Study On The Synthesis Of Aromatic Amines And Derivatives Pentazole

As the traditional energetic materials cannot afford the need of the current society, the nitrogen energetic materials with obvious advantages have attracted much attention. Among that, the reasearch of N5-has been a hot spot. To obtain the pentazole anion, the synthesis of several pentazole derivatives and relevant theoretical calculations were performed.Firstly, six anilines with multi-electron-donating groups were synthesized by reduction of aromatic nitro compounds and azo compounds. Then, they were converted to corresponding arylpentazole derivatives as substrates at low temperatures. The stabilities of these arylpentazole derivatives were studied through experimental tests and quantum chemical calculations with energy barrier and bond length values. Results showed that electron-donating groups are beneficial to the stability of the arylpentazoles. Both para-substituted and meta-substituted electron-donor groups can obviously increase the stability, especially the para-substituted ones. Due to steric effect, the stability of all ortho-substituted arylpentazoles decreases.These anilines are reduced from aromatic nitro compounds using CMC stabilized iron nanoparticles as reductant and [DMFH]H2PO4 as the catalyst. The method is novel, simple and environmental. It shortened the reaction time with a recyclable catalyst.Afterwards, for the synthesis of pentazole anion, synthetic exploration of breaking the C-N bond of arylpentazole derivatives was conducted. We hope to stabilize pentazole ring through the metal cation. Experimental results showed that the metal cation used in the experiment failed to stabilize N5-, resulting in the failure of the experiments. Meanwhile, the results of quantum chemical calculations showed that the bond dissociation energy of C-N bond of arylpentazoles (490～512 kJ/mol) is much larger than the bond dissociation energy of N-N bond of pentazole ring (74～82 kJ/mol). Therefore, breaking C-N bond without decomposing the pentazole ring is difficult. In addition, it was observed that the bond dissociation energy of N-N bond connecting N and pentazole ring is 248～263 kJ/mol, which is smaller than the bond dissociation energy of C-N bond and is beneficial to the breaking experiment.Totally, synthetic explorations of pentazole derivatives were preformed with phenylhydrazine and 1,5-diaminotetrazole as substrates. However, a problem appeared during the diazotization of phenylhydrazine and 1,5-diaminotetrazole. We failed to obtain the corresponding diazonium salt. Instead, both phenylhydrazine and 1,5-diaminotetrazole lost one amino to generate the aniline and 5-aminotetrazole respectively after the reacting with sodium nitrites.