A process for the anilination of phenol to produce p-phenylenediamine

Abstract

The application discloses a method for preparing p-phenylenediamine by aniline amination, and the method comprises the following steps: (1) preparing a mixture I containing aniline, phthalic anhydride and a solvent I, and performing reaction I to obtain a solution of N-phenyl phthalimide; and (2) preparing a mixture II containing the solution of N-phenyl phthalimide, a hydroxylamine salt and a catalyst, and performing reaction II to obtain p-phenylenediamine; wherein the catalyst is a bidentate ligand modified manganese oxide. The method has the advantages of low cost of catalyst and reaction raw materials, high conversion rate and product selectivity, clean reaction process, recyclable catalyst and the like.

Description

Technical Field

[0001] This application relates to a method for preparing p-phenylenediamine by amination of aniline, belonging to the field of organic chemical technology. Background Technology

[0002] p-Phenylenediamine is a widely used intermediate. It can be used to produce azo disperse dyes, acid dyes, direct dyes, and sulfur dyes. It is also used in the production of aramid 1414, polyamide-imide resins, polyurethanes, and other polymers. Additionally, it can be used in the production of fur dyes, rubber antioxidants, and photographic developers. Furthermore, it is a commonly used sensitive reagent for testing iron and copper. For example, the polymer aramid 1414, composed of p-phenylenediamine and terephthaloyl chloride, has a toughness and strength that are 2 times and 6 times that of high-quality steel, respectively, while its density is only 1 / 5 that of steel. It is heat-resistant, exhibits stable thermal shrinkage and creep properties, and can be used normally for extended periods within a temperature range of -196 to 200°C. Its shrinkage rate is zero at 150°C, and it does not melt or burn below 560°C. It also possesses excellent insulation and chemical corrosion resistance, earning it the nickname "synthetic steel wire." It is widely used in defense and military industries, such as in the manufacture of aircraft, rockets, missiles, fireproofing, and bulletproof equipment. Additionally, it can be used in automobiles, ships, rubber reinforcing materials, special ropes, and high-temperature resistant filter materials.

[0003] The main industrial production method for p-phenylenediamine is the reduction method of p-nitroaniline: p-nitroaniline is reduced to p-phenylenediamine in the presence of reducing agents such as iron powder; p-nitroaniline is mainly prepared by ammonolysis of p-chloronitrobenzene or nitration-hydrolysis of N-acetaniline. This method suffers from severe equipment corrosion, long process, high energy consumption and production costs, and generates large amounts of acidic waste gas, waste liquid and waste residue, causing serious environmental pollution. Patent CN111393304A reports a method for preparing p-phenylenediamine from aniline: in the presence of acid-binding agents such as triethylamine, pyridine, and piperidine, aniline and p-toluenesulfonyl chloride react to obtain p-toluenesulfonylaniline; then, in the presence of Ru-Cu / titanium silicate molecular sieve catalyst and oxidants such as hydrogen peroxide, p-benzoquinone, tert-butanol peroxide, and potassium persulfate, using liquid ammonia or ammonia water as the ammonia source, p-aminobenzenesulfonamide is prepared; and then, after deprotection in the presence of calcium fluoride / diatomaceous earth, p-phenylenediamine is obtained through separation and purification. This method uses Ru-based noble metal catalysts, p-toluenesulfonyl chloride, and oxidants such as hydrogen peroxide, p-benzoquinone, tert-butanol peroxide, and potassium persulfide. The catalyst preparation is complex, and the cost of the catalyst and reaction raw materials is high. Summary of the Invention

[0004] To address the problems of severe equipment corrosion, long production routes, high energy consumption and production costs in current p-phenylenediamine production methods, as well as the generation of large amounts of acidic waste gas, waste liquid and waste residue, causing serious environmental pollution, and the high cost of precious metal catalysts and reaction raw materials in the aniline amination method for preparing p-phenylenediamine reported in the literature, this application provides a method for preparing p-phenylenediamine by aniline amination, which has advantages such as low cost of catalysts and reaction raw materials, high conversion rate and product selectivity, clean reaction process, and recyclable catalyst.

[0005] The technical solution for preparing p-phenylenediamine by amination of aniline in this application is as follows: aniline reacts with phthalic anhydride, and then undergoes amination with hydroxylamine salt in the presence of a catalyst, followed by hydrolysis to obtain p-phenylenediamine. The catalyst is an organically modified manganese oxide.

[0006] The reaction process for preparing p-phenylenediamine by amination of aniline in this application is shown in the following diagram:

[0007]

[0008] According to one aspect of this application, a method for preparing p-phenylenediamine by amination of aniline is provided, the method comprising:

[0009] (1) A mixture containing aniline, phthalic anhydride and solvent I is reacted with reaction I to obtain a solution of N-phenylphthalimide;

[0010] (2) Mixture II of N-phenylphthalimide solution, hydroxylamine salt, and catalyst, and react II to obtain p-phenylenediamine;

[0011] The catalyst is a manganese oxide modified with bidentate ligands.

[0012] According to this application, the method for preparing p-phenylenediamine by amination of aniline includes the following steps:

[0013] (1) Aniline, phthalic anhydride and solvent I are mixed and heated to react I to obtain a solution of N-phenylphthalimide;

[0014] (2) The solution of N-phenylphthalimide, hydroxylamine salt and organically modified manganese oxide catalyst are mixed and heated to react II to obtain a reaction mixture containing N-p-aminophenylphthalimide and catalyst;

[0015] (3) The catalyst in the reaction mixture containing N-p-aminophenyl phthalimide and the catalyst is separated to obtain the reaction mixture containing N-p-aminophenyl phthalimide; the separated catalyst is recycled.

[0016] (4) After the solvent is removed from the reaction mixture containing N-p-aminophenyl phthalimide, it is hydrolyzed under alkaline conditions to separate and purify p-phenylenediamine and phthalic acid.

[0017] Optionally, the organically modified manganese oxide is a bidentate ligand-modified manganese oxide.

[0018] Optionally, the bidentate ligands in the bidentate ligand-modified manganese oxide are selected from O,N bidentate ligands and / or O,O bidentate ligands.

[0019] Optionally, after the catalyst reaction is completed, the catalyst can be separated and recycled.

[0020] Optionally, the O,N bidentate ligand is selected from at least one of 8-hydroxyquinoline, N,N-dimethylethanolamine, and N,N-dimethylaminoacetic acid.

[0021] Optionally, the O,O bidentate ligand is selected from at least one of acetylacetone, ethylene glycol, and catechol.

[0022] Optionally, the method for preparing the organically modified manganese oxide includes:

[0023] (1) Add KMnO4 aqueous solution dropwise to (CH3COO)2Mn ethanol-water solution, then add ammonia water dropwise until pH is 8-9, reaction III, to obtain manganese oxide;

[0024] (2) A mixture containing manganese oxide, bidentate ligand, and solvent II is reacted with the mixture III to obtain the organically modified manganese oxide catalyst.

[0025] Optionally, the preparation of the organically modified manganese oxide catalyst includes the following steps:

[0026] (1) Add KMnO4 aqueous solution dropwise to (CH3COO)2Mn ethanol-water solution, then add ammonia water dropwise to the resulting solution until the pH is 8-9, reaction III, filter, wash the resulting solid with distilled water and dry to obtain manganese oxide.

[0027] (2) The manganese oxide, bidentate ligand and solvent II are mixed, reaction IV is carried out, filtered, and the resulting solid is washed with ethanol and then dried at room temperature to obtain the organically modified manganese oxide catalyst.

[0028] Optionally, the concentration of the KMnO4 aqueous solution is 0.2–0.6 mol / L.

[0029] Optionally, the concentration of the KMnO4 aqueous solution is independently selected from any value or a range between 0.2 mol / L, 0.25 mol / L, 0.3 mol / L, 0.35 mol / L, 0.4 mol / L, 0.45 mol / L, 0.5 mol / L, 0.55 mol / L, and 0.6 mol / L.

[0030] Optionally, the molar ratio of (CH3COO)2Mn in the ethanol-water solution and KMnO4 in the KMnO4 aqueous solution is 1:1 to 2:1.

[0031] Optionally, the molar ratio of (CH3COO)2Mn in the ethanol-water solution and KMnO4 in the KMnO4 aqueous solution is independently selected from any value of 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2:1 or any range between two of them.

[0032] Optionally, the concentration of the ethanol-water solution of (CH3COO)2Mn is 0.1 to 0.3 mol / L.

[0033] Optionally, the concentration of the ethanol-water solution of (CH3COO)2Mn is independently selected from any value or a range between 0.1 mol / L, 0.15 mol / L, 0.2 mol / L, 0.25 mol / L, and 0.3 mol / L.

[0034] Optionally, in the ethanol-water solution of (CH3COO)2Mn, the volume ratio of ethanol to water is 3:1 to 7:1.

[0035] Optionally, in the ethanol-water solution of (CH3COO)2Mn, the volume ratio of ethanol to water is independently selected from any value of 3:1, 3.5:1, 4:1, 4.5:1, 5:1, 5.5:1, 6:1, 6.5:1, 7:1 or any range between two of them.

[0036] Optionally, the drying temperature is 60–100°C.

[0037] Optionally, the drying temperature is independently selected from any value or a range between 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, and 100°C.

[0038] Optionally, the drying time is 6 to 24 hours.

[0039] Optionally, the drying time is independently selected from any value of 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h, 24h or a range between any two.

[0040] Optionally, the mass ratio of manganese oxide: bidentate ligand: solvent II is 1:0.2-2:4-8.

[0041] Optionally, the mass ratio of the bidentate ligand to the manganese oxide is 0.2:1 to 2:1;

[0042] Optionally, the mass ratio of the bidentate ligand to the manganese oxide is independently selected from any value or a range between 0.2:1, 0.4:1, 0.6:1, 0.8:1, 1:1, 1.2:1, 1.4:1, 1.6:1, 1.8:1, and 2:1.

[0043] Optionally, the mass ratio of solvent II to manganese oxide is 4:1 to 8:1.

[0044] Optionally, the mass ratio of solvent II to manganese oxide is independently selected from any value of 4:1, 4.5:1, 5:1, 5.5:1, 6:1, 6.5:1, 7:1, 7.5:1, 8:1 or any range between the two.

[0045] Optionally, the temperature of reaction III is 25–50°C, and the reaction time is 6–24 h.

[0046] Optionally, the temperature of reaction III is independently selected from any value of 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, or a range between any two.

[0047] Optionally, the time of reaction III is independently selected from any value of 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h, 24h or a range between any two.

[0048] Optionally, the temperature of reaction IV is 60–120°C.

[0049] Optionally, the temperature of reaction IV is independently selected from any value of 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, or a range between any two.

[0050] Optionally, the reaction IV time is 2 to 6 hours.

[0051] Optionally, the reaction time IV is independently selected from any value of 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, 6h or a range between any two.

[0052] Optionally, the room temperature airing time is 6 to 24 hours.

[0053] Optionally, the airing time is independently selected from any value of 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h, 24h or a range between any two.

[0054] Optionally, solvent II is selected from at least one of toluene, xylene, and petroleum ether.

[0055] Optionally, the hydroxylamine salt is selected from at least one of hydroxylamine hydrochloride, hydroxylamine sulfate, hydroxylamine nitrate, and hydroxylamine phosphate.

[0056] Optionally, solvent I is selected from at least one of toluene, xylene, and petroleum ether.

[0057] Optionally, the molar ratio of aniline to phthalic anhydride is 1:1 to 1:1.1.

[0058] Optionally, the molar ratio of aniline to phthalic anhydride is independently selected from any value or a range between 1:1, 1:1.01, 1:1.02, 1:1.03, 1:1.04, 1:1.05, 1:1.06, 1:1.07, 1:1.08, 1:1.09, and 1:1.1.

[0059] Optionally, the mass ratio of aniline to solvent I is 1:5 to 1:10.

[0060] Optionally, the mass ratio of aniline to solvent I is independently selected from any value of 1:5, 1:6, 1:7, 1:8, 1:9, 1:10 or any range between two of them.

[0061] Optionally, the molar ratio of the N-phenylphthalimide to the hydroxylamine salt is 1:1 to 1:1.2.

[0062] Optionally, the molar ratio of the N-phenylphthalimide to the hydroxylamine salt is independently selected from any value or a range between 1:1, 1:1.02, 1:1.04, 1:1.06, 1:1.08, 1:1.1, 1:1.12, 1:1.14, 1:1.16, 1:1.18, and 1:1.2.

[0063] Optionally, the mass of the catalyst is 1% to 10% of the mass of the N-phenylphthalimide.

[0064] Optionally, the mass of the catalyst is independently selected from any value among 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, and 10% of the mass of the N-phenylphthalimide, or a range between any two.

[0065] Optionally, the temperature of reaction I is 80–150°C, and the reaction time is 2–6 h.

[0066] Optionally, the temperature of reaction I is independently selected from any value among 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, and 150°C, or a range between any two of the above points.

[0067] Optionally, the temperature of reaction II is 50–120°C, and the reaction time is 2–6 h.

[0068] Optionally, the temperature of reaction II is independently selected from any value or a range between 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, and 120°C.

[0069] Optionally, the reaction time II is independently selected from any value of 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, 6h or a range between any two.

[0070] According to this application, the specific operational steps for preparing p-phenylenediamine by amination of aniline are as follows:

[0071] (1) Aniline is mixed with 1 to 1.1 times the amount of phthalic anhydride and 5 to 10 times the mass of the solvent of aniline, and heated and stirred at 80 to 150°C for 2 to 6 hours to obtain a solution of the N-phenylphthalimide.

[0072] (2) The solution of N-phenylphthalimide, 1.0 to 1.2 times the amount of N-phenylphthalimide hydroxylamine salt, and 1% to 10% by mass of N-phenylphthalimide organically modified manganese oxide catalyst are mixed and heated and stirred at 50 to 120°C for 2 to 6 hours to obtain a reaction mixture containing N-p-aminophenylphthalimide and catalyst;

[0073] (3) The reaction mixture containing N-p-aminophenyl phthalimide and catalyst was separated by centrifugation after standing. The solid was an organically modified manganese oxide, and the liquid was a reaction mixture containing N-p-aminophenyl phthalimide.

[0074] (4) After the solvent is removed from the reaction mixture containing N-p-aminophenyl phthalimide, 0.5 to 2 times the mass of N-phenyl phthalimide in a 20 to 40% NaOH or KOH aqueous solution is added. The mixture is heated and stirred at 50 to 100°C for 2 to 6 hours. After cooling to room temperature, the mixture is filtered. The resulting solid is melted and crystallized to obtain the p-phenylenediamine product. The filtrate is added to hydrochloric acid to adjust the pH to 6 to 7, and a colorless solid is precipitated. After filtration, the obtained solid is phthalic acid.

[0075] Optionally, the concentration of the NaOH or KOH aqueous solution is independently selected from any value of 20%, 25%, 30%, 35%, 40%, or any range between both.

[0076] Optionally, the mass of the NaOH or KOH aqueous solution is independently selected from any value among 0.5 times, 0.75 times, 1 time, 1.25 times, 1.5 times, 1.75 times, and 2 times the mass of the N-phenylphthalimide, or a range between any two.

[0077] Optionally, the heating and stirring temperature is independently selected from any value of 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, or a range between any two.

[0078] Optionally, the heating and stirring time is independently selected from any value or a range between 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, and 6h.

[0079] In this application, due to the electronic effect of the amino group in aniline, the reaction of aniline and hydroxylamine salt in the presence of the catalyst produces a mixture of o-phenylenediamine and p-phenylenediamine. In this invention, aniline reacts with phthalic anhydride to produce N-phenylphthalimide. Due to the steric hindrance effect of the phthalimide group, in the presence of the catalyst, N-phenylphthalimide reacts with hydroxylamine salt to produce N-p-aminophenylphthalimide, which is then hydrolyzed to give p-phenylenediamine, without producing the o-phenylenediamine byproduct.

[0080] In this application, the catalyst is crucial to the reaction. Without a catalyst, N-phenylphthalimide and hydroxylamine salt do not react, and the p-phenylenediamine product is not obtained. When the catalyst activity is low, the yield of the p-phenylenediamine product is very low. The catalyst described in this invention is an organically modified manganese oxide.

[0081] In this application, the activity of the organically modified manganese oxide varies greatly depending on the ligand used. Preferably, the organically modified manganese oxide described in this invention is a manganese oxide modified with bidentate ligands.

[0082] The beneficial effects that this application can produce include:

[0083] The method for preparing p-phenylenediamine by amination of aniline provided in this application has advantages such as low cost of catalyst and reaction raw materials, high conversion rate and product selectivity, clean reaction process, and recyclable catalyst. Detailed Implementation

[0084] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0085] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels.

[0086] Unless otherwise specified, all testing methods shall be conventional.

[0087] In the embodiments of this application, room temperature refers to 25°C.

[0088] The yield calculation in the embodiments of this application is as follows:

[0089]

[0090] Example 1

[0091] 100 mL of 0.4 mol / L KMnO4 aqueous solution was added dropwise to 300 mL of 0.2 mol / L (CH3COO)2Mn ethanol-water solution (ethanol / water volume ratio 5 / 1). Ammonia water was added dropwise to the resulting solution until the pH reached 8. The mixture was stirred at 25 °C for 6 h, filtered, and the resulting solid was washed with distilled water and dried at 80 °C for 12 h to obtain 8.69 g of manganese oxide. This mixture was then mixed with 8.69 g of N,N-dimethylethanolamine and 52.14 g of toluene, heated and stirred at 100 °C for 4 h, cooled to room temperature, filtered, and the resulting solid was washed with ethanol and allowed to dry at room temperature for 12 h to obtain 17.20 g of N,N-dimethylethanolamine modified manganese oxide catalyst I.

[0092] Example 2

[0093] 100 mL of 0.6 mol / L KMnO4 aqueous solution was added dropwise to 200 mL of 0.3 mol / L (CH3COO)2Mn ethanol-water solution (ethanol / water volume ratio 3 / 1). Ammonia water was added dropwise to the resulting solution until the pH reached 9. The mixture was stirred at 50 °C for 24 h, filtered, and the resulting solid was washed with distilled water and dried at 100 °C for 6 h to obtain 10.91 g of manganese oxide. This mixture was then mixed with 21.82 g of N,N-dimethylethanolamine and 87.28 g of xylene, heated and stirred at 120 °C for 2 h, cooled to room temperature, filtered, and the resulting solid was washed with ethanol and allowed to dry at room temperature for 6 h to obtain 21.52 g of N,N-dimethylethanolamine modified manganese oxide catalyst II.

[0094] Example 3

[0095] 100 mL of 0.2 mol / L KMnO4 aqueous solution was added dropwise to 400 mL of 0.1 mol / L (CH3COO)2Mn ethanol-water solution (ethanol / water volume ratio 7 / 1). Ammonia water was added dropwise to the resulting solution until the pH reached 8. The mixture was stirred at 40 °C for 12 h, filtered, and the resulting solid was washed with distilled water and dried at 60 °C for 24 h to obtain 5.05 g of manganese oxide. This mixture was then mixed with 1.10 g of N,N-dimethylethanolamine and 20.20 g of petroleum ether (90–120 °C), heated and stirred at 60 °C for 6 h, cooled to room temperature, filtered, and the resulting solid was washed with ethanol and dried at room temperature for 24 h to obtain 6.11 g of N,N-dimethylethanolamine modified manganese oxide catalyst III.

[0096] Examples 4-8

[0097] Examples 4-8 are similar to Example 1, except that the ligands used are different, while the other preparation conditions are the same as in Example 1.

[0098] The difference between Example 4 and Example 1 is that 8.69g of 8-hydroxyquinoline was used as a ligand to obtain 17.28g of 8-hydroxyquinoline-modified manganese oxide catalyst IV.

[0099] The difference between Example 5 and Example 1 is that 8.69g of N,N-dimethylaminoacetic acid was used as a ligand to obtain V17.32g of N,N-dimethylaminoacetic acid-modified manganese oxide catalyst.

[0100] The difference between Example 6 and Example 1 is that 8.69g of acetylacetone was used as a ligand to obtain 17.26g of acetylacetone-modified manganese oxide catalyst VI.

[0101] The difference between Example 7 and Example 1 is that 8.69g of ethylene glycol was used as a ligand to obtain 14.80g of ethylene glycol-modified manganese oxide catalyst VII.

[0102] The difference between Example 8 and Example 1 is that catechol was used as a ligand to obtain 17.29g of catechol-modified manganese oxide catalyst VIII.

[0103] Example 9

[0104] 9.31 g (0.1 mol) aniline, 14.81 g (0.1 mol) phthalic anhydride, and 46.55 g toluene were mixed and heated at 120 °C with stirring for 4 h. GC-MS analysis showed that aniline was completely converted to N-phenylphthalimide, yielding a toluene solution containing 22.32 g (0.1 mol) N-phenylphthalimide. 6.95 g (0.1 mol) hydroxylamine hydrochloride and 1.12 g N,N-dimethylethanolamine-modified manganese oxide catalyst I were added to this solution, and the mixture was stirred at 100 °C for 4 h, yielding a reaction mixture containing N-p-aminophenylphthalimide and the catalyst. The mixture was cooled to room temperature, allowed to stand, and then centrifuged to separate the N,N-dimethylethanolamine-modified manganese oxide catalyst I for recycling. The resulting liquid was the reaction mixture containing N-p-aminophenylphthalimide. After distilling off the solvent, 22.32 g of... A 30% NaOH aqueous solution was heated and stirred at 100℃ for 4 hours. After cooling to room temperature, the mixture was filtered. The resulting solid was melt-crystallized to obtain 9.52 g of p-phenylenediamine product, with a yield of 88% and a purity of >99.95% as determined by GC-MS analysis. The filtrate was adjusted to pH 6 with the addition of hydrochloric acid, resulting in the precipitation of a colorless solid. The solid was filtered, dried, and 16.60 g of phthalic acid was obtained.

[0105] Example 10

[0106] 9.31 g (0.1 mol) aniline, 16.29 g (0.11 mol) phthalic anhydride, and 93.10 g xylene were mixed and heated at 150 °C with stirring for 2 h. GC-MS analysis showed that aniline was completely converted to N-phenylphthalimide, yielding a toluene solution containing 22.32 g (0.1 mol) N-phenylphthalimide. 9.85 g (0.12 mol) hydroxylamine sulfate and 2.23 g N,N-dimethylethanolamine-modified manganese oxide catalyst II were added to this solution, and the mixture was stirred at 120 °C for 2 h, yielding a reaction mixture containing N-p-aminophenylphthalimide and the catalyst. The mixture was cooled to room temperature, allowed to stand, and then centrifuged to separate the N,N-dimethylethanolamine-modified manganese oxide catalyst II for recycling. The resulting liquid was the reaction mixture containing N-p-aminophenylphthalimide. After distilling off the solvent, 44.64 g of xylene was added... A 20% KOH aqueous solution was heated and stirred at 50°C for 6 hours. After cooling to room temperature, the mixture was filtered. The resulting solid was melt-crystallized to obtain 8.87 g of p-phenylenediamine product, with a yield of 82%. GC-MS analysis showed a purity >99.95%. The filtrate was adjusted to pH 7 with hydrochloric acid, and a colorless solid precipitated. The solid was filtered, dried, and 18.18 g of phthalic acid was obtained.

[0107] Example 11

[0108] 9.31 g (0.1 mol) aniline, 15.55 g (0.105 mol) phthalic anhydride, and 74.48 g petroleum ether (90–120 °C) were mixed and heated at 80 °C with stirring for 6 h. GC-MS analysis showed that aniline was completely converted to N-phenylphthalimide, yielding a petroleum ether solution containing 22.32 g (0.1 mol) N-phenylphthalimide. 10.56 g (0.11 mol) hydroxylamine nitrate and 0.22 g N,N-dimethylethanolamine-modified manganese oxide catalyst III were added to this solution, and the mixture was stirred at 50 °C for 6 h. This yielded a reaction mixture containing N-p-aminophenylphthalimide and the catalyst. After cooling to room temperature and allowing to stand, the N,N-dimethylethanolamine-modified manganese oxide catalyst III was separated by centrifugation for recycling. The resulting liquid was the reaction mixture containing N-p-aminophenylphthalimide. After distilling off the solvent, 11.16 g of... A 40% NaOH aqueous solution was heated and stirred at 80°C for 2 hours. After cooling to room temperature, the mixture was filtered. The resulting solid was melt-crystallized to obtain 8.65 g of p-phenylenediamine product, with a yield of 80%. GC-MS analysis showed a purity >99.95%. The filtrate was adjusted to pH 6 with hydrochloric acid, and a colorless solid precipitated. The solid was filtered, dried, and 17.36 g of phthalic acid was obtained.

[0109] Examples 12-17

[0110] Examples 12-17 are similar to Example 9, except that different catalysts are used, while other reaction conditions are the same as in Example 9.

[0111] The difference between Example 12 and Example 9 is that 1.12 g of 8-hydroxyquinoline-modified manganese oxide catalyst IV was used to obtain 8.65 g of p-phenylenediamine product with a yield of 80%; and 16.58 g of phthalic acid was obtained.

[0112] The difference between Example 13 and Example 9 is that: using 1.12g of N,N-dimethylaminoacetic acid-modified manganese oxide catalyst V, 8.98g of p-phenylenediamine product was obtained with a yield of 83%; 16.49g of phthalic acid was also obtained.

[0113] The difference between Example 14 and Example 9 is that: 1.12g of acetylacetone-modified manganese oxide catalyst VI was used to obtain 8.11g of p-phenylenediamine product with a yield of 75%; 16.52g of phthalic acid was also obtained.

[0114] The difference between Example 15 and Example 9 is that 1.12g of ethylene glycol-modified manganese oxide catalyst VII was used to obtain 8.43g of p-phenylenediamine product with a yield of 78%; and 16.56g of phthalic acid was obtained.

[0115] The difference between Example 16 and Example 9 is that 1.12g of catechol-modified manganese oxide catalyst VIII was used to obtain 7.79g of p-phenylenediamine product with a yield of 72%; and 16.60g of phthalic acid was obtained.

[0116] The difference between Example 17 and Example 9 is that: using the N,N-dimethylethanolamine-modified manganese oxide catalyst I separated by centrifugation in Example 9, 9.52 g of p-phenylenediamine product was obtained with a yield of 88%; 16.61 g of phthalic acid was also obtained.

[0117] Comparative Example 18

[0118] Comparative Example 18 is similar to Example 1, except that no ligand is used and the other preparation conditions are the same as in Example 1, yielding 8.69 g of manganese oxide catalyst IX.

[0119] Comparative Examples 19-20

[0120] Comparative Examples 19-20 are similar to Example 1, except that the ligands used are different, while the other preparation conditions are the same as in Example 1.

[0121] The difference between Comparative Example 19 and Example 1 is that 8.69g of o-phenanthroline was used as a ligand to obtain 17.26g of o-phenanthroline-modified manganese oxide catalyst.

[0122] The difference between Comparative Example 20 and Example 1 is that 8.69 g of 2,2'-bipyridine was used as a ligand to obtain 17.30 g of 2,2'-bipyridine-modified manganese oxide catalyst XI.

[0123] Comparative Examples 21-23

[0124] Comparative Examples 21-23 are similar to Example 9, except that the catalyst used is different, while the other reaction conditions are the same as in Example 9.

[0125] The difference between Comparative Example 21 and Example 9 is that 1.12g of manganese oxide catalyst IX was used to obtain 1.73g of p-phenylenediamine product with a yield of 16%; and 16.58g of phthalic acid was obtained.

[0126] The difference between Comparative Example 22 and Example 9 is that 1.12g of o-phenanthroline-modified manganese oxide catalyst X was used to obtain 2.16g of p-phenylenediamine product with a yield of 20%; and 16.59g of phthalic acid was obtained.

[0127] The difference between Comparative Example 23 and Example 9 is that 1.12 g of 2,2'-bipyridine-modified manganese oxide catalyst XI was used to obtain 2.38 g of p-phenylenediamine product with a yield of 22%; and 16.56 g of phthalic acid was obtained.

[0128] Comparative results of Examples 21-23 show that organic modification has a significant impact on the catalytic activity of manganese oxide in the reaction described in this invention. The yield of p-phenylenediamine product is relatively low when manganese oxide catalysts are not modified with ligands or are modified with N,N-bident ligands such as o-phenanthroline and 2,2'-bipyridine.

[0129] Based on the results of the embodiments, it is speculated that the role of the manganese oxide in this invention is to activate the hydroxylamine salt, generating hydroxylamine free radicals that attack N-phenylphthalimide to generate N-p-aminophenylphthalimide; the role of the bidentate ligand is to chelate with the manganese oxide and stabilize it. Due to the electron-donating effect of O, the O,O-bidentate and O,N-bidentate ligands enhance the catalytic activity of the manganese oxide; due to the strong electron-donating effect of N, the N,N-bidentate ligand chelates with the manganese oxide too tightly, which is not conducive to enhancing the catalytic activity of the manganese oxide.

[0130] In summary, this application describes a method for reacting aniline with phthalic anhydride, followed by amination with hydroxylamine salt in the presence of a catalyst, and then hydrolysis to obtain p-phenylenediamine. Using manganese oxide catalysts modified with O,N-bident ligands such as 8-hydroxyquinoline, N,N-dimethylethanolamine, and N,N-dimethylaminoacetic acid, or manganese oxide catalysts modified with O,O-bident ligands such as acetylacetone, ethylene glycol, and catechol, the yield of p-phenylenediamine can reach 72–88%, with a purity >99.95%. This method offers advantages such as low catalyst and reactant cost, high conversion and product selectivity, clean reaction process, and recyclable catalyst.

[0131] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A process for the amination of aniline to produce p-phenylenediamine, characterized in that, The method includes: (1) Mixture I containing aniline, phthalic anhydride and solvent I is reacted to obtain a solution of N-phenylphthalimide; (2) A mixture of N-phenylphthalimide solution, hydroxylamine salt, and catalyst (II) is reacted to obtain p-phenylenediamine; The catalyst is a manganese oxide modified with bidentate ligands; The bidentate ligands in the bidentate ligand-modified manganese oxides are selected from O,N bidentate ligands and / or O,O bidentate ligands; After the catalyst reaction is completed, the catalyst can be separated and recycled. The O,N bidentate ligand is selected from at least one of 8-hydroxyquinoline, N,N-dimethylethanolamine, and N,N-dimethylaminoacetic acid; The O,O bidentate ligand is selected from at least one of acetylacetone, ethylene glycol, and catechol.

2. The method of claim 1, wherein, The method for preparing the organically modified manganese oxide includes: (1) Add KMnO4 aqueous solution dropwise to (CH3COO)2Mn ethanol-water solution, then add ammonia water dropwise until pH is 8~9, reaction III, to obtain manganese oxide; (2) A mixture containing manganese oxide, bidentate ligand, and solvent II is reacted with the mixture III to obtain the organically modified manganese oxide catalyst.

3. The method of claim 2, wherein, The concentration of the KMnO4 aqueous solution is 0.2~0.6 mol / L; The molar ratio of (CH3COO)2Mn in the ethanol-water solution to KMnO4 in the KMnO4 aqueous solution is 1:1 to 2:

1. The concentration of the ethanol-water solution of (CH3COO)2Mn is 0.1~0.3mol / L; In the ethanol-water solution of (CH3COO)2Mn, the volume ratio of ethanol to water is 3:1 to 7:

1. The mass ratio of manganese oxide: bidentate ligand: solvent II is 1:0.2~2:4~8; Solvent II is selected from at least one of toluene, xylene, and petroleum ether.

4. The method according to claim 2, characterized in that, The temperature of reaction III is 25~50℃, and the reaction time is 6~24h; The temperature of reaction IV is 60~120℃, and the reaction time is 2~6h.

5. The method according to claim 1, characterized in that, The hydroxylamine salt is selected from at least one of hydroxylamine hydrochloride, hydroxylamine sulfate, hydroxylamine nitrate, and hydroxylamine phosphate; Solvent I is selected from at least one of toluene, xylene, and petroleum ether.

6. The method according to claim 1, characterized in that, The molar ratio of aniline to phthalic anhydride is 1:1 to 1:1.1; The mass ratio of aniline to solvent I is 1:5 to 1:

10.

7. The method according to claim 1, characterized in that, The molar ratio of the N-phenylphthalimide to the hydroxylamine salt is 1:1 to 1:1.2; The mass of the catalyst is 1% to 10% of the mass of the N-phenylphthalimide.

8. The method according to claim 1, characterized in that, The temperature of reaction I is 80~150℃, and the reaction time is 2~6h; The temperature of reaction II is 50~120℃, and the reaction time is 2~6h.

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