Synthesis method of 1, 4-bis (4-aminophenoxy) benzene

Abstract

The invention relates to a synthesis method of 1, 4-bis (4-aminophenoxy) benzene, and relates to the technical field of organic synthesis. The preparation method comprises the following steps: adding parachloronitrobenzene, potassium carbonate and hydroquinone into N, N-dimethylformamide and toluene, and reacting by using a water separation device; after the reaction is finished, filtering, and leaching a filter cake with ethyl acetate; adding the filter cake into water, stirring, filtering, and leaching the filter cake with ethanol; adding the filter cake into a reaction kettle, adding ethanol, pulping, filtering and drying to obtain 1, 4-bis (4-nitrophenoxy) benzene; the preparation method comprises the following steps: adding 1, 4-bis (4-nitrophenoxy) benzene, a palladium carbon catalyst and tetrahydrofuran into a high-pressure kettle for reaction to obtain crude 1, 4-bis (4-aminophenoxy) benzene; the crude 1, 4-bis (4-aminophenoxy) benzene is subjected to filtration, rotary evaporation, methanol pulping treatment, filtration and drying, and 1, 4-bis (4-aminophenoxy) benzene is obtained; the process is simple, and the yield and the purity of the 1, 4-bis (4-aminophenoxy) benzene are relatively high.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of organic synthesis, and particularly relates to a synthesis method of 1,4-bis(4-aminophenoxy)benzene. BACKGROUND

[0002] 1,4-bis(4-aminophenoxy)benzene as an important organic synthesis intermediate plays a key role in the synthesis of polyimides in the field of high-performance materials. Polyimides are widely used in aerospace, electronic information, automobile industry and other high-tech fields due to their excellent heat resistance, chemical corrosion resistance, good mechanical properties and electrical insulation properties. The synthesis method of 1,4-bis(4-aminophenoxy)benzene as one of the monomers for synthesizing polyimides directly affects the performance and production cost of polyimides.

[0003] Chinese patent CN117466758A provides a preparation method of 1,4-bis(4-aminophenoxy)benzene. 4-aminophenol and p-dibromobenzene are reacted in an organic solvent under the catalysis of a copper salt, a ligand and a base in a protective atmosphere to obtain 1,4-bis(4-aminophenoxy)benzene shown in formula I.

[0004] Chinese patent CN101157623B relates to a preparation method of 1,4-bis(4-aminophenoxy)benzene, which comprises the following steps: (1) p-phenylenediamine and 4-halogenated nitrobenzene are mixed in a molar ratio of 1.00:1.80-2.80, and then the mixture is subjected to water separation reaction by heating reflux in a salt forming agent, a strong polar aprotic and non-aqueous organic solvent system for 2-18 hours. After the reaction solution is concentrated, the reaction system is cooled, water is added, and the yellow-green solid product is precipitated, filtered and dried; (2) 1,4-bis(4-nitrophenoxy)benzene is reduced in a reduction system of ferric chloride / 20%-95% hydrazine hydrate, an alcohol solvent and activated carbon at 50-90 DEG C for 2-20 hours to obtain white 1,4-bis(4-aminophenoxy)benzene crystal product.

[0005] The 1,4-bis(4-aminophenoxy)benzene prepared by the above patents and prior art has complex process, and the purity and yield of the product need to be further improved. SUMMARY

[0006] In order to solve the above problems, the present application provides a synthesis method of 1,4-bis(4-aminophenoxy)benzene, which comprises the following steps in terms of mass fraction: S1: synthesis of 1,4-bis(4-nitrophenoxy)benzene Add 35-42 parts of p-chloronitrobenzene, 20-25 parts of potassium carbonate, and 5-10 parts of hydroquinone to a mixed solution of 170-200 parts of N,N-dimethylformamide and 80-100 parts of toluene, and react using a water separator. After the reaction is complete, cool the reaction solution to room temperature, filter, and wash the filter cake with ethyl acetate. Add the filter cake to a stirrer, add 200-300 parts of water, stir thoroughly, filter, and wash the filter cake with ethanol. Add the filter cake to a reaction vessel, add 170-200 parts of ethanol, heat to 60-70℃, and slurry for 20-30 minutes. Filter and dry to obtain 1,4-bis(4-nitrobenzoxy)benzene. S2: Synthesis of 1,4-bis(4-aminophenoxy)benzene 20-30 parts of 1,4-bis(4-nitrophenoxy)benzene, 0.1-0.6 parts of palladium on carbon catalyst, and 200-300 parts of tetrahydrofuran were added to a high-pressure reactor to react and obtain crude 1,4-bis(4-aminophenoxy)benzene. S3: Post-processing Reduce the temperature of the reactor to 50-55℃, filter to remove the catalyst; remove tetrahydrofuran by rotary evaporation of the filtrate, add 150-200 parts of methanol, and slurry for 20-30 minutes; filter and dry the filter cake; rotary evaporate the filtrate again, add 80-100 parts of methanol, and slurry for 20-30 minutes; filter and dry the filter cake; combine the two filter cakes to obtain 1,4-bis(4-aminophenoxy)benzene.

[0007] As a preferred embodiment of the present invention, the reaction temperature of the water separator in S1 is 130-140°C, the reaction time is 4-5 hours, and the reaction continues for another 40-60 minutes until no water flows out of the water separator.

[0008] As a preferred embodiment of the present invention, before the reaction in the S2 high-pressure reactor, the reactor is first purged with nitrogen twice, then purged with hydrogen twice, the reaction pressure is 2 MPa, the reaction temperature is 60-70℃, and the reaction time is 3-5 h.

[0009] As a preferred embodiment of the present invention, the preparation method of the palladium-on-carbon catalyst is as follows, according to parts by mass: T1: Add 100-120 parts of activated carbon to 600-900 parts of hydrogen peroxide solution with a mass percentage of 5-8%, stir at 50-60℃ for 2-3 hours, filter, wash with deionized water, and vacuum dry at 80-100℃ for 1-4 hours to obtain hydroxylated activated carbon. T2: 60-80 parts of hydroxylated activated carbon is added to 400-600 parts of methanol, then 12-22 parts of gamma-glycidoxypropyltrimethoxysilane, 0.4-0.8 parts of boron trifluoride etherate are added, and the mixture is reacted at 55-65 DEG C for 3-5 hours, then 18-28 parts of 1,4-diamino-2,5-divinylbenzene, 0.1-0.5 parts of benzoyl peroxide are added, and the mixture is reacted at 45-55 DEG C for 4-6 hours, then filtered, washed and dried to obtain an amine-modified activated carbon; T3: 80-100 parts of the amine-modified activated carbon is added to 1200-1800 parts of a 0.8-1.2% by mass palladium nitrate solution, and the mixture is stirred and adsorbed at 30-40 DEG C for 1-3 hours, then 15-25 parts of 10-20% by mass hydrazine hydrate is added, and the mixture is reduced at 60-70 DEG C for 1-2 hours, then filtered, washed and dried to obtain a palladium-carbon catalyst.

[0010] Reaction mechanism S1 step: under the action of a water separator, nucleophilic substitution reaction of p-chloronitrobenzene, potassium carbonate and hydroquinone occurs in a mixed solvent of N,N-dimethylformamide and toluene. Potassium carbonate acts as a base to form a phenolate anion from hydroquinone, which then attacks the chlorine atom of p-chloronitrobenzene to generate 1,4-bis(4-nitrophenoxy)benzene. Toluene acts as a water-carrying agent, and the water generated in the reaction is removed in time through the water separator to promote the forward reaction. Subsequent steps such as elution with ethyl acetate, water washing to remove salt, and ethanol beating are used to purify the product. S2 step: under the catalysis of palladium-carbon catalyst, the nitro group in 1,4-bis(4-nitrophenoxy)benzene is reduced in a hydrogen atmosphere in an autoclave to convert the nitro group into an amino group to generate 1,4-bis(4-aminophenoxy)benzene. Pd 0 Nanoparticles provide active sites for the reaction, and hydrogen is activated on the surface of the nanoparticles to react with the nitro group. Palladium-carbon catalyst preparation mechanism: in T1, hydrogen peroxide oxidizes the surface of activated carbon to generate hydroxyl groups; in T2, the trimethoxysilyl group of gamma-glycidoxypropyltrimethoxysilane condenses with the hydroxyl group to introduce an epoxy group, which is opened by trifluoroboron etherate to react with 1,4-diamino-2,5-divinylbenzene under the initiation of benzoyl peroxide to fix the amine group on the surface of activated carbon; in T3, the amine group coordinates with the Pd 2+ of palladium nitrate to form a palladium-carbon catalyst, which is then reduced by hydrazine hydrate to Pd 0 Nanoparticles, forming a highly active catalyst. Technical effects: Compared with the prior art, the synthesis method of 1,4-bis(4-aminophenoxy)benzene has the following remarkable effects: 1. This invention, through optimization of material ratios and reaction conditions, achieves a yield of over 91% for 1,4-bis(4-nitrophenoxy)benzene; the palladium-on-carbon catalyst, after special modification, has abundant amine sites, which is beneficial for Pd. 2+ With strong coordination ability and high palladium particle dispersion (particle size distribution 2-5nm), it exhibits excellent catalytic activity in the nitro reduction reaction of S2, thereby increasing the yield of 1,4-bis(4-aminophenoxy)benzene; the stepwise methanol slurry process of S3 can effectively remove impurities, and the product purity reaches over 99.7%. 2. The palladium-carbon catalyst used in this invention has good stability and can be reused; the solvent recovery rate is high during the reaction process, which can effectively reduce the amount of waste gas, wastewater, and solid waste. Moreover, the reaction conditions are mild and the energy consumption is low, making it suitable for large-scale industrial production.

[0011] 3. High product yield and purity: This invention can significantly improve the purity and yield of 1,4-bis(4-aminophenoxy)benzene, and has high economic value. Detailed Implementation

[0012] To further illustrate the technical means and effects adopted by the present invention to achieve the intended purpose, the following detailed description is provided in conjunction with embodiments and comparative examples: Purity test of 1,4-bis(4-aminophenoxy)benzene: High performance liquid chromatography was used for detection.

[0013] Example 1

[0014] A method for synthesizing 1,4-bis(4-aminophenoxy)benzene, comprising the following steps: S1: Synthesis of 1,4-bis(4-nitrophenoxy)benzene 35g of p-chloronitrobenzene, 20g of potassium carbonate, and 5g of hydroquinone were added to 170g of N,N-dimethylformamide and 80g of toluene, and the reaction was carried out using a water separator. After the reaction was completed, the reaction solution was cooled to room temperature, filtered, and the filter cake was washed with ethyl acetate. The filter cake was added to a stirrer, 200g of water was added, and the mixture was stirred thoroughly to remove inorganic salts. The mixture was then filtered, and the filter cake was washed with ethanol. The filter cake was added to a reaction vessel, 170g of ethanol was added, the temperature was raised to 60℃, and the mixture was stirred for 20min. The mixture was then filtered and dried to obtain 1,4-bis(4-nitrobenzoxy)benzene. S2: Synthesis of 1,4-bis(4-aminophenoxy)benzene 20g of 1,4-bis(4-nitrophenoxy)benzene, 0.1g of palladium on carbon catalyst, and 200g of tetrahydrofuran were added to a high-pressure reactor to react and obtain crude 1,4-bis(4-aminophenoxy)benzene. S3: Post-processing The temperature of the reactor was reduced to 50℃, and the catalyst was removed by filtration; the filtrate was evaporated to remove tetrahydrofuran, 150 g of methanol was added, and the slurry was treated for 20 min; the slurry was filtered, and the filter cake was dried; the filtrate was evaporated again, 80 g of methanol was added, and the slurry was treated for 20 min; the slurry was filtered, and the filter cake was dried; the two filter cakes were combined to obtain 1,4-bis(4-aminophenoxy)benzene.

[0015] The S1 reaction temperature was 130℃, the reaction time was 4h, no water was discharged from the water trap, and the reaction was continued for 40 min.

[0016] Before the S2 autoclave reaction, the reaction vessel was replaced with nitrogen twice and then replaced with hydrogen twice, the reaction pressure was 2 MPa, the reaction temperature was 60℃, and the reaction time was 3h.

[0017] The preparation method of the palladium-carbon catalyst is as follows: T1: 100 g of activated carbon was added to 600 g of 5% hydrogen peroxide solution, stirred at 50℃ for 2 hours, filtered, washed with deionized water, and dried at 80℃ under vacuum for 1 hour to obtain hydroxylated activated carbon; T2: 60 g of hydroxylated activated carbon was added to 400 g of methanol, 12 g of γ-glycidoxypropyltrimethoxysilane, 0.4 g of boron trifluoride etherate was added, and the reaction was carried out at 55℃ for 3 hours, then 18 g of 1,4-diamino-2,5-divinylbenzene, 0.1 g of benzoyl peroxide was added, and the reaction was carried out at 45℃ for 4 hours, and then filtered, washed and dried to obtain amine-modified activated carbon; T3: 80 g of amine-modified activated carbon was added to 1200 g of 0.8% palladium nitrate solution, stirred and adsorbed at 30℃ for 1 hour, 15 g of 10% hydrazine hydrate was added, and reduced at 60℃ for 1 hour, filtered, washed and dried to obtain palladium-carbon catalyst.

[0018] Example 2

[0019] A method for synthesizing 1,4-bis(4-aminophenoxy)benzene, the operation steps of which are as follows: S1: Synthesis of 1,4-bis(4-nitrophenoxy)benzene 37 g of p-chloronitrobenzene, 21 g of potassium carbonate, and 6 g of hydroquinone were added to 180 g of N,N-dimethylformamide and 85 g of toluene, and the reaction was carried out using a water trap; after the reaction was completed, the reaction solution was cooled to room temperature, filtered, and the filter cake was washed with ethyl acetate; the filter cake was added to a stirrer, 240 g of water was added, and the inorganic salt was removed by stirring; the slurry was filtered, and the filter cake was washed with ethanol; the filter cake was added to a reactor, 180 g of ethanol was added, the temperature was increased to 65℃, the slurry was treated for 25 min, filtered, and dried to obtain 1,4-bis(4-nitrophenoxy)benzene; S2: Synthesis of 1,4-bis(4-aminophenoxy)benzene 23 g of 1,4-bis(4-nitrophenoxy)benzene, 0.2 g of palladium-carbon catalyst, 240 g of tetrahydrofuran were added into a high-pressure reactor for reaction to obtain crude 1,4-bis(4-aminophenoxy)benzene; S3: Post-treatment The temperature of the reactor was reduced to 50°C, and the catalyst was removed by filtration; the filtrate was rotary-evaporated to remove tetrahydrofuran, 160 g of methanol was added for beating treatment for 25 min; filtration was performed, and the filter cake was dried; the filtrate was rotary-evaporated again, 85 g of methanol was added for beating treatment for 25 min; filtration was performed, and the filter cake was dried; the filter cakes obtained in the two times were combined to obtain 1,4-bis(4-aminophenoxy)benzene.

[0020] The reaction temperature of S1 was 135°C, the reaction time was 4.5 h, and the reaction was continued for 45 min after no water was discharged from the water trap.

[0021] Before the high-pressure reactor reaction of S2, nitrogen was replaced twice, and then hydrogen was replaced twice, the reaction pressure was 2 MPa, the reaction temperature was 65°C, and the reaction time was 4 h.

[0022] The preparation method of the palladium-carbon catalyst is as follows: T1: 105 g of activated carbon was added into 700 g of hydrogen peroxide solution with a mass percentage of 6%, stirring was performed at 55°C for 2.5 h, filtration was performed, washing was performed with deionized water, and vacuum drying was performed at 85°C for 2 h to obtain hydroxylated activated carbon; T2: 65 g of hydroxylated activated carbon was added into 450 g of methanol, 16 g of γ-glycidoxypropyltrimethoxysilane, 0.5 g of boron trifluoride etherate was added, reaction was performed at 60°C for 4 h, then 20 g of 1,4-diamino-2,5-divinylbenzene, 0.2 g of benzoyl peroxide was added, reaction was performed at 50°C for 5 h, and filtration was performed, washing and drying were performed to obtain amine-modified activated carbon; T3: 85 g of amine-modified activated carbon was added into 1400 g of palladium nitrate solution with a mass percentage of 0.9%, stirring was performed at 35°C for 2 h, 18 g of hydrazine hydrate with a mass percentage of 15% was added, reduction was performed at 65°C for 1.5 h, filtration was performed, washing was performed, and drying was performed to obtain the palladium-carbon catalyst.

[0023] Example 3

[0024] A synthesis method of 1,4-bis(4-aminophenoxy)benzene, the operation steps of which are as follows: S1: Synthesis of 1,4-bis(4-nitrophenoxy)benzene Into 190 g of N,N-dimethylformamide, 95 g of toluene, 40 g of p-chloronitrobenzene, 24 g of potassium carbonate, and 8 g of hydroquinone were added, and the reaction was performed using a water separator; after the reaction was completed, the reaction solution was cooled to room temperature, filtered, and the filter cake was washed with ethyl acetate; the filter cake was added to a stirrer, 280 g of water was added, and the inorganic salt was removed by thoroughly stirring, filtered, and the filter cake was washed with ethanol; the filter cake was added to a reaction kettle, 190 g of ethanol was added, and the temperature was increased to 65°C, and the slurry was stirred for 25 min, filtered, and dried to obtain 1,4-bis(4-nitrophenoxy)benzene; S2: Synthesis of 1,4-bis(4-aminophenoxy)benzene Into an autoclave, 28 g of 1,4-bis(4-nitrophenoxy)benzene, 0.5 g of palladium-carbon catalyst, and 280 g of tetrahydrofuran were added, and the reaction was performed to obtain crude 1,4-bis(4-aminophenoxy)benzene; S3: Post-treatment The temperature of the reaction kettle was reduced to 55°C, and the catalyst was removed by filtration; the filtrate was rotary evaporated to remove tetrahydrofuran, 190 g of methanol was added, and the slurry was stirred for 25 min; filtered, and the filter cake was dried; the filtrate was again rotary evaporated, 95 g of methanol was added, and the slurry was stirred for 25 min; filtered, and the filter cake was dried; the two filter cakes were combined to obtain 1,4-bis(4-aminophenoxy)benzene.

[0025] The reaction temperature of S1 was 135°C, the reaction time was 4.5 h, and the reaction was continued for another 55 min until no water flowed out of the water separator.

[0026] Before the S2 autoclave reaction, the reaction was replaced with nitrogen twice and then replaced with hydrogen twice, the reaction pressure was 2 MPa, the reaction temperature was 65°C, and the reaction time was 4 h.

[0027] The preparation method of the palladium-carbon catalyst is as follows: T1: 115 g of activated carbon was added to 800 g of 7% hydrogen peroxide solution, stirred at 55°C for 2.5 hours, filtered, washed with deionized water, and dried at 95°C under vacuum for 3 hours to obtain hydroxylated activated carbon; T2: 75 g of hydroxylated activated carbon was added to 550 g of methanol, 20 g of γ-glycidoxypropyltrimethoxysilane, and 0.7 g of boron trifluoride ether were added, and the reaction was performed at 60°C for 4 hours, then 26 g of 1,4-diamino-2,5-divinylbenzene and 0.4 g of benzoyl peroxide were added, and the reaction was performed at 50°C for 5 hours, and the amine-modified activated carbon was obtained by filtering and washing and drying; T3: 95 g amine modified activated carbon was added to 1600 g of 1.1% by mass of palladium nitrate solution, stirred and adsorbed at 35℃ for 2 hours, 23 g of 15% by mass of hydrazine hydrate was added, and reduced at 65℃ for 1.5 hours. After filtering and washing, drying was performed to obtain a palladium-carbon catalyst.

[0028] Example 4

[0029] A synthesis method of 1,4-bis(4-aminophenoxy)benzene, the operation steps are: S1: Synthesis of 1,4-bis(4-nitrophenoxy)benzene 42 g of p-chloronitrobenzene, 25 g of potassium carbonate, 10 g of hydroquinone were added to 200 g of N,N-dimethylformamide, 100 g of toluene, and the reaction was carried out using a water separator; after the reaction was completed, the reaction liquid was cooled to room temperature, filtered, and the filter cake was washed with ethyl acetate; the filter cake was added to a stirrer, 300 g of water was added, and the inorganic salt was removed by stirring; filter, and the filter cake was washed with ethanol; the filter cake was added to a reaction kettle, 200 g of ethanol was added, the temperature was raised to 70℃, and the pulp was treated for 30 min; filter, and dry to obtain 1,4-bis(4-nitrophenoxy)benzene; S2: Synthesis of 1,4-bis(4-aminophenoxy)benzene 30 g of 1,4-bis(4-nitrophenoxy)benzene, 0.6 g of palladium-carbon catalyst, 300 g of tetrahydrofuran were added to an autoclave and reacted to obtain crude 1,4-bis(4-aminophenoxy)benzene; S3: Post-treatment The temperature of the reaction kettle was reduced to 55℃, and the catalyst was removed by filtration; the filtrate was rotary evaporated to remove tetrahydrofuran, 200 g of methanol was added, and the pulp was treated for 30 min; filter, and dry the filter cake; the filtrate was rotary evaporated again, 100 g of methanol was added, and the pulp was treated for 30 min; filter, and dry the filter cake; combine the two filter cakes to obtain 1,4-bis(4-aminophenoxy)benzene.

[0030] The reaction temperature of S1 is 140℃, the reaction time is 5h, until there is no water flowing out of the water separator, and then continue to react for 60min.

[0031] Before the S2 autoclave reaction, replace it twice with nitrogen and twice with hydrogen, the reaction pressure is 2MPa, the reaction temperature is 70℃, and the reaction time is 5h.

[0032] The preparation method of the palladium-carbon catalyst is: T1: 120 g of activated carbon was added to 900 g of 8% by mass of hydrogen peroxide solution, stirred at 60℃ for 3 hours, filtered, washed with deionized water, and dried at 100℃ under vacuum for 4 hours to obtain hydroxylated activated carbon; T2: 80 g of hydroxylated activated carbon was added to 600 g of methanol, then 22 g of γ-glycidoxypropyltrimethoxysilane, 0.8 g of boron trifluoride etherate was added, and the mixture was reacted at 65°C for 5 hours, then 28 g of 1,4-diamino-2,5-divinylbenzene, 0.5 g of benzoyl peroxide was added, and the mixture was reacted at 55°C for 6 hours, then filtered, washed and dried to obtain an amine-modified activated carbon; T3: 100 g of the amine-modified activated carbon was added to 1800 g of a 1.2% by mass palladium nitrate solution, and stirred at 40°C for 3 hours, then 25 g of 20% by mass hydrazine hydrate was added, and the mixture was reduced at 70°C for 2 hours, then filtered, washed and dried to obtain a palladium-carbon catalyst.

[0033] Comparative Example 1 A method for synthesizing 1,4-bis(4-aminophenoxy)benzene, comprising the following steps: S1: Synthesis of 1,4-bis(4-nitrophenoxy)benzene 35 g of p-chloronitrobenzene, 20 g of potassium carbonate, 5 g of hydroquinone were added to 170 g of N,N-dimethylformamide, 80 g of toluene, and the reaction was carried out using a water separator; after the reaction was completed, the reaction liquid was cooled to room temperature, filtered, and the filter cake was washed with ethyl acetate; the filter cake was added to a stirrer, 200 g of water was added, and the inorganic salt was removed by stirring, then filtered, and the filter cake was washed with ethanol; the filter cake was added to a reaction kettle, 170 g of ethanol was added, the temperature was raised to 60°C, and the slurry was treated for 20 min, then filtered, dried, and 1,4-bis(4-nitrophenoxy)benzene was obtained. S2: Synthesis of 1,4-bis(4-aminophenoxy)benzene 20 g of 1,4-bis(4-nitrophenoxy)benzene, 0.1 g of palladium-carbon catalyst, 200 g of tetrahydrofuran were added to an autoclave and reacted to obtain crude 1,4-bis(4-aminophenoxy)benzene. S3: Post-treatment The temperature of the reaction kettle was reduced to 50°C, and the catalyst was removed by filtration; the filtrate was rotary evaporated to remove tetrahydrofuran, 150 g of methanol was added, and the slurry was treated for 20 min; filtered, and the filter cake was dried; the filtrate was rotary evaporated again, 80 g of methanol was added, and the slurry was treated for 20 min; filtered, and the filter cake was dried; the two filter cakes were combined to obtain 1,4-bis(4-aminophenoxy)benzene.

[0034] The reaction temperature of S1 was 130°C, the reaction time was 4h, until no water flowed out of the water separator, and then the reaction was continued for 40 min.

[0035] Before the S2 autoclave reaction, the reaction vessel was replaced with nitrogen twice and then replaced with hydrogen twice, the reaction pressure was 2 MPa, the reaction temperature was 60°C, and the reaction time was 3h.

[0036] The preparation method of the palladium-carbon catalyst is: T1: 100 g of activated carbon is added to 600 g of 5% hydrogen peroxide solution, stirred at 50°C for 2 hours, filtered, washed with deionized water, and dried at 80°C under vacuum for 1 hour to obtain hydroxylated activated carbon; T3: 80 g of hydroxylated activated carbon is added to 1200 g of 0.8% palladium nitrate solution, stirred and adsorbed at 30°C for 1 hour, 15 g of 10% hydrazine hydrate is added, and reduced at 60°C for 1 hour. After washing and filtering, drying is performed to obtain a palladium-carbon catalyst.

[0037] Comparative Example 2 A synthesis method of 1,4-bis(4-aminophenoxy)benzene, the operation steps are: S1: Synthesis of 1,4-bis(4-nitrophenoxy)benzene 35 g of p-chloronitrobenzene, 20 g of potassium carbonate, and 5 g of hydroquinone are added to 170 g of N,N-dimethylformamide and 80 g of toluene, and the reaction is carried out using a water separator. After the reaction is completed, the reaction liquid is cooled to room temperature, filtered, and the filter cake is washed with ethyl acetate. The filter cake is added to a stirrer, 200 g of water is added, and the inorganic salt is removed by stirring. After filtering, the filter cake is washed with ethanol. The filter cake is added to a reaction kettle, 170 g of ethanol is added, the temperature is raised to 60°C, and the slurry is stirred for 20 min. After filtering and drying, 1,4-bis(4-nitrophenoxy)benzene is obtained. S2: Synthesis of 1,4-bis(4-aminophenoxy)benzene 20 g of 1,4-bis(4-nitrophenoxy)benzene, 0.1 g of palladium-carbon catalyst, and 200 g of tetrahydrofuran are added to an autoclave for reaction to obtain crude 1,4-bis(4-aminophenoxy)benzene. S3: Post-treatment The temperature of the reaction kettle is reduced to 50°C, and the catalyst is removed by filtering. The tetrahydrofuran in the filtrate is removed by rotary evaporation, 150 g of methanol is added, and the slurry is stirred for 20 min. After filtering, the filter cake is dried. The filtrate is again subjected to rotary evaporation, 80 g of methanol is added, and the slurry is stirred for 20 min. After filtering, the filter cake is dried. The two filter cakes are combined to obtain 1,4-bis(4-aminophenoxy)benzene.

[0038] The reaction temperature of S1 is 130°C, the reaction time is 4h, and the reaction continues for 40 min after there is no water flow from the water separator.

[0039] Before the S2 autoclave reaction, the reaction vessel is replaced with nitrogen twice and then replaced with hydrogen twice. The reaction pressure is 2 MPa, the reaction temperature is 60°C, and the reaction time is 3h.

[0040] The preparation method of the palladium-carbon catalyst is: T1: 100 g of activated carbon was added to 600 g of 5% hydrogen peroxide solution by mass, stirred at 50°C for 2 hours, filtered, washed with deionized water, and dried at 80°C under vacuum for 1 hour to obtain hydroxylated activated carbon; T2: 60 g of hydroxylated activated carbon was added to 400 g of methanol, and then 18 g of 1,4-diamino-2,5-divinylbenzene and 0.1 g of benzoyl peroxide were added, and reacted at 45°C for 4 hours, filtered, washed and dried to obtain modified activated carbon; T3: 80 g of modified activated carbon was added to 1200 g of 0.8% palladium nitrate solution by mass, stirred and adsorbed at 30°C for 1 hour, and then 15 g of 10% hydrazine hydrate by mass was added and reduced at 60°C for 1 hour, filtered, washed and dried to obtain palladium-carbon catalyst.

[0041] Comparative Example 3 A method for synthesizing 1,4-bis(4-aminophenoxy)benzene, the operation steps of which are as follows: S1: Synthesis of 1,4-bis(4-nitrophenoxy)benzene 35 g of p-chloronitrobenzene, 20 g of potassium carbonate, and 5 g of hydroquinone were added to 170 g of N,N-dimethylformamide and 80 g of toluene, and the reaction was carried out using a water separator; after the reaction was completed, the reaction liquid was cooled to room temperature, filtered, and the filter cake was washed with ethyl acetate; the filter cake was added to a stirrer, 200 g of water was added, and the inorganic salt was removed by stirring; the filter cake was filtered, and the filter cake was washed with ethanol; the filter cake was added to a reaction kettle, 170 g of ethanol was added, and the slurry was prepared at 60°C for 20 min; the slurry was filtered, and the filter cake was dried to obtain 1,4-bis(4-nitrophenoxy)benzene; S2: Synthesis of 1,4-bis(4-aminophenoxy)benzene 20 g of 1,4-bis(4-nitrophenoxy)benzene, 0.1 g of palladium-carbon catalyst, and 200 g of tetrahydrofuran were added to an autoclave and reacted to obtain crude 1,4-bis(4-aminophenoxy)benzene; S3: Post-treatment The temperature of the reaction kettle was reduced to 50°C, and the catalyst was removed by filtration; the filter cake was dried; the filter cake was added to a reaction kettle, 150 g of methanol was added, and the slurry was prepared at 60°C for 20 min; the slurry was filtered, and the filter cake was dried; the filter cake was added to a reaction kettle, 80 g of methanol was added, and the slurry was prepared at 60°C for 20 min; the slurry was filtered, and the filter cake was dried; the filter cakes obtained in the two steps were combined to obtain 1,4-bis(4-aminophenoxy)benzene.

[0042] The reaction temperature of S1 was 130°C, the reaction time was 4h, and the water flow from the water separator stopped, and the reaction was continued for another 40 min.

[0043] The S2 autoclave is replaced twice with nitrogen and twice with hydrogen before reaction, the reaction pressure is 2 MPa, the reaction temperature is 60 DEG C, and the reaction time is 3h.

[0044] The preparation method of the palladium-carbon catalyst is as follows: T1: 100g of activated carbon is added to 600g of 5% hydrogen peroxide solution, stirred at 50 DEG C for 2 hours, filtered, washed with deionized water, and dried at 80 DEG C under vacuum for 1 hour to obtain hydroxylated activated carbon; T2: 60g of hydroxylated activated carbon is added to 400g of methanol, and then 12g of gamma-glycidoxypropyltrimethoxysilane and 0.4g of boron trifluoride etherate are added, and the mixture is reacted at 55 DEG C for 3 hours, filtered, washed and dried to obtain modified activated carbon; T3: 80g of modified activated carbon is added to 1200g of 0.8% palladium nitrate solution, stirred and adsorbed at 30 DEG C for 1 hour, 15g of 10% hydrazine hydrate is added, and the mixture is reduced at 60 DEG C for 1 hour, filtered, washed and dried to obtain a palladium-carbon catalyst.

[0045] Table 1: Test results of examples and comparative examples Purity / % Yield / % Example 1 99.74 91.51 Example 2 99.77 91.55 Example 3 99.82 92.61 Example 4 99.85 92.68 Comparative Example 1 81.52 68.72 Comparative Example 2 94.66 85.93 Comparative Example 3 95.24 86.81 Through the data analysis of the above examples and comparative examples, the purity and yield of 1,4-bis(4-aminophenoxy)benzene can be significantly improved, and the economic value is high.

[0046] The above is only a preferred embodiment of the present application, and does not limit the present application in any form. Although the present application has been disclosed as above with a preferred embodiment, it is not intended to limit the present application. Any person skilled in the art can make some changes or modifications to the above disclosed technical content to obtain equivalent embodiments with equivalent changes, without departing from the scope of the technical solution of the present application. Any modification, change, equivalent change and modification of the above embodiments made in accordance with the technical essence of the present application, without departing from the technical solution of the present application, are still within the scope of the present application.

Claims

1. A method for synthesizing 1,4-bis(4-aminophenoxy)benzene, comprising the following steps: S1: synthesis of 1,4-bis(4-nitrophenoxy)benzene; S2: synthesis of 1,4-bis(4-aminophenoxy)benzene; and S3: post-treatment. S1: synthesis of 1,4-bis(4-nitrophenoxy)benzene; 35-42 parts of p-chloronitrobenzene, 20-25 parts of potassium carbonate, and 5-10 parts of hydroquinone are added to a mixed solution of 170-200 parts of N, N-dimethylformamide and 80-100 parts of toluene, and the reaction is carried out using a water separator; after the reaction is completed, the reaction solution is cooled to room temperature, filtered, and the filter cake is washed with ethyl acetate; the filter cake is added to a stirrer, 200-300 parts of water is added, and the mixture is stirred thoroughly, filtered, and the filter cake is washed with ethanol; the filter cake is added to a reaction kettle, 170-200 parts of ethanol is added, the temperature is raised to 60-70 DEG C, and the mixture is beaten for 20-30 min, filtered, and dried to obtain 1,4-bis(4-nitrophenoxy)benzene. S2: synthesis of 1,4-bis(4-aminophenoxy)benzene; 20-30 parts of 1,4-bis(4-nitrophenoxy)benzene, 0.1-0.6 parts of palladium-carbon catalyst, and 200-300 parts of tetrahydrofuran are added to an autoclave and reacted to obtain crude 1,4-bis(4-aminophenoxy)benzene. S3: post-treatment; the temperature of the reaction kettle is reduced to 50-55 DEG C, and the catalyst is removed by filtration; the tetrahydrofuran is removed from the filtrate by rotary evaporation, 150-200 parts of methanol is added, and the mixture is beaten for 20-30 min; the mixture is filtered, and the filter cake is dried; the filtrate is again subjected to rotary evaporation, 80-100 parts of methanol is added, and the mixture is beaten for 20-30 min; the mixture is filtered, and the filter cake is dried; and the two filter cakes are combined to obtain 1,4-bis(4-aminophenoxy)benzene. The palladium-carbon catalyst is prepared by reacting hydroxylated activated carbon, γ-glycidoxypropyltrimethoxysilane, boron trifluoride etherate, 1,4-diamino-2,5-divinylbenzene, and a palladium nitrate solution. In the S1, the reaction is carried out at a temperature of 130-140 DEG C for 4-5 h until no water is discharged from the water separator, and then the reaction is continued for 40-60 min. In the S2, the autoclave is first replaced with nitrogen twice and then replaced with hydrogen twice, the reaction pressure is 2 MPa, the reaction temperature is 60-70 DEG C, and the reaction time is 3-5 h. The palladium-carbon catalyst is prepared by the following method: T1: 100-120 parts of activated carbon is added to 600-900 parts of a 5-8% hydrogen peroxide solution, stirred at 50-60 DEG C for 2-3 h, filtered, washed with deionized water, and dried at 80-100 DEG C under vacuum for 1-4 h to obtain hydroxylated activated carbon.

2. The method for synthesizing 1,4-bis(4-aminophenoxy)benzene according to claim 1, characterized in that: ​ 3. The method for synthesizing 1,4-bis(4-aminophenoxy)benzene according to claim 1, characterized in that: ​ 4. The method for synthesizing 1,4-bis(4-aminophenoxy)benzene according to claim 1, characterized in that: ​ ​ T2: 60-80 parts of hydroxylated activated carbon is added to 400-600 parts of methanol, then 12-22 parts of γ-glycidoxypropyltrimethoxysilane, 0.4-0.8 parts of boron trifluoride etherate are added, and the mixture is reacted at 55-65°C for 3-5 hours, then 18-28 parts of 1,4-diamino-2,5-divinylbenzene, 0.1-0.5 parts of benzoyl peroxide are added, and the mixture is reacted at 45-55°C for 4-6 hours, then filtered, washed and dried to obtain an amine-modified activated carbon; T3: 80-100 parts of the amine-modified activated carbon is added to 1200-1800 parts of a 0.8-1.2% by mass palladium nitrate solution, and the mixture is stirred and adsorbed at 30-40°C for 1-3 hours, then 15-25 parts of 10-20% by mass hydrazine hydrate is added, and the mixture is reduced at 60-70°C for 1-2 hours, then filtered, washed and dried to obtain a palladium-carbon catalyst.