The Synthesis And Performance Of 5,5'-bis(2,4,6-trinitrophenyl)-2,2'-bis(1,3,4-oxadiazole)

5,5'-bis?2,4,6-trinitrophenyl?-2,2'-bis?1,3,4-oxadiazole??TKX-55?is a new type of thermally stable explosive.It has high density,high energy,high decomposition temperature,etc.Its comprehensive performance is better than 2,2',4,4',6,6'-hexanitrostilbene?HNS,hexanitroguanidine?and 2,6-di?picrylamino?-3,5-dinitropyridine?PYX?,and it is in a high temperature environment for a long time,and has a very stable underwater detonation ability and jet penetration ability.In 2016,TKX-55 was synthesized for the first time in foreign countries,but it has shortcomings such as long reaction cycle,high energy consumption,and environmentally friendly reagents,and there are few reports on its synthesis and application literature.Therefore,this study intends to lay the foundation for the industrial production and application of TKX-55 in China by improving and optimizing the synthesis process of TKX-55.In this study,TKX-55 was synthesized by 4-nitrotoluene as raw material by nitrification,oxidation,chlorination,condensation and cyclization.The melting point determination,infrared spectroscopy,mass spectrometry,elemental analysis,TLC and other methods were used for characterization and analysis.The improved process was as follows:?1?2,4,6-trinitrotoluene?TNT?was synthesized by one-step 4-nitrotoluene;?2?a saturated aqueous solution of sodium chlorate was used instead of sodium chlorate as an oxidant in the oxidation reaction;?3?chlorination in the reaction,the chlorinating agent phosphorus oxychloride?POCl₃?was replaced by thionyl chloride?SOCl₂?;?4?the acid binding agent N,N-dimethylformamide?DMF?was added to the condensation reaction.The optimized process conditions are as follows:?1?Nitrification reaction:4-nitrotoluene as raw material,molar ratio of nitrate to sulfur mixed acid n?NA?:n?SA?=1:3.5,reaction temperature is 110°C,reaction time is 4 h;?2?Oxidation reaction:using 2,4,6-trinitrotoluene?TNT?as raw material,n?TNT?:n?NaClO3?=1:4,reaction time is 4 h,reaction temperature is 90°C;?3?Chlorination reaction:using 2,4,6-trinitrobenzoic acid?TNBA?as raw material,thionyl chloride as chlorinating agent and N,N-dimethylformamide as catalyst,the reaction temperature is 75°C,reaction time is 45 min;?4?condensation reaction:2,4,6-trinitrobenzoyl chloride?TNBC?and oxalyl dihydrazide as raw materials,tetrahydrofuran?THF?as solvent,N,N-dimethylformamide is an acid binding agent,the reaction temperature is 35°C,the reaction time is 36 h;?5?bis?2,4,6-trinitrobenzoyl?oxalyl hydrazide as a raw material,fuming Sulfuric acid?20%?is the reaction solvent,the reaction temperature is 45°C,and the reaction time is 24 h.The total yield of TKX-55 was calculated by calculation to be 63.5%.In this study,the DSC spectra of different heating rates were calculated by Kissinger method,Ozawa method,Starink method,atomization method and Kamlet-Jacob formula to calculate the non-isothermal temperature of TKX-55,such as enthalpy of formation,apparent activation energy and critical temperature of thermal explosion.Kinetic parameters,the 5s explosion temperature is calculated by least squares method and its thermal stability and detonation properties were investigated.The calculation results show that the decomposition peak temperatures of TKX-55 at 5°C is 365.5°C,when the heating rate is close to 0,the decomposition peak temperature T_po is 335.25°C,the apparent activation energy E_a is 340.03kJ.·mol^-1,Gibbs free energy?G is 205.71 kJ·mol^-1,the 5s explosion temperature is T=518.86K,detonation speed is D_TKX-55=8.069 km·s^-1,detonation pressure is P_TKX-55=28.7 GPa.The calculation results show that TKX-55 is a new type of thermally stable explosive with good thermal stability.