Their thermal decomposition properties were measured and detonation performances were predicted by Gaussian 09 program and EXPLO5 software. The results show that these new energetic compounds exhibit good thermal stability with thermal decomposition temperature ranging from 167.3℃ to 294.1℃, and low mechanical sensitivities with impact sensitivity not less than18J and friction sensitivity not less than 240N. The theoretical detonation velocity and detonation pressure are ranging from 7939 to 8448m/s and 25.0GPa to 30.8GPa, respectively.
