The Synthesis Process For The Intermediates Of DNTF

Furazan compounds have merits of energy density, high standard enthalpy offormation, high nitrogen content, etc. Thus Furazan compounds are being investigatedintensively in recent years.3,4-bis (4’-nitrofurazano-3’-yl) furoxan (DATF) is a typical highenergy furazan based explosive, its synthesis process can be devided into three steps, with3-amino-4-amino ximino furazan (AAOF) and3,4-bis (4’-aminofurazano-3’) furoxan(DATF) as the two intermediates.In this study, AAOF was synthesized using malononitrile as the starting material. Thesynthetic process was tracked by on-line infrared technique to investigate how processconditions affected product yield. Thus the optimized reaction conditions were determinedas following: shorten the rearrangement time to0.5h, omitted both neutralization andoximation steps, shorten ring closure reaction time to40min, and changed the addition ofsodium nitrite as aqeous solution, and keeping the reaction temperature as27℃. Underthese conditions, the yield of AAOF was higher than96%, the time of the whole reactioncan be greatly reduced to3h from10h. The synthetic process of AAOF was tracked byon-line infrared technique to investigate how the reacting compnoents change in thesynthesis process to investigate the reaction mechanism. The single crystal was obtained byslow evaporation from ethanol. The achieved crystal structure of AAOF was characterizedby X-ray diffraction. Its crystal is monoclinic, space group P21/c, with a=0.7634(4) nm,b=1.154(2) nm, c=1.911(7) nm, V=1.6730nm3,Z=12, Dc=1.681g/cm3, the molecule ofAAOF has planar structure and inter-molecular hydrogen bonding in the crystal. In addition,the structure of AAOF was calculated by density functional theory (DFT) at b31yp/6-311+g(d, p) level using Gaussian09. The optimized geometry of AAOF showed that there wereno imaginary frequencies, leading to the stable potential energy surface, and the relatedcharge distribution and orbital information were achieved as well.DATF was synthesized using AAOF as the starting material, and the synthetic processwas investigated to understand how process conditions affected product yield. Thus theoptimized reaction conditions were determined as following: the molar ratio of the raw material AAOF with NaNO2was optimized to1.03, the molar ratio of dichloromethane and AAOF was0.6, the cycloaddition reaction time was4h, which could inevitably increase the reaction efficiency and lower the production cost of the whole synthetic process with the overall yield of DATF higher than50%. The thermal decomposition of DATF was studied by DTG and the result showed that the melting point of DATF was166.15℃, the peak temperature of the exothermic peaks was264.67℃, and the kinetic parameters of thermal decomposition reaction, the activation energy and pre-exponential factor are97.1/kJ·mol-1and108.82s-1respectively, and the kinetic equations of exothermically decomposition reaction can be expressed as Meanwhile, DATF was also investigated with DFT calculations at b31yp/6-311+g (d, p) level using Gaussian09. The optimized geometry of DATF showed that there were no imaginary frequencies. The transition state for the final step in the synthesisof DATF, namely1,3-dipolar cycloaddition was calculated by Gaussian09to investigate the initial reaction path.