Process for the preparation of nitrogen-containing heterocyclic compounds and nitrogen-containing heterocyclic compounds alkali metal salts

Abstract

The application discloses a preparation method of a nitrogen-containing heterocyclic compound and an alkali metal salt of the nitrogen-containing heterocyclic compound, and steps of the preparation method of the nitrogen-containing heterocyclic compound comprise: (1) uniformly mixing trithiocyanic acid with a first solvent, introducing sulfuryl fluoride gas or adding an alkenyl sulfonyl fluoride to perform a reaction, and obtaining a crude product through a crude treatment after the reaction is finished; (2) purifying the crude product to obtain the nitrogen-containing heterocyclic compound shown in a structural formula 1; wherein R1, R2 and R3 are each independently selected from -H, -SO2F or -CH2-(CH2) n -SO2F, n is an integer selected from 1-10, and R1, R2 and R3 are not H at the same time. The preparation method of the nitrogen-containing heterocyclic compound and the alkali metal salt of the nitrogen-containing heterocyclic compound can be applied to a large amount of trithiocyanic acid in a lithium battery electrolyte, raw materials are easy to obtain, operation is simple, the yield is high, the condition is mild, the requirement for equipment is low, and the method is suitable for industrial production.

Description

Technical Field

[0001] This invention belongs to the field of compound synthesis technology, and particularly relates to a method for preparing a nitrogen-containing heterocyclic compound and an alkali metal salt of the nitrogen-containing heterocyclic compound. Background Technology

[0002] Lithium-ion battery electrolytes are mainly composed of electrolyte salts (lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, etc.), carbonate solvents (DMC, EMC, EC, PC, etc.), and functional additives (VC, PS, DTD, TMSP, etc.). The electrolyte is a non-aqueous system, and water content is a very important technical indicator. Water in the electrolyte will react with lithium hexafluorophosphate to produce highly corrosive hydrofluoric acid. Since the electrolyte is in direct contact with the positive electrode, negative electrode, and separator, it will have varying degrees of impact on the battery's initial charge and discharge capacity, internal resistance, cycle life, and battery volume. Therefore, the molecular structure of electrolyte additives is generally required to be free of reactive hydrogen protons.

[0003] Trithiocyanate is a high-performance heavy metal ion removal agent. Its sodium salt hydrate (TMT-3Na9H2O) was first reported in US Patent 4849517A. Its mechanism of action mainly involves the reaction of the trithiocyanate anion with Ni in the solution. + Pb 2+ Cu 2+ Ag + Zn 2+ Cd 2+ Hg 2+ The metal ions are removed by forming stable complexes and precipitating. However, because cyanuric acid contains active hydrogen protons, there are few reports on its use as an electrolyte additive.

[0004] Therefore, there is an urgent need for a method for preparing nitrogen-containing heterocyclic compounds and alkali metal salts of nitrogen-containing heterocyclic compounds, so that trithiocyanate can be widely used in lithium battery electrolytes. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing nitrogen-containing heterocyclic compounds. This method is simple to operate, has a high yield, and is under mild conditions. Moreover, it can replace the active proton hydrogen of trithiocyanate with thioyl fluoride or alkenyl sulfonyl fluoride functional groups.

[0006] Another objective of this invention is to provide a method for preparing alkali metal salts of nitrogen-containing heterocyclic compounds. This method is simple to operate, has a high yield, does not require high temperature, operates under mild conditions, and can replace the active proton hydrogen of trithiocyanate with an alkali metal.

[0007] To achieve the above objectives, the present invention provides a method for preparing a nitrogen-containing heterocyclic compound, comprising the following steps:

[0008] (1) Mix trithiocyanate with the first solvent evenly, then introduce sulfuryl fluoride gas or add alkenyl sulfonyl fluoride to react, and after the reaction is completed, crude product is obtained by crude treatment.

[0009] (2) The crude product was purified to obtain the nitrogen-containing heterocyclic compound shown in structural formula 1;

[0010]

[0011] R1, R2, and R3 are each independently selected from -H, -SO2F, or -CH2-(CH2). n -SO2F, where n is an integer selected from 1 to 10, and R1, R2, and R3 are not all H at the same time.

[0012] Compared with the prior art, the method for preparing nitrogen-containing heterocyclic compounds of the present invention uses thioyl fluoride or alkenyl sulfonyl fluoride to modify trithiocyanate molecules to synthesize nitrogen-containing heterocyclic compounds without active hydrogen. Simultaneously, the trithiocyanate ions in the nitrogen-containing heterocyclic compounds have a highly efficient complexing effect on metal ions. Therefore, the nitrogen-containing heterocyclic compounds can be used as electrolyte additives or as coating agents for the positive electrode, thereby improving the Mn content in the positive electrode of LFP batteries. 2+ Addressing the issue of ion dissolution is crucial for improving initial battery efficiency, reducing internal resistance, forming a more stable SEI film, and extending battery cycle life. Therefore, the method for preparing nitrogen-containing heterocyclic compounds according to this invention enables the widespread application of trithiocyanate in lithium-ion battery electrolytes. Furthermore, the method for preparing nitrogen-containing heterocyclic compounds of this invention utilizes readily available raw materials, is simple to operate, yields high efficiency, operates under mild conditions, requires minimal equipment, and is suitable for large-scale industrial production.

[0013] Preferably, the structural formula of the alkenyl sulfonyl fluoride of the present invention is CH2=CH-(CH2). n-1 -SO2F, where n is an integer selected from 1 to 10.

[0014] Preferably, in step (1) of the present invention, the reaction time is 2-3 hours and the reaction temperature is 0-40°C. The reaction temperature is low, which can effectively reduce energy consumption. More specifically, the reaction endpoint can be monitored by LC / MS or GC / MS. After 2-3 hours of reaction, the reaction is stopped after detecting the peak of no raw material.

[0015] Preferably, the molar ratio of trithiocyanate to thioyl fluoride in this invention is 1:1 to 3.2, and the molar ratio of trithiocyanate to alkenyl sulfonyl fluoride is 1:1 to 3.2. Specifically, when the molar ratio of trithiocyanate to thioyl fluoride is 1:1, one of R1, R2, and R3 in structural formula 1 is -SO2F; when the molar ratio of trithiocyanate to thioyl fluoride is 1:2, two of R1, R2, and R3 in structural formula 1 are -SO2F; when the molar ratio of trithiocyanate to thioyl fluoride is 1:3, all R1, R2, and R3 in structural formula 1 are -SO2F; and when the molar ratio of trithiocyanate to alkenyl sulfonyl fluoride is 1:1, one of R1, R2, and R3 in structural formula 1 is -CH2-(CH2). n -SO2F; When the molar ratio of trithiocyanate to alkenyl sulfonyl fluoride is 1:2, two of R1, R2, and R3 in structural formula 1 are -CH2-(CH2). n -SO2F; When the molar ratio of trithiocyanate to alkenyl sulfonyl fluoride is 1:3, R1, R2, and R3 in structural formula 1 are all -CH2-(CH2). n -SO2F.

[0016] Preferably, the boiling point of the first solvent of the present invention is less than 100°C, that is, the first solvent of the present invention is a low-boiling-point solvent. Specifically, the first solvent of the present invention includes at least one selected from alcohols, nitriles, halogenated hydrocarbons, ethers, esters, and ketones. More specifically, the alcohol is methanol, ethanol, or isopropanol; the nitrile is acetonitrile or butyronitrile; the halogenated hydrocarbon is dichloromethane, trichloromethane, 1,2-dichloroethane, or tetrachloroethane; the ether is methyl tert-butyl ether, ethylene glycol dimethyl ether, tetrahydrofuran, or dioxane; the ester is dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, methyl acetate, ethyl acetate, or propyl acetate; and the ketone is acetone, cyclohexanone, or 4-methyl-2-pentanone. Preferably, the first solvent of the present invention is acetonitrile, ethanol, or dichloromethane.

[0017] Preferably, step (1) of the present invention includes uniformly mixing trithiocyanate, organic base and first solvent, introducing sulfuryl fluoride gas to react, and after the reaction is completed, evaporating and drying to obtain an intermediate, which is then subjected to a first pretreatment to obtain a crude product. Sulfoyl fluoride is a gaseous sulfonyl compound, and the reaction condition is a gas-liquid reaction under high pressure; therefore, the reaction apparatus for step (1) is preferably a high-pressure reactor. Specifically, the rate of introduction of sulfuryl fluoride gas can be controlled by controlling the pressure (≤0.5 MPa) inside the high-pressure reactor.

[0018] Preferably, the organic base of the present invention is at least one selected from triethylamine, pyridine, 1,8-diazabicycloundec-7-ene (DBU) and tetramethylpropanediamine (TMPDA).

[0019] Preferably, step (1) of the present invention includes mixing trithiocyanate with a first solvent, adding alkenyl sulfonyl fluoride to react, evaporating and drying to obtain a first intermediate, subjecting the first intermediate to a quenching reaction to obtain a second intermediate, and then subjecting the second intermediate to a first pretreatment to obtain a crude product. Specifically, deionized water or ice water is added to the first intermediate to quench the reaction to obtain the second intermediate. Alkenyl sulfonyl fluoride is a liquid sulfonyl compound, therefore the reaction apparatus for step (1) is preferably a multi-necked flask.

[0020] Preferably, the first pretreatment of the present invention includes dissolving the intermediate or second intermediate in a second solvent, taking the organic phase, and then sequentially washing, dehydrating and drying, filtering and concentrating.

[0021] Preferably, the second solvent of the present invention is an ester, a halogenated hydrocarbon, or an ether; more specifically, the ester is dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, methyl acetate, ethyl acetate, or propyl acetate; the halogenated hydrocarbon is dichloromethane, trichloromethane, 1,2-dichloroethane, or tetrachloroethane; and the ether is diethyl ether, methyl tert-butyl ether, ethylene glycol dimethyl ether, tetrahydrofuran, or dioxane. Preferably, the second solvent is ethyl acetate, dichloromethane, or dichloroethane. Specifically, the organic phase is sequentially washed with brine and dehydrated and dried with anhydrous magnesium sulfate.

[0022] Preferably, step (2) of the present invention includes subjecting the crude product to a second pretreatment and vacuum drying to obtain the nitrogen-containing heterocyclic compound shown in structural formula 1. The second pretreatment includes cooling crystallization or chromatography column separation. Specifically, the vacuum drying temperature is 80-150°C and the drying time is 8-30 h. The cooling crystallization temperature is -20-10°C and the cooling crystallization time is 1-5 h.

[0023] To achieve the above objectives, the present invention also provides a method for preparing alkali metal salts of nitrogen-containing heterocyclic compounds, comprising the following steps:

[0024] (1) Mix the trithiocyanate compound with the third solvent evenly, add the alkali metal compound, and then adjust the pH value to carry out the reaction;

[0025] (2) The product after the reaction in step (1) is purified to obtain the nitrogen-containing heterocyclic compound alkali metal salt shown in structural formula 2;

[0026]

[0027] R4, R5, and R6 are each independently selected from -SO2F or -CH2-(CH2). n -SO2F or alkali metal, n is an integer selected from 1 to 10, and at least one of R4, R5, and R6 is an alkali metal.

[0028] Compared with the prior art, the preparation method of the nitrogen-containing heterocyclic compound alkali metal salt of the present invention uses alkali metal compounds to modify trithiocyanate compounds to synthesize nitrogen-containing heterocyclic compound alkali metal salts without active hydrogen. Simultaneously, the trithiocyanate ions in the nitrogen-containing heterocyclic compound alkali metal salt have a highly efficient complexing effect on metal ions. Therefore, the nitrogen-containing heterocyclic compound alkali metal salt can be used as an electrolyte additive or as a coating agent for the positive electrode, thereby improving the Mn content in the positive electrode of LFP batteries. 2+ Addressing the issue of ion dissolution is crucial for improving initial battery efficiency, reducing internal resistance, forming a more stable SEI film, and extending battery cycle life. Therefore, the preparation method of nitrogen-containing heterocyclic alkali metal salts of this invention allows for the widespread application of trithiocyanate compounds in lithium-ion battery electrolytes. Furthermore, the preparation method of nitrogen-containing heterocyclic alkali metal salts of this invention utilizes readily available raw materials, is simple to operate, yields high output, operates under mild conditions, requires minimal equipment, and is suitable for large-scale industrial production.

[0029] Specifically, the structural formula of the trithiocyanate compound of the present invention is shown in Formula 3:

[0030]

[0031] R7, R8, and R9 are each independently selected from H, -SO2F, or -CH2-(CH2). n -SO2F, where n is an integer selected from 1 to 10, and at least one of R7, R8, and R9 is H.

[0032] Specifically, the trithiocyanate compounds of the present invention are trithiocyanates or nitrogen-containing heterocyclic compounds prepared by the above-mentioned methods for preparing nitrogen-containing heterocyclic compounds.

[0033] Preferably, in step (1) of the present invention, the pH value is 7-8 and the reaction temperature is 40-60°C.

[0034] Preferably, the third solvent of the present invention is at least one selected from alcohols, nitriles, water, esters, and ketones; specifically, the alcohol is methanol, ethanol, or isopropanol; the nitrile is acetonitrile or butyronitrile; the ester is dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, methyl acetate, ethyl acetate, or propyl acetate; and the ketone is acetone, cyclohexanone, or 4-methyl-2-pentanone. Preferably, the third solvent of the present invention is methanol, water, or ethanol.

[0035] Preferably, the alkali metal compound of the present invention is a lithium compound, a sodium compound, a potassium compound, a rubidium compound, or a cesium compound. Specifically, the lithium compound of the present invention is lithium hydroxide, lithium hydroxide monohydrate, lithium carbonate, lithium methoxide, lithium ethoxide, or lithium tert-butoxide; the sodium compound is sodium hydroxide, sodium carbonate, sodium bicarbonate, sodium methoxide, sodium ethoxide, or sodium tert-butoxide; the potassium compound is potassium hydroxide, potassium carbonate, potassium bicarbonate, potassium methoxide, or potassium tert-butoxide; the rubidium compound is rubidium hydroxide or rubidium carbonate; and the cesium compound is cesium hydroxide, cesium hydroxide monohydrate, cesium carbonate, or cesium bicarbonate. Preferably, the lithium compound is lithium hydroxide or lithium hydroxide monohydrate, the sodium compound is sodium hydroxide or sodium carbonate, the potassium compound is potassium hydroxide or potassium carbonate, the rubidium compound is rubidium hydroxide, and the cesium compound is cesium hydroxide or cesium hydroxide monohydrate.

[0036] Preferably, in step (1) of the present invention, the pH value is 7-8, the reaction temperature is 40-60°C, and the reaction time is 1-5h.

[0037] Preferably, the purification process in step (2) of the present invention includes concentration, cooling crystallization, filtration, and drying in sequence. Specifically, the cooling crystallization temperature is -20 to 10°C, the cooling crystallization time is 1 to 5 hours, the drying temperature is 80 to 150°C, and the drying time is 8 to 30 hours. Detailed Implementation

[0038] To further illustrate the purpose, technical solution, and beneficial effects of this invention, the invention will be further described below in conjunction with specific embodiments. It should be noted that, unless specific conditions are specified in the embodiments and comparative examples, conventional conditions or conditions recommended by the manufacturer can be followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0039] The stainless steel high-pressure reactor used in this embodiment is equipped with speed-regulating stirring, electric heating, cooling coil, and temperature and pressure display instruments. At the same time, the gas inlet of the high-pressure reactor is connected to the sulfuryl fluoride cylinder through a stainless steel pipe fitting. The introduction rate and amount of sulfuryl fluoride can be controlled by a gas flow meter and an electronic balance.

[0040] The three-necked flask used in the example is equipped with a speed-regulating stirrer and a constant-pressure funnel.

[0041] Example 1

[0042] A method for preparing a nitrogen-containing heterocyclic compound, comprising the following steps:

[0043] (1) 20g (0.113mol) of trithiocyanate, 13.8g (0.135mol) of triethylamine and 120ml of acetonitrile were placed into a 500mL stainless steel high-pressure reactor. The reactor jacket temperature was set to 0℃ and the cooling coil was circulated with condensate at -10℃. The mixture was stirred at a constant speed for 10min. 11.5g (0.113mol) of sulfuryl fluoride gas was introduced to carry out the reaction. The reaction pressure was 0.5MPa and the reaction time was 2.6h. After the reaction was completed, the intermediate was obtained by evaporation and drying. The intermediate was dissolved in ethyl acetate, filtered to obtain the organic phase, and then washed three times with 100ml of 5% sodium chloride aqueous solution, dried with 8g of anhydrous magnesium sulfate, filtered, and concentrated to obtain the crude product.

[0044] (2) The crude product was cooled to -10℃ for 3 hours to crystallize, filtered, and dried under vacuum at 120℃ for 12 hours to obtain 26.9 g of compound I, with a yield of 92%;

[0045] The reaction equation for the preparation of compound I in this embodiment is as follows:

[0046]

[0047] Example 2

[0048] A method for preparing a nitrogen-containing heterocyclic compound, comprising the following steps:

[0049] (1) 20g (0.113mol) of trithiocyanate, 36.8g (0.361mol) of triethylamine and 160ml of acetonitrile were placed into a 500mL stainless steel high-pressure reactor. The reactor jacket temperature was set to 0℃ and the cooling coil was circulated with condensate at -10℃. The mixture was stirred at a constant speed for 10min. 34.5g (0.339mol) of sulfuryl fluoride gas was introduced to carry out the reaction. The reaction pressure was 0.5MPa and the reaction time was 2.2h. After the reaction was completed, the intermediate was obtained by evaporation and drying. The intermediate was dissolved in ethyl acetate, filtered to obtain the organic phase, and then washed three times with 100ml of 5% sodium chloride aqueous solution, dried with 8g of anhydrous magnesium sulfate, filtered, and concentrated to obtain the crude product.

[0050] (2) The crude product was separated by a chromatography column (EA / PE = 3:7) to obtain wet compound II. The wet compound II was dried under vacuum at 80°C for 24 h to obtain 40.5 g of compound II, with a yield of 85%.

[0051] The reaction equation for the preparation of compound II in this embodiment is as follows:

[0052]

[0053] Example 3

[0054] A method for preparing a nitrogen-containing heterocyclic compound, comprising the following steps:

[0055] (1) 20g (0.113mol) of trithiocyanate and 120ml of anhydrous ethanol were placed in a 500mL three-necked flask. The three-necked flask was placed in an ice-water bath and the temperature of the ice-water bath was controlled at 0℃. The mixture was stirred at a constant speed for 20min. 12.4g (0.113mol) of vinyl sulfonyl fluoride was added to react for 2.4h. After the reaction was completed, the first intermediate was obtained by evaporation and rotary evaporation. Ice water was added to the first intermediate to quench the reaction and obtain the second intermediate. The second intermediate was dissolved in ethyl acetate, filtered to obtain the organic phase, and the organic phase was washed three times with 100ml of 5% sodium chloride aqueous solution, dried with 8g of anhydrous magnesium sulfate, filtered, and concentrated to obtain the crude product.

[0056] (2) The crude product was cooled to -10℃ for 3.2 h to crystallize, filtered, and dried under vacuum at 100℃ for 12 h to obtain 29.2 g of compound III, with a yield of 90%;

[0057] The reaction equation for the preparation of compound III in this embodiment is as follows:

[0058]

[0059] Example 4

[0060] A method for preparing a nitrogen-containing heterocyclic compound, comprising the following steps:

[0061] (1) 20g (0.113mol) of trithiocyanate and 120ml of anhydrous ethanol were placed in a 500mL three-necked flask. The three-necked flask was placed in an ice-water bath and the temperature of the ice-water bath was controlled at 0℃. The mixture was stirred at a constant speed for 20min. 37.2g (0.339mol) of vinyl sulfonyl fluoride was added to carry out the reaction. The reaction time was 2.5h. After the reaction was completed, the first intermediate was obtained by evaporation and rotary drying. Ice water was added to the first intermediate to quench the reaction and obtain the second intermediate. The second intermediate was dissolved in dichloromethane, filtered to obtain the organic phase, and the organic phase was washed three times with 100ml of 5% sodium chloride aqueous solution, dried with 8g of anhydrous magnesium sulfate, filtered, and concentrated to obtain the crude product.

[0062] (2) The crude product was cooled to -20℃ for 2.8 h to crystallize, filtered, and dried under vacuum at 100℃ for 24 h to obtain 49.2 g of compound IV, with a yield of 86%;

[0063] The reaction equation for the preparation of compound IV in this embodiment is as follows:

[0064]

[0065] Example 5

[0066] A method for preparing an alkali metal salt containing a nitrogen-containing heterocyclic compound, comprising the following steps:

[0067] (1) Put 20g (0.113mol) of trithiocyanate and 100ml of methanol into a 500mL three-necked flask, place the three-necked flask in a water bath, control the temperature of the water bath at 50℃, stir at a constant speed for 25min, add 8.1g (0.339mol) of anhydrous lithium hydroxide in batches, adjust the pH value to 7.5, and react for 2h;

[0068] (2) The product after the reaction in step (1) was concentrated, cooled to -10℃ for 2 hours to crystallize, filtered, and dried under vacuum at 150℃ for 24 hours to obtain 20.9 g of compound V, with a yield of 95%.

[0069] The reaction equation for the preparation of compound V in this embodiment is as follows:

[0070]

[0071] Example 6

[0072] A method for preparing an alkali metal salt containing a nitrogen-containing heterocyclic compound, comprising the following steps:

[0073] (1) 20g (0.077mol) of the trithiocyanate compound shown in Compound 1 and 100ml of methanol were put into a 500mL three-necked flask. The three-necked flask was placed in a water bath and the temperature of the water bath was controlled at 50℃. The mixture was stirred at a constant speed for 25min. 3.7g (0.154mol) of anhydrous lithium hydroxide was added in batches. The pH value was then adjusted to 7.2 and the reaction was allowed to proceed for 3h.

[0074] (2) The product after the reaction in step (1) was concentrated, cooled to -10℃ for 2 hours to crystallize, filtered, and dried under vacuum at 150℃ for 24 hours to obtain 17.8 g of compound VI, with a yield of 85%;

[0075] The reaction equation for the preparation of compound VI in this embodiment is as follows:

[0076]

[0077] Example 7

[0078] A method for preparing an alkali metal salt containing a nitrogen-containing heterocyclic compound, comprising the following steps:

[0079] (1) 20g (0.07mol) of the trithiocyanate compound shown in Compound III and 100ml of methanol were put into a 500mL three-necked flask. The three-necked flask was placed in a water bath and the temperature of the water bath was controlled at 50℃. The mixture was stirred at a constant speed for 25min. 3.4g (0.14mol) of anhydrous lithium hydroxide was added in batches. The pH value was then adjusted to 7.3 and the reaction was allowed to proceed for 2h.

[0080] (2) The product after the reaction in step (1) was concentrated, cooled to -10℃ for 2 hours to crystallize, filtered, and dried under vacuum at 120℃ for 24 hours to obtain 18.4 g of compound VII, with a yield of 88%.

[0081] The reaction equation for the preparation of compound VII in this embodiment is as follows:

[0082]

[0083] In summary, this invention modifies trithiocyanate molecules with sulfonyl fluoride, alkenyl sulfonyl fluoride, and alkali metal compounds to synthesize a series of nitrogen-containing heterocyclic compounds and their alkali metal compounds with sulfonyl fluoride and alkyl sulfonyl fluoride functional groups. Therefore, the preparation method of the nitrogen-containing heterocyclic compounds and their alkali metal salts of this invention can enable the widespread application of trithiocyanate in lithium battery electrolytes. Moreover, the preparation method of the nitrogen-containing heterocyclic compounds of this invention uses readily available raw materials, is simple to operate, has high yield, mild conditions, low equipment requirements, and is suitable for large-scale industrial production.

[0084] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, it is not limited to those listed in the embodiments. Those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a nitrogen-containing heterocyclic compound, characterized in that the step... include: (1) Mix trithiocyanic acid with the first solvent evenly, introduce sulfuryl fluoride gas or add alkenyl sulfonyl fluoride to react, and after the reaction is completed, the crude product is obtained by crude treatment. The reaction time is 2~3h, the reaction temperature is -20℃~40℃, the molar ratio of trithiocyanic acid to sulfuryl fluoride is 1:1~3.2, the molar ratio of trithiocyanic acid to alkenyl sulfonyl fluoride is 1:1~3.2, and the boiling point of the first solvent is less than 100℃; (2) The crude product is purified to obtain the nitrogen-containing heterocyclic compound shown in structural formula 1; R1, R2, and R3 are each independently selected from -H, -SO2F, or -CH2-(CH2). n -SO2F, where n is an integer selected from 1 to 10, and R1, R2, and R3 are not all H at the same time.

2. The method for preparing the nitrogen-containing heterocyclic compound according to claim 1, characterized in that, Step (1) includes mixing the trithiocyanate, organic base and first solvent evenly, passing sulfur fluoride gas through to react, and after the reaction is completed, evaporating and drying to obtain an intermediate. The intermediate is then subjected to a first pretreatment to obtain a crude product.

3. The method for preparing the nitrogen-containing heterocyclic compound as described in claim 1, characterized in that, Step (1) includes mixing the trithiocyanate with a first solvent, adding alkenyl sulfonyl fluoride to react, evaporating and drying the mixture after the reaction to obtain a first intermediate, subjecting the first intermediate to a quenching reaction to obtain a second intermediate, and then subjecting the second intermediate to a first pretreatment to obtain a crude product.

4. The method for preparing the nitrogen-containing heterocyclic compound according to any one of claims 2 to 3, characterized in that, The first pretreatment includes dissolving the intermediate or second intermediate in a second solvent, taking the organic phase, and then sequentially washing, dehydrating and drying, filtering, and concentrating.

5. The method for preparing the nitrogen-containing heterocyclic compound according to claim 1, characterized in that, Step (2) includes subjecting the crude product to a second pretreatment and vacuum drying to obtain the nitrogen-containing heterocyclic compound shown in structural formula 1. The second pretreatment includes cooling crystallization or column chromatography separation.

6. A method for preparing an alkali metal salt containing a nitrogen-containing heterocyclic compound, characterized in that the step... include: (1) Mix the trithiocyanate compound with a third solvent evenly, add an alkali metal compound, and then adjust the pH value to carry out the reaction. The trithiocyanate compound is a nitrogen-containing heterocyclic compound prepared by the method of preparing nitrogen-containing heterocyclic compounds according to any one of claims 1 to 5. The method of preparing trithiocyanate compound is the method of preparing nitrogen-containing heterocyclic compounds according to any one of claims 1 to 5. (2) The product after the reaction in step (1) is purified to obtain the nitrogen-containing heterocyclic compound alkali metal salt shown in structural formula 2; R4, R5, and R6 are each independently selected from -SO2F or -CH2-(CH2). n -SO2F or alkali metal, n is an integer selected from 1 to 10, and at least one of R4, R5, and R6 is an alkali metal.

7. The method for preparing the alkali metal salt of the nitrogen-containing heterocyclic compound as described in claim 6, characterized in that, The pH value in step (1) is 7~8, the reaction temperature is 40~60℃, and the reaction time is 1~5h.

8. The method for preparing the alkali metal salt of the nitrogen-containing heterocyclic compound as described in claim 6, characterized in that, The purification process in step (2) includes concentration, cooling crystallization, filtration, and drying.

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