Synthesis, Structure And Property Characterization Of Several Imidazole And Triazole Energetic Compounds

As the high nitrogend and stable energetic materials,azole derivatives including imidazole,triazole and a novel bridged-bis-triazole energetic compound were selected to be studied.The synthesis method,thermal analysis,impact and fiction sensitivity and explosive performance were summarized as follows:（1）Methylhydrazine and dicyandiamide were selected as row materials to preparing 1-methyl-3,5-dinitro-1,2,4-triazole（DNMT）in a two-step synthetic method via condensation cyclization and oxidation reaction.The scalable synthesis technology of this compound has been improved by dripping catalyst.In this process,the optimal technological conditions have been obtained on the condition of the optimized parameter by single factor experiment.The overall yield and purity was raised to 43.1%and 98.68%.On the basis of that,the synthetic technology has been further improved.Also Methylhydrazine and dicyandiamide were also used as row materials to synthesize DNMT in a one-pot synthetic method.Also,the scalable synthesis technology of this compound has been improved too.That is,methylhydrazine solution（260 g,40%）,dicyanodiamide（225 g）,nitric acid（310 g,65%）,hydrogen peroxide（800 mL,50%）and water（300 mL）,65⁹0℃ for 10 h.By this one-pot synthesize method,the overall yield was further raised to 55.2%,the synthesis period was dramatically shortened,the consumption of raw materials and acid wastewater were released.In addition,purity analysis method of DNMT based on high performance liquid chromatography（HPLC）has been established.Results show that under the optimized chromatographic conditions,the calibration curves of DNMT and 1-methyl-3-nitro-1H-1,2,4-triazol-5-amine（NAMT）have good linearity,and the linear correlation coefficient r is greater than 0.999.The relative standard deviations are between 0.44 and 1.01%.A surfactant has been applied to modify the surface appearance and crystal of DNMT.Result showed that the melting point of modified DNMT was advanced by about 2℃,which would contribute to be melted.The DNMT crystal has been prepared,DNMT crystallized in the monoclinic P2₁/C space group with eight molecules in a unit cell.Testing at temperature of 293 K,the crystal density was 1.697 g·cm^–1and cell volume was 1354.87?.FT-IR,multinuclear(¹H,¹³C)NMR spectroscopy,elemental analysis has been used to analyze the molecular structure.Differential thermal analysis（DTA）has been used to analyze thermal properties,and the mechanic sensitivity has also been tested.Result showed that there were an endothermic peak at 93⁹5℃ and an exothermic peak at 288.7℃ in the DTA curve,the explosion rate of fiction sensitivity was 40%and impact sensitivity was 92.7 cm.（2）Choosing N-methylimidazole as raw material,one-pot efficient synthesis of 1-methyl-4,5-dinitroimidazole（MDNI）has been achieved by utilizing a new improved nitration system in the condition of super strong acid.This method contributed to scalable synthesis of MDNI for the reaction time has been shorted to 2.5 h.In this research,single factor experiment has been explored and the optimal technological conditions have been obtained.That is,5 g N-melthylimidazole,100 mL mixed acid,110℃ for 2.5 h.The overall yield and purity was raised to 78.7%and 98.2%.The MDNI crystal has been prepared,MDNI crystallized in the orthorhombic Pna21 space group with four molecules in a unit cell.Testing at temperature of 295 K,the crystal density was 1.627 g·cm^–11 and cell volume was 702.51?.FT-IR,multinuclear(¹H,¹³C)NMR spectroscopy,elemental analysis has been used to analyze the molecular structure and purity.Differentialthermal analysis（DTA）has been used to analyze thermal properties,and the mechanic sensitivity has also been tested.Result showed that there were an endothermic peak at 75℃ and a exothermic peak at 278.7℃ in the DTA curve,the explosion rate of fiction sensitivity was 5%and impact sensitivity was 87.0 cm.（3）2-aminoimidazole hemisulfate were chosen as row materials to prepare a novel energetic compound 2-nitroimidazole perchloric salt（2-NIP）via neutralization reaction.The 2-NIP crystal has been prepared,2-NIP crystallized in the orthorhombic P2₁2₁2₁ space group with four molecules in a unit cell.Testing at temperature of 296 K,the crystal density was 1.890 g·cm^–11 and cell volume was 750.4?.Differential thermal analysis（DTA）has been used to analyze thermal properties,and the mechanic sensitivity has also been tested.Result showed that there was an endothermic peak at 174.2℃ and exothermic peak at 296.2℃ in the DTA curve,the explosion rate of fiction sensitivity was 0%and impact sensitivity was 90.5 cm.（4）1-methyl-3-amino-5-nitro-1,2,4-triazole（MNTA）and 5-amino-3-nitro-1,2,4-triazole（ANTA）were chosen as row materials to prepare a novel bridged-bis-triazole energetic compound2’-methyl-3-nitro-2’H-[1,3’-bi（1,2,4-triazole）]-5,5’-diamine（MNBTO）via ucleophile substitution reaction.In this study,single factor experiment has been explored and the optimal technological conditions have been obtained on the condition of the optimized parameter.That is,MNTA（0.715 g,5.0 mmol）,ANTA（0.65 g,5.0 mmol）,60℃ for 3 h.The overall yield and purity was 18.2%and 97.7%.FT-IR,multinuclear(¹H,¹³C)NMR spectroscopy,elemental analysis,HPLC has been used to analyze the molecular structure and purity.Differential thermal analysis（DTA）has been used to analyze thermal properties,and the mechanic sensitivity has also been tested.Result showed that there was an exothermic peak at 235.6℃ in the DTA curve,the explosion rate of fiction sensitivity was 10%and impact sensitivity was 82.5 cm.（5）The density functional theory（DFT）method has been used to study the quantitative calculation of target product（MNBTO）.The geometric optimization has been obtained with B3LYP functional on the 6-31+G**basis set,molecular structure were proved to be true local energy minima on the potential energy surface without existing imaginary frequencies.Methods to predict the objective compound density was explored.The enthalpy of isodesmic reaction（ΔH_f⁰）was calculated by based on the scaled zero-point energies,the MP2/6-311++G^**energy difference for the reaction and other thermal factors.The enthalpy of formation（HOF）for the objective compound 2-NIP and MNBTO have been obtained,and relative explosive parameter has been calculated based on the Kamlet-Jacobs method.The result showed the HOF、detonation velocity and detonation pressure of 2-NIP and MNBTO were+330.62 kJ·mol^-1、7.24 km·s^-1、22.7 GP and+369 kJ·mol^-1、7.52 km·s^-1、25.4 GPa respectively.