An electrochemical oxidation reaction method for tetrazene compound synthesis

Abstract

The application discloses an electrochemical oxidation reaction method for tetrazene compound synthesis and belongs to the technical field of electrochemical synthesis preparation. The method uses organic hydrazine compounds with a -N-NH2 structural unit as a reactant to generate tetrazene compounds with a -N-N=N-N- structural unit through anode oxidation. In a sealed container containing an electrode, organic hydrazine compounds, an electrolyte solution and a cathode reaction substrate are added, the reaction temperature is -25-35 DEG C, the electrolysis voltage is 0.4-10 V, and after constant voltage or constant current electrolysis, the tetrazene compounds are obtained. The method has the advantages of simple synthesis process, controllable conditions, high repeatability, no by-products and low cost.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical oxidation reaction technology, specifically relating to an electrochemical oxidation reaction method for the synthesis of tetraazine compounds. Background Technology

[0002] Tetraazenes are a class of organic compounds characterized by the -NN=NN- group. Due to the relatively poor stability of this group, they decompose into corresponding nitrogen free radical species under acid catalysis, light irradiation, or heating conditions. Therefore, they are mainly used as free radical initiators in polymer synthesis and in the preparation of energetic materials. Some tetraazene molecules can be used as fuel propellants to replace hydrazine, such as 1,1,4,4-tetramethyl-2-tetraazene (C. MiróSabaté, H. Delalu, Chem.-Asian J. 2015, 10(3), 674-678). Some tetraazene molecules, due to their good biotoxicity, can be used in anticancer drugs, such as 1,4-dimethyl-1,4-diphenyl-2-tetraazene (A. VOGEL, A. SLOBODA, A. TOMCUFCIK, et al. Nature 1963, 197, 85-86).

[0003] Currently, the preparation method of tetrazene compounds is chemical oxidation, and the oxidants involved mainly include HgO, Ag2O, PbO2, Pb(OAc)4, KBrO3, KMnO4, NH2Cl, O3, Br2, I2, dibromoisocyanuric acid, t-BuOCl, PhSeO2H, etc. (N.Jung,S.) Sci. Synth., Knowl. Updates 2010, 41, 641-649).

[0004] Electrochemical oxidation achieves the breaking of old bonds and the formation of new bonds in organic compounds through the oxidation reaction of substrate molecules at the anode (positive electrode). As a green synthesis technology, its reaction system is simple, mainly involving electrolytes, products, and raw materials, and avoids the use of toxic or hazardous oxidants, resulting in minimal environmental pollution. The reaction is carried out at ambient temperature and pressure, requiring less sophisticated equipment, and the products are easily separated from the electrolyte. Furthermore, it allows for highly selective synthesis of target products by controlling the electrolysis voltage, adjusting the current, controlling the reaction rate, and initiating and terminating the reaction. However, current methods for the synthesis of tetrazenes are limited to chemical oxidation, and the oxidants involved are mostly toxic and harmful reagents. No green and environmentally friendly electrochemical oxidation methods have been reported. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a method for converting organically substituted hydrazine compounds with -N-NH2 functional groups into tetraazene compounds with -NN=NN- structures using electrochemical oxidation. The method of this invention is simple to synthesize, operates under mild and controllable conditions, is highly efficient, yields the target product in high quantities, and is environmentally friendly.

[0006] To achieve the above-mentioned technical objectives, the present invention specifically adopts the following technical solution:

[0007] An electrochemical oxidation reaction method for the synthesis of tetrazene compounds involves the anodic electrolytic oxidation of organic hydrazine compounds containing -N-NH2 structural units to generate tetrazene compounds with a -NN=NN- structure.

[0008] The organohydrazine compounds containing -N-NH2 structural units include R1R2N-NH2 organohydrazine compounds and N-amino heterocyclic compounds.

[0009] In the preparation of corresponding R1,R2N-N=N-NR1,R2 tetrazene compounds using R1R2N-NH2 organohydrazine compounds with R1 and R2 as substituents as reactants, the substituents R1 and R2 can be the same group or different groups; the functional groups of R1 and R2 can be saturated alkyl substituents, aromatic groups (including heterocycles), carbonyl substituents (aldehydes, ketones, esters, amides, etc.), ether substituents or alcohols or phenolic compounds that can form ether bonds, cyanide substituents, nitro groups, diazo groups, halogen substituents, etc.

[0010] 1,2-diheterocyclic-diazepines containing the -NN=NN- structure were prepared using N-amino heterocyclic compounds as reactants, wherein the substituents of -N-NH2 were cycloalkyl, heteroatom-substituted cycloalkyl, or heteroatom-containing aromatic groups.

[0011] The rings of the N-amino heterocyclic compounds may also contain side-chain functional groups, such as alkyl, aromatic, carbonyl, ether (alcohol), cyanide, nitro, diazo, halogen, etc.

[0012] For ease of description, and to distinguish them in the naming of specific compounds, the above-mentioned R1R2N-NH2 organohydrazine compounds and N-amino heterocyclic compounds are collectively referred to as organohydrazine compounds containing -N-NH2 structural units; R1,R2N-N=N-NR1,R2 tetrazene compounds and 1,2-diheterocyclic diazenes with the -NN=NN- structure are collectively referred to as tetrazene compounds with the -NN=NN- structure.

[0013] The electrochemical oxidation reaction method of the present invention involves adding an organic hydrazine compound containing -N-NH2 structural units and an electrolyte solution into a sealed container containing electrodes, and adding a cathode reaction substrate.

[0014] Preferably, the cathode reaction substrate is selected from acetic acid or water.

[0015] The electrochemical oxidation reaction electrolysis process described in this invention is carried out in a two-electrode system containing an anode and a cathode, or in a three-electrode system containing an anode (working electrode), a cathode (counter electrode), and a reference electrode.

[0016] Tetraazine compounds with -NN=NN- groups have relatively poor thermal stability and are prone to decomposition at high temperatures. Therefore, the reaction is preferably carried out at room temperature or low temperature. The lower limit of the low temperature is the freezing point of the electrolyte solution. Meanwhile, a higher electrolysis voltage is more conducive to increasing the reaction rate, but the electrochemical window of the electrolyte solution (e.g., 1.23V for water) should be considered to avoid the electrolyte solution discharging at the electrode surface and causing a reaction. Preferably, the electrochemical oxidation reaction temperature is -25 to 35°C, the electrolysis voltage is 0.4 to 10V, and the tetraazine compound is obtained after constant voltage or constant current electrolysis.

[0017] Preferably, the reaction is carried out in a membrane-free reaction tank where the anode and cathode are in the same reaction chamber, or in a membrane electrode tank where the anode and cathode are separated by an ion exchange membrane. In this case, the reaction in the anode region is promoted by stirring to facilitate mass transfer, or by a continuous feed flow pattern to facilitate mass transfer.

[0018] Preferably, the anode electrode is selected from metal electrodes (platinum mesh, silver sheet, nickel foam, copper foam, Ru / Ti mesh), carbon-based electrodes (graphite sheet, RVC porous carbon, Pt / C carbon paper), and oxide hydroxide electrodes (Cu2O / Cu, β-PbO2, Ni(OH)2 / nickel foam). The cathode electrode is selected from platinum mesh, graphite sheet, platinum sheet, Pt / C carbon paper, RVC porous carbon, and β-PbO2. The reference electrode is selected from calomel electrode, Ag / AgCl electrode, and platinum wire.

[0019] Based on the solubility of reactants in electrolyte solutions using the -N-NH2 structural unit, the electrolyte solution for the electrochemical oxidation reaction described in this invention is an aqueous solution, an organic solution, or an organic-aqueous mixture, and higher reactant solubility is more favorable for the reaction. Furthermore, since tetrazene compounds containing -NN=NN- groups readily decompose in strongly acidic solutions, the pH of the aqueous solution or organic-aqueous solution system in this invention is not less than 3. For the organic solution, the concentration of a moderately strong acid or a strong acid is not higher than 10. -3 mol·L -1 .

[0020] Preferably, the organic solution is selected from ethylene glycol, acetonitrile, DMF, propylene carbonate, tetrahydrofuran, triethylamine, ionic liquids (such as 1-butyl-3-methylimidazolium tetrafluoroborate), methyl ethyl carbonate, or DMF solution. The organic-water mixed solution is a mixture of the above-mentioned organic solvent and water. The aqueous solution includes alkaline aqueous solutions, neutral aqueous solutions, and buffer solutions (such as PBS buffer solution, acetate-sodium acetate buffer solution, etc.). The electrolyte is an alkaline electrolyte (such as NaOH solution, Na2CO3 solution, etc.) or a neutral electrolyte (such as Na2SO4, KPF6, LiBF4, Li2SO4, (NEt4)PF6, LiPF6, etc.).

[0021] The beneficial effects of this invention are as follows:

[0022] 1) Provides an electro-oxidative synthesis system for tetrazene;

[0023] 2) The reaction involves electrochemical oxidation, requiring no oxidant, making it green, environmentally friendly, and pollution-free;

[0024] 3) The reaction system only involves raw materials, products and electrolyte solution. The products are easy to separate, without the need for complicated separation and removal of toxic and harmful oxidants.

[0025] 4) The reaction can be carried out at room temperature or a lower reaction temperature. The reaction conditions are mild, and the operation is simple and safe.

[0026] 5) The reaction rate and process can be controlled by applying voltage and current, and the reaction can be stopped by cutting off the current, making the reaction highly controllable and operable. Detailed Implementation

[0027] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Examples 1-8 used N-amino heterocyclic compounds as reactants, and the reaction routes are as follows:

[0029]

[0030] Example 1

[0031]

[0032] This embodiment provides a method for the electrochemical oxidative coupling of 1-aminopiperidine to generate 1,2-bis(1-piperidinyl)-diazeline, as detailed below:

[0033] Dissolve 0.20 g (1 mmol) of 1-aminopiperidine in 0.1 mol·L⁻¹ NaOH solution. -1 ethylene glycol-water mixture (V 乙二醇 :V 水 =1:4). The solution volume was 20 mL. After stirring at room temperature for 1 h, it was transferred to a 50 mL diaphragm-free electrolytic cell. A three-electrode system was used, with platinum mesh (1 cm × 1 cm) as the working and counter electrodes, and a saturated calomel electrode as the reference electrode. Electrolysis was carried out in constant current mode at 0 °C with a current of 0.05 A. Electrolysis was stopped when the charge reached 96.5 C. The product was extracted with diethyl ether and then rotary evaporated to obtain the crude product. The crude product was purified by column chromatography using ethyl acetate and cyclohexane as eluents, finally yielding 0.1820 g of 1,2-bis(1-piperidinyl)-diazepine, with a yield of 91.0%.

[0034] Example 2

[0035]

[0036] This embodiment provides a method for the electrochemical oxidative coupling of 1-aminopyrrolidine to generate 1,2-bis(1-pyrrolyl)-diazeline, as detailed below:

[0037] 0.43 g (5 mmol) of 1-aminopyrrolidine was dissolved in 0.025 mol·L⁻¹ Na₂SO₄. -1 Acetonitrile-water mixed solution (V 乙腈 :V 水 =3:2). The solution volume was 20 mL. After stirring at room temperature for 1 h, it was transferred to a 50 mL diaphragm-free electrolytic cell. A three-electrode system was used, with a silver sheet (1 cm × 1 cm) as the working electrode, a platinum mesh (1 cm × 1 cm) as the counter electrode, and a saturated calomel electrode as the reference electrode. Electrolysis was carried out in constant voltage mode at a reaction temperature of 10 °C, with a working electrode voltage of 0.78 V vs SCE. Electrolysis was stopped when the charge reached 482.5 C. The product was extracted with diethyl ether and then rotary evaporated to obtain the crude product. The crude product was purified by column chromatography using ethyl acetate and cyclohexane as eluents, finally yielding 0.396 g of 1,2-bis(1-pyrrole)-diazeline, with a yield of 92.1%.

[0038] Example 3

[0039]

[0040] This embodiment provides a method for the electrochemical oxidative coupling of 4-aminomorpholine to generate 1,2-bis(4-morpholino)-diazeline, as detailed below:

[0041] 1.02 g (10 mmol) of 4-aminomorpholine was dissolved in KPF6 solution with a concentration of 0.01 mol·L⁻¹. -1 DMF-water mixture (V DMF :V 水 The solution was prepared in a 1:1 ratio (1:1). The solution volume was 40 mL. After stirring at room temperature for 1 h, it was transferred to a 50 mL diaphragm electrolytic cell. A two-electrode system was used, with the working electrode (positive electrode) being nickel foam (2 cm × 2 cm) and the counter electrode (negative electrode) being a graphite sheet (2 cm × 2 cm). Electrolysis was carried out at a constant voltage mode, with the cell voltage at 1.5 V, while maintaining the reaction temperature at 20 °C. Electrolysis was stopped when the charge reached 965 C. The product was extracted with ethyl acetate and then rotary evaporated to obtain the crude product. Column chromatography was used as the eluent to separate and purify the crude product, finally yielding 0.915 g of 1,2-bis(4-morpholino)-diazepine, with a yield of 89.7%.

[0042] Example 4

[0043]

[0044] This embodiment provides a method for the electrochemical oxidative coupling of 4-amino-1,2,4-triazole to generate 1,2-bis(4-(1,2,4-triazole))-diazepine, as detailed below:

[0045] 2.0 g (24 mmol) of 4-amino-1,2,4-triazole was dissolved in PBS buffer (pH 7.2–7.4). The solution volume was 40 mL. After stirring at room temperature for 25 min, the solution was transferred to a 40 mL diaphragm electrolytic cell. A three-electrode system was used, with a Cu₂O / Cu (2 cm × 2 cm) working electrode, a platinum sheet (2.5 cm × 2.5 cm) counter electrode, and a saturated calomel electrode as the reference electrode. The working electrode voltage was 0.8 V vs SCE at a reaction temperature of 5 °C. Electrolysis was stopped when the charge reached 2316 C. After adjusting the pH of the solution to acidic by adding a small amount of phosphoric acid, 1,2-bis(4-(1,2,4-triazole))-diazepine crystallized out to obtain 1.89 g of product, with a yield of 94.5%.

[0046] Example 5

[0047]

[0048] This embodiment provides a method for the electrochemical oxidative coupling of 4-amino-1,2,4-triazole to generate 1,2-bis(4-(1,2,4-triazole))-diazepine, as detailed below:

[0049] 2.0 g (24 mmol) of 4-amino-1,2,4-triazole was dissolved in PBS buffer (pH 7.2–7.4). The solution volume was 40 mL. After stirring at room temperature for 25 min, the solution was transferred to a 40 mL diaphragm electrolytic cell. A three-electrode system was used, with a Cu₂O / Cu (2 cm × 2 cm) working electrode, a platinum sheet (2.5 cm × 2.5 cm) counter electrode, and a saturated calomel electrode as the reference electrode. The working electrode voltage was 0.8 V vs SCE at a reaction temperature of 5 °C. Electrolysis was stopped when the charge reached 2316 C. After adjusting the pH of the solution to acidic by adding a small amount of phosphoric acid, 1,2-bis(4-(1,2,4-triazole))-diazepine crystallized out to obtain 1.89 g of product, with a yield of 94.5%.

[0050] Example 6

[0051]

[0052] This embodiment provides a method for the electrochemical oxidative coupling of (S)-(-)-1-amino-2-hydroxymethylpyrrolidine to generate (S,S)-1,2-bis(2-hydroxymethyl-1-pyrrolyl)-diazeline, as detailed below:

[0053] 0.58 g (5 mmol) of (S)-(-)-1-amino-2-hydroxymethylpyrrolidine was dissolved in (NEt4)PF6 at a concentration of 0.02 mol·L⁻¹. -1 Tetrahydrofuran-triethylamine-acetic acid solution (V 四氢呋喃 :V 三乙胺 The solution was prepared in a ratio of 1:1:0.1 (30 mL). After stirring at room temperature for 15 min, it was transferred to a 50 mL diaphragm-free electrolytic cell. A three-electrode system was used, with both the working and counter electrodes being RVC porous carbon electrodes (1 cm × 1 cm), and the reference electrode being a platinum wire. Electrolysis was performed under constant voltage mode at a reaction temperature of 5 °C, with the working electrode voltage being 1.05 V vs Pt. Electrolysis was stopped when the charge reached 482.5 C. The crude product was obtained by rotary evaporation. The crude product was purified by column chromatography using ethyl acetate and cyclohexane as eluents, ultimately yielding 0.205 g of (S,S)-1,2-bis(2-hydroxymethyl-1-pyrrolyl)-diazeline, with a yield of 35.3%.

[0054] Example 7

[0055]

[0056] This embodiment provides an improved method for the oxidative coupling of (S)-(-)-1-amino-2-hydroxymethylpyrrolidine to generate (S,S)-1,2-bis(2-hydroxymethyl-1-pyrrolyl)-diazepine, as detailed below:

[0057] 0.58 g (5 mmol) of (S)-(-)-1-amino-2-hydroxymethylpyrrolidine was dissolved in (NEt4)PF6 at a concentration of 0.02 mol·L⁻¹. -1 Tetrahydrofuran-triethylamine-acetic acid solution (V 四氢呋喃 :V 三乙胺 The solution was prepared in a ratio of 1:1:0.1 (30 mL). 0.65 g of trimethylchlorosilane was added, and the mixture was stirred at 25 °C for 2 h. The solution was then transferred to a 50 mL diaphragm-free electrolytic cell. A three-electrode system was used, with both the working and counter electrodes being RVC porous carbon electrodes (1 cm × 1 cm), and the reference electrode being a platinum wire. Electrolysis was performed under constant voltage mode at 25 °C, with the working electrode voltage being 1.05 V vs Pt. Electrolysis was stopped when the charge reached 482.5 C. The solution was then transferred to a 100 mL round-bottom flask, and 20 mL of methanol and 0.2 g of sodium carbonate were added. After stirring at room temperature for 2 h, the volatile components were removed by rotary evaporation. The obtained solid was extracted multiple times with methyl tert-butyl ether, and the ether solutions were combined and rotary evaporated to give 0.411 g of (S,S)-1,2-bis(2-hydroxymethyl-1-pyrrolyl)-diazepine, with a yield of 70.9%.

[0058] Example 8

[0059]

[0060] This embodiment provides a method for the electrochemical oxidative coupling of 3-amino-2-oxazolidinone to generate 1,2-bis(2-keto-3-oxazolidinyl)-diazepine, as detailed below:

[0061] 1.02 g (10 mmol) of 3-amino-2-oxazolidinone was dissolved in an acetate-sodium acetate buffer solution (pH = 4.7). The solution volume was 20 mL. After stirring at room temperature for 15 min, the solution was transferred to a 40 mL diaphragm electrolytic cell. A three-electrode system was used, with a working electrode of nickel foam (2 cm × 2 cm), a counter electrode of graphite sheet (2 cm × 2 cm), and a reference electrode of saturated calomel electrode. The working electrode voltage was maintained at 5 °C at 0.66 V vs SCE. Electrolysis was stopped when the charge reached 965 C. The aqueous solution of the product was extracted with ethyl acetate, and the crude product was obtained by rotary evaporation. The crude product was then purified by column chromatography using ethyl acetate and cyclohexane as eluents, finally precipitating 0.83 g of the product, with a yield of 81.3%.

[0062] Examples 9-15 used organohydrazine compounds with the R1R2N-NH2 structural unit as reactants, and the reaction routes are as follows:

[0063]

[0064] Example 9

[0065]

[0066] This embodiment provides a method for the electrochemical oxidative coupling of unsymmetrical dimethylhydrazine to generate tetramethyltetraazene, as detailed below:

[0067] 6.0 g (0.1 mol) of unsymmetrical dimethylhydrazine was dissolved in Na₂CO₃ with a concentration of 0.1 mol·L⁻¹. -1 The solution was prepared in an aqueous solution with a volume of 7.7 mL. After stirring at room temperature for 15 min, the solution was transferred to a 20 mL diaphragm electrolytic cell. A two-electrode system was used, with both the working electrode (positive) and the counter electrode (negative) being graphite sheets (2 cm × 2 cm). Electrolysis was performed under constant voltage mode at a reaction temperature of 5 °C, with a cell voltage of 2.0 V. Electrolysis was stopped when the charge reached 9650 C. The product was extracted with dichloromethane and then rotary evaporated to obtain the crude product. Column chromatography was used as the eluent to separate and purify the product, finally yielding 5.57 g of 1,1,4,4-tetramethyl-2-tetraazane, with a yield of 92.8%.

[0068] Example 10

[0069]

[0070] This embodiment provides a method for the electrochemical oxidative coupling of unsymmetrical dimethylhydrazine to generate tetramethyltetraazene, as detailed below:

[0071] 12.0 g (0.2 mol) of unsymmetrical dimethylhydrazine was dissolved in LiBF4 solution with a concentration of 0.15 mol·L⁻¹. -1 The solution was prepared in a propylene carbonate solution. The solution volume was 7.7 mL. After stirring at room temperature for 15 min, the solution was transferred to a 40 mL diaphragm electrolytic cell. A two-electrode system was used, with the working electrode (positive electrode) being RVC porous carbon (2.5 cm × 2.5 cm) and the counter electrode (negative electrode) being a platinum sheet (2.5 cm × 2.5 cm). Electrolysis was carried out in constant current mode at a reaction temperature of 10–15 °C, with a cell current of 0.1 A and a voltage limit of 8 V. Electrolysis was stopped when the charge reached 1930 °C. 9.98 g of the product 1,1,4,4-tetramethyl-2-tetraazane was obtained by vacuum distillation, with a yield of 83.2%.

[0072] Example 11

[0073]

[0074] This embodiment provides a method for the electrochemical oxidative coupling of 1,1-dibenzylhydrazine to generate 1,1,4,4-tetrabenzyl-2-tetraazene, as detailed below:

[0075] 0.212 g (1 mmol) of 1,1-dibenzylhydrazine was dissolved in Li₂SO₄ with a concentration of 0.05 mol·L⁻¹. -1 propylene carbonate-water solution (V 碳酸丙烯酯 :V 水 The solution was prepared in a 1:2 ratio (1:2). The solution volume was 30 mL. After stirring at room temperature for 45 min, it was transferred to a 40 mL diaphragm electrolytic cell. A three-electrode system was used, with a working electrode of copper foam (2.5 cm × 2.5 cm), a counter electrode of carbon paper coated with 20 wt% Pt / C (2.5 cm × 2.5 cm), and a reference electrode of saturated Ag / AgCl. The working electrode voltage was 0.9 V vsAg / AgCl while maintaining the reaction temperature at 5 °C. Electrolysis was stopped when the charge reached 96.5 C. The product was extracted with diethyl ether and then rotary evaporated to obtain the crude product. 0.184 g of 1,1,4,4-tetrabenzyl-2-tetraazane was obtained by recrystallization from methanol, with a yield of 86.8%.

[0076] Example 12

[0077]

[0078] This embodiment provides a method for the electrochemical oxidative coupling of 1,1-bis(2-hydroxyethyl)hydrazine to generate 1,1,4,4-tetra(2-hydroxyethyl)-2-tetraazaene, as detailed below:

[0079] 0.60 g (5 mmol) of 1,1-bis(2-hydroxyethyl)hydrazine was dissolved in (NEt4)PF6 at a concentration of 0.02 mol·L⁻¹. -1 Tetrahydrofuran-triethylamine-acetic acid solution (V 四氢呋喃 :V 三乙胺 The solution was prepared in a ratio of 1:1:0.1 (30 mL). 0.65 g of trimethylchlorosilane was added, and the mixture was stirred at -10 °C for 6 h. The solution was then transferred to a 50 mL diaphragm-free electrolytic cell. A three-electrode system was used, with both the working and counter electrodes being β-PbO2 electrodes (1 cm × 1 cm), and a platinum wire as the reference electrode. Electrolysis was performed under constant voltage mode at -10 °C, with the working electrode voltage being 0.85 V vs Pt. Electrolysis was stopped when the charge reached 482.5 C. The solution was then transferred to a 100 mL round-bottom flask, and 20 mL of methanol and 0.2 g of sodium carbonate were added. After stirring at room temperature for 2 h, the volatile components were removed by rotary evaporation. The resulting solid was extracted multiple times with diethyl ether, and the ether solutions were combined. After rotary evaporation, column chromatography was performed using methanol and dichloromethane as eluents to purify 1,1,4,4-tetra(2-hydroxyethyl)-2-tetraazaene, yielding 0.313 g of 1,1,4,4-tetra(2-hydroxyethyl)-2-tetraazaene, with a yield of 52.2%.

[0080] Example 13

[0081]

[0082] This embodiment provides a method for the electrochemical oxidative coupling of 1-methyl-1-(2-cyanoethyl)hydrazine to generate 1,4-dimethyl-1,4-di(2-cyanoethyl)-2-tetraazaene, as detailed below:

[0083] 0.99 g (10 mmol) of 1-methyl-1-(2-cyanoethyl)hydrazine was dissolved in an ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate) containing 50 mmol of acetic acid. The solution volume was 10 mL. After stirring at room temperature for 15 min, the solution was transferred to a 10 mL diaphragm electrolytic cell. A two-electrode system was used, with a Ru / Ti mesh (1 cm × 1 cm) as the working electrode and a graphite sheet (2 cm × 2 cm) as the counter electrode. Electrolysis was performed at room temperature in constant voltage mode at a voltage of 1.8 V across the electrodes. Electrolysis was stopped when the charge reached 965 C. The aqueous solution of the product was extracted with diethyl ether and then rotary evaporated to obtain the crude product. The crude product was then purified by column chromatography using ethyl acetate and cyclohexane as eluents to obtain 0.73 g of the product, with a yield of 73.7%.

[0084] Example 14

[0085]

[0086] This embodiment provides a method for the electrochemical oxidative coupling of 1-methyl-1-methoxyhydrazide to generate 1,4-dimethyl-1,4-dimethoxyhydrazide-2-tetraazene, as detailed below:

[0087] 4.16 g (40 mmol) of 1-methyl-1-methoxyhydrazide was dissolved in a solution containing LiBF4 and methyl ethyl carbonate-acetic acid (V... 碳酸甲乙酯 :V 乙酸 =19:1). The solution volume was 40 mL. After stirring at 10 °C for 15 min, the solution was fed into a 2 mL diaphragm electrolytic cell via a peristaltic pump (or circulating feed). A three-electrode system was used, with the working electrode and counter electrode being 20% ​​Pt / C coated carbon paper electrodes (5 cm × 5 cm), and the reference electrode being a platinum wire. Electrolysis was performed in constant voltage mode, with a cell voltage of 6 V vs Pt and a maximum total cell voltage of 10 V. Electrolysis was stopped when the charge reached 3860 C. The product was purified by column chromatography to obtain 0.78 g of 1,4-dimethyl-1,4-dimethoxyacyl-2-tetraazaene, with a yield of 18.8%.

[0088] Example 15

[0089]

[0090] This embodiment provides a method for the electrochemical oxidative coupling of 1-(2-butyl)-1-phenylhydrazine to generate 1,4-bis(2-butyl)-1,4-diphenyl-2-tetraazaene, as detailed below:

[0091] 0.164 g (1 mmol) of 1-(2-butyl)-1-phenylhydrazine was placed in a solution containing LiPF6 (0.01 mol) DMF-acetic acid (V DMF :V 乙酸 A 9:1 mixture was prepared in 10 mL solution. After stirring at 0°C for 15 min, the mixture was fed into a 0.6 mL diaphragm electrolytic cell via a peristaltic pump. A two-electrode system was used, with the working electrode (positive electrode) being a Ni(OH)₂ / nickel foam (1 cm × 1 cm) and the counter electrode (negative electrode) being a RVC-coated porous carbon electrode (1 cm × 1 cm). Electrolysis was stopped when the charge reached 96.5 C. The product was purified by column chromatography, yielding 0.08 g of product with a yield of 48.8%.

[0092] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these examples without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An electrochemical oxidation reaction method for the synthesis of tetraazine compounds, characterized in that, Organohydrazine compounds containing -N-NH2 structural units are anolyte-based compounds with a -NN=NN- structure generated by anodic electrolytic oxidation. The organohydrazine compounds containing -N-NH2 structural units are selected from 1-aminopiperidine, 1-aminopyrrolidine, 4-aminomorpholine, 4-amino-1,2,4-triazole, unsymmetrical dimethylhydrazine, and 1,1-dibenzylhydrazine. The organohydrazine compounds containing -N-NH2 structural units and an electrolyte solution are added to a sealed container containing electrodes, and a cathode substrate is added. The electrolyte solution is 0.1 mol·L⁻¹ NaOH. -1 By V 乙二醇: V 水 An ethylene glycol-water mixture with a 1:4 ratio and a Na₂SO₄ concentration of 0.025 mol·L⁻¹ was prepared. -1 by V 乙腈 :V 水 An acetonitrile-water mixture with a 3:2 ratio and a KPF6 concentration of 0.01 mol·L⁻¹ was prepared. -1 by V DMF :V 水 A 1:1 DMF-water mixture, a PBS buffer solution with a pH of 7.2–7.4, and a concentration of 0.1 mol·L⁻¹ were prepared. -1 An aqueous solution of Na₂CO₃ with a concentration of 0.15 mol·L⁻¹ -1 The LiBF4 propylene carbonate solution and the Li2SO4 concentration were 0.05 mol·L⁻¹. -1 By V 碳酸丙烯酯 :V 水 A propylene carbonate-water solution was prepared in a 1:2 ratio.

2. The electrochemical oxidation reaction method for the synthesis of tetraazine compounds according to claim 1, characterized in that, The cathode reaction substrate is selected from acetic acid or water.

3. The electrochemical oxidation reaction method for the synthesis of tetraazine compounds according to claim 1, characterized in that, The electrolysis process is carried out in a two-electrode system containing an anode and a cathode, or in a three-electrode system containing an anode, a cathode, and a reference electrode.

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