| The direct process, Hale process, is the synthesis of RDX (or Hexogen) from urotropine by direct nitrolysis with nitric acid. This method is indeed widely applied in scale production, due to these characteristics: the abundant supplies, the mature process, the simple equipment, the stable product quality and the safe production. But this process has lots of disadvantages, such as the low utility of methylene and the highly excessive quantity of nitric acid. They are so prominent that the solutions to these problems are worthwhile to research in production process.Different systems were taken to synthesize hexogen and the different influences on the yield were also studied. Meanwhile, the research on the mechanism of the nitrolysis was also done. Column chromatography was applied to separate some stable intermediates and by-products to find that urotropine mononitrate, DPT and N,N-dihydroxymethyl-N-nitroamine were formed in the reaction. That provided some proofs for the mechanism of direct nitrolysis. Acid ionic liquid could be used as good catalyst in direct nitrolysis. The optimized reaction conditions of ionic liquid system were obtained: PEG1000-DAIL(TsO)2 , the optimized mass ratio between nitric acid(95%) and HA was 13:1, the optimized quantity of IL: The molar ratio between PEG1000-DAIL(TsO)2 and HA was 1:25 , the optimized reaction time was 80 min at 0℃～10℃. The average yield of RDX with PEG1000-DAIL(TsO)2 was 72.6% under the optimized conditions ; [HMim]N03, the optimized mass ratio between nitric acid(95%) and HA was 11:1, the optimized quantity of IL: The molar ratio between [HMim]N03 and HA was 3:100, the optimized reaction time was 1 h at 0℃～10℃. The average yield of RDX with [HMim]NO3 was 72.1% under the optimized conditions.PEG1000-DAIL(TsO)2 was synthesized in the laboratory. This ionic liquid has a good catalystic effect in the nitrolysis and improves the yield of RDX. |
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