Design,Synthesis And Properties Of Novel Energetic Materials Based On Pyrazolo[1,2,3]Triazine-2-oxide

According to the different functions,explosives can be be divided into high explosives,primary explosives,percussion and stab detonators,and propellant powder,etc.Different types of explosives need to meet different application performances,such as primary explosives need to achieve the transition from deflagration to detonation very quickly,and the deferred explosives must be able to control the combustion time stably and accurately.Although there are some differences in property parameters,there is a consistent goal in the application of explosives,which is to ensure high efficacy,high energy,high safety,environmental protection,and process operability.In recent years,the design and synthesis of new energetic molecules based on nitrogen-rich fused ring skeleton has become an important research direction to achieve the above goal.In this thesis,the design and synthesis of novel fused-ring energetic molecules based on pyrazolo[1,2,3]-triazine-2-oxide framework were studied,and a variety of novel energetic molecules with excellent properties were obtained,including the organic primary explosive ICM-103,two-dimensional(2D)layered explosive NAPTO and heat-resistant explosive MPTO.The main research contents include:1、Design,synthesis and application of a novel organic primary explosive ICM-103Using 3-amino-4-cyano-1h-pyrazole as the starting material,the synthesis of fused ring and the introduction of energetic functional group were combined into one step by "one-pot method",and the binary fused-ring primary explosive,6-nitro-7-azido-pyrazolo[3,4-d][1,2,3]triazine-2-oxide(ICM-103),which met the standard of green primary explosives,was obtained in high yield.The mechanism of ring formation is studied,and its energetic and safety performances are calculated theoretically and measured experimentally.The results show that the limit initiation charge of ICM-103 is 60 mg,the thermal decomposition temperature reaches 160℃,and ICM-103 has specific sensitivity to flame stimulus(it’s impact sensitivity,friction sensitivity and electrostatic spark sensitivity are 4 J,60N and 135 mJ respectively,but it’s flame sensitivity is better than 60 cm).Moreover,it has good compatibility with iron and RDX.It is not sensitive to light,and has no biological toxicity.The production process optimization and process documents of 100 grams scale are achieved,and the feasibility of using it as the primary explosive in 8#industrial detonator is evaluated.2、Design,synthesis and properties of a novel 2D planar high explosive NAPTOFor a long time,the design and synthesis of new insensitive high explosives has been an important challenge in the field of energetic materials.Based on 4-amino-3-cyanopyrazole as the starting material,a new fused-ring energetic material,4-nitro-7-azidopyrazozo[3,4-d][1,2,3]-triazine-2-oxide(NAPTO),was designed and synthesized by a two-step reaction.The structure characterization and sensitivity test were completed.Single crystal X-ray diffraction analysis shows that the compound has a 2D superflat layered structure,belonging to orthorhombic crystal system,Pnma(no.62)space group,with cell parameters of a=13.307(3)A,b=5.7100(13)A,c=10.531(3),α=β=γ=90°,V=800.2(3)A3,Z=4,D=1.852 g·cm-3.Theoretical and experimental studies showed that the energetic molecule has a high energy level(detonation velocity DV=9.12 km·s-1,detonation pressure P=35.1 GPA),and is relatively insensitive to impact,friction,heat and other external stimuli(impact sensitivity 18 J,friction sensitivity 325 N,electrostatic spark sensitivity 0.32 J,thermal decomposition temperature 203.2℃),achieving a good balance between energy and safety.The mechanism of stabilization was studied by theoretical calculation.The results showed that the superflat 2D layered structure in the crystal can absorb and dissipate the external stimuli by transforming the mechanical energy acting on the material into interlayer sliding and compression,and relying on the hydrogen bond and dipole-dipole interaction,which can buffer the external mechanical stimulation more effectively than other structures,and better explain the synergistic desensitization mechanism of the 2D layered structure in the crystal.3、Design,synthesis and properties of heat resistant explosive MPTOThrough the construction of the binary fused ring structure substituted by the ortho azide group and the nitro group(the azide group and the nitro group are located on two different rings respectively),then the azide group is reduced to amino group,and finally the binary fused ring heat-resistant explosive 4-amino-7-methyl-5-nitro-pyrazozo[3,4-d][1,2,3]triazine-2-oxide(MPTO)with the ortho amino and nitro group structure located on two different rings is obtained.The stability of MPTO is high,which shows that the thermal decomposition temperature is 350℃ the impact sensitivity is 18 J,and the friction sensitivity is 360 N.It is found that the high stability of MPTO is determined by the strong intramolecular hydrogen bonding and intermolecular π-π interaction.The bond dissociation energy of C-NO2 adjacent to amino group in the molecular structure of several high thermal decomposition temperature explosives were compared by the method of quantitative calculation.The bond dissociation energy of C-NO2 in MPTO is 284.49 kJ·mol-1,which is only 3 kJ·mol-1 lower than the corresponding value of TATB,and significantly higher than the calculated value of other substances.This shows that the chemical stability of MPTO is excellent.On the other hand,the Hirshfeld surface analysis and two-dimensional fingerprint spectrum are used to analyze several kinds of high thermal decomposition temperature single explosives.Among them,the ratio of intermolecular π-π interaction of MPTO is as high as 16.6%,which is higher than that of other energetic materials.At the same time,the ratio of intermolecular hydrogen bond interaction of MPTO is also as high as 52%,which shows that MPTO has strong intermolecular hydrogen bond interaction and strong π-π phase interaction,which are of great significance for the reduction of its mechanical sensitivity.