Pyridazine-imidazole condensed ring energetic compound or energetic salt thereof and preparation method thereof

Abstract

The present invention discloses an energetic compound containing a pyridazine imidazole condensed ring or an energetic salt thereof, wherein a series of energetic compounds with high energy density and energetic salts thereof are formed by introducing a nitramine group into the pyridazine imidazole condensed ring. The present invention also discloses a method for preparing an energetic compound containing a pyridazine imidazole condensed ring or an energetic salt thereof, wherein a series of all-nitramine condensed ring energetic compounds with good application prospects are synthesized through simple steps from known available raw materials.

Description

Technical Field

[0001] The invention relates to the technical field of energetic materials, and in particular to an energetic compound containing a pyridazine and imidazole condensed ring or an energetic salt thereof and a preparation method thereof. Background Art

[0002] With the rapid development of modern energetic material technology, the performance requirements for new energetic materials are becoming higher and higher. Not only do we need to develop high-energy and high-density energetic materials, but they are also required to have the advantages of thermal stability and low sensitivity. Therefore, high energy density materials (HEDMs) have received widespread attention in recent years. HEDMs have excellent comprehensive performance and are known as "modern new high-performance explosives". High-energy and low-sensitivity energetic compounds have gradually become a hot spot in energetic material research.

[0003] The nitramine group has the advantage of being able to form a hydrogen bond network. When the atomic skeletons are connected, nitramines can also undergo hydrogen transfer and tautomerize into nitrosamine groups, thereby forming extra intramolecular hydrogen bonds, which can greatly promote the formation of planar conjugated structures. Compared with traditional single rings or chain skeletons, condensed rings often have advantages such as higher heat of formation and better thermal stability and are widely used in the construction of energetic materials. Therefore, fully nitramine-substituted condensed ring energetic compounds have good application prospects in HEDMs. Summary of the invention

[0004] An object of the present invention is to solve at least the above problems and / or disadvantages and to provide at least the advantages which will be described hereinafter.

[0005] Another object of the present invention is to provide an energetic compound containing a pyridazine imidazole fused ring or an energetic salt thereof, which forms a series of energetic compounds with high energy density by combining nitramine with the fused ring.

[0006] Another object of the present invention is to provide a method for preparing a pyridazine-imidazole-containing fused ring energetic compound or an energetic salt thereof, which starts from known available raw materials and synthesizes a series of full-nitramine fused ring energetic compounds with good application prospects through simple steps.

[0007] In order to achieve these purposes and other advantages according to the present invention, there is provided a pyridazine-imidazole fused ring-containing energetic compound or an energetic salt thereof, wherein the energetic compound has the structure of the following formula (I):

[0008]

[0009] Among them, AB is C=N or C-NH, DE is C=N or C-NH, and R1, R2, and R3 are all nitramine groups.

[0010] Preferably, wherein

[0011] When AB is C=N, R1 is

[0012] When AB is C-NH, A-R1 is C=N-NO2.

[0013] Preferably, wherein

[0014] When DE is C=N, R3 is

[0015] When DE is C-NH, D-R3 is C=N-NO2.

[0016] Preferably, wherein R2 is

[0017] Preferably, the energy-containing salt is an ammonium salt, a hydroxylamine salt or a hydrazine salt.

[0018] The object of the present invention can be further achieved by a method for preparing a pyridazine-imidazole fused ring energetic compound or an energetic salt thereof, comprising the following steps:

[0019] Step 1. Synthesis of intermediate compound of formula (II)

[0020] Using 4,5-dicyano-2-aminoimidazole as a raw material, and reacting it with hydrazine hydrate to obtain a compound of formula (II);

[0021] Step 2: Synthesis of the compound of formula (I)

[0022] Using the compound of formula (II) obtained in step 1 as an intermediate to carry out one or more steps of reaction to prepare the compound of formula (I) or its energetic salt;

[0023]

[0024] Preferably, the step 1 specifically includes the following steps:

[0025] S1, add 4,5-dicyano-2-aminoimidazole to 1,4-dioxane, add hydrazine hydrate dropwise, and react at 80°C for 3h;

[0026] S2, removing 1,4-dioxane from the reaction in S1, adding N,N-dimethylformamide and hydrazine hydrate to the reaction system, and continuing the reaction at 80°C for 2h;

[0027] S3, after filtering, washing and drying, add hydrochloric acid, heat to 55°C for 4 hours, cool to precipitate crystals, add water to dissolve, adjust the pH to 7 to precipitate solids, filter and wash with cold water.

[0028] Preferably, in said S1, the hydrazine hydrate is 98% hydrazine hydrate.

[0029] Preferably, in step S3, the solvent used for washing is N,N-dimethylformamide.

[0030] Preferably, in step S3, the hydrochloric acid has a mass fraction of 37%.

[0031] The present invention has at least the following beneficial effects:

[0032] 1. The present invention creatively combines the pyridazine imidazole fused ring and the nitramine group to form an energetic compound with high energy density and better stability, making it more advantageous in the application of energetic materials.

[0033] 2. The method for preparing the pyridazine-imidazole-containing fused ring energetic compound or its energetic salt of the present invention can synthesize a series of full-nitramine fused ring energetic compounds with good application prospects through simple steps starting from known available raw materials.

[0034] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a single crystal structure diagram of the compound 2·2HCl·H2O in Example 1 of the present invention;

[0036] Figure 2 This is a structural representation diagram of compound 2 in Example 1 of the present invention;

[0037] Figure 3 This is a single crystal structure diagram of compound 3·3H2O in Example 1 of the present invention;

[0038] Figure 4 is a differential scanning calorimeter DSC diagram of compound 3 in Example 1 of the present invention;

[0039] Figure 5 is the hydrogen nuclear magnetic resonance spectrum of compound 3 in Example 1 of the present invention;

[0040] Figure 6 is the carbon NMR spectrum of compound 3 in Example 1 of the present invention;

[0041] Figure 7 is the DSC graph of compound 4·2H2O in Example 2 of the present invention;

[0042] Figure 8is the hydrogen nuclear magnetic resonance spectrum of compound 4·2H2O in Example 2 of the present invention;

[0043] Fig. 9 is the carbon nuclear magnetic resonance spectrum of compound 4·2H2O in Example 2 of the present invention;

[0044] Fig.10 is the DSC graph of compound 5·H2O in Example 3 of the present invention;

[0045] Fig.11 is the hydrogen nuclear magnetic resonance spectrum of compound 5·H2O in Example 3 of the present invention;

[0046] Fig.12 is the carbon NMR spectrum of compound 5·H2O in Example 3 of the present invention;

[0047] Fig.13 is the DSC graph of compound 6 in Example 4 of the present invention;

[0048] Fig.14 is the hydrogen nuclear magnetic resonance spectrum of compound 6 in Example 4 of the present invention;

[0049] Fig.15 is the carbon NMR spectrum of compound 6 in Example 4 of the present invention;

[0050] Fig.16 is the DSC graph of compound 7 in Example 5 of the present invention;

[0051] Fig.17 is the hydrogen nuclear magnetic resonance spectrum of compound 7 in Example 5 of the present invention;

[0052] Fig.18 is the carbon NMR spectrum of compound 7 in Example 5 of the present invention;

[0053] Fig.19 is the DSC graph of compound 8·3H2O in Example 5 of the present invention;

[0054] Fig. 20 is the hydrogen nuclear magnetic resonance spectrum of compound 8·3H2O in Example 5 of the present invention;

[0055] Fig.21 is the carbon NMR spectrum of compound 8·3H2O in Example 5 of the present invention;

[0056] Fig. 22 is the DSC graph of compound 9·2H2O in Example 6 of the present invention;

[0057] Fig.23 is the hydrogen nuclear magnetic resonance spectrum of compound 9·2H2O in Example 6 of the present invention;

[0058] Fig.24 is the carbon NMR spectrum of compound 9·2H2O in Example 6 of the present invention;

[0059] Fig.25 is the DSC graph of compound 10·CH3OH in Example 7 of the present invention;

[0060] Fig.26 is the hydrogen nuclear magnetic resonance spectrum of compound 10·CH3OH in Example 7 of the present invention;

[0061] Fig. 27 is the carbon nuclear magnetic resonance spectrum of compound 10·CH3OH in Example 7 of the present invention;

[0062] Fig.28 is the DSC graph of compound 11·2H2O in Example 8 of the present invention;

[0063] Fig.29 is the hydrogen nuclear magnetic resonance spectrum of compound 11·2H2O in Example 8 of the present invention;

[0064] Fig.30 This is the carbon nuclear magnetic resonance spectrum of compound 11·2H2O in Example 8 of the present invention. DETAILED DESCRIPTION

[0065] The present invention is further described in detail below in conjunction with the accompanying drawings so that those skilled in the art can implement the invention with reference to the description.

[0066] It should be understood that terms such as “having”, “including” and “comprising” used herein do not specify the existence or addition of one or more other elements or combinations thereof.

[0067] It should be noted that the experimental methods described in the following embodiments are conventional methods unless otherwise specified, and the reagents and materials can be obtained from commercial channels unless otherwise specified.

[0068] <Example 1>

[0069] The energetic compound 3 has the following structural formula:

[0070]

[0071] The specific synthetic route is as follows:

[0072]

[0073] The specific synthesis steps are as follows:

[0074] Step 1. Synthesis of Compound 2

[0075] 4,5-Dicyano-2-aminoimidazole 1 (1.33 g; 10 mmol) was added to 1,4-dioxane (10 mL), hydrazine hydrate (98%, 3 mL) was added dropwise to dissolve, and then heated at 80°C for 3 h. Then 1,4-dioxane was removed, 2.5 mL of N,N-dimethylformamide (DMF) and hydrazine hydrate (98%, 5 mL) were added to the system, and heating at 80°C was continued for 2 h. The white solid was filtered, washed with DMF (3 mL), dried, and 9 mL of hydrochloric acid (37%) was added. After heating to 55°C for 4 h, 2·2HCl·H2O crystals were precipitated after cooling. After the crystals were dissolved in water, the pH was adjusted to about 7 with NaHCO3 solution, and a large amount of white solid was precipitated. After filtering and washing with cold water (3 mL), 2 (0.58 g, 35%) was obtained. The single crystal structure of compound 2·2HCl·H2O is shown in Figure 1 , the structural representation diagram is shown in Figure 2 . T dec :286.22℃;IR(cm -1 )v~=3456, 3395, 3339, 3104, 2707, 1679, 1625, 1560, 1480, 1432, 1276, 1242, 1118, 1033, 829, 784, 752, 639, 583. 1 H NMR (DMSO-d6): 5.75 (s, 6H); 13 C{ 1 H} NMR (DMSO-d6): δ130.4, 145.4, 163.2; EA (C5H7N7·0.2H2O, 165.16): Calcd, C: 35.59; H: 4.42; N: 58.10; Found, C: 35.23; H: 4.65; N: 58.83.

[0076] Step 2: Synthesis of Compound 3

[0077] 2 (0.66 g, 4 mmol) was added to nitric acid (100%, 6 mL) at 0°C. After complete addition, the reaction mixture was stirred at room temperature for 2 h. After complete reaction, ice (10 g) was added, and the mixture was allowed to stand for precipitation. The mixture was filtered and washed with cold water (3 mL) to obtain a yellow solid 3 (0.54 g, 45%). The single crystal structure of compound 3·3H2O is shown in Figure 3 The DSC diagram of compound 3 is shown in Figure 4 , H NMR spectrum is shown in Figure 5 , NMR carbon spectrum see Figure 6 . T dec :115.82℃;IR(cm -1)v~=3551, 3478, 3199, 1603, 1571, 1542, 1479, 1440, 1396, 1320, 1295, 1183, 1138, 965, 873, 820, 768, 653. 1 H NMR (DMSO-d6): δ8.36 (s, 1H); 13 C{ 1 H}NMR(DMSO-d6): δ128.2, 140.4, 154.76; EA(C5H4N 10 O6, 300.15): Calcd, C: 20.01; H: 1.34; N: 46.67; Found, C: 19.54; H: 1.68; N: 46.18.

[0078] <Example 2>

[0079] The energetic salt containing pyridazine and imidazole condensed ring 4·2H2O has the following structural formula:

[0080]

[0081] The specific synthetic route is as follows:

[0082]

[0083] The specific synthesis steps are:

[0084] Compound 3 (0.3 g, 1 mmol) was added to a mixed solution (10 mL) of water and methanol (1:1), and an aqueous ammonia solution (28 wt.%, 2.2 mmol) was added dropwise. The mixture was reacted at room temperature for 1 h, filtered, and washed with cold water (3 mL) to obtain a yellow-brown solid 4·2H2O (0.28 g, 76%). The DSC graph of compound 4·2H2O is shown in Figure 7 , H NMR spectrum is shown in Figure 8 , NMR carbon spectrum see Fig. 9 . T dec : 192.34℃, IR(cm-1)v~=3436, 3231, 1612, 1571, 1499, 1405, 1293, 1203, 1087, 1046, 1013, 862, 828, 764, 730, 654, 617, 601. 1 H NMR (DMSO-d6): 8.4 (s, 10H); 13 C{ 1 H}NMR(DMSO-d6): δ130.6, 146.4, 157.5; EA(C5H 10 N 12O6·2H2O, 370.24): Calcd, C: 16.22; H: 3.81; N: 45.4; Found, C: 16.36; H: 3.76; N: 46.06.

[0085] <Example 3>

[0086] The energetic salt containing pyridazine and imidazole condensed ring 5·H2O has the following structural formula:

[0087]

[0088] The specific synthetic route is:

[0089]

[0090] The specific synthesis steps are:

[0091] Compound 3 (0.3 g, 1 mmol) was added to a mixed solution (10 mL) of water and methanol (1:1), and hydrazine hydrate solution (90%, 2.2 mmol) was added dropwise. The mixture was reacted at room temperature for 1 h, and filtered to obtain a yellow-brown solid 5·H2O (0.29 g, 76%). The DSC diagram of compound 5·H2O is shown in Fig.10 , H NMR spectrum is shown in Fig.11 , NMR carbon spectrum see Fig.12 . T dec :224.18℃,IR(cm -1 )v~=3450, 3342, 3158, 1630, 1604, 1577, 1497, 1466, 1438, 1337, 1280, 1203, 1086, 1046, 996, 863, 830, 765, 730, 666, 651, 615, 599. 1 H NMR (DMSO-d6): 8.4 (s, 10H); 13 C{ 1 H}NMR(DMSO-d6): δ130.6, 146.4, 157.5; EA(C5H 12 N 14 O6·H2O, 382.26): Calcd, C: 15.71; H: 3.69; N: 51.3; Found, C: 15.52; H: 3.88; N: 50.87.

[0092] <Example 4>

[0093] The energetic salt 6 containing pyridazine and imidazole condensed ring has the following structural formula:

[0094]

[0095] The specific synthetic route is as follows:

[0096]

[0097] The specific synthesis steps are as follows:

[0098] Compound 3 (0.3 g, 1 mmol) was added to a mixed solution (10 mL) of water and methanol (1:1), and hydroxylamine aqueous solution (50 wt.%, 2.2 mmol) was added dropwise. The mixture was reacted at room temperature for 1 h, and filtered to obtain a yellow-brown solid 6 (0.31 g, 85%). The DSC diagram of compound 6 is shown in Fig.13 , H NMR spectrum is shown in Fig.14 , NMR carbon spectrum see Fig.15 . T dec :192.13℃,IR(cm -1 )v~=3377, 3231, 3168, 2708, 1749, 1613, 1572, 1506, 1294, 1202, 1088, 1050, 1007, 892, 864, 829, 766, 729, 667, 640, 619, 600. 1 H NMR (DMSO-d6): 10.31 (s, 8H); 13 C{ 1 H}NMR(DMSO-d6): δ130.6, 146.4, 157.5; EA(C5H 10 N 12 O8, 366.21): Calcd, C: 16.4; H: 2.75; N: 45.9; Found, C: 15.95; H: 3.36; N: 45.53.

[0099] <Example 5>

[0100] The energetic compound 8·3H2O containing pyridazine and imidazole condensed ring has the following structural formula:

[0101]

[0102] The specific synthetic route is:

[0103]

[0104] The specific synthesis steps are:

[0105] Step 1. Synthesis of compound 7·1.5H2O

[0106] Compound 2 (0.99 g, 6 mmol) was dissolved in hydrochloric acid (37%, 9 mL), and KMnO4 solution (0.65 g, 4.1 mmol in 4.5 mL of water) was added dropwise under ice bath conditions. The mixture was reacted at 55°C for 5 h, and an orange-yellow solid was obtained by filtration. The solid was then washed with a large amount of water and dried to obtain compound 7 (0.59 g, 56%). The DSC diagram of compound 7 is shown in Fig.16 , H NMR spectrum is shown in Fig.17 , NMR carbon spectrum see Fig.18 . T dec :379.11℃,IR(cm -1 )v~=3323, 3131, 1658, 1542, 1488, 1405, 1373, 1307, 1201, 1073, 1021, 805, 597. 1 H NMR(DMSO-d6): 7.34(s, 4H), 8.62(s, 4H); 13 C{ 1 H}NMR(DMSO-d6): δ24.6, 132.7, 146.6, 148.3, 158.9; EA(C 10 H 10 N 14 ·1.5H2O, 353.31): Calcd, C: 34.00; H: 3.71; N: 55.50; Found, C: 34.18; H: 4.08; N: 54.71.

[0107] Step 2: Synthesis of compound 8·3H2O

[0108] Compound 7·1.5H2O (0.35 g, 1 mmol) was added to fuming nitric acid (100%, 5 mL) in batches at -5°C. After the addition was completed, the mixture was stirred at room temperature for 2 h and poured into ice water (10 mL) to precipitate a large amount of orange-yellow solids. The solids were filtered and washed with a large amount of water to obtain compound 8·3H2O (0.25 g, 45%). The DSC diagram of compound 8·3H2O is shown in Fig.19 , H NMR spectrum is shown in Fig. 20 , NMR carbon spectrum see Fig.21 . T dec :117.14℃,IR(cm - 1) v~=3551, 3400, 3130, 1695, 1641, 1600, 1565, 1483, 1438, 1383, 1356, 1278, 1222, 1192, 1148, 1058, 973, 858, 772, 727, 670. 1 H NMR (DMSO-d6): 5.28 (s, 4H); 13 C{1 H}NMR(DMSO-d6): δ124.5, 126.5, 145.6, 147.4, 155.0; EA(C 10 H 16 N 18 O8·3H2O, 560.32): Calcd, C: 21.44; H: 2.16; N: 45.00; Found, C: 21.67; H: 2.27; N: 44.77.

[0109] <Example 6>

[0110] The energetic salt containing pyridazine and imidazole condensed ring 9·2H2O has the following structural formula:

[0111]

[0112] The specific synthetic route is:

[0113]

[0114] The specific synthesis steps are:

[0115] Compound 8·3H2O (0.56 g, 1 mmol) was added to a methanol solution (10 mL), and an aqueous ammonia solution (28 wt.%, 2.2 mmol) was added dropwise. The mixture was reacted at room temperature for 1 h, and filtered to obtain a reddish brown solid 9·2H2O (0.46 g, 80%). The DSC graph of compound 9·2H2O is shown in Fig. 22 , H NMR spectrum is shown in Fig.23 , NMR carbon spectrum see Fig.24 . T dec :200.21℃, IR(cm-1)v~=3377, 3196, 1603, 1561, 1495, 1438, 1353, 1260, 1194, 1152, 1069, 970, 850, 770, 725, 674, 553. 1 H NMR (DMSO-d6): 7.14 (s, 8H); 13 C{ 1 H}NMR(DMSO-d6): δ126.7, 130.6, 147.0, 147.9, 158.4; EA(C 10 H 16 N 18 O8·3H2O, 560.32): Calcd, C: 20.84; H: 2.80; N: 48.6; Found, C: 21.45; H: 3.01; N: 47.16.

[0116] <Example 7>

[0117] The energetic salt containing pyridazine and imidazole condensed ring 10·CH3OH has the following structural formula:

[0118]

[0119] The specific synthetic route is:

[0120]

[0121] The specific synthesis steps are:

[0122] Compound 8·3H2O (0.56 g, 1 mmol) was added to a methanol solution (10 mL), and a hydrazine hydrate solution (98%, 2.2 mmol) was added dropwise. The mixture was reacted at room temperature for 1 h, and filtered to obtain a reddish brown solid 10·CH3OH (0.47 g, 78%). The DSC diagram of compound 10·CH3OH is shown in Fig.25 , H NMR spectrum is shown in Fig.26 , NMR carbon spectrum see Fig. 27 . T dec :208.32℃, IR(cm-1)v~=3379, 3330, 3150, 1606, 1459, 1354, 1262, 1203, 1064, 968, 861, 770, 674. 1 H NMR (DMSO-d6): 6.83 (s, 10H); 13 C{ 1 H}NMR (DMSO-d6): δ126.5, 131.1, 147.1, 148, 158.9; EA (C 10 H 16 N 18 O8·3H2O, 560.32): Calcd, C: 21.93; H: 3.01; N: 51.15; Found, C: 21.73; H: 2.84; N: 51.25.

[0123] <Example 8>

[0124] The energetic salt containing pyridazine and imidazole condensed ring 11·2H2O has the following structural formula:

[0125]

[0126] The specific synthetic route is:

[0127]

[0128] The specific synthesis steps are:

[0129] Compound 8·3H2O (0.56 g, 1 mmol) was added to a methanol solution (10 mL), and a hydroxylamine aqueous solution (50 wt.%, 2.2 mmol) was added dropwise. The mixture was reacted at room temperature for 1 h, and filtered to obtain a reddish brown solid 11·2H2O (0.50 g, 83%). The DSC diagram of compound 11·2H2O is shown in Fig.28 , H NMR spectrum is shown in Fig.29 , NMR carbon spectrum see Fig.30 . T dec : 190.49℃, IR(cm-1)v~=3452, 3163, 2712, 1607, 1490, 1447, 1270, 1201, 1155, 1074, 975, 855, 771, 675, 555. 1 H NMR (DMSO-d6): 8.05 (s, 8H); 13 C{ 1 H}NMR(DMSO-d6): δ126.7, 131.0, 147.1, 148, 158.7; EA(C 10 H 12 N 20 O 10 ·2H2O, 608.37): Calcd, C: 19.74; H: 2.65; N: 46.05; Found, C: 20.09; H: 2.97; N: 45.52.

[0130] <Example 9>

[0131] Performance comparison of energetic compounds 3-6, 8-11 synthesized in the embodiments of the present invention and existing explosives RDX and HMX:

[0132] The performance comparison of compounds 3-6, 8-11 and RDX, HMX is shown in Table 1 below.

[0133] Table 1: Test and calculated properties of compounds 3-6, 8-11, RDX and HMX

[0134]

[0135] a Nitrogen content, b Thermal decomposition temperature (DSC, 5℃min -1 ), c Density of anhydrous compounds measured by gas pycnometer method (25°C), d Calculate the enthalpy of formation, e The calculated detonation velocity, g The calculated detonation pressure, h Impact sensitivity, i Friction sensitivity.

[0136] The properties of neutral compounds 3 and 8·3H2O and their salts, as well as the comparison with existing high-performance energetic materials RDX and HMX are shown in the table above. From the comparison of detonation velocity v and detonation pressure P, it can be seen that the energetic salt 6 containing pyridazine and imidazole condensed ring has the best performance, with the highest density, detonation velocity and detonation pressure in the series, and good thermal stability and sensitivity. Its performance is better than RDX and close to HMX. It is a high energy density material with comprehensive performance.

[0137] The formation enthalpy and density jointly determine the detonation velocity and detonation pressure. The detonation velocity and detonation pressure are the key to the performance of energetic materials, and the higher the better; the impact sensitivity and friction sensitivity are the key to whether they can be used. The higher the sensitivity, the better the stability, which means that the material is safer in preparation, use and storage.

[0138] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and the embodiments. It can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily realized. Therefore, without departing from the general concept defined by the claims and equivalent scope, the present invention is not limited to the specific details and the illustrations shown and described here.

Claims

1. A pyridazine-imidazole fused ring energetic compound or an energetic salt thereof, wherein the energetic compound has the following structure:

2. A method for preparing the pyridazine-imidazole fused ring energetic compound or its energetic salt according to claim 1, comprising the following steps: Step 1, synthesis of intermediate compound of formula (II): Using 4,5-dicyano-2-aminoimidazole as a raw material, and reacting it with hydrazine hydrate to obtain a compound of formula (II); Step 2: Synthesis of target compound: Using the compound of formula (II) obtained in step 1 as an intermediate to carry out one or more steps of reaction to prepare the target compound; The step 1 specifically includes the following steps: S1, add 4,5-dicyano-2-aminoimidazole to 1,4-dioxane, add hydrazine hydrate dropwise, and react at 80°C for 3h; S2, removing 1,4-dioxane from the reaction in S1, adding N,N-dimethylformamide and hydrazine hydrate to the reaction system, and continuing the reaction at 80°C for 2h; S3, after filtering, washing, and drying, add hydrochloric acid, heat to 55°C for 4 hours, cool to precipitate crystals, add water to dissolve, adjust the pH to 7 to precipitate solids, filter, and wash with cold water; In step S3, the washing solvent is N,N-dimethylformamide; In the step S3, the hydrochloric acid is hydrochloric acid with a mass fraction of 37%.

3. The method of claim 2, wherein: In the step S1, the hydrazine hydrate is 98% hydrazine hydrate.

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