Method for synthesizing bisphenol A diphenyl ether type bismaleimide and catalytic composition

Abstract

The invention relates to a method for synthesizing bisphenol A diphenyl ether type bismaleimide and a catalytic composition, the catalytic composition comprises p-toluenesulfonic acid and sulfate, and the sulfate is selected from one or two of magnesium sulfate or sodium hydrogen sulfate. The bisphenol A diphenyl ether type bismaleimide synthesized by taking maleic anhydride and 2, 2 '-bis [4-(4-aminophenoxy phenyl)] propane as raw materials and taking the catalytic composition disclosed by the invention as a catalytic system has the characteristic of high melting point.

Description

Technical Field

[0001] This application belongs to the technical field of the preparation of bismaleimide resins, and specifically relates to a method for synthesizing bisphenol A diphenyl ether type bismaleimide and a catalytic composition. Background Art

[0002] As a type of high-performance polymer material, bismaleimide (BMI) resin, with its excellent heat resistance, high glass transition temperature (Tg), and low coefficient of thermal expansion (CTE), etc., shows extensive application potential in many high-tech fields such as aviation, aerospace, mechanical engineering, and the electronics industry, especially as key materials such as the resin matrix of advanced composites, high-temperature insulating layers, and high-performance adhesives. Among them, bisphenol A diphenyl ether type bismaleimide (BPA-BMI) has become the research focus in this field due to its excellent thermal stability, outstanding mechanical strength, and excellent corrosion resistance.

[0003] Currently, the mainstream process in the industry for synthesizing BPA-BMI uses maleic anhydride (MAH) and 2,2'-bis[4-(4-aminophenoxyphenyl)]propane (BAPP) as starting materials and is prepared through a condensation reaction pathway. This process is usually carried out in an aqueous solution system or an organic solvent environment, where the carboxyl functional group of MAH reacts with the amino functional group of BAPP to undergo an amidation reaction, followed by intramolecular cyclization to form a stable bismaleimide structure.

[0004] In order to further improve the synthesis efficiency and material properties of BPA-BMI, domestic and foreign research teams have carried out a series of modification studies and explorations of new synthesis methods. Specifically, through azeotropic distillation technology, researchers have successfully prepared bismaleimide monomers with self-toughening properties. By introducing an ether bond structure into the polymer molecular chain, the toughness of the resin has been effectively improved, and its application scope has been broadened. In addition, microwave radiation synthesis method, as a new synthesis strategy, provides a new perspective and possibility for the preparation of BPA-BMI due to its advantages such as rapid reaction, high energy efficiency, simple operation, and environmental friendliness. The microwave method can not only significantly shorten the reaction time but also may optimize the microstructure of the product by promoting intermolecular and intramolecular interactions, thereby improving the comprehensive properties of the material.

[0005] However, although the existing synthesis methods have made significant progress in promoting the industrial production of BPA-BMI, with the continuous improvement of usage requirements, higher requirements have also been put forward for the melting point of BPA-BMI. Currently, how to further increase the melting point of BPA-BMI to meet the usage requirements in a higher temperature environment has become an urgent problem to be solved. Summary of the Invention

[0006] The present application aims to provide a specific catalytic composition for synthesizing bisphenol A diphenyl ether type bismaleimide. In the synthesis route of preparing bisphenol A diphenyl ether type bismaleimide using maleic anhydride and 2,2'-bis[4-(4-aminophenoxyphenyl)]propane as raw materials, by introducing the catalytic composition of the present invention, the melting point of the obtained product can be significantly increased. Meanwhile, the present invention also provides a specific method for catalytically preparing bisphenol A diphenyl ether type bismaleimide using this catalytic composition, providing a new technical route for efficiently and highly producing bisphenol A diphenyl ether type bismaleimide with a high melting point.

[0007] In one aspect of the present application, there is provided a catalytic composition for synthesizing bisphenol A diphenyl ether type bismaleimide, comprising p-toluenesulfonic acid and a sulfate.

[0008] In one embodiment, the mass ratio of p-toluenesulfonic acid to the sulfate is 10 - 15:1.

[0009] In one embodiment, the mass ratio of p-toluenesulfonic acid to the sulfate is 13:1.

[0010] In one embodiment, the sulfate is selected from one or both of magnesium sulfate and sodium bisulfate.

[0011] In one embodiment, maleic anhydride and 2,2'-bis[4-(4-aminophenoxyphenyl)]propane are used as reaction raw materials, and bisphenol A diphenyl ether type bismaleimide is obtained by condensation reaction under the action of the catalytic composition.

[0012] In one embodiment, the molar ratio of maleic anhydride to 2,2'-bis[4-(4-aminophenoxyphenyl)]propane is 4 - 6:2.

[0013] In one embodiment, the molar ratio of maleic anhydride to 2,2'-bis[4-(4-aminophenoxyphenyl)]propane is 5:2.

[0014] In one embodiment, the mass ratio of the catalytic composition to maleic anhydride is 1:1 - 3.

[0015] In another aspect of the present application, there is provided a method for synthesizing bisphenol A diphenyl ether type bismaleimide, comprising:

[0016] Dropping an organic solution of 2,2'-bis[4-(4-aminophenoxyphenyl)]propane into an organic solution of maleic anhydride, and heating and stirring;

[0017] Adding the catalytic composition and heating to the reflux temperature for condensation reaction; the catalytic composition comprises p-toluenesulfonic acid and a sulfate;

[0018] After the reaction is completed, the target product is obtained by washing and crystallization.

[0019] In one embodiment, the mass ratio of the p-toluenesulfonic acid to the sulfate is 10 to 15:1.

[0020] In one embodiment, the mass ratio of the p-toluenesulfonic acid to the sulfate is 13:1.

[0021] In one embodiment, the sulfate is selected from one or both of magnesium sulfate and sodium bisulfate.

[0022] In one embodiment, the solvent of the organic solution includes a polar organic solvent and a non-polar organic solvent.

[0023] In one embodiment, the polar organic solvent is selected from one or more of N,N-dimethylformamide, N-methylpyrrolidone, and dimethyl sulfoxide.

[0024] In one embodiment, the non-polar organic solvent is selected from one or more of toluene, o-xylene, m-xylene, and p-xylene.

[0025] In one embodiment, the molar ratio of maleic anhydride to 2,2'-bis[4-(4-aminophenoxyphenyl)]propane is 4 to 6:2.

[0026] In one embodiment, the molar ratio of maleic anhydride to 2,2'-bis[4-(4-aminophenoxyphenyl)]propane is 5:2.

[0027] In one embodiment, the mass ratio of the catalytic composition to maleic anhydride is 1:1 to 3.

[0028] In one embodiment, the organic solution of 2,2'-bis[4-(4-aminophenoxyphenyl)]propane is prepared under nitrogen protection.

[0029] In one embodiment, the dropping process of the organic solution of 2,2'-bis[4-(4-aminophenoxyphenyl)]propane is carried out under nitrogen protection.

[0030] In one embodiment, the condensation reaction is carried out under nitrogen protection.

[0031] In one embodiment, the heating and stirring temperature is 50 to 55 °C.

[0032] In one embodiment, the reflux temperature is 110 to 113 °C.

[0033] In one embodiment, the crystallization is carried out at 20 to 25 °C.

[0034] In one embodiment, the crystallization product is dried under vacuum, and the drying conditions are 70-80 °C.

[0035] In another aspect of the present application, there is provided the use of a catalytic composition in the preparation of bisphenol A diphenyl ether type bismaleimide, wherein the catalytic composition comprises p-toluenesulfonic acid and a sulfate, and the sulfate is selected from one or both of magnesium sulfate or sodium bisulfate.

[0036] In one embodiment, the mass ratio of p-toluenesulfonic acid to the sulfate is 10-15:1.

[0037] In one embodiment, the mass ratio of p-toluenesulfonic acid to the sulfate is 13:1.

[0038] Advantages of the present application:

[0039] For the synthesis route of bisphenol A diphenyl ether type bismaleimide using maleic anhydride and 2,2'-bis[4-(4-aminophenoxyphenyl)]propane as reaction raw materials, the present application provides a composite catalytic composition, which can significantly improve the melting point and yield of the target product bisphenol A diphenyl ether type bismaleimide. It has been experimentally proven that the melting point of the synthesized bisphenol A diphenyl ether type bismaleimide reaches above 160 °C. Description of the drawings

[0040] Figure 1 is the DSC curve of the product of Example 1 of the present application;

[0041] Figure 2 is the DSC curve of the product of Example 2 of the present application;

[0042] Figure 3 is the DSC curve of the product of Example 3 of the present application;

[0043] Figure 4 is the DSC curve of the product of Comparative Example 1 of the present application;

[0044] Figure 5 is the liquid phase chromatogram of the product of Example 1 of the present application;

[0045] Figure 6 is the liquid phase chromatogram of the product of Example 3 of the present application;

[0046] Figure 7 is the liquid phase chromatogram of the product of Comparative Example 1 of the present application;

[0047] Figure 8 is the liquid phase chromatogram of the product of Comparative Example 4 of the present application. Detailed embodiments

[0048] The technical solutions of the present application will be clearly and completely described below in conjunction with specific embodiments. However, those skilled in the art will understand that the following described embodiments are part of the embodiments of the present application, rather than all of the embodiments, and are only used to illustrate the present application, and should not be construed as limiting the scope of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application. For those conditions not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. For reagents or instruments not specified by the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0049] In the current industrial community, using maleic anhydride (MAH) and 2,2'-bis[4-(4-aminophenoxyphenyl)]propane (BAPP) as key starting materials and preparing bisphenol A diphenyl ether type bismaleimide (BPA-BMI) through a carefully designed condensation reaction path has become a mainstream and mature process technology. This synthesis process not only requires strict control of reaction conditions but also has an in-depth understanding of the purity of raw materials and reaction mechanisms.

[0050] In production practice, in order to continuously improve the synthesis efficiency of BPA-BMI, researchers have invested a lot of energy in process optimization and innovation. After unremitting efforts, the synthesis purity of BPA-BMI has now stably reached over 98%. However, the industrial community is not satisfied with this and is still continuously researching and exploring to further optimize reaction conditions, increase the conversion rate of raw materials, and reduce the generation of by-products, thereby further improving the overall yield of the product.

[0051] In this context, the applicant made a breakthrough discovery during the research process. By systematically screening and optimizing the catalytic system, a specific composite catalyst system was accidentally discovered, which can significantly increase the melting point of the synthesized product BPA-BMI. This discovery is of great significance for improving the performance of BPA-BMI because BPA-BMI with a high melting point exhibits more excellent characteristics in terms of thermal stability, mechanical strength, and processing performance.

[0052] Specifically, during the synthesis process using maleic anhydride (MAH) and 2,2'-bis[4-(4-aminophenoxyphenyl)]propane (BAPP), the applicant innovatively introduced a composite catalytic system composed of p-toluenesulfonic acid and sulfate. This composite catalyst can not only effectively promote the reaction and increase the reaction rate, but also significantly improve the melting point of BPA-BMI while ensuring the product purity. This achievement not only provides new ideas and methods for the synthesis process of BPA-BMI, but also brings potential technological innovation and industrial upgrading to the industrial production in related fields.

[0053] In one aspect of the present application, there is provided a catalytic composition for synthesizing bisphenol A diphenyl ether type bismaleimide, comprising p-toluenesulfonic acid and sulfate.

[0054] p-Toluenesulfonic acid is an important organic compound and is commonly used as an acid catalyst in organic synthesis. It has moderate toxicity and can stimulate the skin, eyes and mucous membranes. In catalytic reactions, p-toluenesulfonic acid can significantly increase the reaction rate and the selectivity of the product, especially showing excellent performance in esterification, acylation, acetylation and other reactions. As a protonic acid, p-toluenesulfonic acid can provide protons, promote the proton transfer between reactants, thereby reducing the activation energy of the reaction and accelerating the reaction. Sulfates are a class of widely existing inorganic salts, including sodium bisulfate, sodium sulfate, magnesium sulfate, potassium sulfate, ammonium sulfate, etc. In industry, sulfates are commonly used as polymerization initiators for synthesizing resins, synthetic fibers and synthetic industrial rubbers. The combined use of p-toluenesulfonic acid and sulfate can significantly improve the catalytic efficiency of the reaction, shorten the reaction time, increase the yield and purity of the product, and most importantly, can significantly increase the melting point of the synthesized bisphenol A diphenyl ether type bismaleimide.

[0055] In some embodiments, the mass ratio of p-toluenesulfonic acid to sulfate is 10-15:1. Preferably, the mass ratio of p-toluenesulfonic acid to sulfate is 13:1. The p-toluenesulfonic acid and sulfate within this dosage range exhibit excellent synergistic effects. This dosage range not only significantly increases the yield and purity of the product, but also endows the prepared bisphenol A diphenyl ether type bismaleimide with a significantly high melting point property. Specifically, the mass ratio of p-toluenesulfonic acid to sulfate can be 10:1, 11:1, 12:1, 13:1, 14:1, 15:1.

[0056] In some embodiments, the sulfate is selected from magnesium sulfate or sodium bisulfate, or any combination of the two. Specifically, the catalytic composition can be constructed as a binary system of p-toluenesulfonic acid and magnesium sulfate, or a binary system of p-toluenesulfonic acid and sodium bisulfate, or even a ternary composite system containing p-toluenesulfonic acid, magnesium sulfate and sodium bisulfate. Regardless of the combination form, p-toluenesulfonic acid serves as the dominant component in the catalytic composition and plays a core catalytic role. When the catalytic composition is designed as a ternary system containing p-toluenesulfonic acid, magnesium sulfate and sodium bisulfate, there is no strict limitation on the specific dosage ratio between magnesium sulfate and sodium bisulfate in this technical solution, aiming to provide flexible ratio options to meet different catalytic requirements. However, from the perspective of optimizing catalytic performance, a preferred embodiment is to adopt a binary combination of p-toluenesulfonic acid and sodium bisulfate. This combination exhibits excellent catalytic efficiency, not only significantly improving the yield and purity of the target product, but also performing outstandingly in enhancing the heat resistance of the product, providing strong technical support for the synthesis of high-quality compounds such as bisphenol A diphenyl ether type bismaleimide.

[0057] In some embodiments, maleic anhydride (MA) and 2,2'-bis[4-(4-aminophenoxyphenyl)]propane (BAPP) are used as reaction raw materials, and through the action of the catalytic composition, a condensation reaction is carried out to synthesize bisphenol A diphenyl ether type bismaleimide (BPA-BMI). Among them, maleic anhydride, as an important raw material for synthesizing bismaleimide, provides the maleimide structural unit, and 2,2'-bis[4-(4-aminophenoxyphenyl)]propane, as a precursor for synthesizing bismaleimide, undergoes a condensation reaction with maleic anhydride. Specifically, maleic anhydride and BAPP are pretreated, such as drying, purification, etc., to ensure the purity and activity of the reaction raw materials. After pretreatment, maleic anhydride and BAPP are mixed in a certain proportion, an appropriate amount of solvent (such as benzene, toluene, etc.) and the catalytic composition are added, and a condensation reaction is carried out at an appropriate reaction temperature and time. During the reaction process, the anhydride group of maleic anhydride reacts with the amino group of BAPP to undergo amidation reaction, and then dehydration and ring closure occur to form bisphenol A diphenyl ether type bismaleimide. After the reaction is completed, the target product bisphenol A diphenyl ether type bismaleimide is obtained through steps such as filtration, washing, and drying.

[0058] In some embodiments, the molar ratio of maleic anhydride to 2,2'-bis[4-(4-aminophenoxyphenyl)]propane is 4 to 6:2. Preferably, the molar ratio of maleic anhydride to 2,2'-bis[4-(4-aminophenoxyphenyl)]propane is 5:2. In this system, the number of moles of maleic anhydride is more than twice the number of moles of BAPP, which helps to ensure sufficient contact and reaction between the anhydride groups of maleic anhydride and the amino groups of BAPP, increasing the collision frequency between reactants and accelerating the reaction rate. However, too high a concentration may also lead to side reactions, so it is necessary to determine the optimal molar ratio. Specifically, the molar ratio of maleic anhydride to 2,2'-bis[4-(4-aminophenoxyphenyl)]propane can be 4:2, 5:2, 6:2.

[0059] In some embodiments, the mass ratio of the catalytic composition to maleic anhydride is 1:1 to 3. The amount of the catalytic composition directly affects its catalytic efficiency. An appropriate amount of the catalytic composition can provide sufficient active sites to promote the condensation reaction between maleic anhydride and BAPP. However, too much of the catalytic composition may make the reaction system too complex, increasing the risk of side reactions and at the same time raising the production cost. Specifically, the mass ratio of the catalytic composition to maleic anhydride is 1:1, 1:2, 1:3.

[0060] In another aspect of the present application, a method for synthesizing bisphenol A diphenyl ether type bismaleimide is provided, including: dropping an organic solution of 2,2'-bis[4-(4-aminophenoxyphenyl)]propane into an organic solution of maleic anhydride, heating and stirring; adding the catalytic composition and raising the temperature to the reflux temperature for condensation reaction; the catalytic composition includes p-toluenesulfonic acid and sulfate; after the reaction is completed, washing and crystallization are carried out to obtain the target product.

[0061] In the present application, an organic solution refers to a homogeneous and stable liquid mixture formed by dissolving reaction raw materials (such as 2,2'-bis[4-(4-aminophenoxyphenyl)]propane and maleic anhydride) with one or more organic compounds as solvents. The selection of the organic solvent should meet the following conditions: it can fully dissolve the reaction raw materials, ensure the uniform dispersion of the reactants in the solution, and form a homogeneous reaction system; it remains chemically stable under the reaction conditions, does not react with the reaction raw materials or products, and avoids introducing impurities or affecting the reaction process; it has appropriate volatility and is convenient to be removed by distillation, evaporation, etc. after the reaction is completed, so as to obtain a pure target product.

[0062] In some embodiments, the solvent of the organic solution includes a polar organic solvent and a non-polar organic solvent. A polar organic solvent refers to an organic compound containing polar groups such as hydroxyl, carbonyl, amino, etc., and its molecules have polarity. A non-polar organic solvent refers to a type of solvent with a low dielectric constant and a small dipole moment, and its molecular structure is symmetric or the electron cloud distribution is uniform, and it cannot form hydrogen bonds or significant solvation effects with polar substances. Using a solvent system including a polar organic solvent and a non-polar organic solvent can ensure the smooth progress of the process of synthesizing bisphenol A diphenyl ether type bismaleimide and obtain a target product with high quality.

[0063] Furthermore, the polar organic solvent is selected from one or more of N,N-dimethylformamide, N-methylpyrrolidone, and dimethyl sulfoxide. The non-polar organic solvent is selected from one or more of toluene, o-xylene, m-xylene, and p-xylene. Specifically, the solvent system of the organic solution in the present application can be N,N-dimethylformamide and toluene, N,N-dimethylformamide and o-xylene, N,N-dimethylformamide and m-xylene, N,N-dimethylformamide and p-xylene.

[0064] Preferably, the solvent system of the organic solution is N,N-dimethylformamide and toluene. Among them, N,N-dimethylformamide also has a catalytic effect during the process of synthesizing bisphenol A diphenyl ether type bismaleimide. The system of N,N-dimethylformamide and toluene helps the full dissolution of 2,2'-bis[4-(4-aminophenoxyphenyl)]propane. The use of toluene is on the one hand as a solvent, and on the other hand it is immiscible with water and forms an azeotrope with water during subsequent distillation and evaporation processes, bringing out water, which helps to improve the purity of the target product.

[0065] In some embodiments, the molar ratio of maleic anhydride to 2,2'-bis[4-(4-aminophenoxyphenyl)]propane is 4-6:2. Preferably, the molar ratio of maleic anhydride to 2,2'-bis[4-(4-aminophenoxyphenyl)]propane is 5:2. Specifically, the molar ratio of maleic anhydride to 2,2'-bis[4-(4-aminophenoxyphenyl)]propane can be 4:2, 5:2, 6:2.

[0066] In some embodiments, the mass ratio of p-toluenesulfonic acid to sulfate is 10-15:1. Preferably, the mass ratio of p-toluenesulfonic acid to sulfate is 13:1. Specifically, the mass ratio of the catalytic composition to maleic anhydride is 10:1, 11:1, 12:1, 13:1, 14:1, 15:1.

[0067] In some embodiments, the sulfate is selected from magnesium sulfate or sodium bisulfate, or any combination of the two. Specifically, the catalytic composition can be constructed as a binary system of p-toluenesulfonic acid and magnesium sulfate, or a binary system of p-toluenesulfonic acid and sodium bisulfate, or even a ternary composite system containing p-toluenesulfonic acid, magnesium sulfate and sodium bisulfate. Regardless of the combination form, p-toluenesulfonic acid serves as the dominant component in the catalytic composition and plays a core catalytic role. When the catalytic composition is designed as a ternary system containing p-toluenesulfonic acid, magnesium sulfate and sodium bisulfate, there is no strict limitation on the specific dosage ratio between magnesium sulfate and sodium bisulfate in this technical solution, aiming to provide flexible ratio selection to meet different catalytic requirements. However, from the perspective of optimizing catalytic performance, a preferred embodiment is to adopt a binary combination of p-toluenesulfonic acid and sodium bisulfate. This combination exhibits excellent catalytic efficiency, not only significantly improving the yield and purity of the target product, but also performing outstandingly in enhancing the heat resistance of the product, providing strong technical support for the synthesis of high-quality compounds such as bisphenol A diphenyl ether type bismaleimide.

[0068] In some embodiments, the mass ratio of the catalytic composition to the maleic anhydride is 1:1 to 3. Specifically, the mass ratio of the catalytic composition to the maleic anhydride is 1:1, 1:2, 1:3.

[0069] In some embodiments, the organic solution of 2,2'-bis[4-(4-aminophenoxyphenyl)]propane is prepared under nitrogen protection. 2,2'-bis[4-(4-aminophenoxyphenyl)]propane is sensitive to oxygen and prone to oxidation reaction, resulting in a decrease in the purity of the target product. Nitrogen is a gas with stable chemical properties and is not easily reactive with other substances, so it is often used as a protective gas to isolate oxygen and water vapor in the air and prevent the reactants or intermediate products from being oxidized.

[0070] In some embodiments, the dropping process of the organic solution of 2,2'-bis[4-(4-aminophenoxyphenyl)]propane is carried out under nitrogen protection. The dropping process under nitrogen protection can effectively prevent the reactants from contacting with oxygen in the air during the dropping process, thus avoiding the occurrence of oxidation reaction and ensuring the smooth progress of the reaction. Specifically, before the dropping operation, the reaction system needs to be placed in a nitrogen atmosphere first. This is usually achieved by introducing nitrogen into the reaction vessel and discharging the air in the vessel. After the dropping is completed, nitrogen is continuously introduced for a period of time to ensure that the oxygen in the reaction system is fully excluded.

[0071] In some embodiments, the condensation reaction is carried out under nitrogen protection. Specifically, during the process of dropping the organic solution of 2,2'-bis[4-(4-aminophenoxyphenyl)]propane into the organic solution of maleic anhydride and heating with stirring, nitrogen should be continuously introduced to maintain the nitrogen atmosphere in the reaction system. After adding the catalytic composition (p-toluenesulfonic acid and sulfate), when the temperature is raised to the reflux temperature for the condensation reaction, nitrogen protection still needs to be continuously carried out to prevent the reactants or intermediate products from reacting with oxygen in the air at high temperatures. After the condensation reaction is completed, subsequent steps such as washing and crystallization can be carried out under nitrogen protection to obtain a pure target product.

[0072] In some embodiments, the heating and stirring temperature is 50-55°C. During the process of dropping the organic solution of 2,2'-bis[4-(4-aminophenoxyphenyl)]propane into the organic solution of maleic anhydride, the reaction mixture needs to be heated and stirred, and the heating temperature range is controlled between 50°C and 55°C. At this temperature, the reactants can be fully mixed, which is beneficial to the uniform reaction during the dropping process. At the same time, this temperature is not too high to avoid possible side reactions or decomposition of the reactants. Heating can be carried out by means of a water bath, an oil bath or an electric heating mantle, etc. Stirring while heating can ensure that the reaction mixture is heated evenly and avoid local overheating or uneven reaction.

[0073] In some embodiments, the reflux temperature is 110-113°C. Reflux is usually achieved by heating the reaction mixture above its boiling point and condensing the evaporated solvent in a condenser and then returning it to the reaction flask. In this application, appropriate heating equipment (such as an electric heating mantle, an oil bath, etc.) and a condensing device (such as a reflux condenser) are needed to control and maintain the reflux state. After the reflux reaction is completed, heating needs to be stopped and the reaction mixture is allowed to cool to room temperature. Specifically, the reflux temperature can be 110°C, 111°C, 112°C, 113°C.

[0074] In some embodiments, the crystallization is carried out at 20-25°C. Crystallization is an important step in the post-treatment of chemical reactions. By lowering the temperature or changing the solvent conditions, the solute is precipitated from the solution to form crystals. Crystallization is usually carried out by cooling the reaction mixture to a certain temperature and maintaining it at this temperature for a period of time to gradually precipitate the solute. In this application, a cooling water bath, an ice-water mixture or other appropriate cooling means can be used to control and maintain the crystallization temperature. Precise control of the crystallization temperature is crucial for ensuring the quality and yield of the crystals. Too high a temperature may cause the crystals to grow too fast, forming irregular or agglomerated crystals; too low a temperature may make the crystallization rate too slow and prolong the crystallization time. Selecting 20-25°C as the crystallization temperature can ensure that the target product precipitates at an appropriate rate to form crystals with good quality.

[0075] In some embodiments, the crystallized product is dried under vacuum, and the drying conditions are 70 - 80 °C. Vacuum drying is achieved by heating under a low-pressure environment, which can lower the boiling point of substances, thereby accelerating the evaporation of water and the removal of solvents. For the crystallized product in this application, vacuum drying can remove residual organic solvents and water, improving the purity and stability of the product. Selecting 70 - 80 °C as the drying temperature can ensure that the product will not decompose or deteriorate due to excessive temperature, while efficiently removing residual solvents and water. Vacuum drying usually needs to be carried out in a vacuum drying oven or a vacuum baking oven, which can provide the required low-pressure environment and heating conditions. During the drying process, the crystallized product needs to be placed on a suitable container or tray, and it is ensured that the container or tray has good air permeability so that water and solvents can evaporate smoothly.

[0076] In another aspect of the present application, there is provided the use of a catalytic composition in the preparation of bisphenol A diphenyl ether type bismaleimide. The catalytic composition includes p-toluenesulfonic acid and a sulfate salt, and the sulfate salt is selected from one or both of magnesium sulfate or sodium bisulfate.

[0077] Wherein, the mass ratio of p-toluenesulfonic acid to the sulfate salt is 10 - 15:1. Preferably, the mass ratio of p-toluenesulfonic acid to the sulfate salt is 13:1.

[0078] In the synthesis process of bisphenol A diphenyl ether type bismaleimide, the catalytic composition of p-toluenesulfonic acid and the sulfate salt can promote the condensation reaction. By dropping an organic solution of 2,2'-bis[4-(4-aminophenoxyphenyl)]propane into an organic solution of maleic anhydride and adding the catalytic composition under heating and stirring conditions, and raising the temperature to the reflux temperature, the condensation reaction can be carried out. The use of the catalytic composition can improve the reaction efficiency and yield. The synergistic effect of p-toluenesulfonic acid and the sulfate salt can accelerate the reaction, reduce the generation of by-products, thereby improving the purity and yield of the target product. At the same time, it can significantly increase the melting point of the synthesized bisphenol A diphenyl ether type bismaleimide, making the product have excellent heat resistance.

[0079] The technical solution of the present application will be described in detail below with specific example embodiments.

[0080] Example 1

[0081] 1 mol of maleic anhydride was added to 600 ml of toluene and 12 g of DMF and dissolved. After stirring in a 50 °C water bath, it was designated as solution ①. In a nitrogen atmosphere, 0.4 mol of 2,2'-bis[4-(4-aminophenoxyphenyl)]propane was mixed with 600 ml of toluene and 40 g of DMF until clear, and it was designated as solution ②. In a nitrogen atmosphere, solution ② was added dropwise to solution ① while controlling the temperature at 50 - 55 °C. After the addition was complete, it was stirred at 50 - 55 °C for 1 h. Then, 39 g of p-toluenesulfonic acid and 3 g of sodium bisulfate were added to the system, and the temperature was raised to 110 - 113 °C for reflux reaction. After 3 h of reflux reaction, the temperature was lowered to 75 - 80 °C, and it was washed 5 times with 300 ml of water. The first two times were washed with weak alkaline water until the system was neutral, and then the last three times were washed with clear water. Then, the temperature was raised to 110 °C for reflux to separate out the residual water in the system, and then the temperature was lowered to 20 - 25 °C for crystallization for 8 h. The product was obtained by filtration and vacuum dried at 75 °C to obtain 185 g of a yellow solid.

[0082] Example 2

[0083] 1 mol of maleic anhydride was added to 600 ml of toluene and 12 g of DMF and dissolved. After stirring in a 50 °C water bath, it was designated as solution ①. In a nitrogen atmosphere, 0.4 mol of 2,2'-bis[4-(4-aminophenoxyphenyl)]propane was mixed with 600 ml of toluene and 40 g of DMF until clear, and it was designated as solution ②. In a nitrogen atmosphere, solution ② was added dropwise to solution ① while controlling the temperature at 50 - 55 °C. After the addition was complete, it was stirred at 50 - 55 °C for 1 h. Then, 60 g of p-toluenesulfonic acid and 4.5 g of sodium bisulfate were added to the system, and the temperature was raised to 110 - 113 °C for reflux reaction. After 3 h of reflux reaction, the temperature was lowered to 75 - 80 °C, and it was washed 5 times with 300 ml of water. The first two times were washed with weak alkaline water until the system was neutral, and then the last three times were washed with clear water. Then, the temperature was raised to 110 °C for reflux to separate out the residual water in the system, and then the temperature was lowered to 20 - 25 °C for crystallization for 8 h. The product was obtained by filtration and vacuum dried at 75 °C to obtain 180 g of a yellow solid.

[0084] Example 3

[0085] 1 mol of maleic anhydride was added to 600 ml of toluene and 12 g of DMF and dissolved, and the solution was stirred in a 50 °C water bath and denoted as solution ①. Under a nitrogen atmosphere, 0.4 mol of 2,2'-bis[4-(4-aminophenoxyphenyl)]propane was mixed with 600 ml of toluene and 40 g of DMF until clear and denoted as solution ②. Solution ② was added dropwise to solution ① under a nitrogen atmosphere while controlling the temperature at 50 - 55 °C. After the addition was complete, stirring was continued at 50 - 55 °C for 1 h. Then, 80 g of p-toluenesulfonic acid and 6 g of sodium bisulfate were added to the system, and the temperature was raised to 110 - 113 °C for reflux reaction. After 3 h of reflux reaction, the temperature was lowered to 75 - 80 °C, and 5 washes were carried out with 300 ml of water. The first two washes were with weak alkaline water to wash the system to neutrality, and then the next three washes were with pure water. Then, the temperature was raised to 110 °C for reflux to remove the residual water in the system, and then the temperature was lowered to 20 - 25 °C for crystallization for 8 h. The product was obtained by filtration and vacuum dried at 75 °C to obtain 175 g of a yellow solid.

[0086] Example 4

[0087] 1 mol of maleic anhydride was added to 600 ml of toluene and 12 g of DMF and dissolved, and the solution was stirred in a 50 °C water bath and denoted as solution ①. Under a nitrogen atmosphere, 0.4 mol of 2,2'-bis[4-(4-aminophenoxyphenyl)]propane was mixed with 600 ml of toluene and 40 g of DMF until clear and denoted as solution ②. Solution ② was added dropwise to solution ① under a nitrogen atmosphere while controlling the temperature at 50 - 55 °C. After the addition was complete, stirring was continued at 50 - 55 °C for 1 h. Then, 39 g of p-toluenesulfonic acid and 3 g of magnesium sulfate were added to the system, and the temperature was raised to 110 - 113 °C for reflux reaction. After 3 h of reflux reaction, the temperature was lowered to 75 - 80 °C, and 5 washes were carried out with 300 ml of water. The first two washes were with weak alkaline water to wash the system to neutrality, and then the next three washes were with pure water. Then, the temperature was raised to 110 °C for reflux to remove the residual water in the system, and then the temperature was lowered to 20 - 25 °C for crystallization for 8 h. The product was obtained by filtration and vacuum dried at 75 °C to obtain 160 g of a yellow solid.

[0088] Example 5

[0089] 1 mol of maleic anhydride was added to 600 ml of toluene and 12 g of DMF, and after dissolution, it was stirred in a 50 °C water bath and denoted as solution ①. In a nitrogen atmosphere, 0.4 mol of 2,2'-bis[4-(4-aminophenoxyphenyl)]propane was mixed with 600 ml of toluene and 40 g of DMF until clear and denoted as solution ②. Solution ② was added dropwise to solution ① in a nitrogen atmosphere while controlling the temperature at 50 - 55 °C. After the addition was complete, it was stirred at 50 - 55 °C for 1 h. Then, 86 g of a catalytic composition was added to the system. The catalytic composition was composed of p-toluenesulfonic acid and sodium bisulfate with a mass ratio of 10:1. The temperature was raised to 110 - 113 °C for reflux reaction. After 3 h of reflux reaction, the temperature was lowered to 75 - 80 °C, and it was washed 5 times with 300 ml of water. The first two times were washed with weak alkaline water until the system was neutral, and then the last three times were washed with clear water. Then, the temperature was raised to 110 °C for reflux to separate out the residual water in the system. Then, the temperature was lowered to 20 - 25 °C for crystallization for 8 h, and the product was obtained by filtration. After vacuum drying at 75 °C, 170 g of a yellow solid was obtained.

[0090] Example 6

[0091] 1 mol of maleic anhydride was added to 600 ml of toluene and 12 g of DMF, and after dissolution, it was stirred in a 50 °C water bath and denoted as solution ①. In a nitrogen atmosphere, 0.4 mol of 2,2'-bis[4-(4-aminophenoxyphenyl)]propane was mixed with 600 ml of toluene and 40 g of DMF until clear and denoted as solution ②. Solution ② was added dropwise to solution ① in a nitrogen atmosphere while controlling the temperature at 50 - 55 °C. After the addition was complete, it was stirred at 50 - 55 °C for 1 h. Then, 86 g of a catalytic composition was added to the system. The catalytic composition was composed of p-toluenesulfonic acid and sodium bisulfate with a mass ratio of 15:1. The temperature was raised to 110 - 113 °C for reflux reaction. After 3 h of reflux reaction, the temperature was lowered to 75 - 80 °C, and it was washed 5 times with 300 ml of water. The first two times were washed with weak alkaline water until the system was neutral, and then the last three times were washed with clear water. Then, the temperature was raised to 110 °C for reflux to separate out the residual water in the system. Then, the temperature was lowered to 20 - 25 °C for crystallization for 8 h, and the product was obtained by filtration. After vacuum drying at 75 °C, 172 g of a yellow solid was obtained.

[0092] Example 7

[0093] 1 mol of maleic anhydride was added to 600 ml of toluene and 12 g of DMF and dissolved, and the solution was stirred in a 50 °C water bath and denoted as solution ①. In a nitrogen atmosphere, 0.5 mol of 2,2'-bis[4-(4-aminophenoxyphenyl)]propane was mixed with 600 ml of toluene and 40 g of DMF to form a clear solution, denoted as solution ②. Solution ② was added dropwise to solution ① in a nitrogen atmosphere while controlling the temperature at 50 - 55 °C. After the addition was completed, the mixture was stirred at 50 - 55 °C for 1 h. Then, 39 g of p-toluenesulfonic acid and 3 g of magnesium sulfate were added to the system, and the temperature was raised to 110 - 113 °C for reflux reaction. After 3 h of reflux reaction, the temperature was lowered to 75 - 80 °C, and 300 ml of water was used for 5 washes. The first two washes were carried out with weak alkaline water to wash the system to neutrality, and then the next three washes were carried out with pure water. Then, the temperature was raised to 110 °C for reflux to separate out the residual water in the system, and then the temperature was lowered to 20 - 25 °C for crystallization for 8 h. The product was obtained by filtration and vacuum dried at 75 °C to obtain 150 g of a yellow solid.

[0094] Example 8

[0095] 1 mol of maleic anhydride was added to 600 ml of toluene and 12 g of DMF and dissolved, and the solution was stirred in a 50 °C water bath and denoted as solution ①. In a nitrogen atmosphere, 0.3 mol of 2,2'-bis[4-(4-aminophenoxyphenyl)]propane was mixed with 600 ml of toluene and 40 g of DMF to form a clear solution, denoted as solution ②. Solution ② was added dropwise to solution ① in a nitrogen atmosphere while controlling the temperature at 50 - 55 °C. After the addition was completed, the mixture was stirred at 50 - 55 °C for 1 h. Then, 39 g of p-toluenesulfonic acid and 3 g of magnesium sulfate were added to the system, and the temperature was raised to 110 - 113 °C for reflux reaction. After 3 h of reflux reaction, the temperature was lowered to 75 - 80 °C, and 300 ml of water was used for 5 washes. The first two washes were carried out with weak alkaline water to wash the system to neutrality, and then the next three washes were carried out with pure water. Then, the temperature was raised to 110 °C for reflux to separate out the residual water in the system, and then the temperature was lowered to 20 - 25 °C for crystallization for 8 h. The product was obtained by filtration and vacuum dried at 75 °C to obtain 180 g of a yellow solid.

[0096] Comparative Example 1

[0097] 1 mol of maleic anhydride was added to 600 ml of toluene and 12 g of DMF, and after dissolution, it was stirred in a 50 °C water bath and denoted as solution ①. In a nitrogen atmosphere, 0.4 mol of 2,2'-bis[4-(4-aminophenoxyphenyl)]propane was mixed with 600 ml of toluene and 40 g of DMF until clear and denoted as solution ②. In a nitrogen atmosphere, solution ② was added dropwise to solution ① while controlling the temperature at 50 - 55 °C. After the addition was complete, it was stirred at 50 - 55 °C for 1 h. Then, 86 g of p-toluenesulfonic acid was added to the system, and the temperature was raised to 110 °C for reflux reaction. After 3 h of reflux reaction, the temperature was lowered to 75 - 80 °C, and it was washed 5 times with 300 ml of water. The first two times were washed with weak alkaline water until the system was neutral, and then the last three times were washed with pure water. Then, the temperature was raised to 110 °C for reflux to separate out the residual water in the system. Then, the temperature was lowered to 20 - 25 °C for crystallization for 8 h, and the product was obtained by filtration and vacuum dried at 75 °C to obtain 162 g of a yellow solid.

[0098] Comparative Example 2

[0099] 1 mol of maleic anhydride was added to 600 ml of toluene and 12 g of DMF, and after dissolution, it was stirred in a 50 °C water bath and denoted as solution ①. In a nitrogen atmosphere, 0.4 mol of 2,2'-bis[4-(4-aminophenoxyphenyl)]propane was mixed with 600 ml of toluene and 40 g of DMF until clear and denoted as solution ②. In a nitrogen atmosphere, solution ② was added dropwise to solution ① while controlling the temperature at 50 - 55 °C. After the addition was complete, it was stirred at 50 - 55 °C for 1 h. Then, 86 g of sodium bisulfate was added to the system, and the temperature was raised to 110 - 113 °C for reflux reaction. After 3 h of reflux reaction, the temperature was lowered to 75 - 80 °C, and it was washed 5 times with 300 ml of water. The first two times were washed with weak alkaline water until the system was neutral, and then the last three times were washed with pure water. Then, the temperature was raised to 110 °C for reflux to separate out the residual water in the system. Then, the temperature was lowered to 20 - 25 °C for crystallization for 8 h, and the product was obtained by filtration. After chromatographic detection, no effective product was obtained.

[0100] Comparative Example 3

[0101] 1 mol of maleic anhydride was added to 600 ml of toluene and 12 g of DMF and dissolved, and the solution was stirred in a 50 °C water bath and denoted as solution ①. Under a nitrogen atmosphere, 0.4 mol of 2,2'-bis[4-(4-aminophenoxyphenyl)]propane was mixed with 600 ml of toluene and 40 g of DMF until dissolved and denoted as solution ②. Under a nitrogen atmosphere, solution ② was added dropwise to solution ① while controlling the temperature at 50 - 55 °C. After the addition was completed, the mixture was stirred at 50 - 55 °C for 1 h. Then, 39 g of p-toluenesulfonic acid and 3 g of sodium sulfate were added to the system, and the temperature was raised to 110 °C for reflux reaction. After 3 h of reflux reaction, the temperature was lowered to 75 - 80 °C, and 300 ml of water was used for washing 5 times. The first two times were washed with weak alkaline water until the system was neutral, and then the last three times were washed with pure water. Then, the temperature was raised to 110 °C for reflux to separate out the residual water in the system, and then the temperature was lowered to 20 - 25 °C for crystallization for 8 h. The product was obtained by filtration and vacuum dried at 75 °C to obtain 166 g of a yellow solid.

[0102] Comparative Example 4

[0103] 1 mol of maleic anhydride was added to 600 ml of toluene and 12 g of DMF and dissolved, and the solution was stirred in a 50 °C water bath and denoted as solution ①. Under a nitrogen atmosphere, 0.4 mol of 2,2'-bis[4-(4-aminophenoxyphenyl)]propane was mixed with 600 ml of toluene and 40 g of DMF until dissolved and denoted as solution ②. Under a nitrogen atmosphere, solution ② was added dropwise to solution ① while controlling the temperature at 50 - 55 °C. After the addition was completed, the mixture was stirred at 50 - 55 °C for 1 h. Then, 39 g of p-toluenesulfonic acid and 3 g of zinc acetate were added to the system, and the temperature was raised to 110 °C for reflux reaction. After 3 h of reflux reaction, the temperature was lowered to 75 - 80 °C, and 300 ml of water was used for washing 5 times. The first two times were washed with weak alkaline water until the system was neutral, and then the last three times were washed with pure water. Then, the temperature was raised to 110 °C for reflux to separate out the residual water in the system, and then the temperature was lowered to 20 - 25 °C for crystallization for 8 h. The product was obtained by filtration and vacuum dried at 75 °C to obtain 157 g of a yellow solid.

[0104] Comparative Example 5

[0105] 1 mol of maleic anhydride was added to 600 ml of toluene and 12 g of DMF, and after dissolution, it was stirred in a 50 °C water bath and denoted as solution ①. In a nitrogen atmosphere, 0.4 mol of 2,2'-bis[4-(4-aminophenoxyphenyl)]propane was mixed with 600 ml of toluene and 40 g of DMF until clear and denoted as solution ②. Solution ② was added dropwise to solution ① in a nitrogen atmosphere while controlling the temperature at 50 - 55 °C. After the addition was complete, it was stirred at 50 - 55 °C for 1 h. Then, 39 g of p-toluenesulfonic acid and 3 g of sodium acetate were added to the system, and the temperature was raised to 110 - 113 °C for reflux reaction. After 3 h of reflux reaction, the temperature was lowered to 75 - 80 °C, and it was washed 5 times with 300 ml of water. The first two times were washed with weak alkaline water until the system was neutral, and then the last three times were washed with clear water. Then, the temperature was raised to 110 °C for reflux to separate out the residual water in the system, and then the temperature was lowered to 20 - 25 °C for crystallization for 8 h. The product was obtained by filtration and vacuum dried at 75 °C to obtain 150 g of a yellow solid.

[0106] Comparative Example 6

[0107] 1 mol of maleic anhydride was added to 600 ml of toluene and 12 g of DMF, and after dissolution, it was stirred in a 50 °C water bath and denoted as solution ①. In a nitrogen atmosphere, 0.4 mol of 2,2'-bis[4-(4-aminophenoxyphenyl)]propane was mixed with 600 ml of toluene and 40 g of DMF until clear and denoted as solution ②. Solution ② was added dropwise to solution ① in a nitrogen atmosphere while controlling the temperature at 50 - 55 °C. After the addition was complete, it was stirred at 50 - 55 °C for 1 h. Then, 39 g of p-toluenesulfonic acid and 3 g of magnesium acetate were added to the system, and the temperature was raised to 110 - 113 °C for reflux reaction. After 3 h of reflux reaction, the temperature was lowered to 75 - 80 °C, and it was washed 5 times with 300 ml of water. The first two times were washed with weak alkaline water until the system was neutral, and then the last three times were washed with clear water. Then, the temperature was raised to 110 °C for reflux to separate out the residual water in the system, and then the temperature was lowered to 20 - 25 °C for crystallization for 8 h. The product was obtained by filtration and vacuum dried at 75 °C to obtain 162 g of a yellow solid.

[0108] Comparative Example 7

[0109] 1.7 mol of maleic anhydride was added to 600 ml of toluene and 12 g of DMF and dissolved, and the solution was stirred in a 50 °C water bath and denoted as solution ①. In a nitrogen atmosphere, 0.68 mol of 2,2'-bis[4-(4-aminophenoxyphenyl)]propane was mixed with 600 ml of toluene and 40 g of DMF until clear and denoted as solution ②. Solution ② was added dropwise to solution ① in a nitrogen atmosphere while controlling the temperature at 50 - 55 °C. After the addition was complete, the mixture was stirred at 50 - 55 °C for 1 h. Then, 39 g of p-toluenesulfonic acid and 3 g of sodium bisulfate were added to the system, and the temperature was raised to 110 - 113 °C for reflux reaction. After 3 h of reflux reaction, the temperature was lowered to 75 - 80 °C, and 300 ml of water was used for 5 washes. The first two washes were with weak alkaline water to wash the system to neutral, and then the next three washes were with pure water. Then, the temperature was raised to 110 °C for reflux to separate out the residual water in the system, and then the temperature was lowered to 20 - 25 °C for crystallization for 8 h. The product was obtained by filtration and vacuum dried at 75 °C to obtain 255 g of a yellow solid.

[0110] Comparative Example 8

[0111] 1.7 mol of maleic anhydride was added to 600 ml of toluene and 12 g of DMF and dissolved, and the solution was stirred in a 50 °C water bath and denoted as solution ①. In a nitrogen atmosphere, 0.68 mol of 2,2'-bis[4-(4-aminophenoxyphenyl)]propane was mixed with 600 ml of toluene and 40 g of DMF until clear and denoted as solution ②. Solution ② was added dropwise to solution ① in a nitrogen atmosphere while controlling the temperature at 50 - 55 °C. After the addition was complete, the mixture was stirred at 50 - 55 °C for 1 h. Then, 86 g of a catalytic composition was added to the system. The catalytic composition was composed of p-toluenesulfonic acid and sodium bisulfate in a mass ratio of 8:1. The temperature was raised to 110 - 113 °C for reflux reaction. After 3 h of reflux reaction, the temperature was lowered to 75 - 80 °C, and 300 ml of water was used for 5 washes. The first two washes were with weak alkaline water to wash the system to neutral, and then the next three washes were with pure water for the water system. Then, the temperature was raised to 110 °C for reflux to separate out the residual water in the system, and then the temperature was lowered to 20 - 25 °C for crystallization for 8 h. The product was obtained by filtration and vacuum dried at 75 °C to obtain 258 g of a yellow solid.

[0112] Comparative Example 9

[0113] 1.7 mol of maleic anhydride was added to 600 ml of toluene and 12 g of DMF, and after dissolution, it was stirred in a 50 °C water bath and denoted as solution ①. In a nitrogen atmosphere, 0.68 mol of 2,2'-bis[4-(4-aminophenoxyphenyl)]propane was mixed with 600 ml of toluene and 40 g of DMF until clear and denoted as solution ②. Solution ② was added dropwise to solution ① in a nitrogen atmosphere while controlling the temperature at 50 - 55 °C. After the addition was complete, it was stirred at 50 - 55 °C for 1 h. Then, 86 g of a catalytic composition was added to the system. The catalytic composition consisted of p-toluenesulfonic acid and sodium bisulfate with a mass ratio of 17:1. The temperature was raised to 110 - 113 °C for reflux reaction. After 3 h of reflux reaction, the temperature was lowered to 75 - 80 °C, and it was washed 5 times with 300 ml of water. The first two times were washed with weak alkaline water until the system was neutral, and then the last three times were washed with clear water. Then, the temperature was raised to 110 °C for reflux to separate the residual water in the system, and then the temperature was lowered to 20 - 25 °C for crystallization for 8 h. The product was obtained by filtration and vacuum dried at 75 °C to obtain 246.5 g of a yellow solid.

[0114] Comparative Example 10

[0115] The preparation and reaction process of solution ② were not protected by nitrogen: 1 mol of maleic anhydride was added to 600 ml of toluene and 12 g of DMF, and after dissolution, it was stirred in a 50 °C water bath and denoted as solution ①. 0.4 mol of 2,2'-bis[4-(4-aminophenoxyphenyl)]propane was mixed with 600 ml of toluene and 40 g of DMF until clear and denoted as solution ②. Solution ② was added dropwise to solution ① while controlling the temperature at 50 - 55 °C. After the addition was complete, it was stirred at 50 - 55 °C for 1 h. Then, 39 g of p-toluenesulfonic acid and 3 g of sodium bisulfate were added to the system. The temperature was raised to 110 - 113 °C for reflux reaction. After 3 h of reflux reaction, the temperature was lowered to 75 - 80 °C, and it was washed 5 times with 300 ml of water. The first two times were washed with weak alkaline water until the system was neutral, and then the last three times were washed with clear water. Then, the temperature was raised to 110 °C for reflux to separate the residual water in the system, and then the temperature was lowered to 20 - 25 °C for crystallization for 8 h. The product was obtained by filtration and vacuum dried at 75 °C to obtain 175 g of a yellow solid.

[0116] The purity and melting point of the products of Examples 1 - 8 and Comparative Examples 1 - 10 were detected.

[0117] Using a NETZSCH STA449C type thermal analyzer, in a nitrogen atmosphere, the melting point of the bisphenol A diphenyl ether type bismaleimide monomer was analyzed with a heating rate of 10 °C / min; Figure 1 It is the DSC curve of the product of Example 1, Figure 2 It is the DSC curve of the product of Example 2, Figure 3 It is the DSC curve of the product of Example 3, Figure 4 It is the DSC curve of the product of Comparative Example 1. The purity of the product was analyzed using an Agilent 1100 type high performance liquid chromatograph of Agilent Corporation,Figure 5 It is the liquid chromatogram of the product of Example 1. Figure 6 It is the liquid chromatogram of the product of Example 3. Figure 7 It is the liquid chromatogram of the product of Comparative Example 1. Figure 8 It is the liquid chromatogram of the product of Comparative Example 4.

[0118] The results are shown in Table 1.

[0119] Table 1 Characterization of the synthesized BPA-BMI

[0120]

[0121] According to the experimental data of Examples 1 to 3 and Comparative Example 7, it can be observed that as the amount of the catalytic composition changes, both the yield and melting point of bisphenol A diphenyl ether type bismaleimide show a downward trend. This indicates that when the mass ratio of the catalytic composition to maleic anhydride is controlled within the range of 1:1 to 1:3, a better catalytic effect can be achieved.

[0122] Furthermore, through the comparative analysis of Examples 1 to 4 and Comparative Examples 3 to 6, it can be observed that when the catalytic composition is selected as a combination of p-toluenesulfonic acid and magnesium sulfate or sodium bisulfate, the product shows high levels in terms of purity, yield, and melting point.

[0123] In addition, the comparative studies of Example 3 and Comparative Examples 1 to 2, as well as Examples 5 to 6 and Comparative Examples 8 to 9, reveal that when the catalytic composition uses p-toluenesulfonic acid and magnesium sulfate or sodium bisulfate, and their mass ratio is controlled within the range of 10 to 15:1, the catalytic composition exhibits a significant synergistic effect. This synergistic effect not only improves the purity of the product but also significantly enhances the yield and melting point of the product.

[0124] Finally, through the comparative experiment of Example 1 and Comparative Example 10, the importance of the nitrogen atmosphere for the synthesis of the target product can be confirmed. Conducting the condensation reaction in a nitrogen atmosphere can effectively promote the formation of the product, improve the yield and melting point of the product, and further optimize the synthesis process.

[0125] Although the embodiments of the present application have been described above, the present application is not limited to the above specific embodiments and application fields. The above specific embodiments are merely illustrative and guiding, rather than restrictive. Those of ordinary skill in the art can also make many forms under the inspiration of this specification and without departing from the scope protected by the claims of the present application, and these all fall within the scope of protection of the present application.

Claims

1. A method for synthesizing bisphenol A diphenyl ether type bismaleimide, characterized in that: include: The organic solution of 2,2'-bis[4-(4-aminophenoxyphenyl)]propane is added dropwise to the organic solution of maleic anhydride and heated with stirring; Adding a catalyst composition and heating to reflux temperature to carry out a condensation reaction; the catalyst composition comprises p-toluenesulfonic acid and sodium bisulfate; After the reaction is completed, washing and crystallization are performed to obtain the target product; The mass ratio of p-toluenesulfonic acid to sodium bisulfate is 10-15:1; The mass ratio of the catalytic composition to the maleic anhydride is 1:1-3.

2. The method according to claim 1, characterized in that The mass ratio of p-toluenesulfonic acid to sodium bisulfate is 13:

1.

3. The method according to claim 1, characterized in that The molar ratio of the maleic anhydride to the 2,2'-bis[4-(4-aminophenoxyphenyl)]propane is 4-6:

2.

4. The method according to claim 1, characterized in that: The organic solution of 2,2'-bis[4-(4-aminophenoxyphenyl)]propane is prepared under nitrogen protection; The organic solution of 2,2'-bis[4-(4-aminophenoxyphenyl)]propane is added dropwise under nitrogen protection; The condensation reaction is carried out under nitrogen protection.

5. The method according to claim 1, characterized in that The reflux temperature is 110-113°C; The heating and stirring temperature is 50-55°C; The crystallization is carried out at 20-25°C; The crystallized product is vacuum dried at a temperature of 70-80°C.

6. The method according to claim 1, characterized in that The solvent of the organic solution includes a polar organic solvent and a non-polar organic solvent; The polar organic solvent is selected from one or more of N,N-dimethylformamide, N-methylpyrrolidone and dimethyl sulfoxide; The non-polar organic solvent is selected from one or more of toluene, o-xylene, m-xylene and p-xylene.

7. The method according to claim 6, characterized in that The solvent of the organic solution is selected from a combination of N,N-dimethylformamide and toluene.

8. A catalytic composition for synthesizing bisphenol A diphenyl ether type bismaleimide, characterized in that: The invention comprises p-toluenesulfonic acid and sodium bisulfate, wherein the mass ratio of the p-toluenesulfonic acid to the sodium bisulfate is 10-15:

1.

9. Use of the catalytic composition according to claim 8 in the preparation of bisphenol A diphenyl ether type bismaleimide.

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