Method for synthesizing 3,4-dinitropyrazole by using micro-channel reactor

A technology of microchannel reactor and dinitropyrazole, which is applied in chemical instruments and methods, chemistry/physics/physicochemical reactors, organic chemistry, etc., can solve the problems of reduced purity of nitropyrazole, unstable product properties, It is unfavorable for continuous production and other problems, and achieves the effect of reducing production risk, reducing production and by-product generation, and avoiding separation problems

Active Publication Date: 2018-09-25
NANJING UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] 3,4-Dinitropyrazole is mainly used for melting and casting explosive carriers. In conventional tank reactors, the process is difficult to control and the reaction heat is concentrated. During the reaction, the concentrated sulfuric acid is diluted by the reaction water to release a large amount of heat. If it is not transferred in time, the partial reaction of the reactor will be overheated, resulting in huge safety hazards, and side reactions and over-reactions are prone to occur at the same time, the purity of 3,4-dinitropyrazole is reduced, and the properties of the corresponding products are unstable and prone to Flammable and explosive
Document 2 (Latypov NV, Silevich V A, and Lvanov P A, etc. Diazotization of aminonnitro pyrazoles [J]. Khimiya Geterotsikl Soedin, 1976, 12, 1649–1653.) uses 3-amino-4-nitro pyrazoles for diazo Nitrate or nitric acid are added after chemical reaction to prepare 3,4-dinitropyrazole, but the steps of synthesizing 3-amino-4-nitropyrazole are complicated and difficult to prepare, thus increasing the production cost
Patent application 201110144597.3 discloses a method for obtaining 3,4-dinitropyrazole by nitration reaction in a conventional tank reactor, which may cause production safety and environmental pollution, and is not conducive to continuous production

Method used

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  • Method for synthesizing 3,4-dinitropyrazole by using micro-channel reactor

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Experimental program
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Effect test

Embodiment 1

[0036] Slowly mix acetic anhydride and fuming nitric acid in an ice-water bath at a volume ratio of 5.5:1 to obtain a nitrating agent, and transport the acetic acid solution of the nitrating agent and pyrazole to the microchannel reactor via a high-pressure constant-flow pump with precise flow control. Two inlets, the molar ratio of nitric acid and pyrazole is controlled to be 1.1:1, and the two liquids are mixed and contacted in the microchannel reactor at 45-70°C for a moment and react, and the reaction solution is poured into crushed ice and filtered. Wash with ice water and dry in vacuum to obtain N-nitropyrazole; the flow rate of the acetic acid solution of pyrazole is 0.1 mL / min. N-nitropyrazole yield, purity are shown in Table 1 and figure 2 .

[0037] Table 1

[0038]

[0039] When the reaction temperature is lower than 45°C, there will be solids in the microreactor that will cause pipe blockage; as the reaction temperature increases, the yield and purity of N-ni...

Embodiment 2

[0041] Slowly mix acetic anhydride and fuming nitric acid in an ice-water bath at a volume ratio of 5.5:1 to obtain a nitrating agent, and transport the acetic acid solution of the nitrating agent and pyrazole to the microchannel reactor via a high-pressure constant-flow pump with precise flow control. Two inlets, the molar ratio of nitric acid and pyrazole is controlled to be 1-1.3:1, and the two liquids are mixed and contacted in the microchannel reactor at 55°C for a moment and react, and the reaction solution is poured into crushed ice and filtered. Wash with ice water and dry in vacuum to obtain N-nitropyrazole; the flow rate of the acetic acid solution of pyrazole is 0.1 mL / min. N-nitropyrazole yield, purity are shown in Table 2 and image 3 .

[0042] Table 2

[0043]

[0044] When the amount of nitric acid was less, along with the increase of nitric acid and pyrazole mol ratio, more nitric acid participated in the reaction, and the yield and purity of N-nitropyrazol...

Embodiment 3

[0046] Slowly mix acetic anhydride and fuming nitric acid in an ice-water bath at a volume ratio of 3 to 6:1 to obtain a nitrating agent, and transport the nitrating agent and the acetic acid solution of pyrazole to the microchannel reaction via a high-pressure constant-flow pump with precise flow control The two inlets of the reactor, the molar ratio of nitric acid and pyrazole is controlled to be 1.1:1, and the two liquids are mixed and contacted in the microchannel reactor at 55 °C for a moment and react, and the reaction solution is poured into crushed ice and filtered. Wash with ice water and dry in vacuum to obtain N-nitropyrazole; the flow rate of the acetic acid solution of pyrazole is 0.1 mL / min. N-nitropyrazole yield, purity are shown in Table 3 and Figure 4 .

[0047] table 3

[0048]

[0049] Along with acetic anhydride and nitric acid volume ratio constantly increase, the yield and the purity of N-nitropyrazole also increase gradually; When nitric acid and a...

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Abstract

The invention discloses a method for synthesizing 3,4-dinitropyrazole by using a micro-channel reactor. The method comprises the following steps: with pyrazole as a raw material, subjecting pyrazole and a nitric-acetic anhydride system to nitration in the micro-channel reactor so as to synthesize N-nitropyrazole; then with N-nitropyrazole as a raw material, carrying out thermal rearrangement so asto synthesize 3-nitropyrazole; and finally, with 3-nitropyrazole as a raw material, synthesizing 3,4-dinitropyrazole in virtue of a nitric acid-sulfur acid mixed acid system in the micro-channel reactor. According to the invention, the micro-channel reactor is employed, so the adverse outcomes of hardly controllable process, proneness to local overheating which leads to dangers, easy generation of side reactions and the like of convetional tank reactors are avoided, rapid reaction is realized, and direct enlargement can be realized through increase of the number of parallel micro-channel reactors. With the method, the yield of the synthesized 3,4-dinitropyrazole reaches 87.5%, and the purity of the synthesized 3,4-dinitropyrazole reaches 99.8%.

Description

technical field [0001] The invention relates to a method for synthesizing 3,4-dinitropyrazole in a microchannel reactor, and belongs to the technical field of synthesizing energetic compounds. Background technique [0002] 3,4-Dinitropyrazole (DNP) is an energetic compound of nitroazoles with excellent performance. It is easily soluble in acetonitrile and methanol and other compounds at room temperature. It has low melting point, high density, high nitrogen content, and high detonation velocity. , good oxygen balance and so on. Because the structure of the azole nitrogen heterocyclic molecule has the advantages of improveability, compactness and stability, the work of nitration and derivation using it as the parent becomes relatively simple and easy, and it is used in high-energy insensitive explosives, Casting explosives, propellants, pyrotechnics, etc. were put into use. [0003] 3,4-Dinitropyrazole is mainly used for melting and casting explosive carriers. In convention...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D231/16B01J19/00
CPCB01J19/0093C07D231/16
Inventor 李斌栋朱翔
Owner NANJING UNIV OF SCI & TECH
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