CN109705053B

CN109705053B - 2,2 '-dinitro-5, 5' -bis (1,3, 4-oxadiazole) and preparation method and application thereof

Info

Publication number: CN109705053B
Application number: CN201811608276.2A
Authority: CN
Inventors: 马英杰; 卢艳华; 雷晴; 任晓婷; 叶丹阳; 曹一林; 何金选; 孙绍海
Original assignee: Hubei Institute of Aerospace Chemical Technology
Current assignee: Hubei Institute of Aerospace Chemical Technology
Priority date: 2018-12-26
Filing date: 2018-12-26
Publication date: 2020-06-09
Anticipated expiration: 2038-12-26
Also published as: CN109705053A

Abstract

The invention provides 2,2 '-dinitro-5, 5' -bis (1,3, 4-oxadiazole) and a preparation method and application thereof, belonging to the technical field of energetic materials. The 2,2 '-dinitro-5, 5' -bis (1,3, 4-oxadiazole provided by the embodiment of the invention has high density (1.79 g/cm)³) The 2,2 '-dinitro-5, 5' -bis (1,3, 4-oxadiazole) has good compatibility with other components of the propellant and is easy to prepare when applied to the insensitive high-energy solid propellant.

Description

2,2 '-dinitro-5, 5' -bis (1,3, 4-oxadiazole) and preparation method and application thereof

Technical Field

The invention relates to 2,2 '-dinitro-5, 5' -bis (1,3, 4-oxadiazole) and a preparation method and application thereof, belonging to the technical field of energetic materials.

Background

In the search for novel energetic materials, oxadiazole energetic materials have attracted extensive attention due to their high density, high nitrogen content, high oxygen balance and high thermal stability, and among them, 1,2, 5-oxadiazole has been favored by researchers for a long time because of its highest enthalpy of formation (216.3kJ/mol) in its isomers, and a series of energetic materials have been synthesized on the basis of this. However, further research finds that although the density and detonation performance of the 1,2, 5-oxadiazole are high, the high sensitivity of the 1,2, 5-oxadiazole hinders the practical application of the 1,2, 5-oxadiazole. In pursuit of a balance between high performance and low sensitivity, the attention of researchers has gradually moved towards the isomer 1,3, 4-oxadiazole of 1,2, 5-oxadiazole.

Zhang Qinghua et al synthesized 2,2 '-dinitroamino-5, 5' -bis (1,3, 4-oxadiazole) as an energetic material based on a 1,3, 4-oxadiazole structure, and has the advantages of high density, low sensitivity and the like, but the raw material used in the structure synthesis method selects virulent cyanogen bromide, and has obvious defects, so that the industrial production of the material is difficult; meanwhile, due to the existence of nitro-amino, when the product is used as an energetic material in a propellant, active hydrogen in molecules can react with isocyanate serving as a curing agent component of the propellant, so that the propellant is not favorable for forming a medicament, and the compatibility problem is caused.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: the 2,2 '-dinitro-5, 5' -bis (1,3, 4-oxadiazole) and the preparation method and application thereof are provided, bromine and cyanogen are not needed in the preparation process of the 2,2 '-dinitro-5, 5' -bis (1,3, 4-oxadiazole), the preparation method is safe and environment-friendly, and when the preparation method is applied to a insensitive high-energy solid propellant, the compatibility with other components is good.

In order to achieve the above purpose, the invention provides the following technical scheme:

2,2 '-dinitro-5, 5' -bis (1,3, 4-oxadiazole), characterized by the following chemical structural formula:

a preparation method of 2,2 '-dinitro-5, 5' -bis (1,3, 4-oxadiazole) is characterized by comprising the following steps:

(1) refluxing a mixture of ammonium thiocyanate and dilute acid at a certain temperature for a period of time, adding oxalyl dihydrazide, continuously stirring for reaction, cooling and filtering after the reaction is finished, and washing and drying a precipitate to obtain a white intermediate product N, N' -dithioamide-oxalyl dihydrazide;

(2) adding the N, N ' -dithio amide-oxalyl dihydrazide, diisopropylcarbodiimide and diisopropylethylamine into a certain amount of polar solvent, stirring and reacting at a certain temperature, filtering and separating after the reaction is finished, and washing, drying and recrystallizing a precipitate to obtain a light yellow intermediate 2,2 ' -diamino-5, 5 ' -bis (1,3, 4-oxadiazole);

(3) dissolving a certain amount of 2,2 '-diamino-5, 5' -bis (1,3, 4-oxadiazole) and sodium nitrite in water, dropwise adding strong acid at a certain temperature to react until no reddish brown nitrogen dioxide gas is generated, cooling to generate precipitate, filtering and separating, and removing impurities to obtain the final product 2,2 '-dinitro-5, 5' -bis (1,3, 4-oxadiazole).

In an optional embodiment, the dilute acid in the step (1) is hydrochloric acid with a molar concentration of 0.8-1.2 mol/L, and the mass ratio of HCl to ammonium thiocyanate is 1: 2.1-1: 4.4.

in an optional embodiment, the mixture of ammonium thiocyanate and dilute acid in step (1) is refluxed at 110 ℃ and 130 ℃ for 30-60 min.

In an alternative embodiment, the mass ratio of oxalyl dihydrazide to ammonium thiocyanate in the step (1) is 1: 2-1: 4.

in an optional embodiment, the reaction time after adding oxalyl dihydrazide in the step (1) is 4.5-5.5 h.

In an alternative embodiment, the mass ratio of N, N' -dithioamide-oxalyl dihydrazide to diisopropylcarbodiimide in step (2) is 1: 1-1: 2.

in an alternative embodiment, the mass ratio of N, N' -dithioamide-oxalyl dihydrazide to diisopropyethylamine in step (2) is 1: 1-1: 2.

in an alternative embodiment, the mass ratio of N, N' -dithioamide-oxalyl dihydrazide to the polar solvent in the step (2) is 1: 10-1: 20.

in an optional embodiment, the reaction temperature in the step (2) is 45-55 ℃, and the reaction time is 20-24 hours.

In an alternative embodiment, the mass ratio of 2,2 '-diamino-5, 5' -bis (1,3, 4-oxadiazole) to sodium nitrite in step (3) is 1: 8-1: 15.

in an alternative embodiment, the strong acid in step (3) is concentrated sulfuric acid, 2,2 '-diamino-5, 5' -bis (1,3, 4-oxadiazole) and H₂SO₄The mass ratio of (1): 1.6-1: 3.

in an alternative embodiment, the mass ratio of 2,2 '-diamino-5, 5' -bis (1,3, 4-oxadiazole) to water in step (3) is 1: 15-1: 30.

in an optional embodiment, the reaction temperature in the step (3) is 40 to 50 ℃, and the reaction time is 0.5 to 1.5 hours.

In an alternative embodiment, the removal of impurities as described in step (3) provides the final product 2,2 '-dinitro-5, 5' -bis (1,3, 4-oxadiazole) comprising:

dissolving the filter cake in hot water at the temperature of 80-100 ℃, filtering to remove insoluble impurities, standing the obtained clear solution at the temperature of 0-5 ℃ for crystallization, and filtering to obtain the final product 2,2 '-dinitro-5, 5' -bis (1,3, 4-oxadiazole).

In an alternative embodiment, the recrystallization in step (2) is performed in ethanol. A

In an alternative embodiment, the polar solvent in step (2) is at least one of acetonitrile, dichloromethane or acetone.

18. Application of 2,2 '-dinitro-5, 5' -bis (1,3, 4-oxadiazole) as an energy-containing material in a solid propellant.

Compared with the prior art, the invention has the following beneficial effects:

the 2,2 '-dinitro-5, 5' -bis (1,3, 4-oxadiazole) provided by the embodiment of the invention has high density (1.79 g/cm)³) The 2,2 '-binitro-5, 5' -bis (1,3, 4-oxadiazole) provided by the invention is an insensitive energetic material, and when the material is applied to a solid propellant, the material does not contain active hydrogen, does not react with a curing agent in the propellant, and is safe and environment-friendly because bromine cyanide is not needed in the preparation process of the energetic material with the advantages of low sensitivity (23J, 253N for friction sensitivity, 0.80J for static sensitivity) and the likeThe all-performance is good and the compatibility is good.

Detailed Description

The following describes the embodiments of the present invention in further detail with reference to specific examples.

The embodiment of the invention provides 2,2 '-binitro-5, 5' -bis (1,3, 4-oxadiazole), the chemical structural formula of which is shown as formula (1):

the 2,2 '-dinitro-5, 5' -bis (1,3, 4-oxadiazole provided by the embodiment of the invention is an energetic material with the advantages of high density, low sensitivity and the like, bromine and cyanogen are not needed in the preparation process, the preparation method is safe and environment-friendly, and when the 2,2 '-dinitro-5, 5' -bis (1,3, 4-oxadiazole provided by the invention is applied to a solid propellant, the safety performance is good and the compatibility is good.

The embodiment of the invention also provides a preparation method of 2,2 '-binitro-5, 5' -bis (1,3, 4-oxadiazole), which comprises the following steps:

step (1): as shown in formula (2), refluxing a mixture of ammonium thiocyanate and dilute acid (such as hydrochloric acid) at a certain temperature for a period of time, adding oxalyl dihydrazide, continuously stirring for reaction, cooling and filtering after the reaction is finished, washing and drying a precipitate to obtain a white intermediate product N, N' -dithioamide-oxalyl dihydrazide (short for: DSODH);

the diluted acid is hydrochloric acid with the molar concentration of 0.8-1.2 mol/L, and the mass ratio of HCl to ammonium thiocyanate is 1: 2.1-1: 4.4; the mass ratio of oxalyl dihydrazide to ammonium thiocyanate is preferably 1: 2-1: 4.

the mixture of ammonium thiocyanate and dilute acid is preferably refluxed for 30-60 min at the temperature of 110-130 ℃, the reaction temperature is kept unchanged after oxalyl dihydrazide is added, and the reaction time is 4.5-5.5 h.

Step (2): as shown in formula (3), adding N, N ' -dithio-amide-oxalyl dihydrazide, a coupling agent of diisopropyl carbodiimide (DIC) and diisopropyl ethylamine into a certain amount of polar solvent, stirring and reacting at a certain temperature, filtering and separating after the reaction is finished, and washing, drying and recrystallizing a precipitate to obtain a light yellow intermediate 2,2 ' -diamino-5, 5 ' -bis (1,3, 4-oxadiazole) (abbreviated as DAOZ).

Specifically, the mass ratio of N, N' -dithioamide-oxalyl dihydrazide to diisopropylcarbodiimide in the step (2) is preferably 1: 1-1: 2; the mass ratio of the N, N' -dithio amide-oxalyl dihydrazide to the diisopropylethylamine is preferably 1: 1-1: 2; the mass ratio of the N, N' -dithio amide-oxalyl dihydrazide to the polar solvent in the step (2) is preferably 1: 10-1: 20, wherein the polar solvent is preferably at least one of acetonitrile or dichloromethane or acetone.

Specifically, the reaction temperature in the step (2) is preferably 45-55 ℃, and the reaction time is preferably 20-24 h; the recrystallization is preferably carried out in ethanol.

And (3): dissolving a certain amount of 2,2 '-diamino-5, 5' -bis (1,3, 4-oxadiazole) and sodium nitrite in water, dropwise adding strong acid at a certain temperature to react until no red-brown nitrogen dioxide gas is generated, cooling, generating precipitate, filtering and separating, and removing impurities to obtain a final product 2,2 '-dinitro-5, 5' -bis (1,3, 4-oxadiazole) (abbreviated as DNOZ).

Specifically, the mass ratio of the 2,2 '-diamino-5, 5' -bis (1,3, 4-oxadiazole) to the sodium nitrite is preferably 1: 8-1: 15; the strong acid is concentrated sulfuric acid, 2,2 '-diamino-5, 5' -bi (1,3, 4-oxadiazole) and H₂SO₄The mass ratio of (b) is preferably 1: 1.6-1: 3; the 2,2 '-diamino-5, 5' -bis (1,3, 4-oxa)Oxadiazole) to water is preferably 1: 15-1: 30.

specifically, the reaction temperature in the step (3) is preferably 40-50 ℃, and the reaction time is preferably 0.5-1.5 h.

In an alternative embodiment, the removal of impurities to obtain the final product 2,2 '-dinitro-5, 5' -bis (1,3, 4-oxadiazole) comprises:

The embodiment of the invention also provides application of 2,2 '-dinitro-5, 5' -bis (1,3, 4-oxadiazole) as an energetic material in a solid propellant, wherein the energetic material is shown as the formula (1).

The following are some specific examples of the present invention, and reagents and raw materials used in the examples are commercially available products.

Example 1

This example provides a method for preparing 2,2 '-dinitro-5, 5' -bis (1,3, 4-oxadiazole), comprising:

a four-necked flask was charged with 400mL of 1M hydrochloric acid and ammonium thiocyanate (30.45g, 0.4 mol). The reaction mixture was magnetically stirred at reflux at 110 ℃ for 30 min. Oxalyl dihydrazide (0.1mol,11.8g) was then added to the reaction mixture, and stirring was continued while maintaining the temperature at 110 ℃ for 4.5 h. After the reaction was completed, ice was added to cool, and the precipitate was filtered, washed and dried to obtain 16.73g of white intermediate product DSODH with a yield of 70.80%.

Into a four-necked flask was added DSODH (0.08mol, 18.88g), followed by the addition of the coupling agent DIC (0.15mol, 18.88g), diisopropylethylamine (0.15mol, 18.88g) and 200g of acetonitrile as a solvent, and the reaction mixture was stirred at 45 ℃ for 20 h. After the reaction was completed, the product was separated by filtration, and the precipitate was washed with methanol and then dried. The product was recrystallized from ethanol and further purified. This gave 92.94% yield of DAOZ12.50g as a pale yellow intermediate.

DAOZ (12.00g,0.072mol), sodium nitrite (96g) and water (180g) were added slowly dropwise to a four-necked flask, and 19.2g of concentrated sulfuric acid (98% by mass) was stirred at 40 ℃ for 0.5h until no nitrogen dioxide gas was generated. The solution was then cooled to 0 ℃ and the precipitate formed was separated by filtration, dissolved in 80 ℃ hot water and filtered to remove insoluble impurities, the clear solution obtained was crystallised by standing at 0 ℃ and filtered to give the final product dnoz13.40g in 82.63% yield.

Table 1 shows the elemental analysis results of the 2,2 '-dinitro-5, 5' -bis (1,3, 4-oxadiazole) prepared in this example, and the measured results are in accordance with the theoretical calculation values.¹³C Nuclear magnetic test results (125MHz, DMSO-d)₆25 ℃ C. delta.: 158.7, 149.9. Confirmed as the target compound DNOZ.

Table 1 elemental analysis values for DNOZ prepared in example 1

	C/％	N/％	O/％
				Theoretical value	21.05	36.84	42.11
Measured value	21.12	36.78	-

Examples of the inventionThe DNOZ density provided was 1.79g/cm³The impact sensitivity was 23J, the friction sensitivity was 253N, and the electrostatic sensitivity was 0.80J.

Example 2

a four-necked flask was charged with 400mL of 1M hydrochloric acid, ammonium thiocyanate (22.83g, 0.3 mol). The reaction mixture was magnetically stirred at reflux at 120 ℃ for 35 min. Oxalyl dihydrazide (0.097mol,11.42g) was then added to the reaction mixture, and stirring was continued while maintaining the temperature at 120 ℃ for 5 hours. After completion of the reaction, ice was added to cool, and the precipitate was filtered, washed and dried to obtain 12.30g of white intermediate product DSODH with a yield of 52.06%.

Into a four-necked flask was added DSODH (0.08mol, 18.88g), followed by the addition of the coupling agent DIC (0.19mol, 24.60g), diisopropylethylamine (0.19mol, 24.60g) and 250g of dichloromethane as a solvent, and the reaction mixture was stirred at 50 ℃ for 21 h. After the reaction was completed, the product was separated by filtration, and the precipitate was washed with methanol and then dried. The product was recrystallized from ethanol and further purified. This gave 84.77% yield of DAOZ11.40g as a pale yellow intermediate.

DAOZ (12.00g,0.072mol), sodium nitrite (120g) and water (264g) were added dropwise to a four-necked flask, and 24g of concentrated sulfuric acid (98% by mass) was stirred at 42 ℃ for 1 hour until no nitrogen dioxide gas was generated. The solution was then cooled to 0 ℃ and the precipitate formed was separated by filtration, redissolved in hot water at 85 ℃ and filtered to remove insoluble impurities, the resulting clear solution was crystallized by standing at 1 ℃ and filtered to give the final product dnoz13.47g in 82.02% yield.

Table 2 shows the elemental analysis values of 2,2 '-dinitro-5, 5' -bis (1,3, 4-oxadiazole) prepared in this example, and the measured results are consistent with the theoretical calculation values.¹³C Nuclear magnetic test results (125MHz, DMSO-d)₆25 ℃ C. delta.: 158.7, 149.9. Confirmed as the target compound DNOZ.

Table 2 elemental analysis values for DNOZ prepared in example 2

	C/％	N/％	O/％
				Theoretical value	21.05	36.84	42.11
Measured value	21.08	36.54	-

The DNOZ density provided by the embodiment of the invention is 1.79g/cm³The impact sensitivity was 24J, the friction sensitivity was 257N, and the electrostatic sensitivity was 0.80J.

Example 3

A four-necked flask was charged with 400mL of 1M hydrochloric acid and ammonium thiocyanate (15.00g, 0.2 mol). The reaction mixture was magnetically stirred at 130 ℃ under reflux for 45 min. Oxalyl dihydrazide (0.04mol, 5g) was then added to the reaction mixture, stirring was continued, and heating was continued for 5.5 h. After completion of the reaction, ice was added to cool, and the precipitate was filtered, washed and dried to give 15.80g of white intermediate product DSODH with a yield of 66.92%.

Into a four-necked flask was added DSODH (0.08mol, 18.88g), followed by the addition of the coupling agent DIC (0.24mol, 30.00g), diisopropylethylamine (0.23mol, 30.00g) and 300g of acetone as a solvent, and the reaction mixture was stirred at 48 ℃ for 22 h. After the reaction was completed, the product was separated by filtration, and the precipitate was washed with methanol and then dried. The product was recrystallized from ethanol and further purified. This gave 86.18% yield of DAOZ11.59g as a pale yellow intermediate.

DAOZ (12.00g,0.072mol), sodium nitrite (144g) and water (300g) are added into a four-neck flask, 27.6g of concentrated sulfuric acid (98 percent by mass) is added dropwise, and the mixture is stirred for 1.2h at 45 ℃ until no nitrogen dioxide gas is generated. The solution was then cooled to 0 ℃ and the precipitate formed was separated by filtration, dissolved in 90 ℃ hot water and filtered to remove insoluble impurities, the clear solution obtained was allowed to stand at 2 ℃ for crystallisation and filtered to give the final product DNOZ 5.48g with a yield of 33.37%.

The DNOZ density provided by the embodiment of the invention is 1.79g/cm³The impact sensitivity was 23J, the friction sensitivity was 253N, and the electrostatic sensitivity was 0.80J.

Example 4

A four-necked flask was charged with 200mL of 1M hydrochloric acid, and ammonium thiocyanate (8.76g, 0.12mol) was added. The reaction mixture was magnetically stirred at reflux at 125 ℃ for 50 min. Oxalyl dihydrazide (0.018mol, 2.19g) was then added to the reaction mixture, stirring was continued, and heating was continued for 4.5 h. After the reaction was completed, ice was added to cool, and the precipitate was filtered, washed and dried to obtain 6.25g of white intermediate product DSODH with a yield of 26.45%.

Into a four-necked flask was added DSODH (0.08mol, 18.88g), followed by the addition of the coupling agent DIC (0.27mol, 34.00g), diisopropylethylamine (0.26mol, 34.00g) and 350g of acetonitrile as a solvent, and the reaction mixture was stirred at 52 ℃ for 23 h. After the reaction was completed, the product was separated by filtration, and the precipitate was washed with methanol and then dried. The product was recrystallized from ethanol and further purified. This gave 9.17g of DAOZ as a pale yellow intermediate in 68.18% yield.

DAOZ (12.00g,0.072mol), sodium nitrite (156g) and water (336g) were added to a four-necked flask, and 33.6g of concentrated sulfuric acid (98% by mass) was added dropwise thereto, followed by stirring at 48 ℃ for 1.5 hours until no nitrogen dioxide gas was generated. The solution was then cooled to 0 ℃ and the precipitate formed was separated by filtration, dissolved in 95 ℃ hot water and filtered to remove insoluble impurities, the clear solution obtained was crystallised by standing at 3 ℃ and filtered to give 6.8g of the final product DNOZ with a yield of 41.41%.

Example 5

A four-necked flask was charged with 300mL of 1M hydrochloric acid, and ammonium thiocyanate (19.71g, 0.26mol) was added. The reaction mixture was magnetically stirred at reflux at 115 ℃ for 60 min. Oxalyl dihydrazide (0.048mol,5.63g) was then added to the reaction mixture, stirring was continued, and heating was continued for 5 h. After the reaction was completed, ice was added to cool, and the precipitate was filtered, washed and dried to obtain 8.63g of white intermediate product DSODH with a yield of 36.52%.

Into a four-necked flask was added DSODH (0.08mol, 18.88g), followed by the addition of coupling agent DIC (0.30 mol,37.50g), diisopropylethylamine (0.24mol,37.50g) and 400g of acetonitrile as a solvent, and the reaction mixture was stirred at 55 ℃ for 24 h. After the reaction was completed, the product was separated by filtration, and the precipitate was washed with methanol and then dried. The product was recrystallized from ethanol and further purified. DAOZ10.25g was obtained as a pale yellow intermediate in 76.21% yield.

DAOZ (12.00g,0.072mol), sodium nitrite (180g) and water (360g) were added to a four-necked flask, and 36g of concentrated sulfuric acid (98% by mass) was added dropwise thereto and stirred at 50 ℃ for 0.5 hour until no nitrogen dioxide gas was generated. The solution was then cooled to 0 ℃ and the precipitate formed was separated by filtration, dissolved in 100 ℃ boiling water and filtered to remove insoluble impurities, the clear solution obtained was crystallised by standing at 5 ℃ and filtered to give 8.84g of the final product DNOZ with a yield of 47.27%.

The DNOZ provided by the embodiment 1-5 of the invention is applied to a solid propellant as an energetic material, and specifically, the propellant comprises the following components in percentage by mass:

oxidant AP 40%, DNOZ 22%, fuel spherical aluminum powder 18%, binder PEG and curing agent IPDI 8%, NG and BTTN 12%;

the components are uniformly mixed and cured for 7 days at the temperature of 55 ℃ to obtain propellant tablets, and the tablets have uniform section and no air holes.

The above description is only for the best mode of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention.

The invention is not described in detail and is within the knowledge of a person skilled in the art.

Claims

2,2 '-dinitro-5, 5' -bis (1,3, 4-oxadiazole), characterized by the following chemical structural formula:
2. a preparation method of 2,2 '-dinitro-5, 5' -bis (1,3, 4-oxadiazole) is characterized by comprising the following steps:

(1) refluxing a mixture of ammonium thiocyanate and dilute acid at a certain temperature for a period of time, adding oxalyl dihydrazide, continuously stirring for reaction, cooling and filtering after the reaction is finished, and washing and drying a precipitate to obtain a white intermediate product N, N' -dithioamide-oxalyl dihydrazide;

(2) adding the N, N ' -dithio amide-oxalyl dihydrazide, diisopropylcarbodiimide and diisopropylethylamine into a certain amount of polar solvent, stirring and reacting at a certain temperature, filtering and separating after the reaction is finished, and washing, drying and recrystallizing a precipitate to obtain a light yellow intermediate 2,2 ' -diamino-5, 5 ' -bis (1,3, 4-oxadiazole);

(3) dissolving a certain amount of 2,2 '-diamino-5, 5' -bis (1,3, 4-oxadiazole) and sodium nitrite in water, dropwise adding strong acid at a certain temperature to react until no reddish brown nitrogen dioxide gas is generated, cooling to generate precipitate, filtering and separating, and removing impurities to obtain the final product 2,2 '-dinitro-5, 5' -bis (1,3, 4-oxadiazole).
3. The method for preparing 2,2 '-dinitro-5, 5' -bis (1,3, 4-oxadiazole) according to claim 2, wherein: the diluted acid in the step (1) is hydrochloric acid with the molar concentration of 0.8-1.2 mol/L, and the mass ratio of HCl to ammonium thiocyanate is 1: 2.1-1: 4.4.
4. the method for preparing 2,2 '-dinitro-5, 5' -bis (1,3, 4-oxadiazole) according to claim 2, wherein: refluxing the mixture of ammonium thiocyanate and dilute acid in the step (1) at the temperature of 110 ℃ and 130 ℃ for 30-60 min.
5. The method for preparing 2,2 '-dinitro-5, 5' -bis (1,3, 4-oxadiazole) according to claim 2, wherein: the mass ratio of oxalyl dihydrazide to ammonium thiocyanate in the step (1) is 1: 2-1: 4.
6. the method for preparing 2,2 '-dinitro-5, 5' -bis (1,3, 4-oxadiazole) according to claim 2, wherein: the reaction time after the oxalyl dihydrazide is added in the step (1) is 4.5-5.5 h.
7. The method for preparing 2,2 '-dinitro-5, 5' -bis (1,3, 4-oxadiazole) according to claim 2, wherein: the mass ratio of the N, N' -dithio amide-oxalyl dihydrazide to the diisopropylcarbodiimide in the step (2) is 1: 1-1: 2.
8. the method for preparing 2,2 '-dinitro-5, 5' -bis (1,3, 4-oxadiazole) according to claim 2, wherein: the mass ratio of the N, N' -dithio amide-oxalyl dihydrazide to the diisopropylethylamine in the step (2) is 1: 1-1: 2.
9. the method for preparing 2,2 '-dinitro-5, 5' -bis (1,3, 4-oxadiazole) according to claim 2, wherein: the mass ratio of the N, N' -dithio amide-oxalyl dihydrazide in the step (2) to the polar solvent is 1: 10-1: 20.
10. the method for preparing 2,2 '-dinitro-5, 5' -bis (1,3, 4-oxadiazole) according to claim 2, wherein: the reaction temperature in the step (2) is 45-55 ℃, and the reaction time is 20-24 h.
11. The method for preparing 2,2 '-dinitro-5, 5' -bis (1,3, 4-oxadiazole) according to claim 2, wherein: the mass ratio of the 2,2 '-diamino-5, 5' -bis (1,3, 4-oxadiazole) to the sodium nitrite in the step (3) is 1: 8-1: 15.
12. the method for preparing 2,2 '-dinitro-5, 5' -bis (1,3, 4-oxadiazole) according to claim 2, wherein: the strong acid in the step (3) is concentrated sulfuric acid, 2,2 '-diamino-5, 5' -bis (1,3, 4-oxadiazole) and H₂SO₄The mass ratio of (1): 1.6-1: 3.
13. the method for preparing 2,2 '-dinitro-5, 5' -bis (1,3, 4-oxadiazole) according to claim 2, wherein: the mass ratio of the 2,2 '-diamino-5, 5' -bis (1,3, 4-oxadiazole) to the water in the step (3) is 1: 15-1: 30.
14. the method for preparing 2,2 '-dinitro-5, 5' -bis (1,3, 4-oxadiazole) according to claim 2, wherein: the reaction temperature of the step (3) is 40-50 ℃, and the reaction time is 0.5-1.5 h.
15. The method for preparing 2,2 '-dinitro-5, 5' -bis (1,3, 4-oxadiazole) according to claim 2, wherein: removing impurities in the step (3) to obtain a final product 2,2 '-dinitro-5, 5' -bis (1,3, 4-oxadiazole), which comprises the following steps:

dissolving the filter cake in hot water at the temperature of 80-100 ℃, filtering to remove insoluble impurities, standing the obtained clear solution at the temperature of 0-5 ℃ for crystallization, and filtering to obtain the final product 2,2 '-dinitro-5, 5' -bis (1,3, 4-oxadiazole).
16. The method for preparing 2,2 '-dinitro-5, 5' -bis (1,3, 4-oxadiazole) according to claim 2, wherein: and (3) carrying out recrystallization in ethanol.
17. The method for preparing 2,2 '-dinitro-5, 5' -bis (1,3, 4-oxadiazole) according to claim 2, wherein: the polar solvent in the step (2) is at least one of acetonitrile, dichloromethane or acetone.
The application of 2,2 '-dinitro-5, 5' -bis (1,3, 4-oxadiazole) as an energetic material in a solid propellant.