Studies On The Synthesis Of New Energetic Compounds Based On Pyrazole And Triazole

The large number of energetic C-N,C=N,N-N and N=N bonds in the azole compounds supports high positive enthalpy of formation and high density,which has become the main structural motifs in the design and synthesis of new high energy density materials(HEDMs).However,there is an essential contradiction between the energy and sensitivity.The higher the energy and the higher the sensitivity.In recent years,researchers have devoted lots of work to the pursuit of new energetic compounds with high energy,low sensitivity and good thermal stability.In this paper,pyrazole and1,2,4-triazole are used as the molecular backbone to synthesize a number of high energy and low sensitivity compounds.This peper is mainly divided into the following three parts:1.Studies of synthesis and properties on the energetic metal salts based on nitropyrazole backbone and dinitromethyl group3-Nitro-4-dinitromethypyrazole potassium(116)or sodium(117)were synthesized from 3-amino-4 cyanopyrazole as starting material through oxidation,amine oximation,chlorine oximation,nitration and reduction.The structures of the two compounds were characterized by ¹H NMR,¹³C NMR,IR,DSC and single crystal X-ray diffraction.The detonation properties were estimated by theoretical calculation.The priming ability of compound 116 was studied and the result indicated that compound 116 could be used as a substitute for traditional priming explosive-lead azide.2.Studies on synthesis and properties of 3-nitro-4-dinitromethypyrazole and its organic salts3-Nitro-4-dinitromethypyrazole(119)was obtained by acidizing potassium 3-nitro-4-dinitromethypyrazole.A series of nitrogen-rich energetic organic salts(119a-d)featuring 3-nitro-4-dinitromethypyrazole were synthesized by facile deprotonation or metathesis reactions with different nitrogen-rich bases or salts.Structural characterization,safety performance testing and theoretical calculation of detonation performance were carried out for these new compounds.The structure of compounds of 119 and 119a were analyzed by single crystal diffraction.The experimental measurements and theoretical calculations confirm that the ammonium salt 119a has a higher density,greater detonation performance,higher decomposition temperature,and lower impact and friction sensitivities than its neutral molecule.Among these energetic compounds,hydroxylamonium salt 119b exhibited satisfactory calculated detonation velocity(8700 m s^-1),which was comparable to the commonly used high explosive RDX(8748 m s^-1).3.Study on the synthesis and properties of green metal-free primary explosive 3,3'-azo-5,5'-diazido-1,2,4-triazoleThe 3-azido-5-amino-1,2,4-triazole(120)was prepared from 5-hydrazinotetrazolium chloride reacting with cyanogen bromide.And a possible reaction process was described.The target compound 3,3'-azo-5,5'-diazido-1,2,4-triazol(121)was obtained by further coupling reaction of compound 120 with potassium permanganate.Compound 121 was well characterized by NMR spectra,IR spectroscopy,elemental analysis,differential scanning calorimetry(DSC)and single crystal X-ray diffraction.The sensitivities towards impact and friction of 121 were characterized by BAM Fallhammer and BAM Friction.Compound 121 exhibited good density(1.68 g cm^-3),good thermal stability(193^oC),high heat of formation(1345.1 KJ mol^-1),excellent detonation performance(26.7 GPa,8345 m s^-1)and acceptable sensitivity(IS=6 J,FS=72 N,EDS=0.224 J).Moreover,compound 121was tested for its priming ability by detonating RDX.The result indicates that compound 121 could be used as a potential green metal-free primary explosive.