Synthesis Of 3,5-Dinitropyrazole In The Different Nitration System

3,5-Dinitropyrazole was prepared via four steps: nitration,σ-rearrangement,nitration andσ-rearrangement, using pyrazole as a raw material. Pyrazole was nitratedby the mixture acid,mixture of nitric acid and acetic anhydride,N₂O₅/organic solutionsystem, in the phase of nitration and further nitration. Nitric acid and acetic anhydridenitrition system, we mostly adopt the method reported, of which the yield hadincreased significantly to 60% and 68.2% respectively, compared with 49% and 57%reported. The increasing of nitration efficiency is attributed to the certain improvementon the conditions of the two nitration steps. In the N₂O₅/organic inert solution system,by inspected in the different systems,separately. The nitration and further nitration wastook place in 100% nitric acid, organic inert solution and organic inert solution/ionicliquid system with N₂O₅, which is a clean nitrating agent. As a result, the yield of thefirst nitration is 75%～85% with the temperature controlled around 0℃, while thesecond nitration is 70%～75%, around 20℃. By the catalysis of ionic liquid(TMPSHSO₄), the nitration efficiency and the reaction speed of the nitration inN₂O₅/organic solution system had been improved respectively. Specifically, thenitration efficiency is close to N₂O₅/nitric acid system, and keep the selectiveadvantage as well, meanwhile, the influence of organic solution polarity iscounteracted. The temperature of rearrangement reaction was controlled between185～195℃, utilizing benzophenone, n-octano, beneonitrile as the solvent. The structureof the final product was confirmed by ¹HNMR, IR and MS.