Green and environment-friendly method for preparing photosensitive polyimide raw material

Abstract

The invention relates to a green and environment-friendly method for preparing a photosensitive polyimide raw material, which comprises the following steps: by taking 2.3, 5, 6-tetramethyl-1, 4-phenylenediamine and m-nitrobenzoyl chloride as raw materials, respectively mixing and reacting the raw materials in the presence of a solvent, adding an eluate after the reaction, and filtering to obtain an intermediate; and performing catalytic hydrogenation on the intermediate under the action of a catalyst and a solvent. The obtained product is high in yield and purity, the used reaction solvent can be repeatedly recycled and reused, the catalytic efficiency is high, the reaction condition is mild, the product is environment-friendly, the operation is simple and convenient, less three wastes are generated, and the application range is wide.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of green environmental protection preparation photosensitive polyimide raw material method, belong to organic synthesis technical field. BACKGROUND

[0002] Polyimide (Polyimide, referred to as PI) as a special engineering plastics, with excellent heat resistance, mechanical properties and electrical properties, film-forming property, its application field has been in aerospace, automotive industry and electronic appliances, in microelectronics industry PI is widely used as photoresist. Photosensitive polyimide (Photosensitive Polyimide, referred to as PSPI) is a kind of polymer material with photosensitive and heat-resistant double function, can greatly simplify the complex photoetching process when using non-photosensitive polyimide, while meeting the special requirements of large-scale integrated circuits and very large scale integrated circuit multilayer internal system, surface passivation layer and ion implantation mask, electron beam lithography and many other aspects, thus increasingly attracts people's attention.

[0003] The preparation method of photosensitive polyimide, the traditional method is to add photosensitizer in polyamide acid stage, or directly synthesize diamine or dianhydride monomer with photosensitive group, therefore, diamine or dianhydride monomer with photosensitive group is one of the key raw materials (monomer) of photosensitive polyimide resin, however, dianhydride and diamine synthesis is complex, photosensitive group needs special chemical treatment, greatly increases the difficulty and cost, the existing status is that the raw material for preparing photosensitive polyimide is less, the cost is high, which limits the popularization and utilization of photosensitive polyimide, becomes the core pain point of commercial application of photosensitive polyimide (PSPI). SUMMARY

[0004] In view of the deficiencies of the prior art, especially the problem that the raw material of photosensitive polyimide is less and the cost is high, which limits the popularization and utilization of photosensitive polyimide, the present application provides a kind of green environmental protection preparation photosensitive polyimide raw material method.

[0005] The raw material used in the present application is non-corrosive, the equipment requirement is low, the safety is high, the reaction solvent can be repeatedly recovered and reused, the operation is simple, the waste is less, and the environment is friendly, which is suitable for industrial production.

[0006] The specific technical scheme of the present application is as follows:

[0007] On the one hand, a kind of green environmental protection preparation photosensitive polyimide raw material method, comprising the following steps:

[0008] 1) 2.3, 5, 6-tetramethyl-1, 4-phenylenediamine and m-nitrobenzoyl chloride are used as raw materials, and intermediate is obtained by condensation reaction in the presence of DMM, and the reaction route is as follows:

[0009]

[0010] 2) The intermediate obtained in step 1) is dissolved in DMF, and the final product, a photosensitive polyimide raw material, is obtained by the action of a catalyst and hydrogen, as shown in the following reaction scheme:

[0011]

[0012] Specifically, a method for preparing a photosensitive polyimide raw material in an environmentally friendly manner comprises the following steps:

[0013] (1) 2.3,5,6-tetramethyl-1,4-phenylenediamine is mixed with dimethyl maleate DMM to form a homogeneous solution, and then m-nitrobenzoyl chloride dissolved in dimethyl maleate DMM is added dropwise at 0-25°C. After the dropwise addition, the reaction is incubated at 15-30°C for 3-4 h. After the reaction, the intermediate is obtained by post-treatment.

[0014] (2) The intermediate obtained in step 1) is dissolved in N,N-dimethylformamide DMF, and stirred until completely dissolved. After the addition of a catalyst, the whole is transferred to a hydrogenation reactor, and nitrogen is introduced to 0.5 MPa, followed by vacuum pumping for 3-5 times. The reactor is heated to 55°C, and hydrogen is introduced. The reaction is completed when the pressure remains unchanged. After the reaction is completed, the solid catalyst is filtered out, and the mother liquor is added dropwise to the precipitation liquid b, washed, and dried to obtain the final product.

[0015] According to the present application, in step (1), the post-treatment is that, within 0.5-1 h after the reaction, precipitation liquid a is added to the reaction solution and stirred for 1-2 h. After the precipitation is precipitated, the temperature is lowered to 0-10°C, and stirring is continued for 0.5-1 h. After vacuum filtration, the filter cake is washed with pure water, and dried at a temperature of 60-100°C and a vacuum degree of -0.090-0.095 MPa to obtain the intermediate N,N'-(2,3,5,6-tetramethyl-1,4-phenylene) bis(3-nitrobenzamide).

[0016] The reaction solvent DMM used in step (1) can be repeatedly recovered and reused, and the obtained intermediate can be directly used, which is simple to operate and suitable for industrial production.

[0017] According to the present application, in step (1), the precipitation liquid a is one of methanol, ethanol, isopropanol, and 1,4-dioxane.

[0018] According to the present application, in step (1), the mass ratio of the precipitation liquid a to dimethyl maleate DMM is (3-9):1.

[0019] Further preferably, in step (1), the mass ratio of the precipitation liquid a to dimethyl maleate DMM is (3-6):1.

[0020] According to the application, preferably, in step (1), the mass of DMM is the total mass of DMM used for mixing and dissolving m-nitrobenzoyl chloride.

[0021] According to the application, preferably, in step (1), the precipitate a can be easily separated from the solvent used for solvent recovery, which helps to improve the purity of the product and reduce the loss of the product to improve the yield.

[0022] According to the application, preferably, in step (1), the molar ratio of 2.3,5,6-tetramethyl-1,4-phenylenediamine to m-nitrobenzoyl chloride is 1:(1.9-2.4).

[0023] Further preferably, in step (1), the molar ratio of 2.3,5,6-tetramethyl-1,4-phenylenediamine to m-nitrobenzoyl chloride is 1:(2.0-2.1).

[0024] According to the application, preferably, in step (1), the mass ratio of 2.3,5,6-tetramethyl-1,4-phenylenediamine to DMM is 1:2.0-3.5.

[0025] According to the application, preferably, in step (1), the mass ratio of m-nitrobenzoyl chloride to dimethyl maleate DMM is 1:1.0-1:2.0.

[0026] According to the application, preferably, in step (2), the mass ratio of the intermediate to solvent N,N-dimethylformamide DMF is 1:(6.5-10.5).

[0027] According to the application, preferably, in step (2), the amount of catalyst used is 1-5% of the mass of the intermediate.

[0028] According to the application, preferably, in step (2), the amount of precipitate b used is 1-7 times the mass of the hydrogenation mother liquor.

[0029] According to the application, preferably, in step (2), the precipitate is an ethanol-water mixed solution, and the volume ratio of ethanol to water in the ethanol-water mixed solution is 30:70.

[0030] According to the application, preferably, in step (2), the dropping speed of the mother liquor is 1-8 mL / min.

[0031] According to the application, preferably, in step (2), after hydrogen is introduced, the pressure in the reactor is 0.5-1 MPa, and during the reaction, hydrogen is supplemented to the reactor when the pressure is less than 0.5 MPa, and the hydrogen pressure is less than or equal to 1 MPa during the reaction, and the reaction ends when the pressure remains unchanged.

[0032] According to the application, in step 2), the elution drying is carried out by first elution with 5 DEG C cold water, 50 DEG C vacuum drying, then elution with deionized water for 2-3 times, and 80 DEG C drying.

[0033] The application innovatively uses dimethyl maleate DMM to make 2.3, 5, 6-tetramethyl-1, 4-phenylenediamine and m-nitrobenzoyl chloride condense in one step, on the one hand, the ester carbonyl in the DMM molecule can form a highly active intermediate with acyl chloride, which can significantly improve the electrophilicity of m-nitrobenzoyl chloride, on the other hand, DMM as a polar aprotic solvent can reduce the reaction energy barrier by stabilizing the transition state, promote the deprotonation of amine group and the efficiency of nucleophilic attack, and successfully prepare the intermediate; The catalyst used in the hydrogenation stage is a new type of catalyst, which focuses on the high selectivity reduction of double nitro functional groups, and Ni2B preferentially adsorbs the nitro group and avoids the space steric hindrance of the tetramethylphenyl and amide bond; Each nitro group independently undergoes a hydrogenation path to generate a corresponding amino group, and the product is a diamino derivative, and the amide group remains intact, avoiding decomposition or side reactions. DMF solvent optimizes the solubility and homogeneous reaction environment, and cooperates with the nitrogen / hydrogen circulation of the hydrogenation kettle to ensure the completeness of the reduction and the purity of the product. In the preparation process of the new type of catalyst, cerium nitrate is also added, which can realize the efficient and selective reduction of nitro group by constructing "metal-oxide" double active sites, especially suitable for complex molecular systems with large steric hindrance or sensitive groups; Cerium nitrate prolongs the service life of the catalyst through the triple mechanism of surface protection, structure stabilization and poison capture, especially in the hydrogenation system containing nitro group / sensitive group, which can reduce the activity decay rate by more than 80%.

[0034] Application of the photosensitive polyimide raw material to the preparation of photosensitive polyimide.

[0035] The application has the advantages that:

[0036] 1、The application innovatively uses DMM as a reaction solvent to dissolve the material, after the reaction, the target product intermediate can be obtained by adding a precipitation liquid, the product purity obtained by the cooperation of DMF and the new type of catalyst can reach more than 99%, which meets the purity use requirements of electronic grade products, is safer, more friendly to the environment, and the single reaction solvent can be repeatedly recovered and used, the operation is simple, the product does not need secondary refining, the purity requirement can be met, the application is suitable for industrial production, the operation is simple, the waste is less, the application is friendly to the environment, and the application range is wide.

[0037] 2、The preparation method is simple, and the product has high yield and high purity.

[0038] 3. The N, N'-(2, 3, 5, 6-tetramethyl-1, 4-phenylene) bis(3-nitrobenzamide) of the present application enriches the raw materials for preparing photosensitive polyimide, and the photosensitive polyimide prepared therefrom has super-high thermal stability due to the perfluoro structure of the material, and extremely low dielectric performance is realized through the nitro group conjugation effect, which is significantly superior to traditional polyimide. DETAILED DESCRIPTION

[0039] The present application will be further described in detail below in conjunction with specific examples, which are merely illustrative and do not limit the scope of protection.

[0040] Unless otherwise specified, each raw material used in the following examples is a commercially available product.

[0041] The catalyst in the examples is prepared by the following method:

[0042] Under the protection of nitrogen, 2.0 equivalents of anhydrous NiCl2·6H2O are dissolved in 20 mL of pre-cooled anhydrous methanol at 0±2℃ to form a blue-green solution, 4.0 equivalents of dry NaBH4 powder are slowly added in 4 batches (≤0.5 g at a time, with an interval of 2 minutes), the temperature is controlled to be ≤10℃, the solution is quickly changed into a black Ni2B suspension, the cerium nitrate modifier is dissolved in 0.5 mL of anhydrous methanol, and is added dropwise into the black suspension, the temperature is maintained at 10℃ or below, and the stirring speed is increased to 1200 rpm; the ice bath is continued for 8 minutes, and then the catalyst is used immediately, the whole process needs to maintain the water content of the solvent <0.1% and the residual oxygen ≤50 ppm, the catalyst is prepared and used immediately, the activity decays by 40% within 30 minutes, and is suitable for high selectivity reduction of nitro / benzyl functional groups. In the catalyst, nickel boride is the main body, the proportion of nickel is 78-82%, and the proportion of boron is 8-10%; cerium nitrate is the modifier, and the proportion of cerium in the main body is 0.8-1.2%.

[0043] Example 1

[0044] A method for green and environmentally friendly preparation of a photosensitive polyimide raw material, the steps are as follows:

[0045] 1) 229.78 g (1.238 mol) of m-nitrobenzoyl chloride is added to a beaker containing 229.78 g of DMM, and stirred uniformly to obtain a m-nitrobenzoyl chloride solution;

[0046] 2) 100 g (0.61 mol) of 2.3, 5, 6-tetramethyl-1, 4-phenylenediamine is added to a three-necked flask containing 230 g of DMM, and stirred until completely dissolved, and then cooled to 20℃ to obtain a 2.3, 5, 6-tetramethyl-1, 4-phenylenediamine solution;

[0047] 3) The m-nitrobenzoyl chloride solution is added dropwise into the three-neck flask of step 2) by using a peristaltic pump through a latex tube, the dropwise time is 0.5 h, the temperature during the reaction is less than 30°C, after the dropwise addition is completed, the temperature is adjusted to 25°C, and the reaction is continued for 4 h, after the reaction is completed, the reaction solution is added dropwise into 1379.34 g of a methanol aqueous solution to precipitate, after the dropwise addition is completed, stirring is continued for 0.5 h, the temperature is lowered to 10°C, and stirring is continued for 0.5 h, after filtration, the filter cake is washed with 1600 ml of pure water, and drying is performed at 85°C under vacuum-0.095 MPa to obtain the intermediate; the yield is 97.6%, and the purity is 98.87%.

[0048] 4) The intermediate is dissolved in 7.5 times of DMF, and stirring is continued until complete dissolution, a catalyst with a mass of 2% of the intermediate is added, and then the whole is transferred into a hydrogenation reaction kettle, nitrogen is introduced until the pressure reaches 0.5 MPa, and then vacuum is applied, the process is repeated for 3 times, the reaction kettle is heated to 55°C, and then hydrogen is introduced, the hydrogen pressure is 0.5-1 MPa, during the reaction, hydrogen is supplemented into the kettle when the pressure is less than 0.5 MPa, the hydrogen pressure is not more than 1 MPa, and the reaction is completed when the pressure is constant. After the reaction is completed, the solid catalyst is filtered out, the mother liquor is added dropwise into 2.5 times of an ethanol aqueous mixed solution, the dropwise addition speed is 1 ml / min, the filter cake is washed with pure water, and the filter cake is dried under vacuum at 50°C after being washed with deionized water for 2-3 times, and then the filter cake is dried at 80°C to obtain the final product, the yield is 98.7%, and the purity is 99.79%.

[0049] Example 2

[0050] A green and environmentally friendly method for preparing a photosensitive polyimide raw material, the steps are as follows:

[0051] 1) 233.17 g (1.257 mol) of m-nitrobenzoyl chloride is added into a beaker containing 396.389 g of DMM, and stirring is continued until uniform, to obtain a m-nitrobenzoyl chloride solution;

[0052] 2) 100 g (0.61 mol) of 2.3, 5, 6-tetramethyl-1, 4-phenylenediamine is added into a three-neck flask containing 300 g of DMM, and stirring is continued until complete dissolution, and then the temperature is lowered to 20°C, to obtain a 2.3, 5, 6-tetramethyl-1, 4-phenylenediamine solution;

[0053] 3) The m-nitrobenzoyl chloride solution is added dropwise into the three-neck flask of step 2) by using a peristaltic pump through a latex tube, the dropwise time is 0.5 h, after the dropwise addition is completed, the temperature is adjusted to 25°C, and the reaction is continued for 4 h, after the reaction is completed, the reaction solution is added dropwise into 2437.36 g of a methanol aqueous solution to precipitate, after the dropwise addition is completed, stirring is continued for 0.5 h, the temperature is lowered to 10°C, and stirring is continued for 0.5 h, after filtration, the filter cake is washed with 2600 ml of pure water, and drying is performed at 85°C under vacuum-0.095 MPa to obtain the intermediate; the yield is 96.9%, and the product purity is 98.75%

[0054] 4) The intermediate is dissolved in 7.5 times DMF, stirred until completely dissolved, and then transferred to a hydrogenation reactor after adding a catalyst of 2% of the mass of the intermediate. Nitrogen is passed to 0.5 MPa, and then vacuum is extracted, repeated 3-5 times. The reactor is heated to 55°C, and then hydrogen is passed in. The hydrogen pressure is 0.5-1 MPa. During the reaction, if the pressure is lower than 0.5 MPa, hydrogen is supplemented into the reactor. The hydrogen filling pressure is not more than 1 MPa. The reaction is completed when the pressure is constant. After the reaction is completed, the solid catalyst is filtered out, the mother liquor is added dropwise into 2.5 times ethanol water mixed solution at a dropwise speed of 1 ml / min, and then filtered, washed with pure water, and then washed with deionized water at 50°C under vacuum drying for 2-3 times, and then dried at 80°C to obtain the final product, with a yield of 98.0% and a purity of 99.66%.

[0055] Example 3

[0056] A green and environmentally friendly method for preparing a photosensitive polyimide raw material, the steps are as follows:

[0057] 1) 232.04 g (1.251 mol) of m-nitrobenzoyl chloride is added to a beaker containing 324.86 g of DMM, and stirred uniformly to obtain a m-nitrobenzoyl chloride solution;

[0058] 2) 100 g (0.61 mol) of 2.3, 5, 6-tetramethyl-1, 4-phenylenediamine is added to a three-necked flask containing 270 g of DMM, and stirred until completely dissolved. After completely dissolved, it is cooled to 20°C to obtain a 2.3, 5, 6-tetramethyl-1, 4-phenylenediamine solution;

[0059] 3) The m-nitrobenzoyl chloride solution is added dropwise to the three-necked flask of step 2) by using a peristaltic pump through a latex tube, and the dropwise time is 0.5 h. After the dropwise addition is completed, the temperature is adjusted to 25°C, and the reaction is continued for 4 h. After the reaction is completed, the reaction liquid is added dropwise into 1963.04 g of a methanol aqueous solution to precipitate. After the dropwise addition is completed, it is stirred for 0.5 h, cooled to 10°C, and then stirred for 0.5 h. After filtered, washed with 2100 ml of pure water, and then dried at 85°C under vacuum-0.095 MPa, the intermediate is obtained. The yield is 97.3%, and the product purity is 98.78%.

[0060] 4) The intermediate is dissolved in 7.5 times DMF, stirred until completely dissolved, and then transferred to a hydrogenation reactor after adding a catalyst of 2% of the mass of the intermediate. Nitrogen is passed to 0.5 MPa, and then vacuum is applied, repeated 3-5 times. The reactor is heated to 55°C, and then hydrogen is passed in. The hydrogen pressure is 0.5-1 MPa. During the reaction, hydrogen is supplemented to the reactor when the pressure is lower than 0.5 MPa. The hydrogen filling pressure is not more than 1 MPa. The reaction is completed when the pressure is constant. After the reaction is completed, the solid catalyst is filtered out, the mother liquor is added dropwise to 2.5 times of an ethanol water mixed solution, the dropwise speed is 1 ml / min, and then filtration is performed. The product is washed with pure water, and then vacuum dried at 50°C. The product is washed with deionized water 2-3 times, and then dried at 80°C. The final product is obtained, the yield is 98.4%, and the purity is 99.71%.

[0061] Comparative Example 1

[0062] The method described in Example 1 is used, except that

[0063] Step (1) is performed using N-methyl pyrrolidone instead of DMM, and the other steps are performed according to Example 1. The product yield is 94.1%, and the purity is 95.52%.

[0064] Comparative Example 2

[0065] The method described in Example 1 is used, except that

[0066] Step (1) is performed using ethylene glycol butyl ether instead of DMM, and the other steps are performed according to Example 1. The product yield is 94.6%, and the purity is 95.05%.

[0067] Comparative Example 3

[0068] The method described in Example 1 is used, except that

[0069] Step (1) is performed using methanol instead of DMM, and the other steps are performed according to Example 1. The product yield is 93.7%, and the purity is 94.73%.

[0070] Comparative Example 4

[0071] In Step 4), Pd / c is used instead of the catalyst in Example 1 during the hydrogenation stage, and the other steps are performed according to Example 1. The product yield is 85.7%, and the purity is 97.91%.

[0072] Based on the above, it can be seen from Comparative Examples 1-4 that the product yield is significantly reduced when N-methyl pyrrolidone, ethylene glycol butyl ether, or methanol is used instead of DMM.

[0073] Experimental Example 1

[0074] 1. Change the amount of DMM in step 1) of Example 1, respectively 92.5g, 150.5g, 505.51g, 574.45g, and other according to Example 1, and compare the reaction yield and purity after the reaction is completed. The results are shown in Table 1.

[0075] Table 1

[0076] m-nitrobenzoyl chloride / g amount of dmm % yield % purity 229.78g 92.5g 83.2 86.78 229.78g 150.5g 88.5 92.01 229.78g 229.78g 98.7％ 99.79％ 229.78g 505.51g 91.6 95.43 229.78g 574.45g 89.2 93.84

[0077] As can be seen from the data in Table 1, the yield is low when the amount of DMM is too small. With the increase of the amount of DMM, the yield gradually increases, but when the amount of DMM is too large, the yield begins to decrease. Too much DMM affects the yield of the product and also causes side reactions, which affects the purity of the product.

[0078] 2. Change the mass ratio of methanol to pure water in Example 1, and the mass ratio of methanol to pure water is 8:2, 7:3, 6:4, 1:1, 4:6, 3:7, respectively. Other according to Example 1, and compare the reaction yield and purity after the reaction is completed. The results are shown in Table 2.

[0079] Table 2

[0080] methanol / water mass ratio % yield % purity 8:2 96.5 97.85 7:3 97.5 98.69 6:4 96.9 97.41 5:5 96.4 96.88 4:6 95.5 97.61 3:7 94.8 97.45

[0081] As can be seen from the data in Table 2, the yield and purity are the highest when the mass ratio of methanol to pure water is 7:3.

[0082] Experimental Example 2

[0083] Preparation of photosensitive polyimide

[0084] Preparation process: 2.257g of the final product prepared in Example 1 and 1.177g of biphenyl tetracarboxylic dianhydride (BPDA) as monomers, the monomers are added to 12ml of γ-butyrolactone and 3ml of DMSO mixed solvent, and 0.0024g of DMAP catalyst is added, and the pre-polymerization is carried out at 60°C under nitrogen protection for 4 hours (300rpm stirring). Then, the temperature is increased to 180°C at a gradient of 20°C / h to complete the imidization, and maintained for 5 hours and monitored by FT-IR in real time. The reaction solution is settled by 80ml of methanol and 20ml of water, and then purified by Soxhlet extraction with ethanol for 10 hours, and dried at 100°C under vacuum for 24 hours to obtain the photosensitive polyimide polymer.

[0085] Film formation: the photosensitive polyimide polymer is dissolved in DMAc to prepare a 12wt% solution, and then filtered and ladder dried (80°C→120°C→180°C, vacuum≤10Pa) to obtain a high-performance polyimide film.

[0086] The mechanical properties, stability, dielectric properties and lithographic resolution of the photosensitive polyimide film are tested, and the test results are shown in Table 3.

[0087] Table 3

[0088]

[0089]

[0090] As shown in Table 3, the high imidization completeness and thermal stability of this film are synergistically improved, significantly outperforming traditional systems. The 2,3,5,6-tetramethyl-1,4-phenylene structure inhibits molecular chain rotation through steric hindrance, increasing the glass transition temperature while reducing the CTE to 17.0 ppm / ℃. The 3-nitrobenzamide unit initiates efficient photocrosslinking at a wavelength of 365 nm, achieving a pattern resolution of 1.50 μm while maintaining 90% transmittance, thus achieving high-precision patterning and optical transparency. The low coefficient of thermal expansion and high dimensional stability are suitable for precision manufacturing. Optimized dielectric properties ensure high-frequency signal transmission efficiency. By precisely controlling the degree of imidization, the tetramethylnitro-based PI film comprehensively surpasses traditional systems in photosensitivity, thermomechanical stability, and high-frequency dielectric properties, making it suitable for 5G millimeter-wave communication and high-end flexible display fields.

Claims

1. A green and environmentally friendly method for preparing photosensitive polyimide raw materials, comprising the following steps: 1) Using 2,3,5,6-tetramethyl-1,4-phenylenediamine and m-nitrobenzoyl chloride as starting materials, an intermediate was obtained by condensation reaction in the presence of DMM. The reaction route is as follows: 2) The intermediate obtained in step 1) is dissolved in DMF, and under the action of a catalyst and hydrogen, the final product, photosensitive polyimide raw material, is obtained. The reaction route is as follows:

2. A green and environmentally friendly method for preparing photosensitive polyimide raw materials, comprising the following steps: (1) 2,3,5,6-Tetramethyl-1,4-phenylenediamine and dimethyl maleate (DMM) were mixed to form a homogeneous solution. Then, m-nitrobenzoyl chloride dissolved in DMM was added dropwise at 0-25℃. After the addition, the mixture was kept at 15-30℃ for 3-4 hours. After the reaction, the intermediate was obtained by post-treatment. (2) Dissolve the intermediate obtained in step 1) in N,N-dimethylformamide DMF and stir until completely dissolved. After adding the catalyst, transfer the entire mixture to a hydrogenation reactor. Purge with nitrogen to 0.5 MPa and then evacuate. Repeat this process 3-5 times. Heat the reactor to 55°C and then purge with hydrogen. The reaction ends when the pressure remains constant. After the reaction is complete, filter out the solid catalyst to obtain the mother liquor. Add the mother liquor dropwise to the precipitate b, wash, and dry to obtain the final product.

3. The method according to claim 2, characterized in that, In step (1), the post-treatment involves adding precipitate a to the reaction solution and stirring for 1-2 hours within 0.5-1 hours after the reaction. After the precipitate is formed, the temperature is lowered to 0-10℃, and stirring is continued for 0.5-1 hours. The mixture is then filtered, washed with pure water, and dried at a temperature of 60-100℃ and a vacuum degree of -0.090-0.095 MPa to obtain intermediate N,N'-(2,3,5,6-tetramethyl-1,4-phenylene)bis(3-nitrobenzamide).

4. The method according to claim 2, characterized in that, In step (1), the precipitate a is one of methanol, ethanol, isopropanol, and 1,4-dioxane.

5. The method according to claim 2, characterized in that, In step (1), the mass ratio of precipitate a to dimethyl maleate (DMM) is (3-9):1, and the mass of DMM is the total mass of DMM used to mix with 2,3,5,6-tetramethyl-1,4-phenylenediamine and dissolve m-nitrobenzoyl chloride.

6. The method according to claim 2, characterized in that, In step (1), the molar ratio of 2,3,5,6-tetramethyl-1,4-phenylenediamine to m-nitrobenzoyl chloride is 1:(1.9-2.4).

7. The method according to claim 2, characterized in that, In step (1), the mass ratio of 2,3,5,6-tetramethyl-1,4-phenylenediamine to DMM is 1:2.0-3.5, and the mass ratio of m-nitrobenzoyl chloride to dimethyl maleate (DMM) is 1:1.0-1:2.

0.

8. The method according to claim 2, characterized in that, In step (2), the mass ratio of the intermediate to the solvent N,N-dimethylformamide (DMF) is 1:(6.5-10.5), and the amount of catalyst used is 1-5% of the mass of the intermediate.

9. The method according to claim 2, characterized in that, In step (2), the amount of precipitate b is 1-7 times the mass of the hydrogenation mother liquor. The precipitate is an ethanol-water mixed solution with a volume ratio of ethanol to water of 30:

70. The dropping rate of the mother liquor is 1-8 mL / min.

10. The method according to claim 2, characterized in that, In step (2), after hydrogen is introduced, the pressure inside the reactor is 0.5-1 MPa. During the reaction, if the pressure is less than 0.5 MPa, hydrogen is added to the reactor. During the reaction, the hydrogen pressure is less than or equal to 1 MPa. The reaction ends when the pressure remains constant. The rinsing and drying process involves first rinsing with cold water at 5°C, then vacuum drying at 50°C, then rinsing with deionized water 2-3 times, and finally drying at 80°C.

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