Synthesis And Properties Of Energetic Compounds Based On Tetrazine Fused Ring

Tetrazine fused ring compounds have multiple rings that exist in a coplanar plane and also a conjugated system.They usually exhibit higher density and better molecular stability.Due to the existence of ring tension,they have a higher positive enthalpy of formation.Thus,it exhibits better energetic performance.This paper attempts to synthesize nitroguanidine-tetrazine fused ring,furazane-tetrazine fused ring,then optimize the reaction conditions.All new compounds were well characterized and the detonation performances were evaluated.In this paper,3,6-bis(3,5-dimethylpyrazole)-s-tetrazine(BT)was synthesized as the original material.After a seris of reactions,3-amino-6-(3,5-dimethylpyrazole)-1,2,4-triazole[4,3-b][1,2,4,5]tetrazine was synthesized.Under basic conditions,nitroguanidine was connected with tetrazine fused ring.All new compounds were well characterized by infrared radiation and multinuclear nuclear magnetic resonance spectroscopy.Then we explored the best condition which is to add Na H to DMF at25°C,feed according to n(Na H):n(nitroguanidine)=10:7,magnetically stir for 30min,then add AHTZ,according to n(nitroguanidine):n(AHTZ)=2:1,keep at 25?for 1 h.In this paper,we have investigated an efficient synthesis strategy for the preparation of nitramino-furazan-functionalization fused energetic compounds so as to improve the stability and performance of these compounds.All new compounds were well characterized by infrared radiation and multinuclear nuclear magnetic resonance spectroscopy,thermal analysis.Parts of them were further determined by using single crystal X-ray diffraction.The reaction conditions were optimized,and the optimal synthesis conditions were that at 25°C,Na H was added to the DMF and the material was fed according to n(Na H):n(DAF)=2:1.The magnetic stirring time was performed for 25min,and then AHTZ was added at n(DAF):n(AHTZ)=2:1,keep at 25°C for 1 h.In this paper,the amino groups on the new furazine-tetrazine were transformed into nitroamino group through pure nitric acid and made into different energetic salts to improve their energetic performance.Parts of them were further determined by using single crystal X-ray diffraction.As supported by experimental and theoretical data,these fused organic salts possess good densities of 1.73 to 1.85 g·cm^-3,and high enthalpies ranging from 49.3%to 61.2%,higher than RDX(37.8%)and HMX(37.8%).Their formation enthalpy is 415.2 to 1295.3 k J·mol^-1,which are higher than RDX(70.3 k J·mol^-1)and HMX(70.4 k J·mol^-1),thereby exhibiting excellent detonation velocities of 7775 to 9368 m·s^-1 and detonation pressures of 22.7 to 37.6GPa.Among them,the dihydroxylammonium salt exhibits the best detonation performance(D:9366 m·s^-1;P:37.6 GPa),comparable to the powerful explosive HMX(D:9144 m·s^-1;P:39.2 GPa).