Method for preparing 6-nitrobenzofuroxan by one-pot method

Abstract

The invention discloses a method for preparing 6-nitrobenzofuroxan by a one-pot method, which comprises the following steps: firstly, mixing 2, 4-dichloro-1, 3, 6-trinitrobenzene and monobasic organic acid according to a mass ratio of 1: (8-20) until the 2, 4-dichloro-1, 3, 6-trinitrobenzene and the monobasic organic acid are dissolved; the preparation method comprises the following steps: mixing 2, 4-diazido-1, 3, 6-trinitrobenzene and 2, 4-dichloro-1, 3, 6-trinitrobenzene according to a molar ratio of 1: (0.5-2), adding sodium azide into a mixed solution obtained in the step 1, and reacting at 20-50 DEG C for 0.5-2 hours to obtain an acid solution of 2, 4-diazido-1, 3, 6-trinitrobenzene, with the molar ratio of 2, 4-dichloro-1, 3, 6-trinitrobenzene to sodium azide being 1: (0.5-2); then, the temperature of the acid solution of the 2, 4-diazido-1, 3, 6-trinitrobenzene is increased to 70 DEG C to 120 DEG C, and a reaction is conducted for 0.5 h to 3 h at the temperature; and finally, carrying out rotary evaporation on the reaction liquid, removing the monobasic organic acid to obtain orange powder, adding water, washing, filtering and drying to obtain the 6-nitrobenzofuroxan. According to the preparation method disclosed by the invention, the 6-nitrobenzofuroxan can be obtained by carrying out azidation reaction and pyrolysis condensation reaction on 2, 4-dichloro-1, 3, 6-trinitrobenzene only by using one organic solvent, so that the generation of organic waste liquid is greatly reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of energetic material preparation, and particularly relates to a one-pot method for preparing 6-nitrobenzofuroxan. Background Art

[0002] 6-nitrobenzodifuroxa, English name: 6-nitrobenzodifuroxa, molecular formula: C6H1N5O6, structural formula:

[0003]

[0004] It has a melting point of 160-161°C, a theoretical density of 1.86 g·cm-3, and a detonation velocity of up to 8234 m·s-1. It is easily soluble in organic solvents such as methanol, ethanol, acetone, ethyl acetate, and dichloromethane, but poorly soluble in water. It is a high-energy, high-density energetic compound and an excellent detonating explosive. It is an important intermediate in the synthesis of 7-amino-6-nitrobenzofuroxan.

[0005] The research status of 6-nitrobenzofuroxan is summarized as follows:

[0006] Most literature reports use 2,4-dichloro-1,3,6-trinitrobenzene as the raw material, methanol, acetone, DMSO, etc. as solvents, react with sodium azide, add water, filter, and dry to obtain 2,4-diazide-1,3,6-trinitrobenzene; then, 2,4-diazide-1,3,6-trinitrobenzene is dissolved in acetic acid or propionic acid to undergo thermal decomposition and condensation reaction, diluted with water or distilled to remove the solvent, washed with water, filtered, and dried to obtain 6-nitrobenzenedioxide furazan.

[0007] The synthesis of 2,4-diazide-1,3,6-trinitrobenzene. Literature reports indicate that using 2,4-dichloro-1,3,6-trinitrobenzene as the raw material, methanol-acetone-water or DMSO-water as the solvent, and NaN3 as the azidation reagent, DATNB is obtained in yields of 84.0% to 97.1%. This process generates organic waste, such as methanol-acetone aqueous solutions and DMSO aqueous solutions, which pose challenges in disposal, high costs, and significant environmental pollution. To address the above-mentioned problems, Wang Jianlong et al. (CN 116283653 A, a green and efficient method for synthesizing 2,4-diazide-1,3,5-trinitrobenzene) reported adding NaN3 solid to an acetone solution of 2,4-dichloro-1,3,6-trinitrobenzene, stirring the reaction to obtain an acetone solution of 2,4-diazide-1,3,6-trinitrobenzene, filtering to remove insoluble matter, and distilling under reduced pressure to remove acetone to obtain a crude product of 2,4-diazide-1,3,6-trinitrobenzene. The crude product was washed with distilled water, filtered, and dried to obtain pure 2,4-diazide-1,3,6-trinitrobenzene powder with a yield of 99.16% and a purity of 99.74%. This method solves the problem of organic solvent waste liquid pollution in the synthesis of 2,4-diazide-1,3,6-trinitrobenzene and also improves the yield.

[0008] The synthesis of 6-nitrobenzofuroxan dioxide. Literature reports indicate that 2,4-diazide-1,3,6-trinitrobenzene is used as the raw material. A thermal decomposition and condensation reaction in acetic acid or propionic acid is performed, followed by dilution with water, filtration, and drying to obtain 6-nitrobenzofuroxan dioxide powder with a yield of 79% to 85%. This method produces an aqueous acetic acid solution containing energetic compounds, which poses significant safety risks, difficulty in treatment, high costs, and significant environmental pollution during the wastewater treatment process. Liu Yunzhang from North University of China reported a process using 2,4-diazide-1,3,6-trinitrobenzene as raw material and acetic acid as solvent, with the reaction kept at 110°C for 1 hour. After the insulation, the system temperature was cooled to below 50°C, and the acetic acid was removed by vacuum distillation to obtain an orange powder. The powder was washed with water, filtered, and dried to obtain 6-nitrobenzene dioxide with a yield of 87.94%. The acetic acid obtained by distillation can be reused. Compared with other methods, this method greatly reduces the amount of energy-containing waste solvents produced, reduces costs, and improves yields.

[0009] Current literature reports that the highest yield of 6-nitrobenzofuroxan is 87.20%. Its synthesis method has the following main problems: ① The two-step reaction process is an intermittent reaction, which is relatively complicated; ② The synthesis of the product 6-nitrobenzofuroxan and the intermediate 2,4-diazide-1,3,6-trinitrobenzene still requires reactions in different solvent systems, resulting in large solvent usage, high recovery costs, and severe environmental pollution. Summary of the Invention

[0010] The purpose of the present invention is to provide a one-pot method for preparing 6-nitrobenzofuroxan dioxide in response to the deficiencies in the prior art.

[0011] The purpose of the present invention is achieved through the following technical solutions:

[0012] The one-pot method for preparing 6-nitrobenzofuroxan dioxide of the present invention specifically comprises the following steps:

[0013] 1) Mix 2,4-dichloro-1,3,6-trinitrobenzene and a monobasic organic acid in a mass ratio of 1:(8-20) until dissolved;

[0014] 2) adding sodium azide to the mixed solution obtained in step 1, reacting at 20-50° C. for 0.5-2 h to obtain an acid solution of 2,4-diazide-1,3,6-trinitrobenzene, wherein the molar ratio of 2,4-dichloro-1,3,6-trinitrobenzene to sodium azide is 1:(0.5-2);

[0015] 3) heating the acid solution of 2,4-diazide-1,3,6-trinitrobenzene to 70-120° C. and reacting at this temperature for 0.5-3 h;

[0016] 4) the reaction solution obtained in step 3 is subjected to rotary evaporation to remove the monobasic organic acid to obtain an orange powder, which is washed with water, filtered, and dried to obtain 6-nitrobenzofuroxan;

[0017] The monobasic organic acid is formic acid, acetic acid, propionic acid, butyric acid, valeric acid, hexanoic acid, heptanoic acid and the like.

[0018] Furthermore, the monobasic organic acid is acetic acid.

[0019] Furthermore, the mass ratio of 2,4-dichloro-1,3,6-trinitrobenzene to the monobasic organic acid is 1:(10-15).

[0020] Furthermore, the molar ratio of 2,4-dichloro-1,3,6-trinitrobenzene to sodium azide is 1:0.67-1.5.

[0021] Furthermore, after sodium azide is added in step 2), the mixture is reacted at 25-35° C. for 0.5-1 h to obtain an acid solution of 2,4-diazide-1,3,6-trinitrobenzene.

[0022] Furthermore, in step 3), the acid solution of 2,4-diazide-1,3,6-trinitrobenzene is heated to 80-110° C. and reacted at this temperature for 0.5-1.5 h.

[0023] Beneficial effects

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) A one-pot method is used to synthesize 6-nitrobenzofuroxan, which does not require separation of the intermediate, is simple to operate, reduces losses, and improves the yield, which is 90.0% to 95.0%.

[0026] (2) Only one organic solvent is used to obtain 6-nitrobenzofuroxan through azidation reaction and thermal decomposition condensation reaction of 2,4-dichloro-1,3,6-trinitrobenzene, which greatly reduces the generation of organic waste liquid. The recovered organic acid reagent can be recycled, has good environmental benefits, and greatly reduces costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is the infrared spectrum of the product of the present invention, 6-nitrobenzofuroxan;

[0028] Figure 2 This is the H NMR spectrum of the product 6-nitrobenzofurazan dioxide;

[0029] Figure 3 This is the NMR carbon spectrum of the product 6-nitrobenzofurazan dioxide;

[0030] Figure 4 The figure is a high performance liquid chromatogram of 6-nitrobenzofuroxan dioxide, a product of the present invention. DETAILED DESCRIPTION

[0031] In order to make those skilled in the art better understand the present invention, the present invention is further clearly and completely described below in conjunction with specific embodiments. It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of this application can be combined with each other.

[0032] A one-pot method for preparing 6-nitrobenzofuroxan dioxide is shown in the following figure.

[0033]

[0034] Example 1

[0035] Dissolve 21.9 g of 2,4-dichloro-1,3,6-trinitrobenzene in 175 g of acetic acid; add 4.4 g of sodium azide, and react at 20°C for 0.5 h. Heat the reaction solution to 70°C and react at this temperature for 0.5 h. Rotary evaporate the reaction solution to remove the acetic acid to obtain an orange powder, which is washed with water to dissolve the generated NaCl and unreacted sodium azide. Filter and dry to obtain 6-nitrobenzofuroxan dioxide in a yield of 91.3%.

[0036] Figure 1 The infrared spectrum of 6-nitrobenzofuroxan obtained in Example 1, the main absorption peak of which is (KBr, cm-1 ): 1659, 1623, 1597, 1564, 1533, 1345, 1087, 996, 750, which are basically consistent with the infrared spectrum absorption peaks in the literature.

[0037] Figure 2 is the H NMR spectrum of 6-nitrobenzofurazan obtained in Example 1, 1 H NMR (600 MHz, C3D6O-d6) 8.78 (s, 1H) ppm, consistent with the product structure having only one hydrogen species.

[0038] Figure 3 is the C NMR spectrum of 6-nitrobenzofurazan dioxide obtained in Example 1, 13 C NMR (150 MHz, C3D6O-d6) 151.02, 147.41, 131.03, 121.50, 111.48, 104.52 ppm, consistent with the product structure having 6 carbon species.

[0039] Figure 4 This is the HPLC chromatogram of 6-nitrobenzofuroxan obtained in Example 1. The test conditions are: Hypersil ODS2 column (250 mm × 4.6 mm, 5 μm), UV detection wavelength of 237 nm, mobile phase of chromatographic methanol, flow rate of 0.8 mL min -1 , column temperature was 20℃, injection volume was 15μL, and the product purity was measured to be 99.5%.

[0040] Example 2

[0041] Dissolve 21.9 g of 2,4-dichloro-1,3,6-trinitrobenzene in 430 g of acetic acid; add 9.8 g of sodium azide, and react at 30°C for 1 hour. Heat the reaction solution to 110°C and react at this temperature for 1 hour. Rotary evaporate the reaction solution to remove the acetic acid to obtain an orange powder, which is washed with water to dissolve the generated NaCl and unreacted sodium azide. Filter and dry to obtain 6-nitrobenzofuroxan dioxide in a yield of 91.6%.

[0042] Example 3

[0043] Dissolve 21.9 g of 2,4-dichloro-1,3,6-trinitrobenzene in 220 g of acetic acid; add 4.4 g of sodium azide, and react at 30°C for 1 hour. Heat the reaction solution to 110°C and react at this temperature for 1 hour. Rotary evaporate the reaction solution to remove the acetic acid to obtain an orange powder, which is washed with water to dissolve the generated NaCl and unreacted sodium azide. Filter and dry to obtain 6-nitrobenzofuroxan dioxide in a yield of 94.8%.

[0044] Example 4

[0045] Dissolve 21.9 g of 2,4-dichloro-1,3,6-trinitrobenzene in 220 g of acetic acid; add 4.4 g of sodium azide, and react at 30°C for 1 hour. Heat the reaction solution to 80°C and react at this temperature for 1 hour. Rotary evaporate the reaction solution to remove the acetic acid to obtain an orange powder, which is washed with water to dissolve the generated NaCl and unreacted sodium azide. Filter and dry to obtain 6-nitrobenzofuroxan dioxide in a yield of 94.5%.

[0046] Example 5

[0047] Dissolve 21.9 g of 2,4-dichloro-1,3,6-trinitrobenzene in 220 g of acetic acid; add 4.4 g of sodium azide, and react at 30°C for 1 hour. Heat the reaction solution to 80°C and react at this temperature for 3 hours. Rotary evaporate the reaction solution to remove the acetic acid to obtain an orange powder, which is washed with water to dissolve the generated NaCl and unreacted sodium azide. Filter and dry to obtain 6-nitrobenzofuroxan dioxide in a yield of 90.7%.

Claims

1. A method for preparing 6-nitrobenzofuroxan dioxide by a one-pot process, characterized in that: The specific steps include: 1) Mix 2,4-dichloro-1,3,6-trinitrobenzene and a monobasic organic acid in a mass ratio of 1:(8-20) until dissolved; 2) adding sodium azide to the mixed solution obtained in step 1, reacting at 20-50° C. for 0.5-2 h to obtain an acid solution of 2,4-diazide-1,3,6-trinitrobenzene, wherein the molar ratio of 2,4-dichloro-1,3,6-trinitrobenzene to sodium azide is 1:(0.5-2); 3) heating the acid solution of 2,4-diazide-1,3,6-trinitrobenzene to 70-120° C. and reacting at this temperature for 0.5-3 h; 4) The reaction solution obtained in step 3 is subjected to rotary evaporation to remove the monobasic organic acid to obtain an orange powder, which is washed with water, filtered, and dried to obtain 6-nitrobenzofuroxan. The monobasic organic acid is formic acid, acetic acid, propionic acid, butyric acid, valeric acid, hexanoic acid, heptanoic acid and the like.

2. A method for preparing 6-nitrobenzofuroxan by a one-pot process as claimed in claim 1, characterized in that: The monobasic organic acid is acetic acid.

3. A method for preparing 6-nitrobenzofuroxan by a one-pot process as claimed in claim 1, characterized in that: The mass ratio of 2,4-dichloro-1,3,6-trinitrobenzene to the monobasic organic acid is 1:(10-15).

4. A method for preparing 6-nitrobenzofuroxan by a one-pot process as claimed in claim 1, characterized in that: The molar ratio of 2,4-dichloro-1,3,6-trinitrobenzene to sodium azide is 1:0.67-1.

5.

5. A one-pot method for preparing 6-nitrobenzofuroxan as claimed in claim 1, characterized in that: After sodium azide is added in step 2), the mixture is reacted at 25-35° C. for 0.5-1 h to obtain an acid solution of 2,4-diazide-1,3,6-trinitrobenzene.

6. The method for preparing 6-nitrobenzofuroxan by a one-pot process as claimed in claim 1, wherein: In the step 3), the acid solution of 2,4-diazide-1,3,6-trinitrobenzene is heated to 80-110° C. and reacted at this temperature for 0.5-1.5 hours.

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