Synthesis And Properties Of Nitrogen-rich Heterocycle Based On Triazole Fused With Tetrazine

1,2,4,5-tetrazine compounds are a new kind of energetic compounds,with good performance of high nitrogen content,high formation enthalpy,and the explosive products are environmentally friendly.However,there are two major problems with the currently reported 1,2,4,5-tetrazine energetic compounds(except for a small amount of salt and fused ring compounds): one is the density is lower than 1.80 g cm-3,and detonation performance is not as good as RDX,the second is due to the fact that little oxygen-containing groups are contained,resulting in the oxygen content of the compound is insufficient to completely oxidize the combustible elements(mainly nitrogen-rich heterocyclic skeleton);The results show that the compound density of the nitrogen-rich fused ring is very high;the introduction of nitro group and ligand oxygen on the skeleton can improve the density and explosive properties of the compound.Based on this,the paper has carried out four aspects of research work.(1)3,6-bis(3,5-dimethyl-1H-pyrazol-1-yl)-1,2,4,5-tetrazine(BT)was synthesized in turn cyclization reaction,oxidation reaction,using 1,2,3-triaminoguanidinium chloride and acetyl acetone as the raw materials.Different experimental conditions,such as the synthetic methods,molar ratio of reactants,temperature and reaction time,on BT purity and yield were investigated and discussed.The better experimental conditions were obtained.(2)3,6-diamino-1,2,4-triazole-[4,3-b] [1,2,4,5] tetrazine(AATZ)was synthesized by nucleophilic substitution reaction and ring-forming reaction using BT as raw material,the synthesis process was optimized and improved,and the better synthetic process and reaction conditions were obtained.(3)To obtain AATZ derivatives with higher density and better explosion performance,3,6-dinitro-1,2,4-triazolo-[4,3-b][1,2,4,5]tetrazine(BNTZ),3,6-dinitramino-1,2,4-triazolo-[4,3-b][1,2,4,5]tetrazine(NATZ)and AATZ nitrogen oxides AAZTOn,the methods of introducing nitro and ligand oxygen on AATZ structure were investigated.A research idea for the introduction of nitro and coordination oxygen on the structure of tetrazine compounds was provided.(4)Structural optimization and frequency calculations on the 1,2,4,5-tetrazine compounds were performed at the B3LYP/6-31G* level in Gaussian 09 program.The stable configuration and thermodynamic constants of each compound were obtained,then the theoretical density,detonation velocity and detonation pressure were calculated according to these data.Theoretical calculation shows that AATZ and its derivatives can be used as a potential energetic material.