Studies On The Synthesis And Properties Of BNTF

At present,the focus of the research on the ideal carrier of melt cast explosives is to design and synthesize energetic explosives with rich energy,low sensitivity and low melting point.In order to develop high energy ideal carrier,researchers have optimized the molecular structure of explosives with excellent performance.For example,3,4-Bis(3'-nitrofurazan-4'-furazan)(BNTF)is synthesized by removing coordination oxygen from the molecule of 3,4-dinitrofuran-4'-furazan(DNTF).BNTF has high energy density and thermal decomposition temperature,low melting temperature,good detonation performance and low mechanical sensitivity.It has great potential to replace the traditional explosive 2,4,6-trinitrotoluene(TNT)and develop into an ideal carrier for melt cast explosives.In order to provide a reference for the subsequent process amplification and application performance evaluation of BNTF,the following researches were carried out on the synthesis process,single crystal and energetic properties of BNTF:(1)The synthesis process of 3,4-Bis(3'-aminofurazan-4'-)furazan(BATF)was optimized.In order to avoid the use of strong corrosive and volatile concentrated hydrochloric acid,the green and economic glycerol was used to stabilize the reducing agent Sn Cl₂·2H₂O,which can reduce the synthesis cost and production operation difficulty.The synthesis mechanism of BATF was described in detail,and the structure confirmation spectrums of BATF were obtained.The effects of different reaction conditions on the yield of BATF were investigated.The optimal synthesis conditions were described as follows:n(BAFF):n(Sn Cl₂·2H₂O)=1:3,reaction at 75?for 3 h.The yield of BATF was 63.2%,and the purity was 95.2%(2)BNTF was synthesized by oxidizing BATF with Na₂WO₄·2H₂O as catalyst and 35%H₂O₂as oxidant.The effects of different reaction conditions on the yield of BNTF were investigated.The optimal synthesis conditions were described as follows:n(BATF):n(35%H₂O₂):n(98%H₂SO₄):n(Na₂WO₄·2H₂O)=1:40:30:0.85,reaction at 30?for 3 h.The yield of BNTF is 93.3%,and the purity is more than 95%.The synthetic mechanism of BNTF was described in detail,and the structure confirmation spectrums of BNTF were obtained by testing.(3)The stability of the synthesis process of 100-gram BNTF was studied.The optimum process parameters were obtained:n(BATF):n(Na₂WO₄·2H₂O):n(98%H₂SO₄):n(35%H₂O₂)=1:40:30:0.85,reaction at 25?for 7 h.Three parallel tests were carried out.The yield and purity of BNTF were above 75.0%and95.0%,which indicates that the synthesis process of BNTF is stable and is expected to realize industrial scale-up production.(4)The single crystal structure parameters of BNTF were determined by X-ray single crystal diffractometer:a=0.71437(10)nm,b=0.96839(11)nm,c=1.51555(17)nm,D_c=1.876 g·cm^-3,V=1.0484(2)nm³,Z=4,F(000)=592.The space group of BNTF is P2₁2₁2₁,which belongings to orthorhombic system.The BNTF molecules form chair conformation in space.The van der Waals force and the strong conjugation system make the molecular stack compact,which makes BNTF have good thermal stability and high density;(5)The thermal stability of BNTF was studied by DSC and TG-DTG.The melting point of BNTF is 86.9?,and the thermal decomposition temperature is198.6?.The apparent activation energy E_a(147.83 k J·mol^-1),decomposition rate constant k(2.18×10^-44),pre exponential factor A(9.33×10¹⁵min^-1)and critical temperature of thermal explosion T_b(201.36?)of BNTF were calculated by Kissingerg,Rogers and Arrenhis equations.(6)The molecular structure of BNTF was optimized on the basis set of6-31+G(2df,p H)by using Gauss SHELXL 09 software.The detonation velocity(8.3km·s^-1),detonation pressure(31.3 GPa)and detonation heat(6478.8 J·g^-1)of BNTF were calculated by kamlet-Jacobs equation combined with B3LYP theory.According to GJB772A-1997 method 601.2 and GJB772A-1997 method 602.1,the characteristic drop height H₅₀(85.0 cm/2.5 kg)and friction sensitivity(36.0%)of BNTF were measured.