Search

CN-121974854-A - Synthesis method of fusion casting carrier explosive 4-methoxy-1-methyl-3, 5-dinitropyrazole

CN121974854ACN 121974854 ACN121974854 ACN 121974854ACN-121974854-A

Abstract

The application belongs to the technical field of energetic materials, and discloses a method for synthesizing a fusion casting carrier explosive 4-methoxy-1-methyl-3, 5-dinitropyrazole, which takes commercially available 1-methylpyrazole-4-boric acid pinacol ester as a raw material, synthesizes a key intermediate 4-methoxy-1-methyl-1H-pyrazole through a one-pot method two-step substitution reaction, can directly nitrify a product without purification and simple post-treatment, and obtains the fusion casting carrier explosive product 4-methoxy-1-methyl-3, 5-dinitropyrazole. Compared with the prior art, the preparation method provided by the application has the advantages of simplicity, convenience, high efficiency, low cost and the like, and has the potential of large-scale synthesis.

Inventors

  • WANG YI
  • ZHANG QINGHUA
  • Zhe Weiqing
  • LIU PEI
  • SONG SIWEI

Assignees

  • 西北工业大学

Dates

Publication Date
20260505
Application Date
20260109

Claims (10)

  1. 1. The synthesis method of the fusion casting carrier explosive 4-methoxy-1-methyl-3, 5-dinitropyrazole is characterized by comprising the following steps: 1) Dissolving 1-methylpyrazole-4-pinacol borate in an organic solvent under the condition of ice water bath, adding a sodium hydroxide aqueous solution, then dropwise adding hydrogen peroxide, naturally heating to normal temperature after the dropwise adding is finished to perform a first-step substitution reaction, dropwise adding dimethyl sulfate after the reaction is finished, heating to reflux temperature to perform a second-step substitution reaction, concentrating the reaction solution under reduced pressure to remove the organic solvent, extracting the residual water layer by using an extracting agent, merging the extracting solutions, drying, and concentrating to obtain a crude product of 4-methoxy-1-methyl-1H-pyrazole; 2) Slowly dripping the obtained crude 4-methoxy-1-methyl-1H-pyrazole into concentrated sulfuric acid under the condition of ice water bath, adding fuming nitric acid after dripping, naturally heating to normal temperature for reaction, heating to a specified temperature for continuous reaction, pouring the reaction solution into crushed ice after the reaction is finished, filtering, washing and drying to obtain 4-methoxy-1-methyl-3, 5-dinitropyrazole.
  2. 2. The method for synthesizing 4-methoxy-1-methyl-3, 5-dinitropyrazole according to claim 1, wherein the organic solvent in the step 1) is one of tetrahydrofuran, methanol, ethanol and acetonitrile.
  3. 3. The method for synthesizing 4-methoxy-1-methyl-3, 5-dinitropyrazole according to claim 1, wherein the extractant in the step 1) is one of dichloromethane, diethyl ether, chloroform and ethyl acetate.
  4. 4. The method for synthesizing 4-methoxy-1-methyl-3, 5-dinitropyrazole according to claim 1, wherein the concentration of hydrogen peroxide in the step 1) is 25% -30%.
  5. 5. The method for synthesizing 4-methoxy-1-methyl-3, 5-dinitropyrazole according to claim 1, wherein the mass fraction of the aqueous sodium hydroxide solution in the step 1) is 10% -12%.
  6. 6. The method for synthesizing 4-methoxy-1-methyl-3, 5-dinitropyrazole according to claim 1, wherein the duration of the first substitution reaction in step 1) is 3h to 5h.
  7. 7. The method for synthesizing 4-methoxy-1-methyl-3, 5-dinitropyrazole according to claim 1, wherein the second substitution reaction in step 1) is performed for 10-12 hours.
  8. 8. The method for synthesizing 4-methoxy-1-methyl-3, 5-dinitropyrazole according to claim 1, wherein the reaction time at the normal temperature in the step 2) is 0.5h to 1h.
  9. 9. The method for synthesizing 4-methoxy-1-methyl-3, 5-dinitropyrazole according to claim 1, wherein the temperature in the step 2) is raised to the designated temperature again, the reaction is continued at 40-50 ℃ for 3-4 h.
  10. 10. The method for synthesizing 4-methoxy-1-methyl-3, 5-dinitropyrazole according to claim 1, wherein the mass ratio of the 1-methylpyrazole-4-boronic acid pinacol ester to hydrogen peroxide, sodium hydroxide, dimethyl sulfate, concentrated sulfuric acid and fuming nitric acid is1 (0.32-0.41): 0.38-0.48): 2.42-4.85): 4.42-7.08): 7.21-10.82.

Description

Synthesis method of fusion casting carrier explosive 4-methoxy-1-methyl-3, 5-dinitropyrazole Technical Field The application belongs to the technical field of energetic materials, and particularly relates to a method for synthesizing 4-methoxy-1-methyl-3, 5-dinitropyrazole serving as a fusion casting carrier explosive. Background The fusion-cast explosive is a mixed explosive formed by adding solid-phase high-energy main explosive (such as black soxhlet, octogen and the like) into melted liquid-phase carrier explosive (such as trinitrotoluene and TNT) and solidifying, and the application of the explosive in military mixed explosive is more than 90%. At present, the fusion casting carrier explosive is mainly TNT, and has the defects of low energy, non-ideal mechanical property, poor safety performance, high toxicity and the like, so that the fusion casting carrier explosive has a plurality of defects in the application process. For this reason, countries are constantly exploring for new fusion-cast carrier explosives to replace the currently used TNT. 4-methoxy-1-methyl-3, 5-dinitropyrazole (DMDNP) is a casting carrier explosive with excellent comprehensive performance, which is developed in recent years, and has the characteristics of low energy feel, low toxicity, good compatibility and the like ,"Promising Energetic Melt-Castable Material with Balanced Properties". ACS Applied Materials&Interfaces, 2023, 15(20), 183-187,, and the synthetic route is as follows: 。 The method takes 4-methoxy-1-methyl-1H-pyrazole as a raw material, and synthesizes 4-methoxy-1-methyl-3, 5-dinitropyrazole through one-step nitration reaction, and the yield is 90%. The raw materials of the method are extremely expensive and the synthesis difficulty is high. The current synthesis mode of 4-methoxy-1-methyl-1H-pyrazole comprises the following steps: (a) The methoxy substitution method "Cu(i)/sucrose-catalyzed hydroxylation of arenes in water: the dual role of sucrose". Organic&Biomolecular Chemistry, 2020, 18, 7827, has the following synthetic route: 。 (b) The synthetic route of the methyl substitution method "Heterocyclic derivatives for the treatment of diseases mediated by stearoyl-CoA desaturase enzymes". US, CA2580787A1. 2006., is as follows: 。 (c) Cyclization method Product Class 1: pyrazoles, science of Synthesis, 2003, 34 (46) was synthesized as follows: 。 The three methods need high temperature and high pressure, dangerous reagent sodium hydride and anhydrous and anaerobic conditions, and the synthesis mode with harsh conditions and complicated operation ensures that the 4-methoxy-1-methyl-3, 5-dinitropyrazole has higher synthesis cost and is not beneficial to large-scale application. Disclosure of Invention The application aims to overcome the defects of harsh conditions, complicated steps and high cost of a 4-methoxy-1-methyl-1H-pyrazole synthetic route in the prior art, and provides an alternative synthetic method with easily available raw materials and simplified operation. The key intermediate is constructed by adopting a one-pot method for continuous reaction, and is directly nitrified without separation and purification, so that the efficient and low-cost preparation of the 4-methoxy-1-methyl-3, 5-dinitropyrazole is realized. In order to achieve the technical purpose, the application adopts the following technical scheme: In one aspect of the application, there is provided a method of synthesizing a fused and cast carrier explosive 4-methoxy-1-methyl-3, 5-dinitropyrazole comprising the steps of: 1) Dissolving 1-methylpyrazole-4-pinacol borate in an organic solvent under the condition of ice water bath, adding a sodium hydroxide aqueous solution, then dropwise adding hydrogen peroxide, naturally heating to normal temperature after the dropwise adding is finished to perform a first-step substitution reaction, dropwise adding dimethyl sulfate after the reaction is finished, heating to reflux temperature to perform a second-step substitution reaction, concentrating the reaction solution under reduced pressure to remove the organic solvent, extracting the residual water layer by using an extracting agent, merging the extracting solutions, drying, and concentrating to obtain a crude product of 4-methoxy-1-methyl-1H-pyrazole; 2) Slowly dripping the obtained crude 4-methoxy-1-methyl-1H-pyrazole into concentrated sulfuric acid under the condition of ice water bath, adding fuming nitric acid after dripping, naturally heating to normal temperature for reaction, heating to a specified temperature for continuous reaction, pouring the reaction solution into crushed ice after the reaction is finished, filtering, washing and drying to obtain 4-methoxy-1-methyl-3, 5-dinitropyrazole. In one embodiment, the organic solvent in step 1) is one of tetrahydrofuran, methanol, ethanol, acetonitrile. In one embodiment, the extractant in step 1) is one of dichloromethane, diethyl ether, chloroform and ethyl acetate. In one embodiment, the conc