Study On The Synthesis Of Ammonium 2,4,5-trinitroimidazole And Its Performance

Ammonium 2,4,5-trinitroimidazole was prepared via five steps:twice nitration, rearrangement, nitration and neutralization, using imidazole as a starting material. The total yield is 57.7% in a purity of 96%. The reaction mechanisms of mixed acid nitration, acetic nitration and rearrangement were studied. Major factors which influenced on reaction were investigated and the optimal technological conditions of unit reaction were optimized.The optimum synthesis conditions of 4-nitroimidazole were obtained as follows:the molar radio of imidazole to nitric acid (68%) to sulfuric acid(98%) was 1:3:4, react 12 h under 125℃, the yield of 4-nitroimidazole was 80.3%. The optimum synthesis conditions of 1,4-dinitroimidazole were obtained as follows:the molar radio of 4-nitroimidazole to acetic acid to acetic anhydride to nitric acid was 1:3.5:2:2, react 10h under 25℃, the yield of 1,4-dinitroimidazole was 94.1%. The optimum synthesis conditions of 2,4-dinitroimidazole were obtained as follows:the reaction solution contain 1 g 1,4-dinitroimidazole per 1 mL chlorobenzene, react 10 h under 25℃, the yield of 2,4-dinitroimidazole was 93.3%. The optimum synthesis conditions of ammonium 2,4,5-trinitroimidazole were obtained as follows:the molar radio of 2,4-dinitroimidazole to fuming nitric acid to fuming sulfuric acid was 1:12:13.7, react 15 min under 95℃, the pH of reaction solution after treatment was 0.5, using aether as the extracting agent, the yield of ammonium 2,4,5-trinitroimidazole was 81.7%.The products were characterized by MS, IR,1H NMR, and the properties of ammonium 2,4,5-trinitroimidazole were studied. The thermal stability was tested by differential scanning calorimetry(DSC), the decomposition temperature was 308℃; the explosive performances including explosion velocity, detonation pressure, heat of explosion, explosion temperature and specific volume were obtained by theoretical calculation, the values are 8782 m·s-1,34.6 GPa,1203.94 kJ·mol-1,4395.88 K,814.55 L·kg-1, respectively, and were found to be comparable to those of RDX. The results of mechanical sensitivity tests showed that the safety performances of the product were close to TNT, better than RDX. To conclude, ammonium 2,4,5-trinitroimidazole could be used in the field of insensitive high energy materials.