Studies On Synthesis Of High Nitrogen Energetic Compounds

The goal of novel energetic materials is to synthesize compounds with high detonation performance, low sensitivity, chemical and thermal stability. In contrast to traditional energetic materials, high nitrogen compounds are ideal high energy density materials due to their high positive heat of formation. In addition, they can be easy to implement oxygen balance and release clean product (N2). However, the high tension and stability tend to be mutually exclusive, thereby making the synthesis of such highly energetic materials an enormous challenge. Nowadays, novel developments have been focused on the synthesis of high nitrogen compounds. Several high energetic compounds with novel structure were designed and synthesized in the thesis. It mainly consists of the following five parts:1. Study on synthesis of poly-nitrogen energetic compounds based on-N-NH2in azole ringsA novel nitrogen-rich energetic salt containing the longest reported nitrogen chain (N11), was obtained by an azo coupling reaction from1,5-diaminotetrazole. The formation of N11arises from the first example of an azo reaction between the diazonium salt of N-NH2in the tetrazole ring and an amine derivative. This type of nitrogen-nitrogen bond-forming reaction provides a new means for the discovery of novel nitrogen-rich energetic compounds.A high-nitrogen compound (N10structure),1,1’-azobis-(5-methyltetrazole) which is relatively stable, was obtained by azo coupling reactions with three different oxidants such as trichloroisocyanuric acid (TCICA), sodium dichloroisocyanurate (SDCI) and tert-butyl hypochlorite (t-BuOCl). In particular, TCICA has been used for the first time to oxidize N-NH2to the N-N=N-N linkage. The structural elucidation of the title compound was made by spectral and X-ray crystallographic analyses. The new N10linkage containing compound exhibits both relative thermal stability and chemical stability.A high nitrogen compound containing six directed linked nitrogen atoms was prepared by the treatment of1-amino-1,2,3-triazole with a,a-dichlorotosylhydrazone. Furthermore, the reaction mechanism was studied.2. Study on synthesis of energetic1,5-diaminotetrazole and furoxan derivativesThe condensation reaction of4-formyl-3-methylfuroxan with1,5-diaminotetrazole led to4-(1-amino-5-aminotetrazolyl)-methyleneimino-3-methylfuroxan (51) in high yield.4-(1-Amino-5-nitriminotetrazolyl)methyleneimino-3-methylfuroxan (52) and4-(1-amino-5,5’-azotetrazolyl)methyleneimino-3-methylfuroxan (56) was obtained through nitration and oxidation, respectively. The nitrogen-rich salts of nitrate product with bases such as 1-amino-1,2,3-triazole,4-amino-1,2,4-triazole, and3-amino-1,2,4-triazole were synthesized and characterized by IR, Raman, and NMR spectroscopy and elemental analysis. In addition, the structures of several compounds were further confirmed by single-crystal X-ray diffraction analyses. The heats of formation, detonation parameters, and impact sensitivity were investigated by theoretical and experimental methods.3. Study on synthesis of energetic compounds of nitro-triazolesThe N-aminated reaction was investigated by4-methyl-5-nitro-1,2,3-triazole and5,5’-dinitro-2H,2’H-4,4’-bi(1,2,3-triazole) as start materials. The N-amino products were obtained on the2-position and3-position of4-methyl-5-nitro-1,2,3-triazole. Furthermore, a novel high nitrogen compounds with eight continuous nitrogen atoms was synthesized by oxidation of2-amino-4-methyl-5-nitro-1,2,3-triazole. In this work,4-methyl-5-nitro-1,2,3-tri-azole and5,5’-dinitro-2H,2’H-4,4’-bi(1,2,3-triazole) were substituted by bromopropanone, yielding their respective products. The crystal structures of both compounds were determined by X-ray single crystal diffraction analysis.4. Study on the nucleophilic attack reaction of1,5-diaminotetrazole with polynitrobenzeneThe reaction of1,5-diaminotetrazole with picryl chloride (PiCl) forms5-picrylamino-1,2,3,4-tetrazole (PAT) rather than the expected1-picrylamino-5-amino-1,2,3,4-tetrazole or5-picrylamino-1-amino-1,2,3,4-tetrazole. The structure of PAT was confirmed by single-crystal X-ray diffraction, a proposed mechanism was presented.5. Study on synthesis and properties of novel energetic compounds based on5-methyl-l-amino tetrazoleTwo energetic compounds based on5-methyl-l-aminotetrazole were prepared. The trinitroethyl moiety and furazan ring were introduced to tetrazole, respectively. The trinitroethyl moiety can increase the oxygen balance, and the furazan ring can improve the detonation properties. The structures of both compounds were confirmed by X-ray crystallography. Their thermal stability and explosive performance were also investigated.