Pyrazinopyridazine fused-ring compounds and their preparation methods

Abstract

This invention discloses pyrazinopyridazine fused-ring compounds, which develop novel compounds with excellent comprehensive properties by constructing a stable pyrazinopyridazine fused-ring skeleton. This invention also discloses a method for preparing pyrazinopyridazine fused-ring compounds, which can synthesize a key intermediate from known and available raw materials through simple steps. The key intermediate is then ring-closed with hydrazine hydrate to successfully achieve a one-step, efficient construction of the pyrazinopyridazine fused-ring compound. This compound exhibits strong thermal stability, is highly insensitive, and also possesses certain detonation properties, making it suitable for use as a heat-resistant explosive.

Description

Technical Field

[0001] This invention relates to the field of energetic materials technology, specifically to pyrazinoid pyridazine fused ring compounds and their preparation methods. Background Technology

[0002] With the rapid development of modern energetic materials technology, there is increasing attention being paid to the comprehensive performance of novel energetic materials. Energetic materials are required not only to possess high energy and high density, but also to have advantages such as thermal stability and low sensitivity. Therefore, in recent years, high-energy, low-sensitivity energetic compounds have gradually become a hot topic in energetic materials research.

[0003] Compared to traditional monocyclic or chain-like frameworks, fused-ring frameworks often possess advantages such as higher heat of formation and better stability, and are therefore widely used in the construction of novel energetic materials. Once a novel and stable fused-ring framework is developed, various construction strategies can be used to adapt it to different energy groups, thereby developing a variety of novel energetic materials with excellent overall performance. Summary of the Invention

[0004] One object of the present invention is to solve at least the above-mentioned problems and / or defects, and to provide at least the advantages described below.

[0005] Another objective of this invention is to provide a pyrazinoid pyridazine fused-ring compound, which develops a novel compound with excellent overall performance by constructing a pyrazinoid pyridazine fused-ring skeleton with good stability.

[0006] Another objective of this invention is to provide a method for preparing pyrazinopyridazine fused-ring compounds. Starting from known and available raw materials, a key intermediate can be synthesized through simple steps. By cyclizing this key intermediate with hydrazine hydrate, a one-step efficient construction of pyrazinopyridazine fused-ring compounds is successfully achieved. These compounds exhibit strong thermal stability, are highly insensitive, and also possess certain detonation properties, making them suitable for use as heat-resistant explosives.

[0007] To achieve these and other advantages according to the present invention, a pyrazinoid pyridazine fused-ring compound is provided having the structure of formula (I):

[0008]

[0009] Among them, R1, R2, R3, and R4 are all nitrogen-containing substituents.

[0010] Preferably, R1, R2, R3, and R4 are all amino groups.

[0011] The objective of this invention can also be further achieved by a method for preparing pyrazine-pyridazine fused-ring compounds, including: synthesizing a pyrazine ring intermediate from diaminomaleitrile, and further reacting the pyrazine ring intermediate to synthesize compound (I).

[0012] Preferably, the step of synthesizing the pyrazine ring intermediate from diaminomaleitrile specifically includes:

[0013] S1. An intermediate with the following structure (II) is obtained by reacting diaminomaleonitrile with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone.

[0014] S2. The intermediate of formula (II) was reacted with diaminomaleonitrile in the presence of a catalyst, and the mixture was filtered and recrystallized to obtain the pyrazine ring intermediate of formula (III) as follows:

[0015]

[0016] Preferably, the synthesis of compound (I) by further reaction of the pyrazine ring intermediate specifically includes: dissolving the pyrazine ring intermediate in an organic solvent, slowly adding hydrazine hydrate, stirring at room temperature, and then heating to react.

[0017] Preferably, in step S1, the molar ratio of diaminomaleitrile to 2,3-dichloro-5,6-dicyano-1,4-benzoquinone is 1:1, the reaction temperature is room temperature, and the reaction time is 0.5 h.

[0018] Preferably, in step S2, the catalyst is 98% concentrated sulfuric acid.

[0019] Preferably, in step S2, the solvent used for recrystallization is acetonitrile.

[0020] Preferably, in step S2, the molar ratio of diaminomaleitrile to the intermediate of formula (II) is 1:1.2.

[0021] Preferably, the organic solvent is isopropanol, and the ratio of pyrazine ring intermediate to hydrazine hydrate is 1 mmol: 0.5 mL.

[0022] The present invention has at least the following beneficial effects:

[0023] 1. This invention develops novel compounds with excellent comprehensive performance by constructing a stable pyrazinoid pyridazine fused ring skeleton, making them more advantageous in energetic material applications.

[0024] 2. The method for preparing the pyrazinopyridazine fused-ring compound of the present invention can synthesize the key intermediate from known and available raw materials through simple steps. By cyclizing the key intermediate with hydrazine hydrate, the pyrazinopyridazine fused-ring compound can be successfully constructed in one step with high efficiency. The compound has strong thermal stability, is very insensitive, and also has certain detonation performance, so it can be used as a heat-resistant explosive.

[0025] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0026] Figure 1 This is a single-crystal structure diagram of compound 4·H2O in Example 1 of the present invention;

[0027] Figure 2 The above is the 1H NMR spectrum of compound 4 in Example 1 of this invention;

[0028] Figure 3 This is the carbon NMR spectrum of compound 4 in Example 1 of the present invention. Detailed Implementation

[0029] The present invention will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.

[0030] It should be understood that terms such as “having,” “comprising,” and “including” as used herein do not imply the presence or addition of one or more other elements or combinations thereof.

[0031] It should be noted that, unless otherwise specified, the experimental methods described in the following implementation plan are all conventional methods, and the reagents and materials described are all commercially available unless otherwise specified.

[0032] <Example 1>

[0033] Pyrazinopyridazine fused-ring compound 4 has the following structural formula:

[0034]

[0035] The specific synthesis route is as follows:

[0036]

[0037] The specific synthesis steps are as follows:

[0038] Step 1: Synthesis of diiminosuccinate (compound 2)

[0039] Compound 1, diaminomaleonitrile (1.08 g, 20 mmol), was dissolved in 100 mL of acetonitrile, and then 20 mmol of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (2.27 g, 20 mmol) was added. The mixture was reacted at room temperature for 0.5 h, filtered, and the filtrate was evaporated to dryness to give a brown solid compound 2, diiminosuccinate (2.02 g, yield: 95%).

[0040] Step 2: Synthesis of 5,6-diamino-2,3-dicyanopyrazine (compound 3)

[0041] Compound 1 (5.94 g, 55 mmol) was dissolved in 200 mL of acetonitrile, and then compound 2 (7.00 g, 66 mmol) was added. After stirring in a water bath for half an hour, 0.25 mL of 98% concentrated sulfuric acid (catalyst) was added. After stirring for 2 hours, the mixture was filtered to obtain a brown crude product. The crude product was recrystallized from acetonitrile, filtered, and dried to obtain a yellow compound 3 (3.20 g, yield: 36%).

[0042] Step 3: Synthesis of 2,3,5,8-tetraaminopyrazine[2,3-d]pyridazine (compound 4)

[0043] Compound 3 (1.60 g, 10 mmol) was mixed with 30 mL of isopropanol, and then hydrazine hydrate (5 mL, 98%) was slowly added dropwise. After the addition was complete, the mixture was stirred at room temperature for 1 h, and then heated to 80 °C for 2 days. After the reaction was complete, the mixture was filtered, washed with isopropanol and water respectively, and dried to obtain an orange solid compound 4 (0.60 g, 31%). R (cm) -1 )ν~=3427,3343,1594,1509,1452,1384,1352,683,570. 1 H NMR(DMSO-d6):7.10(s,4H),5.20(s,4H); 13 C{ 1 H}NMR(DMSO-d6): δ151.2,146.8,123.1; EA(C5H7N7·0.2H2O,165.16): Calcd, C:37.50; H:4.20; N:58.31; Found, C:37.32; H:4.02; N:58.66.

[0044] The single-crystal structure diagram of compound 4 is shown below. Figure 1 The proton NMR spectrum is shown below. Figure 2 The carbon NMR spectrum is shown below. Figure 3 .

[0045] <Example 2>

[0046] Performance table of compound 4 synthesized in the embodiments of the present invention:

[0047] Table 1 Performance of Compound 4

[0048]

[0049] a Thermal decomposition temperature (DSC, 5℃ min) -1 ), b The density of anhydrous compounds (25℃) was measured using the gas specific gravity bottle method. cCalculated enthalpy of formation, d Calculated detonation velocity, e Calculated detonation pressure, f Impact sensitivity g Friction sensitivity.

[0050] As can be seen from the table above, compound 4 has strong thermal stability, is very insensitive, and also has certain detonation properties, so it can be used as a heat-resistant explosive.

[0051] The enthalpy of formation and density together determine the detonation velocity and detonation pressure. Detonation velocity and detonation pressure are key to the performance of energetic materials, and the higher the better. Impact sensitivity and friction sensitivity are key to whether the material can be used. The higher the sensitivity, the more insensitive the material. Insensitive energetic materials have good stability and are safer to use and store.

[0052] This invention develops novel compounds with excellent overall performance by constructing a stable pyrazinopyridazine fused-ring skeleton. The invention also discloses a method for preparing pyrazinopyridazine fused-ring compounds, which synthesizes a key intermediate from known and available raw materials through simple steps. The key intermediate is then ring-closed with hydrazine hydrate to achieve a one-step, efficient construction of the pyrazinopyridazine fused-ring compound. This compound exhibits strong thermal stability, is highly insensitive, and also possesses certain detonation properties, making it suitable for use as a heat-resistant explosive.

[0053] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. It can be applied to various fields suitable for the present invention. Other modifications can be readily made by those skilled in the art. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and examples shown and described herein.

Claims

1. Pyrazinopyridazine fused-ring compounds having the structure of formula (I): （I） in, R1, R2, R3, and R4 are all amino groups.

2. A method for preparing the pyrazinopyridazine fused-ring compound of claim 1, comprising the following steps: S1. An intermediate with the following structure (II) is obtained by reacting diaminomaleonitrile with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone. S2. The intermediate of formula (II) was reacted with diaminomaleonitrile in the presence of a catalyst, and the mixture was filtered and recrystallized to obtain the pyrazine ring intermediate of formula (III) as follows: (II)) (III)) S3. Dissolve the pyrazine ring intermediate of formula (III) in an organic solvent, slowly add hydrazine hydrate, stir at room temperature and then heat to react to obtain compound (I).

3. The method as described in claim 2, wherein, In step S1, the molar ratio of diaminomaleonitrile to 2,3-dichloro-5,6-dicyano-1,4-benzoquinone is 1:1, the reaction temperature is room temperature, and the reaction time is 0.5 h.

4. The method of claim 2, wherein, In step S2, the catalyst is 98% concentrated sulfuric acid.

5. The method of claim 2, wherein, In step S2, the solvent used for recrystallization is acetonitrile.

6. The method of claim 2, wherein, In step S2, the molar ratio of diaminomaleitrile to the intermediate of formula (II) is 1:1.

2.

7. The method of claim 2, wherein, In step S3, the organic solvent is isopropanol, and the ratio of pyrazine ring intermediate to hydrazine hydrate is 1 mmol: 0.5 mL.

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