A method for synthesizing a high content N-phenylmaleimide product
By using amide and cyclization reactions with a supported aniline phosphate catalyst, combined with filtration, water washing, and vacuum distillation steps, the problems of high energy consumption and large amounts of wastewater in existing technologies have been solved, achieving the synthesis of high-purity, high-yield N-phenylmaleimide.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- LIUYANG LIDE MATERIAL SCI & TECH CO LTD
- Filing Date
- 2026-05-12
- Publication Date
- 2026-06-12
AI Technical Summary
The existing N-phenylmaleimide synthesis process suffers from high energy consumption, high production costs, and the generation of large amounts of acidic wastewater.
Using supported aniline phosphate as a catalyst, high-content N-phenylmaleimide is synthesized through amide reaction, cyclization reaction, filtration, water washing, neutralization and vacuum distillation steps, avoiding the use of acetic anhydride and reducing the generation of acidic wastewater.
The process was simplified, production costs were reduced, product purity and yield were improved, and efficient N-PMI synthesis was achieved.
Abstract
Description
Technical Field
[0001] This invention relates to the field of organic synthesis technology, and particularly to a high-content N Synthetic method for phenylmaleimide products. Background Technology
[0002] N -Phenylanimide (abbreviated as ) N -PMI is a heterocyclic compound with a rigid planar five-membered ring structure. It appears as pale yellow needle-like crystals and has the molecular formula C2. 10 H7NO2, with a molecular weight of 173.17, a melting point of 88–90℃, and a boiling point of 162–163℃, is readily soluble in organic solvents such as ethanol, acetone, and toluene. It is also soluble in hot cyclohexane and benzene, but sparingly soluble in water and petroleum ether. It is chemically stable but readily combines with oxides.
[0003] N -PMI, as a unique organic synthesis intermediate and polymer modifier, has demonstrated irreplaceable application value in many fields, including polymer material modification (copolymerization or blending with thermoplastic resins such as ABS, PVC, and PMMA), functional chemicals (intermediates for pesticides and agrochemicals, pharmaceuticals and fine chemicals, electronic materials, etc.), coatings and adhesives, thanks to its excellent heat resistance, reactivity and functionality.
[0004] From a market demand perspective, the rapid development of high-end manufacturing industries such as new energy vehicles, 5G electronics, and high-end home appliances has led to an explosive growth in demand for heat-resistant and high-strength polymer materials. Simultaneously, the increasing demand for antifouling coatings and high-strength adhesives in fields such as marine engineering and high-end equipment has further opened up new avenues for demand. N - Market potential for PMI.
[0005] In existing synthesis techniques, patent CN 114349677 A uses maleic anhydride and aniline as raw materials, p-toluenesulfonic acid monohydrate as a catalyst, and toluene and xylene as solvents. An aprotic solvent is added to the synthesis reaction to obtain the desired product. N -PMI product. This process generates a large amount of acidic wastewater during production, and product purification requires vacuum distillation at high temperatures to remove the product. This process places stringent requirements on system vacuum and temperature control, resulting in high overall energy consumption. Patent application US5136052A discloses a method for preparing PMI products using maleic anhydride and aniline as raw materials, p-toluenesulfonic acid as a catalyst, 4-tert-butylphenol as a polymerization inhibitor, and xylene as a solvent, through steps including high-temperature dehydration cyclization, cooling filtration, and vacuum distillation of the filtrate. N-The process of PMI products. However, this method generates a large amount of production residue in the vacuum distillation purification step, and in order to effectively distill off the target product for purification, a relatively high distillation temperature needs to be controlled, resulting in high energy consumption in the production process, increasing production costs and energy consumption pressure. Cui Kai et al. synthesized a product using sodium acetate and triethylamine as co-catalysts, acetic anhydride as a dehydrating agent, acetone as a solvent, and maleic anhydride and aniline as raw materials. N -Phenylanimide ( N -PMI). This process can obtain the target product at a lower temperature and has the advantage of lower energy consumption. However, the reaction requires a large amount of acetic anhydride, which not only increases production costs, but also generates a large amount of acidic wastewater in the post-treatment process, resulting in environmental and economic drawbacks. Summary of the Invention
[0006] The purpose of this invention is to provide a high content N The synthesis method for PMI products improves upon existing processes by using supported aniline phosphate as a catalyst. High-content PMI is obtained through steps including amide reaction, cyclization reaction, filtration, water washing, neutralization, vacuum distillation, and product discharge. N -Phenylated maleimide products.
[0007] The high content N The method for synthesizing phenylmaleimide products includes the following steps: (1) Amide reaction: maleic anhydride and solvent are added to a synthesis reaction flask equipped with a condenser and a water separator, heated and stirred, and a fixed amount of aniline is added under controlled temperature and the reaction is maintained at the temperature; (2) Cyclic reaction: After the amide reaction is completed, add the polymerization inhibitor and supported aniline phosphate to the reaction flask, heat to reflux, and carry out reflux water separation. After the water separation process is completed, cool the reaction system to room temperature. (3) Filtration: Transfer the reaction solution to a filtration device to separate the solid from the filtrate. The obtained solid is the catalyst. The filtrate is transferred to a reaction flask. The obtained catalyst can be used directly in the next batch of reaction. (4) Water washing and neutralization: Add water to the reaction solution for one water washing, then use alkaline solution to adjust the pH to neutral, let it stand and separate the aqueous phase; (5) Vacuum distillation: Control the vacuum level and perform vacuum distillation until no fractions are distilled off; (6) Discharge: Discharge and crush the material.
[0008] In step (1), the molar ratio of aniline to maleic anhydride is 1:(1.05-1.30), preferably 1:1.1.
[0009] The reaction temperature in step (1) is 25-45℃, preferably 40-45℃.
[0010] The solvent in step (1) is toluene, xylene, N , N One or more of dimethylformamides, preferably toluene.
[0011] In step (2), the polymerization inhibitor is one or more of hydroquinone, p-hydroxyanisole, ferric chloride, and phenothiazine, with hydroquinone being preferred.
[0012] In step (1), the mass of the solvent is 11-15 times the mass of aniline, preferably 14 times.
[0013] The filtration temperature in step (3) is 20-30℃.
[0014] The alkaline substance used to adjust pH in step (4) is one or more of sodium carbonate, sodium bicarbonate, and triethylamine, preferably sodium bicarbonate.
[0015] Compared to the azeotropic dehydration process used in existing synthesis technologies, the process flow of this invention is simpler, requires no secondary purification of the product after the reaction, and the catalyst can be recovered and reused multiple times. Compared to methods using acid anhydride dehydration, the synthesis process of this invention does not use acetic anhydride, avoiding the problem of generating large amounts of acidic wastewater in subsequent treatment, thereby effectively reducing production costs. This method features low process cost, high product purity, and high yield, giving it stronger market competitiveness. Detailed Implementation Example 1
[0016] To a 500 mL four-necked flask equipped with a stirrer, a condenser with a water separator, and a thermometer, 200.0 g of toluene, 100.0 g of silica gel, and 37.8 g of phosphoric acid were added sequentially. Stirring was started, and 18.0 g of aniline was added dropwise while maintaining the temperature between 25 and 50 °C. After the addition was complete, the mixture was stirred and kept at the same temperature range for 1 h, followed by vacuum filtration. The resulting solid was dried at 80 °C for 8 h to obtain supported aniline phosphate. Example 2
[0017] To a 500 mL four-necked flask equipped with a stirrer, a condenser with a water separator, and a thermometer, add 280.0 g of xylene and 23.2 g of maleic anhydride sequentially, and start stirring. Add 20.0 g of aniline dropwise at a controlled temperature of 35-45 °C. After the addition is complete, maintain the reaction temperature for 2 hours. Then add 0.2 g of hydroquinone and supported aniline phosphate, and heat to reflux. Maintain reflux and separate the water using a water separator until no water is collected. Cool the reaction solution to 20-30 °C and filter. Wash the filter cake with a small amount of toluene. The resulting filter cake is a catalyst and can be directly reused in the next batch of reaction. Combine the mother liquors, wash with water, neutralize, and perform vacuum distillation at 0.09 MPa and 90 °C to recover the solvent until no fraction is distilled off. A yellow liquid is obtained, poured off, cooled to room temperature, and pulverized. 30.2 g of yellow powder was obtained, with a yield of 80.90%, and the content was determined to be 99.4% by high performance liquid chromatography. Example 3
[0018] To a 500 mL four-necked flask equipped with a stirrer, a condenser with a water separator, and a thermometer, add 118.0 g of toluene, ... N , N 12.0 g of dimethylformamide and 11.6 g of maleic anhydride were added, and stirring was started. 10.0 g of aniline was added dropwise at a controlled temperature of 35-45 °C. After addition, the reaction was maintained at this temperature for 2 hours. Then, 0.1 g of hydroquinone and supported aniline phosphate were added, and the temperature was raised to reflux. The mixture was kept under reflux, and water was separated using a separator until no water was collected. The reaction solution was cooled to 20-30 °C and filtered. The filter cake was washed with a small amount of toluene. The resulting filter cake served as a catalyst and could be directly reused in the next batch of reaction. The mother liquors were combined, washed with water, neutralized, and subjected to vacuum distillation at 0.09 MPa and 90 °C to recover the solvent until no fraction was distilled off. A yellow liquid was obtained, poured off, cooled to room temperature, and pulverized. 16.5 g of yellow powder was obtained, with a yield of 88.5%, and the content was determined to be 99.1% by high-performance liquid chromatography. Example 4
[0019] To a 500 mL four-necked flask equipped with a stirrer, a condenser with a water separator, and a thermometer, add 280.0 g of toluene and 23.2 g of maleic anhydride sequentially, and start stirring. Add 20.0 g of aniline dropwise at a controlled temperature of 35-45 °C. After the addition is complete, maintain the reaction temperature for 2 hours. Then add 0.2 g of hydroquinone and supported aniline phosphate, and heat to reflux. Maintain reflux and separate the water using a water separator until no water is collected. Cool the reaction solution to 20-30 °C and filter. Wash the filter cake with a small amount of toluene. The resulting filter cake is a catalyst and can be directly reused in the next batch of reaction. Combine the mother liquors, wash with water, neutralize, and perform vacuum distillation at 0.09 MPa and 90 °C to recover the solvent until no fraction is distilled off. A yellow liquid is obtained, poured off, and cooled to room temperature. Grind into powder. 34.1 g of yellow powder was obtained, with a yield of 91.35%, and the content was determined to be 99.2% by high performance liquid chromatography. Example 5
[0020] To a 500 mL four-necked flask equipped with a stirrer, a condenser with a water separator, and a thermometer, add 220.0 g of toluene and 23.2 g of maleic anhydride sequentially, and start stirring. Add 20.0 g of aniline dropwise at a controlled temperature of 35-45 °C. After the addition is complete, maintain the reaction temperature for 2 hours. Then add 0.2 g of hydroquinone and supported aniline phosphate, and heat to reflux. Maintain reflux and separate the water using a water separator until no water is collected. Cool the reaction solution to 20-30 °C and filter. Wash the filter cake with a small amount of toluene. The resulting filter cake is a catalyst and can be directly reused in the next batch of reaction. Combine the mother liquors, wash with water, neutralize, and perform vacuum distillation at 0.09 MPa and 90 °C to recover the solvent until no fraction is distilled off. A yellow liquid is obtained, poured off, cooled to room temperature, and pulverized. 33.6 g of yellow powder was obtained, with a yield of 90.32%, and the content was determined to be 99.3% by high performance liquid chromatography. Example 6
[0021] To a 500 mL four-necked flask equipped with a stirrer, a condenser with a water separator, and a thermometer, add 300.0 g of toluene and 23.2 g of maleic anhydride sequentially, and start stirring. Add 20.0 g of aniline dropwise at a controlled temperature of 35-45 °C. After the addition is complete, maintain the reaction temperature for 2 hours. Then add 0.2 g of hydroquinone and supported aniline phosphate, and heat to reflux. Maintain reflux and separate the water using a water separator until no water is collected. Cool the reaction solution to 20-30 °C and filter. Wash the filter cake with a small amount of toluene. The resulting filter cake is a catalyst and can be directly reused in the next batch of reaction. Combine the mother liquors, wash with water, neutralize, and perform vacuum distillation at 0.09 MPa and 90 °C to recover the solvent until no fraction is distilled off. A yellow liquid is obtained, poured off, cooled to room temperature, and pulverized. 33.1 g of yellow powder was obtained, with a yield of 88.98%, and the content was determined to be 99.2% by high performance liquid chromatography. Example 7
[0022] To a 500 mL four-necked flask equipped with a stirrer, a condenser with a water separator, and a thermometer, 240.0 g of toluene and 23.2 g of maleic anhydride were added sequentially, and stirring was started. 20.0 g of aniline was added dropwise at a controlled temperature of 35-45 °C. After the addition was complete, the reaction was maintained at this temperature for 2 hours. Subsequently, 0.2 g of ferric chloride and supported aniline phosphate were added, and the temperature was raised to reflux. The mixture was kept under reflux, and water was separated using a water separator until no water was collected. The reaction solution was cooled to 20-30 °C and filtered. The filter cake was washed with a small amount of toluene. The resulting filter cake served as a catalyst and could be directly reused in the next batch of reaction. The mother liquors were combined, washed with water, neutralized, and subjected to vacuum distillation at 0.09 MPa and 90 °C to recover the solvent until no fraction was distilled off. A yellow liquid was obtained, which was poured off, cooled to room temperature, and pulverized. 28.5 g of a yellow powder was obtained, with a yield of 79.4%, and the content was determined to be 99.2% by high-performance liquid chromatography. Example 8
[0023] To a 500 mL four-necked flask equipped with a stirrer, a condenser with a water separator, and a thermometer, 150.0 g of toluene and 11.6 g of maleic anhydride were added sequentially, and stirring was started. 10.0 g of aniline was added dropwise at a controlled temperature of 35-45 °C. After the addition was complete, the reaction was maintained at this temperature for 2 hours. Subsequently, 0.1 g of phenothiazine and supported aniline phosphate were added, and the temperature was raised to reflux. The mixture was kept under reflux, and water was separated using a water separator until no water was collected. The reaction solution was cooled to 20-30 °C and filtered. The filter cake was washed with a small amount of toluene. The resulting filter cake served as a catalyst and could be directly reused in the next batch of reaction. The mother liquors were combined, washed with water, neutralized, and subjected to vacuum distillation at 0.09 MPa and 90 °C to recover the solvent until no fraction was distilled off. A yellow liquid was obtained, which was poured off, cooled to room temperature, and pulverized. 16.2 g of a yellow powder was obtained, with a yield of 86.9%, and the content was determined to be 99.4% by high-performance liquid chromatography.
[0024] The embodiments described above are only some embodiments of the present invention. The detailed description of the embodiments should not be construed as limiting the present invention. The scope of protection of the present invention is determined by the appended claims. Various equivalent substitutions, modifications, or improvements made by those skilled in the art to the technical solutions and their implementation methods without departing from the spirit and scope of the present invention fall within the scope of the claims of the present invention and their equivalents.
Claims
1. A high-content N The method for synthesizing phenylmaleimide products is characterized by... Includes the following steps: (1) Amide reaction: maleic anhydride and solvent are added to a synthesis reaction flask equipped with a condenser and a water separator, heated and stirred, and a fixed amount of aniline is added under controlled temperature and the reaction is maintained at the temperature; (2) Cyclic reaction: After the amide reaction is completed, add the polymerization inhibitor and supported aniline phosphate to the reaction flask, heat to reflux, and carry out reflux water separation. After the water separation process is completed, cool the reaction system to room temperature. (3) Filtration: Transfer the reaction solution to a filtration device to separate the solid from the filtrate. The obtained solid is the catalyst. The filtrate is transferred to a reaction flask. The obtained catalyst can be used directly in the next batch of reaction. (4) Water washing and neutralization: Add water to the reaction solution for one water washing, then use alkaline solution to adjust the pH to neutral, let it stand and separate the aqueous phase; (5) Vacuum distillation: Control the vacuum level and perform vacuum distillation until no fractions are distilled off; (6) Discharge: Discharge and crush the material.
2. A high-content [material] according to claim 1 N The method for synthesizing phenylmaleimide products is characterized by... In step (1), the molar ratio of aniline to maleic anhydride is 1:(1.05-1.30).
3. A high-content [material] according to claim 1 N The method for synthesizing phenylmaleimide products is characterized by... The reaction temperature in step (1) is 25-45℃.
4. A high-content [material] according to claim 1 N The method for synthesizing phenylmaleimide products is characterized by... In step (1), the solvent is toluene, xylene, N,N One or more of dimethylformamides.
5. A high-content [material] according to claim 1 N The method for synthesizing phenylmaleimide products is characterized by... In step (2), the polymerization inhibitor is one or more of hydroquinone, p-hydroxyanisole, ferric chloride, and phenothiazine.
6. A high-content [material] according to claim 1 N The method for synthesizing phenylmaleimide products is characterized by... In step (1), the mass of the solvent is 11-15 times the mass of aniline.
7. A high-content [material] according to claim 1 N The method for synthesizing phenylmaleimide products is characterized by... The filtration temperature in step (3) is 20-30℃.
8. A high-content [material] according to claim 1 N The method for synthesizing phenylmaleimide products is characterized by... The alkaline substance used to adjust pH in step (4) is one or more of sodium carbonate, sodium bicarbonate, and triethylamine.