Synthesis And Properties Of 3,5-Dinitro-1,2,4-Triazole Derivatives

The energetic compound 3,5-dinitro-1,2,4-triazole（DNT）has excellent energy properties,but its sensitivity and acidity limit its application.In order to eliminate this limitation,new derivative derived from 3,5-dinitro-1,2,4-triazole:1-difluoromethyl-3,5-dinitro-1,2,4-triazole（FMNTZ）and 3,5-dinitro-1,2,4-triazole hydroxylamine salts（DNT hydroxylamine salts）were synthesized by introducing difluoromethyl and hydroxylamine ions into DNT respectively.Compared with DNT,the energy properties,sensitivity and acidity of the two derivatives were improved.The thesis mainly completed the following parts of work:（1）The substructures of FMNTZ and DNT hydroxylamine salt were optimized by Using Gaussian 09 in the B3LYP/6-311G*basis group of density functional theory,and the molecular bond length,Mayer bond order,Hirshfeld atomic charge,molecular surface electrostatic potential distribution and electrostatic potential parameters were obtained.The theoretical density of FMNTZ is 1.923 g·cm^-3,the theoretical detonation velocity is 9.547km·s^-1,and the theoretical detonation pressure is 42.03 GPa.The theoretical density of DNT hydroxylamine salt is 1.910 g·cm^-3,the theoretical detonation velocity is 9.081 km·s^-1,and the theoretical detonation pressure is 37.86 GPa.The results showed that the introduction of difluoromethyl or hydroxylamine ions did not affect the stability of the product molecule and the distribution area of positive and negative electrostatic potential on the surface.The detonation performance of the derivatives is better than that of 3,5-dinitro-1,2,4-triazole（DNT）when difluoromethyl or hydroxylamine ions are introduced.（2）The correct synthesis route of 1-difluoromethyl-3,5-dinitro-1,2,4-triazole（FMNTZ）was selected.FMNTZ was synthesized from 3,5-dinitro-1,2,4-triazole（DAT）by difluoromethylation,diazotization and substitution reaction with the yield of 81%.The thermal performance of FMNTZ was tested and analyzed,and the thermal decomposition peak temperature of FMNTZ was 346.8℃.The thermal decomposition curves with heating rates of 5,10,15 and 20℃·min^-1were obtained and the kinetics of non-isothermal thermal decomposition was studied.The apparent activation energy,activation enthalpy,activation entropy and activation Gibbs free energy were 144.27 k J·mol^-1,142.07 k J·mol^-1,-36.57k J·mol^-1and 164.93 k J·mol^-1respectively by using F-W-O method and Kissinger method.The mechanical sensitivity of the product was tested.The characteristic drop height H₅₀was78 cm,and the probability of friction sensitivity explosion was 18%.The optimum synthesis conditions were as follows:reaction temperature 60℃,reaction time 1 h,molar feeding ratio of 1-difluoromethyl-3,5-diamino-1,2,4-triazole to sodium nitrite 1:2.2.The results show that the introduction of difluoromethyl and the properties of fluorine make the product more stable,so that the decomposition temperature and thermal properties of FMNTZ are at a higher level,and the mechanical sensitivity is lower.According to orthogonal experiment,reaction time is the main factor affecting FMNTZ yield,followed by feed ratio and reaction temperature.（3）DNT hydroxylamine salt was synthesized from 3,5-diamino-1,2,4-triazole（DAT）by diazotization,substitution and hydroxylamine reaction,with a yield of 47%.The thermal properties of DNT hydroxylamine salt were tested and analyzed,and its thermal decomposition peak temperature was 357.3℃.The mechanical sensitivity of DNT hydroxylamine salt was tested.Its characteristic drop height H₅₀was 74 cm,and the probability of friction sensitivity explosion was 24%.The results show that the introduction of hydroxyl ion makes the decomposition temperature of DNT hydroxylamine salt at a higher level,and the mechanical sensitivity is lower.The properties of the two products were compared with DNT and several common explosives.The results show that the synthesis of FMNTZ and DNT hydroxylamine salt can effectively improve the detonation performance,mechanical sensitivity and acidity of DNT.Both FMNTZ and DNT hydroxylamine salt are heat-resistant and insensitive energetic compounds with good performance.（4）The DSC curves of RDX,HMX and LLM-105 at different heating rates were measured by DSC tester.Meanwhile,the DSC curves of FMNTZ and RDX,HMX and LLM-105 at different heating rates were measured by mixing the mass ratio of FMNTZ with RDX,HMX and LLM-105 at 1:1.The compatibility of energetic compounds was evaluated according to the thermal decomposition temperature and the calculated thermal dynamic parameters.The results show that the molecular structures of RDX,HMX and LLM-105 are unstable due to the interaction of fluorine atoms in FMNTZ,and their compatibility with RDX,HMX and LLM-105 is poor.