A process for the preparation of high quality 4,4'-diamino-2,2'-dimethylbiphenyl

Abstract

The application provides a preparation method of high-quality 4,4'-diamino-2,2'-dimethylbiphenyl, which comprises the following steps: 2,2'-bis(trifluoromethyl)-(1,1'-diphenyl)-4,4'-diamine is added into an acid solution, a catalyst and ammonium formate are added; after the reaction is completed, the catalyst is recovered by filtration, the filtrate is subjected to decolorization and removal of metal ions; and 4,4'-diamino-2,2'-dimethylbiphenyl is obtained through post-treatment. The application has the beneficial effects that: the preparation method uses a new process system, is environment-friendly, safe to operate, and high in product quality, and is suitable for large-scale production.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of organic synthesis, and particularly relates to a preparation method of high-quality 4,4'-diamino-2,2'-dimethylbiphenyl. BACKGROUND

[0002] Polyimide (PI) is a kind of high polymer material containing imide rings in the main chain. Due to its unique structure, it has excellent comprehensive performance and is at the forefront of high polymer materials. Polyimide has been widely used in flexible display, aerospace, electrical insulation, microelectronics, batteries, photoresist and other fields.

[0003] Aromatic polyimide has more excellent mechanical properties and thermal stability due to the presence of rigid imide rings and benzene rings. 4,4'-diamino-2,2'-dimethylbiphenyl is an important polyimide monomer, and the polyimide synthesized therefrom has broad application prospects.

[0004] At present, there are mainly two routes for the common synthesis method. The first route (DOI: 10.1021 / acs.orglett.2c02866) synthesizes 3,3'-dimethylazobenzene from 3-methylaniline, and then acidizes to obtain 4,4'-diamino-2,2'-dimethylbiphenyl. In the first step, a strong alkaline catalyst is needed, which is expensive and has high industrialization cost. The second route (KR2020 / 99468) is prepared by coupling 2-bromo-5-nitrotoluene, and then reduced to obtain 4,4'-diamino-2,2'-dimethylbiphenyl. In the first step, the coupling yield is low, and in the second step, palladium-carbon-hydrogen gas reduction is used, so the cost of this route is also high, and the scale production is limited to a certain extent. SUMMARY

[0005] Therefore, the application aims to provide a preparation method of high-quality 4,4'-diamino-2,2'-dimethylbiphenyl to solve the problems of high industrialization cost, low product quality and yield, and unsuitability for scale production in the preparation of 4,4'-diamino-2,2'-dimethylbiphenyl.

[0006] To achieve the above-mentioned purpose, the technical scheme of the application is as follows:

[0007] A preparation method of high-quality 4,4'-diamino-2,2'-dimethylbiphenyl, comprising the following steps:

[0008] 2,2'-bis(trifluoromethyl)-(1,1'-biphenyl)-4,4'-diamine (TFMB) is added to an acid solution, a catalyst, ammonium formate are added; after the reaction is completed, the catalyst is recovered by filtration, and the filtrate is subjected to decolorization and removal of metal ions; post-treatment to obtain 4,4'-diamino-2,2'-dimethylbiphenyl. The 4,4'-diamino-2,2'-dimethylbiphenyl prepared by the above steps has a color YI of less than 0.8, a single metal ion of less than 80 ppb, and a polymerization viscosity of 0.98-1.2 million when polymerized with commercial hexafluorodianhydride (6FDA), 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA), and 4,4'-diphenyl ether dianhydride (ODPA).

[0009] Further, the 2,2'-bis(trifluoromethyl)-(1,1'-biphenyl)-4,4'-diamine is reacted with an acid solution, a catalyst, and ammonium formate for 1-5 h, and the mass ratio of the acid solution, the catalyst, and the 2,2'-bis(trifluoromethyl)-(1,1'-biphenyl)-4,4'-diamine is 2-5:0.1-0.4:1.

[0010] Further, the molar ratio of the ammonium formate and the 2,2'-bis(trifluoromethyl)-(1,1'-biphenyl)-4,4'-diamine is 6-10:1.

[0011] Further, activated carbon and resin are sequentially added to the filtrate to perform decolorization and removal of metal ions, and the mass ratio of the activated carbon, the resin, and the 2,2'-bis(trifluoromethyl)-(1,1'-biphenyl)-4,4'-diamine is 0.05-0.2:0.5-1:1.

[0012] Further, the acid solution is one of an aqueous hydrochloric acid solution, an aqueous sulfuric acid solution, an aqueous hydrogen fluoride solution, and an aqueous phosphoric acid solution, and is preferably an aqueous hydrochloric acid solution; the concentration of the aqueous hydrochloric acid solution is 0.5-1.5 mol / L.

[0013] Further, the reaction temperature is 60-90℃, and the reaction pressure is 0.3-0.5 MPa.

[0014] Further, the post-treatment step is as follows: the PH of the filtrate is adjusted to 7.5-8.5 by using a PH adjusting solvent to precipitate a large amount of white solids, the white solids are washed with ethanol and then vacuum dried; the PH adjusting solvent is one or two or more of pyridine, triethylamine, and aqueous ammonia, and is preferably aqueous ammonia.

[0015] Further, the preparation method of the catalyst comprises the following steps:

[0016] The carbon nanotube is added into ethanol, heated to reflux, and N-(6-aminohexyl) aminomethyl triethoxysilane is added dropwise, and then the mixture is kept warm, cooled to room temperature, and filtered to obtain functionalized carbon nanotube N-CNT; the functionalized carbon nanotube N-CNT is added into an aqueous ferric chloride solution, stirred at room temperature, and filtered, and the solid is vacuum dried to obtain the catalyst.

[0017] Further, the mass ratio of the N-(6-aminohexyl) aminomethyl triethoxysilane to the carbon nanotube is 0.01-0.1:1, the mass ratio of the aqueous ferric chloride solution to the functionalized carbon nanotube N-CNT is 8-15:1, and the concentration of the aqueous ferric chloride solution is 70-120 mg / L.

[0018] Further, the keeping warm time is 6-12 h, the stirring time at room temperature is 10-18 h, and the vacuum drying temperature is 90-120 DEG C.

[0019] Compared with the prior art, the preparation method of high-quality 4,4'-diamino-2,2'-dimethyl diphenyl has the following advantages:

[0020] The preparation method uses a new process system, uses commercial 2,2'-bis(trifluoromethyl)-(1,1'-diphenyl)-4,4'-diamine as a starting material, has simple preparation process, safe operation, low production cost, green environmental protection, and the catalyst can be repeatedly used, and has high product yield and high purity, and is suitable for large-scale production. BRIEF DESCRIPTION OF DRAWINGS

[0021] The drawings constituting a part of this application are used to provide further understanding of the application, and the schematic embodiments of the application and the description thereof are used to explain the application, and do not constitute improper limitation on the application. In the drawings:

[0022] Figure 1 The synthesis route diagram of 4,4'-diamino-2,2'-dimethyl diphenyl described in the embodiments of the application;

[0023] Figure 2 The HPLC diagram of 4,4'-diamino-2,2'-dimethyl diphenyl described in the embodiment 1 of the application;

[0024] Figure 3 The TEM diagram of the catalyst described in the embodiment 1 of the application. DETAILED DESCRIPTION

[0025] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other in the case of no conflict. Unless defined, the technical terms used in the following embodiments have the same meaning as generally understood by those skilled in the art to which the present application belongs. The test reagents used in the following embodiments are all conventional biochemical reagents unless otherwise specified; and the experimental methods used are all conventional methods unless otherwise specified.

[0026] The present application will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0027] Embodiment 1

[0028] (I) Preparation of catalyst

[0029] 20 g of carbon nanotubes were added to 400 ml of ethanol, heated to reflux, and 0.8 g of N-(6-aminohexyl) aminomethyl triethoxysilane was added dropwise, and the reaction was maintained for 10 h, and then reduced to room temperature, and functionalized carbon nanotubes N-CNT were obtained by filtration. The functionalized carbon nanotubes N-CNT were added to 220 mL of 100 mg / L aqueous solution of ferric chloride, stirred at room temperature for 12 h, filtered, and the solid was vacuum dried at 110°C for 24 h to obtain 19.5 g of catalyst.

[0030] (II) Synthesis of 4,4'-diamino-2,2'-dimethylbiphenyl

[0031] 10 g of 2,2'-bis(trifluoromethyl)-(1,1'-diphenyl)-4,4'-diamine, 0.3 g of catalyst, 11.81 g of ammonium formate, and 30 g of 0.8 mol / L aqueous hydrochloric acid solution were added to an autoclave, heated to 70°C, and the pressure was maintained at 0.4 MPa for 3 h; reduced to room temperature, recovered the catalyst by filtration, added 0.1 g of activated carbon to the filtrate, stirred at room temperature for 1 h, filtered, added 6 g of resin to the filtrate and stirred for 1 h, and filtered; the pH of the filtrate was adjusted to 7.6 with ammonia water, and a large amount of white solid was precipitated, the white solid was washed with 50 mL of ethanol at room temperature for 30 min, filtered, and dried at 90°C under vacuum for 12 h to obtain 6.47 g of 4,4'-diamino-2,2'-dimethylbiphenyl, with a molar yield of 97.59%, a purity of 99.99%, YI = 0.31, and a single metal ion of less than 80 ppb, and a polymerization viscosity with 6FDA of 1.18 million.

[0032] Embodiment 2

[0033] Into an autoclave were added 10 g of 2,2'-bis(trifluoromethyl)-(1,1'-biphenyl)-4,4'-diamine, 0.2 g of catalyst, 9.12 g of ammonium formate, and 40 g of 1.5 mol / L aqueous hydrochloric acid solution, and the temperature was raised to 90°C, and the pressure was maintained at 0.3 MPa for 3 h. The temperature was lowered to room temperature, and the catalyst was recovered by filtration. 0.15 g of activated carbon was added to the filtrate, and stirred at room temperature for 1 h, and filtered. 5 g of resin was added to the filtrate, and stirred for 1 h, and filtered. The pH of the filtrate was adjusted to 7.8 using ammonia water, and a large amount of white solid was precipitated. The white solid was washed with 50 mL of ethanol at room temperature for 30 min, and filtered, and dried at 90°C under vacuum for 12 h to obtain 6.44 g of 4,4'-diamino-2,2'-dimethylbiphenyl, with a molar yield of 97.21%, a purity of 99.93%, YI = 0.38, and a single metal ion of less than 80 ppb, and a polymerization viscosity with BTDA of 1.03 million.

[0034] Example 3

[0035] Into an autoclave were added 10 g of 2,2'-bis(trifluoromethyl)-(1,1'-biphenyl)-4,4'-diamine, 0.2 g of catalyst, 9.12 g of ammonium formate, and 40 g of 1.5 mol / L aqueous hydrochloric acid solution, and the temperature was raised to 90°C, and the pressure was maintained at 0.3 MPa for 3 h. The temperature was lowered to room temperature, and the catalyst was recovered by filtration. 0.15 g of activated carbon was added to the filtrate, and stirred at room temperature for 1 h, and filtered. 5 g of resin was added to the filtrate, and stirred for 1 h, and filtered. The pH of the filtrate was adjusted to 7.8 using ammonia water, and a large amount of white solid was precipitated. The white solid was washed with 50 mL of ethanol at room temperature for 30 min, and filtered, and dried at 90°C under vacuum for 12 h to obtain 6.44 g of 4,4'-diamino-2,2'-dimethylbiphenyl, with a molar yield of 97.21%, a purity of 99.93%, YI = 0.38, and a single metal ion of less than 80 ppb, and a polymerization viscosity with BTDA of 1.03 million.

[0036] Example 4

[0037] The 10 g 2,2'-di(trifluoromethyl)-(1,1'-biphenyl)-4,4'-diamine, the catalyst recovered in Example 1, 11.81 g of ammonium formate, 30 g of 0.8 mol / L hydrochloric acid aqueous solution were added into an autoclave, heated to 70°C, and the pressure was kept at 0.4 MPa for 3 h; reduced to room temperature, filtered to recover the catalyst, 0.1 g of activated carbon was added into the filtrate, stirred at room temperature for 1 h, filtered, 6 g of resin was added into the filtrate and stirred for 1 h, filtered; the pH of the filtrate was adjusted to 7.6 with ammonia water, and a large amount of white solid was precipitated, the white solid was washed with 50 mL of ethanol at room temperature for 30 min, filtered, and dried at 90°C under vacuum for 12 h to obtain 6.45 g of 4,4'-diamino-2,2'-dimethylbiphenyl, the molar yield was 97.29%, the purity was 99.95%, YI=0.34, the single metal ion was less than 80 ppb, and the polymerization viscosity with 6FDA was 1.18 million.

[0038] The catalyst was reused in this way, and repeated 4 times, the molar yield was 96.97%-97.21%, the purity was 99.87%-99.94%, the single metal ion was less than 80 ppb, and the polymerization viscosity with 6FDA was 115-117 million.

[0039] Comparative Example 1

[0040] Under nitrogen protection, 10 g of 3-methylaniline, 0.3 g of cuprous bromide, and 0.7 g of pyridine were added into 400 g of toluene, heated to 60°C and reacted for 20 h. After the reaction was completed, 300 g of toluene was distilled off, the temperature was reduced to 0°C, and a solid was precipitated, which was dried at 110°C under vacuum for 12 h to obtain 8.45 g of intermediate (3,3'-azotoluene); 8.45 g of 3,3'-azotoluene was added into 80 g of methanol, and then 15 g of concentrated sulfuric acid was added dropwise, heated to 60°C and reacted for 12 h. After the reaction was completed, the temperature was reduced to 0°C, and a white solid was precipitated, which was recrystallized again using 80 g of methanol reflux, washed with ammonia water to pH=7-8, and dried at 110°C under vacuum for 12 h to obtain 7.42 g of 4,4'-diamino-2,2'-dimethylbiphenyl, the total molar yield was 74.95%, the purity was 99.18%, YI=6.8, the single metal ion was greater than 800 ppb (copper ion was 3.2 ppm), and the polymerization viscosity with ODPA was 0.39 million.

[0041] Comparative Example 2

[0042] Under nitrogen protection, 10 g of 2-bromo-5-nitrotoluene, 0.2 g of copper powder, 80 mL of dimethylformamide were added into an autoclave, heated to 180 °C, the pressure was 2 MPa, and the reaction was kept for 24 h. After the reaction was completed, the temperature was reduced to room temperature, 100 g of deionized water was added, yellow solid was precipitated, 200 g of methanol was used to wash for 30 min, and then the solid was filtered and dried at 90 °C under vacuum to obtain 4.79 g of 4,4'-dinitro-2,2'-dimethylbiphenyl; 4.79 g of 4,4'-dinitro-2,2'-dimethylbiphenyl, 0.3 g of 10% palladium on carbon and 100 g of methanol were added into an autoclave, heated to 50 °C, hydrogen was introduced, the pressure was 0.6 MPa, and the reaction was kept for 9 h. After the reaction was completed, the mixture was filtered hot, the filtrate was reduced to 5 °C, white solid was precipitated, and the solid was dried at 90 °C under vacuum for 12 h to obtain 3.55 g of 4,4'-diamino-2,2'-dimethylbiphenyl, the total molar yield was 72.3%, the purity was 99.72%, YI = 7.9, the single metal ion was greater than 600 ppb (the copper ion was 1.5 ppm), and the polymerization viscosity of ODPA was 410,000.

[0043] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A process for the preparation of 4,4'-diamino-2,2'-dimethylbiphenyl, characterized in that: It comprises the following steps: 2,2'-bis(trifluoromethyl)-(1,1'-biphenyl)-4,4'-diamine is added to an acid solution, a catalyst, ammonium formate are added, the reaction temperature is 60-90 DEG C, the reaction pressure is 0.3-0.5 MPa; after the reaction is completed, the catalyst is recovered by filtration, the filtrate is decolorized and metal ions are removed; after-treatment is carried out to obtain 4,4'-diamino-2,2'-dimethyl biphenyl; The acid solution is one of an aqueous hydrochloric acid solution, an aqueous sulfuric acid solution, an aqueous hydrogen fluoride solution and an aqueous phosphoric acid solution. The preparation method of the catalyst comprises the following steps: Carbon nanotubes are added to ethanol, the temperature is raised to reflux, N-(6-aminohexyl) aminomethyl triethoxysilane is added dropwise, the temperature is kept constant, the temperature is lowered to room temperature, and functionalized carbon nanotubes N-CNT are obtained after filtration; the functionalized carbon nanotubes N-CNT are added to an aqueous ferric chloride solution, stirring is carried out at room temperature, and the catalyst is obtained after filtration and vacuum drying of the solid; The mass ratio of the N-(6-aminohexyl) aminomethyl triethoxysilane to the carbon nanotubes is 0.01-0.1:1, the mass ratio of the aqueous ferric chloride solution to the functionalized carbon nanotubes N-CNT is 8-15:1, and the concentration of the aqueous ferric chloride solution is 70-120 mg / L.

2. A process for the preparation of 4,4'-diamino-2,2'-dimethylbiphenyl according to claim 1, characterized in that: The 2,2'-bis(trifluoromethyl)-(1,1'-biphenyl)-4,4'-diamine is reacted with the acid solution, the catalyst and ammonium formate for 1-5 h, and the mass ratio of the acid solution, the catalyst and the 2,2'-bis(trifluoromethyl)-(1,1'-biphenyl)-4,4'-diamine is 2-5:0.1-0.4:

1.

3. The process for the preparation of 4,4'-diamino-2,2'-dimethylbiphenyl according to claim 1, characterized in that: The molar ratio of the ammonium formate to the 2,2'-bis(trifluoromethyl)-(1,1'-biphenyl)-4,4'-diamine is 6-10:

1.

4. The process for the preparation of 4,4'-diamino-2,2'-dimethylbiphenyl according to claim 1, characterized in that: The filtrate is decolorized and metal ions are removed by sequentially adding activated carbon and resin, and the mass ratio of the activated carbon, the resin and the 2,2'-bis(trifluoromethyl)-(1,1'-biphenyl)-4,4'-diamine is 0.05-0.2:0.5-1:

1.

5. The process for the preparation of 4,4'-diamino-2,2'-dimethylbiphenyl according to claim 1, characterized in that: The acid solution is an aqueous hydrochloric acid solution.

6. The process for the preparation of 4,4'-diamino-2,2'-dimethylbiphenyl according to claim 1, characterized in that: The after-treatment step is that the PH of the filtrate is adjusted to 7.5-8.5 by using a PH adjusting solvent, a large amount of white solid is precipitated, the white solid is washed by ethanol and vacuum dried; The PH adjusting solvent is one or two or more of pyridine, triethylamine and aqueous ammonia.

7. A process for the preparation of 4,4'-diamino-2,2'-dimethylbiphenyl according to claim 6, characterized in that: The PH adjusting solvent is aqueous ammonia.

8. The process for the preparation of 4,4'-diamino-2,2'-dimethylbiphenyl according to claim 1, characterized in that: In the preparation method of the catalyst, the heat preservation time is 6-12 h, the stirring time at room temperature is 10-18 h, and the vacuum drying temperature is 90-120 DEG C.

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