A method for producing p-phenylene-diphenyltriphthalate dianhydride

Abstract

The present invention provides a production method of p-phenylene-diphenyltrimethylol dianhydride, relates to the technical field of chemical synthesis, and comprises the following steps: S1, trimellitic anhydride chloride dissolution reaction, 1.0-3.0mol trimellitic anhydride chloride is added to reactor A, 25mol acetonitrile solvent is pumped in, trimellitic anhydride chloride is completely dissolved, the temperature of reactor A is set at 0-5°C, and continuous stirring is performed to ensure uniform dissolution, so that the solution is transparent and there is no solid suspension, and trimellitic anhydride chloride solution is obtained. The present invention selects acetonitrile as reaction solvent, and the product is easy to separate, and the separation energy consumption is small; At the same time, the whole process and the material transportation between the processes are all in a closed state, and the continuous operation of product generation is realized, which greatly reduces the production safety hidden danger, and is conducive to the stable production and quality control of the product.

Description

Technical Field

[0001] The invention relates to the technical field of chemical synthesis, in particular to a method for producing p-phenylene-diphenyltriphthalate dianhydride. Background Art

[0002] Polyimide (PI) is an organic polymer material with excellent performance and is widely used in aviation, aerospace, microelectronics, nanotechnology, liquid crystal, separation membranes, lasers and other fields. The product forms of polyimide include PI film, PI resin, photosensitive PI (PSPI), etc. Among them, PI film is the earliest commercialized, most mature and largest market capacity product form of polyimide.

[0003] CN115301287A uses a self-made catalyst (made by a one-pot process of formaldehyde, dialkylamine, and ionic resin, and the ionic resin is XR935J from Shanghai Weishener Company). The patent mixes the catalyst, trimellitic anhydride chloride, hydroquinone, and the first solvent under heating conditions to react and generate TAHQ. The reaction solution is then cooled to 5±2°C, washed with a second solvent, vacuum dried, and mixed with acetonitrile and dioxane mixed solvents and activated carbon is added for decolorization. Petroleum ether is then added, and the temperature is reduced for crystallization, filtration, and vacuum drying to obtain high-purity TAHQ. The first solvent includes acetonitrile, tetrahydrofuran, dichloromethane, acetone, toluene, dioxane, N,N-dimethylformamide, etc., and the second solvent includes toluene, tetrahydrofuran, methyl isobutyl ketone, heptane, etc. The reaction was protected by nitrogen, and trimellitic anhydride chloride was mixed by dripping for 3 hours. The ratio of hydroquinone, trimellitic anhydride chloride, and solvent was 1:2.1:25 (mol), the ratio of hydroquinone and catalyst was 1:0.9, the heating temperature was 30~80℃, the dropping temperature was 45~80±3℃, and the TAHQ yield was as high as 98%. The catalyst obtained after filtration can be regenerated by soaking in potassium carbonate solution. The patent mentions that using N,N-dimethylformamide as solvent and pyridine as catalyst, the solvent consumption is large, recycling is difficult, and N,N-dimethylformamide residues in the target product are not easy to remove.

[0004] Patent No. 10-36364 adopts the transesterification method to synthesize TAHQ, and uses the lower alkyl acid ester of hydroquinone and TMA (trimellitic anhydride) to carry out transesterification reaction to obtain TAHQ. The lower alkyl acid ester used in the transesterification reaction is hydroquinone diacetate, which is obtained by reacting hydroquinone with acetic anhydride under N2 protection and 140℃ for 3h. The transesterification reaction is carried out under the conditions of N2, 240~280℃ and stirring. The reaction can use silica-alumina catalyst, alkaline substances or no catalyst. The ratio of hydroquinone ester to TMA is 1:2.6~4.0 (mol), and the TAHQ yield can reach 98.5%. Using xylene, toluene, anisole as entrainer or continuously passing inert gases such as N2 and CO2 in the reaction is more conducive to the transesterification. The second half of the transesterification reaction can be gradually reduced to 500~20mmHg, which can be more effective. It is worth noting that the ratio of the amount of TMA added to the hydroquinone ester in the transesterification reaction cannot be less than 2.5, otherwise the crude product may solidify in the reaction system during the reaction and cannot be stirred, and it is difficult to separate from the reaction system, which is very risky. Even if it does not solidify, the by-product polymer condensation products produced by the reaction will increase; if the ratio exceeds 5.0, the purity of the crude product is low. In these two cases, the number of purification times needs to be increased in the subsequent refining process to achieve the target purity. The obtained TAHQ crude product is crushed into a particle size of 3 cm, and a mixed solvent of xylene and cyclohexanone is used. It is heated to 100~200℃ for dissolution, slowly cooled to below 40℃, filtered, and the residual solvent is dried and removed to obtain high-purity TAHQ. The mixing ratio of the mixed solvent used is 3 / 7~6 / 4, and the ratio of crude product to solvent is 1:2.5~4.

[0005] JP2010001250A reacts trimellitic anhydride chloride with hydroquinone to synthesize TAHQ in the presence of an alkaline substance, pyridine, and uses acetonitrile as a solvent to dissolve the hydrochloride generated by the reaction. The crude product is then washed and purified using DMF to which acetic anhydride is added. During the reaction, the acetonitrile solution of hydroquinone is added dropwise to the acetonitrile solution of trimellitic anhydride chloride, the dropping temperature is 15-25°C, and the temperature is controlled at 20-30°C after the dropping is completed, and the reaction is performed for 1-10 hours. The amount of acetonitrile used to dissolve hydroquinone is 9-10 times the mass of hydroquinone added, the amount of acetonitrile used for trimellitic anhydride chloride is 1.5-2 times, and the raw material ratio of hydroquinone, trimellitic anhydride chloride, and pyridine is 1:2-2.4:2-2.88. The pyridine hydrochloride generated by the reaction is dissolved in acetonitrile, and is taken away with the reaction solution after the reaction is completed. The solid left is the crude product of TAHQ. The crude product is dissolved in DMF solvent at 70-85°C, and the added mass of the solvent is 3.0-4.0 times that of the crude product, wherein about 1wt% of acetic anhydride is added as a dehydrating agent. After the crude TAHQ product is dissolved, it is cooled to 5-25°C to crystallize TAHQ, and washed with aliphatic ketones, ethers, aromatic hydrocarbon organic solvents such as acetone, methyl isobutyl ketone, tetrahydrofuran, benzene, toluene, etc. The washed TAHQ solid is dried under reduced pressure at 80°C for about 24 hours to obtain high-purity TAHQ.

[0006] In general, the existing disclosed technologies have the following problems: (1) The production process adopts an intermittent method, which poses a safety hazard when transferring materials between processes and makes it difficult to control the overall product quality; (2) The solvent consumption is large and it is difficult to recycle and reuse the solvent, and the residue in the product is difficult to remove. Summary of the invention

[0007] The purpose of the present invention is to solve the shortcomings in the prior art and to propose a method for producing p-phenylene-diphenyltriphenyl ester dianhydride.

[0008] In order to achieve the above object, the present invention adopts the following technical scheme: a method for producing p-phenylene-diphenylamine trimellitic acid dianhydride, the method for producing p-phenylene-diphenylamine trimellitic acid dianhydride comprises the following steps:

[0009] S1, dissolving reaction of trimellitic anhydride chloride, adding 1.0-3.0 mol of trimellitic anhydride chloride into reactor A, pumping in 25 mol of acetonitrile solvent to completely dissolve the trimellitic anhydride chloride, setting the temperature of reactor A at 0-5°C, and continuously stirring to ensure uniform dissolution, making the solution transparent and free of solid suspension, to obtain a trimellitic anhydride chloride solution;

[0010] S2, dissolving hydroquinone and pyridine, adding 1.0-3.0 mol of hydroquinone and 1.0-4.0 mol of pyridine into a storage tank, maintaining the ambient temperature not exceeding 20-25° C. to prevent the pyridine from volatilizing too quickly, pumping in 10-20 mol of acetonitrile solution, stirring evenly to completely dissolve the hydroquinone and pyridine, and obtaining an acetonitrile solution of hydroquinone and pyridine;

[0011] S3, reacting hydroquinone with trimellitic anhydride chloride, pumping the acetonitrile solution of hydroquinone and pyridine into reactor A at 20-25° C. to react with the trimellitic anhydride chloride solution, maintaining the temperature in reactor A at 0-5° C., using a mechanical stirrer to keep the solution uniformly mixed, the reaction time is 0.5-2 hours, after the reaction is completed, the solution presents a light yellow transparent state, and a preliminary reaction mixture is obtained, and the preliminary reaction mixture is electrolytically treated to obtain a slurry after electrolysis treatment;

[0012] S4, heating the reactor A to react, heating the slurry after the electrolysis treatment, gradually raising the temperature in the reactor A to 20-25° C., and maintaining the constant temperature for 8-12 hours. During the heating process, the solid product reacts and rearranges. After the reaction is completed, the solution is allowed to stand, the solid and liquid are separated, and the solvent is discharged through the drain valve at the bottom of the reactor A to obtain a solid crude product;

[0013] S5, washing the solid crude product, adding 3-8 mol of acetonitrile solvent to the solid crude product for washing, controlling the washing temperature at room temperature, stirring for 5-20 minutes, standing for 2 hours, draining the solvent, and then adding 20-25 mol of dioxane for washing to obtain a washing liquid C;

[0014] S6, supercritical carbon dioxide dissolution, adding the washing liquid C into the reactor B, pumping the carbon dioxide solution into the reactor B, controlling the temperature of the carbon dioxide solution at the supercritical point, and controlling the pressure at above 7.4 MPa, so that the carbon dioxide solution is in a supercritical state;

[0015] S601, supercritical fluid recrystallization, maintaining the temperature and pressure of reactor B, performing supercritical fluid recrystallization operation, and promoting crystal precipitation of the product in the solution by controlling the carbon dioxide flow rate to 2 L / min, to obtain a supercritical recrystallization slurry;

[0016] S602, pressure reduction, separation and filtration, for the supercritical recrystallization slurry, the pressure of the reactor B is gradually reduced to normal pressure by gradually reducing the pressure, so that the supercritical carbon dioxide is restored to a gaseous state and discharged from the reactor B, and the discharged slurry is vacuum filtered to separate the solid product to obtain p-phenylene-diphenyltriphthalate dianhydride.

[0017] Preferably, in step S5, the room temperature ranges from 20 to 25°C.

[0018] Preferably, in step S3, the molar ratio of trimellitic anhydride chloride, hydroquinone and pyridine is 1:2:2.

[0019] Preferably, in step S1, the dissolution process lasts for 30 minutes.

[0020] Preferably, in step S3, the electrolytic treatment comprises the following steps:

[0021] S301, installation of an electrochemical reaction device, installing an electrochemical reaction device in reactor A, the electrochemical reaction device comprising two titanium electrodes, the anode and the cathode are respectively inserted into the reaction solution, the electrode spacing is set to 2 cm, a DC power supply is connected, the current intensity is set to 1.5 A, the voltage is controlled within 10 V, and the conductivity sensor equipped inside the reactor monitors the conductivity of the solution in real time;

[0022] S302, electrochemical reaction process, applying current to the preliminary reaction mixture for electrochemical reaction, controlling the potential at 3V-4V to ensure chemical bond breaking and rearrangement, optimizing the potential by regularly detecting the current change during the reaction to ensure the efficiency of the electrochemical reaction, the reaction time is 1 hour, when the current change trend tends to be stable, turn off the power supply to obtain a mixture after the electrochemical reaction;

[0023] S303, electrolyte recovery, the mixture after the electrochemical reaction is separated from the electrolyte solution and the solid crude product by a vacuum filtration device, and the separated solution is filtered and recovered by an electrolyte recovery system for subsequent reactions.

[0024] 1. Compared with the prior art, the present invention uses acetonitrile as the reaction solvent, the product is easy to separate, and the separation energy consumption is small; at the same time, the whole process and the material transportation between the processes are all in a closed state, and the continuous operation of product generation is realized, which greatly reduces the hidden dangers of production safety and is conducive to the stable production and quality control of the product.

[0025] 2. Compared with the prior art, in the present invention, the electrolytic treatment brings a high degree of controllability of intermolecular bonding during the reaction process by precisely controlling the current and potential. By directly acting on the reactive active sites, the reaction process is accelerated, while reducing the dependence on high temperature or catalysts. The electrochemical reaction achieves higher reaction selectivity and product generation rate while maintaining low energy consumption, reduces the generation of by-products, and ensures a cleaner reaction environment. The electrolyte recovery system effectively reduces the consumption of production resources, enables electrochemical materials to be reused, and improves the economic and environmental benefits of production. The supercritical carbon dioxide recrystallization scheme further optimizes the product purity. By controlling the flow rate and pressure, the crystal particles are uniformly precipitated, avoiding the pollution problems caused by traditional organic solvents. The operation of gradually reducing the pressure to recover supercritical carbon dioxide enables efficient recycling of solvents and improves the overall sustainability of the process. The unique properties of supercritical fluids make the recrystallization process more efficient, ensure the high purity and particle size consistency of the target product, and optimize the performance of the final product.

[0026] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description, claims, and drawings.

[0027] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 The present invention provides a preparation step diagram of a preparation method for producing p-phenylene-diphenyltriphthalate dianhydride. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] See also Figure 1Embodiment 1, a method for producing p-phenylene-diphenyltrimethylol dianhydride, comprising the following steps:

[0032] S1, dissolving reaction of trimellitic anhydride chloride, adding 3.0 mol of trimellitic anhydride chloride into reactor A, pumping in 25 mol of acetonitrile solvent to completely dissolve the trimellitic anhydride chloride, setting the temperature of reactor A at 5°C, and continuously stirring to ensure uniform dissolution, making the solution transparent and free of solid suspension, to obtain a trimellitic anhydride chloride solution;

[0033] S2, dissolving hydroquinone and pyridine, adding 3.0 mol of hydroquinone and 4.0 mol of pyridine into a storage tank, maintaining the ambient temperature not exceeding 20°C to prevent pyridine from volatilizing too quickly, pumping in 20 mol of acetonitrile solution, stirring evenly to completely dissolve the hydroquinone and pyridine, and obtaining an acetonitrile solution of hydroquinone and pyridine;

[0034] S3, reacting hydroquinone with trimellitic anhydride chloride, pumping the acetonitrile solution of hydroquinone and pyridine into reactor A at 25°C to react with the trimellitic anhydride chloride solution, maintaining the temperature in reactor A at 3°C, using a mechanical stirrer to keep the solution uniformly mixed, the reaction time is 2 hours, after the reaction is completed, the solution is in a light yellow transparent state, and a preliminary reaction mixture is obtained, and the preliminary reaction mixture is electrolytically treated to obtain a slurry after electrolysis treatment;

[0035] The electrolytic treatment is specifically, transferring the preliminary reaction mixture to an electrochemical cell, wherein the electrode material used in the electrochemical cell is platinum or graphite, the current range is set to 1.0 A, the voltage is controlled at 10 volts, and the electrochemical reaction time is set to 3 hours;

[0036] S4, heating the reactor A to react, heating the slurry after the electrolysis treatment, gradually raising the temperature in the reactor A to 22° C. and maintaining the constant temperature for 12 hours. During the heating process, the solid product reacts and rearranges. After the reaction is completed, the solution is allowed to stand, the solid and liquid are separated, and the solvent is discharged through the drain valve at the bottom of the reactor A to obtain a solid crude product;

[0037] S5, washing the solid crude product, adding 8 mol of acetonitrile solvent to the solid crude product for washing, controlling the washing temperature at room temperature, stirring for 20 minutes, standing for 2 hours, draining the solvent, and then adding 25 mol of dioxane for washing to obtain a washing liquid C;

[0038] S6, supercritical carbon dioxide dissolution, adding the washing liquid C into the reactor B, pumping the carbon dioxide solution into the reactor B, controlling the temperature of the carbon dioxide solution at the supercritical point, and controlling the pressure at above 7.4 MPa, so that the carbon dioxide solution is in a supercritical state;

[0039] S601, supercritical fluid recrystallization, maintaining the temperature and pressure of reactor B, performing supercritical fluid recrystallization operation, and promoting crystal precipitation of the product in the solution by controlling the carbon dioxide flow rate to 2 L / min, to obtain a supercritical recrystallization slurry;

[0040] S602, pressure reduction, separation and filtration. The supercritical recrystallization slurry is subjected to a stepwise pressure reduction method to gradually reduce the pressure of the reactor B to normal pressure, so that the supercritical carbon dioxide is restored to a gaseous state and discharged from the reactor B. The discharged slurry is vacuum filtered to separate the solid product to obtain p-phenylene-diphenyltriphenylene dianhydride, which is a white product with a yield of 84.6% and a purity of 99.9%.

[0041] In this embodiment, in step S5, the room temperature range is 25°C.

[0042] In this embodiment, in step S3, the molar ratio of trimellitic anhydride chloride, hydroquinone and pyridine is 1:2:2.

[0043] In this embodiment, in step S1, the dissolution process lasts for 30 minutes.

[0044] In this embodiment, in step S3, the electrolytic treatment includes the following steps:

[0045] S301, installation of an electrochemical reaction device, installing an electrochemical reaction device in reactor A, the electrochemical reaction device comprising two titanium electrodes, the anode and the cathode are respectively inserted into the reaction solution, the electrode spacing is set to 2 cm, a DC power supply is connected, the current intensity is set to 1.5 A, the voltage is controlled within 10 V, and the conductivity sensor equipped inside the reactor monitors the conductivity of the solution in real time;

[0046] S302, electrochemical reaction process, applying current to the preliminary reaction mixture for electrochemical reaction, controlling the potential at 4V to ensure chemical bond breaking and rearrangement, optimizing the potential by regularly detecting the current change during the reaction to ensure the efficiency of the electrochemical reaction, the reaction time is 1 hour, when the current change trend tends to be stable, turning off the power supply to obtain a mixture after the electrochemical reaction;

[0047] S303, electrolyte recovery, the mixture after the electrochemical reaction is separated from the electrolyte solution and the solid crude product by a vacuum filtration device, and the separated solution is filtered and recovered by an electrolyte recovery system for subsequent reactions.

[0048] See also Figure 1 Embodiment 2, a method for producing p-phenylene-diphenyltrimethylol dianhydride, comprising the following steps:

[0049] S1, dissolving reaction of trimellitic anhydride chloride, adding 2.0 mol of trimellitic anhydride chloride into reactor A, pumping in 25 mol of acetonitrile solvent to completely dissolve the trimellitic anhydride chloride, setting the temperature of reactor A at 4°C, and continuously stirring to ensure uniform dissolution, making the solution transparent and free of solid suspension, to obtain a trimellitic anhydride chloride solution;

[0050] S2, dissolving hydroquinone and pyridine, adding 2.0 mol of hydroquinone and 4.0 mol of pyridine into a storage tank, maintaining the ambient temperature not exceeding 20°C to prevent pyridine from volatilizing too quickly, pumping in 20 mol of acetonitrile solution, stirring evenly to completely dissolve the hydroquinone and pyridine, and obtaining an acetonitrile solution of hydroquinone and pyridine;

[0051] S3, reacting hydroquinone with trimellitic anhydride chloride, pumping the acetonitrile solution of hydroquinone and pyridine into reactor A at 25°C to react with the trimellitic anhydride chloride solution, maintaining the temperature in reactor A at 3°C, using a mechanical stirrer to keep the solution uniformly mixed, the reaction time is 2 hours, after the reaction is completed, the solution is in a light yellow transparent state, and a preliminary reaction mixture is obtained, and the preliminary reaction mixture is electrolytically treated to obtain a slurry after electrolysis treatment;

[0052] The electrolytic treatment is specifically, transferring the preliminary reaction mixture to an electrochemical cell, wherein the electrode material used in the electrochemical cell is platinum or graphite, the current range is set to 1.0 A, the voltage is controlled at 10 volts, and the electrochemical reaction time is set to 2.5 hours;

[0053] S4, heating the reactor A to react, heating the slurry after the electrolysis treatment, gradually raising the temperature in the reactor A to 25° C. and maintaining the constant temperature for 12 hours. During the heating process, the solid product reacts and rearranges. After the reaction is completed, the solution is allowed to stand, the solid and liquid are separated, and the solvent is discharged through the drain valve at the bottom of the reactor A to obtain a solid crude product;

[0054] S5, washing the solid crude product, adding 8 mol of acetonitrile solvent to the solid crude product for washing, controlling the washing temperature at room temperature, stirring for 20 minutes, standing for 2 hours, draining the solvent, and then adding 25 mol of dioxane for washing to obtain a washing liquid C;

[0055] S6, supercritical carbon dioxide dissolution, adding the washing liquid C into the reactor B, pumping the carbon dioxide solution into the reactor B, controlling the temperature of the carbon dioxide solution at the supercritical point, and controlling the pressure at above 7.4 MPa, so that the carbon dioxide solution is in a supercritical state;

[0056] S601, supercritical fluid recrystallization, maintaining the temperature and pressure of reactor B, performing supercritical fluid recrystallization operation, and promoting crystal precipitation of the product in the solution by controlling the carbon dioxide flow rate to 2 L / min, to obtain a supercritical recrystallization slurry;

[0057] S602, pressure reduction, separation and filtration. The supercritical recrystallization slurry is subjected to a stepwise pressure reduction method to gradually reduce the pressure of the reactor B to normal pressure, so that the supercritical carbon dioxide is restored to a gaseous state and discharged from the reactor B. The discharged slurry is vacuum filtered to separate the solid product to obtain p-phenylene-diphenyltriphenylene dianhydride, which is a white product with a yield of 81.2% and a purity of 99.9%.

[0058] In this embodiment, in step S5, the room temperature range is 25°C.

[0059] In this embodiment, in step S3, the molar ratio of trimellitic anhydride chloride, hydroquinone and pyridine is 1:2:2.

[0060] In this embodiment, in step S1, the dissolution process lasts for 30 minutes.

[0061] In this embodiment, in step S3, the electrolytic treatment includes the following steps:

[0062] S301, installation of an electrochemical reaction device, installing an electrochemical reaction device in reactor A, the electrochemical reaction device comprising two titanium electrodes, the anode and the cathode are respectively inserted into the reaction solution, the electrode spacing is set to 2 cm, a DC power supply is connected, the current intensity is set to 1.5 A, the voltage is controlled within 10 V, and the conductivity sensor equipped inside the reactor monitors the conductivity of the solution in real time;

[0063] S302, electrochemical reaction process, applying current to the preliminary reaction mixture for electrochemical reaction, controlling the potential at 4V to ensure chemical bond breaking and rearrangement, optimizing the potential by regularly detecting the current change during the reaction to ensure the efficiency of the electrochemical reaction, the reaction time is 1 hour, when the current change trend tends to be stable, turning off the power supply to obtain a mixture after the electrochemical reaction;

[0064] S303, electrolyte recovery, the mixture after the electrochemical reaction is separated from the electrolyte solution and the solid crude product by a vacuum filtration device, and the separated solution is filtered and recovered by an electrolyte recovery system for subsequent reactions.

[0065] Comparative Example 1: Under nitrogen protection, trimellitic anhydride chloride (2.0 mol) and tetrahydrofuran (25 mol) were added to the reactor A, and a solution of hydroquinone (1.0 mol) and pyridine (2.0 mol) in acetonitrile (15 mol) was added dropwise with a syringe pump, and the temperature was controlled at 0±2°C. The addition was completed in 2.5 hours, and the reaction was kept warm for 12 hours, and then the mixture was allowed to stand for 2 hours, and the reaction solvent was discharged. The solid material was added to acetonitrile (5 mol), stirred at room temperature for 0.5 hours, and then allowed to stand for 2 hours, and the washing solvent was discharged. Dioxane (5 mol) was added and stirred at 80°C for 2 hours, and a white powder product was obtained by suction filtration while hot, and dried in a vacuum drying oven at 220°C for 12 hours to obtain a white product with a yield of 74.8% and a purity of 99.3%.

[0066] It can be seen from the above examples that the yield of the product obtained in Example 1 is 84.6% and the purity is 99.9%, which are higher than the yield and purity of Comparative Example 1.

[0067] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for producing p-phenylene-diphenyltriphthalate dianhydride, characterized in that: The production method of the p-phenylene-diphenyltrimethylol dianhydride comprises the following steps: S1, dissolving reaction of trimellitic anhydride chloride, adding 1.0-3.0 mol of trimellitic anhydride chloride into reactor A, pumping in 25 mol of acetonitrile solvent to completely dissolve the trimellitic anhydride chloride, setting the temperature of reactor A at 0-5°C, and continuously stirring to ensure uniform dissolution, making the solution transparent and free of solid suspension, to obtain a trimellitic anhydride chloride solution; S2, dissolving hydroquinone and pyridine, adding 1.0-3.0 mol of hydroquinone and 1.0-4.0 mol of pyridine into a storage tank, maintaining the ambient temperature not exceeding 20-25° C. to prevent the pyridine from volatilizing too quickly, pumping in 10-20 mol of acetonitrile solution, stirring evenly to completely dissolve the hydroquinone and pyridine, and obtaining an acetonitrile solution of hydroquinone and pyridine; S3, reacting hydroquinone with trimellitic anhydride chloride, pumping the acetonitrile solution of hydroquinone and pyridine into reactor A at 20-25° C. to react with the trimellitic anhydride chloride solution, maintaining the temperature in reactor A at 0-5° C., using a mechanical stirrer to keep the solution uniformly mixed, the reaction time is 0.5-2 hours, after the reaction is completed, the solution presents a light yellow transparent state, and a preliminary reaction mixture is obtained, and the preliminary reaction mixture is electrolytically treated to obtain a slurry after electrolysis treatment; The electrolytic treatment comprises the following steps: S301, installation of an electrochemical reaction device, installing an electrochemical reaction device in reactor A, the electrochemical reaction device comprising two titanium electrodes, the anode and the cathode are respectively inserted into the reaction solution, the electrode spacing is set to 2 cm, a DC power supply is connected, the current intensity is set to 1.5 A, the voltage is controlled within 10 V, and the conductivity sensor equipped inside the reactor monitors the conductivity of the solution in real time; S302, electrochemical reaction process, applying current to the preliminary reaction mixture for electrochemical reaction, controlling the potential at 3V-4V to ensure chemical bond breaking and rearrangement, optimizing the potential by regularly detecting the current change during the reaction to ensure the efficiency of the electrochemical reaction, the reaction time is 1 hour, when the current change trend tends to be stable, turn off the power supply to obtain a mixture after the electrochemical reaction; S303, electrolyte recovery, separating the electrolyte solution and the solid crude product from the mixture after the electrochemical reaction by a vacuum filtration device, and filtering and recovering the separated solution through an electrolyte recovery system for subsequent reactions; S4, heating the reactor A to react, heating the slurry after the electrolysis treatment, gradually raising the temperature in the reactor A to 20-25° C., and maintaining the constant temperature for 8-12 hours. During the heating process, the solid product reacts and rearranges. After the reaction is completed, the solution is allowed to stand, the solid and liquid are separated, and the solvent is discharged through the drain valve at the bottom of the reactor A to obtain a solid crude product; S5, washing the solid crude product, adding 3-8 mol of acetonitrile solvent to the solid crude product for washing, controlling the washing temperature at room temperature, stirring for 5-20 minutes, standing for 2 hours, draining the solvent, and then adding 20-25 mol of dioxane for washing to obtain a washing liquid C; S6, supercritical carbon dioxide dissolution, adding the washing liquid C into the reactor B, pumping the carbon dioxide solution into the reactor B, controlling the temperature of the carbon dioxide solution at the supercritical point, and controlling the pressure at above 7.4 MPa, so that the carbon dioxide solution is in a supercritical state; S601, supercritical fluid recrystallization, maintaining the temperature and pressure of reactor B, performing supercritical fluid recrystallization operation, and promoting crystal precipitation of the product in the solution by controlling the carbon dioxide flow rate to 2 L / min, to obtain a supercritical recrystallization slurry; S602, pressure reduction, separation and filtration, for the supercritical recrystallization slurry, the pressure of the reactor B is gradually reduced to normal pressure by gradually reducing the pressure, so that the supercritical carbon dioxide is restored to a gaseous state and discharged from the reactor B, and the discharged slurry is vacuum filtered to separate the solid product to obtain p-phenylene-diphenyltriphthalate dianhydride.

2. The method for producing p-phenylene-diphenyltriphthalate dianhydride according to claim 1, wherein: In step S5, the room temperature ranges from 20°C to 25°C.

3. The method for producing p-phenylene-diphenyltriphthalate dianhydride according to claim 1, wherein: In step S3, the molar ratio of trimellitic anhydride chloride, hydroquinone and pyridine is 1:2:

2.

4. The method for producing p-phenylene-diphenyltriphthalate dianhydride according to claim 1, wherein: In step S1, the dissolution process lasted for 30 minutes.

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