A preparation method of 2,3,3',4'-biphenyltetracarboxylic dianhydride

Abstract

The present invention provides a preparation method of 2,3,3',4'-biphenyltetracarboxylic dianhydride, comprising the following steps: S1: adding 2,3,3',4'-tetramethylbiphenyl and a catalyst into deionized water, introducing air, and reacting at a certain temperature and pressure; S2: after the reaction is completed, cooling to room temperature, adding activated carbon for decolorization, adding a solvent to the filtrate after decolorization, and forming an anhydride at a high temperature; reducing the temperature to precipitate a white solid, and drying the solid to obtain 2,3,3',4'-biphenyltetracarboxylic dianhydride. The beneficial effects of the present invention are as follows: the preparation method of the present invention uses a new process system, is simple to prepare, safe to operate, has little environmental pollution, has a high yield and high purity of the synthesized product, and is suitable for large-scale production.

Description

Technical Field

[0001] The present invention belongs to the field of organic synthesis, and particularly relates to a method for preparing 2,3,3',4'-biphenyltetracarboxylic dianhydride. Background Art

[0002] Polyimide (PI) is a polymer material with an imide ring in its main chain. Due to its unique structure, it has excellent comprehensive properties and is at the forefront of polymer materials. PI has been widely used in the fields of flexible displays, aerospace, electrical insulation, microelectronics, batteries, photoresists, etc.

[0003] Aromatic polyimide contains a rigid imide ring and benzene ring, making it have more excellent thermal stability, mechanical properties and thermal stability. 2,3,3',4'-Biphenyltetracarboxylic dianhydride is an important polyimide monomer, and the polyimide synthesized therefrom has broad application prospects.

[0004] At present, there are mainly two common synthesis methods. One is to synthesize using 3-chlorophthalic anhydride and 4-chlorophthalic anhydride as raw materials. However, this method has a long synthesis route, a long cycle, and a relatively low overall yield. The other is to use 2,3,3',4'-tetramethylbiphenyl as the starting material and form an anhydride after oxidation. The main problem with this oxidation method currently is the oxidation process. The main oxidation methods include pyridine-potassium permanganate, concentrated nitric acid-concentrated sulfuric acid, catalyst-oxygen, etc. The pyridine-potassium permanganate system will produce a large amount of waste solids and has a long reaction cycle; the concentrated nitric acid-concentrated sulfuric acid system will produce a large amount of waste acid solution, polluting the environment; the catalyst-oxygen system, in this method, the catalyst is generally a noble metal, which is expensive and the production cost is too high. Summary of the Invention

[0005] In view of this, the present invention aims to provide a method for preparing 2,3,3',4'-biphenyltetracarboxylic dianhydride with simple process, low production cost, green environmental protection, high product quality and yield, and suitable for large-scale production.

[0006] To achieve the above object, the technical solution of the present invention is realized as follows:

[0007] A method for preparing 2,3,3',4'-biphenyltetracarboxylic dianhydride, comprising the following steps:

[0008] S1: Add 2,3,3',4'-tetramethylbiphenyl and a catalyst to deionized water, introduce air, and react at a certain temperature and pressure;

[0009] S2: After the reaction is completed, cool to room temperature, add activated carbon for decolorization, add a solvent to the filtrate after decolorization, and form an anhydride at high temperature; lower the temperature to precipitate a white solid, and the solid is dried to obtain 2,3,3',4'-biphenyltetracarboxylic dianhydride.

[0010] The mass ratio of the catalyst, deionized water, and 2,3,3',4'-tetramethylbiphenyl is 0.8 - 1.5:10 - 30:1;

[0011] Preferably, the temperature in step S1 is 40 - 70°C;

[0012] Preferably, the pressure in step S1 is 1 - 3 MPa;

[0013] Preferably, the reaction time in step S1 is 24 - 48 h.

[0014] The solvent in step S2 is one or more of benzene, toluene, o-xylene, and o-dichlorobenzene, preferably o-dichlorobenzene;

[0015] Preferably, the mass ratio of the solvent to the filtrate in step S2 is 1.2 - 2:1.

[0016] The temperature for forming the anhydride in step S2 is 110 - 140°C.

[0017] The preparation method of the catalyst includes the following steps: Grind indium nitrate and molybdenum chloride, add them to dimethyl sulfoxide and disperse evenly by ultrasonic wave, then add melamine and cyclohexane-1,4-dialdehyde to the above system, carry out a high-temperature reaction, after the reaction ends, lower the temperature to room temperature, and the solid obtained by filtration is dried in vacuum to obtain the catalyst.

[0018] The molar ratio of indium nitrate, molybdenum chloride, dimethyl sulfoxide, cyclohexane-1,4-dialdehyde, and melamine is 0.1 - 0.3:0.3 - 0.5:20 - 40:1 - 2:1.

[0019] The temperature of the high-temperature reaction is 130 - 160°C.

[0020] Compared with the prior art, the preparation method of 2,3,3',4'-biphenyltetracarboxylic dianhydride described in the present invention has the following advantages:

[0021] The preparation method described in the present invention uses a new process system, which is simple to prepare, safe to operate, has little environmental pollution, has a high yield and high purity of the synthesized product, and is suitable for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0023] Figure 1 It is the synthesis route diagram of 2,3,3',4'-biphenyltetracarboxylic dianhydride prepared in Example 1 of the present invention;

[0024] Figure 2 SEM image of the catalyst prepared in Example 1 of the present invention;

[0025] Figure 3 HPLC chart of 2,3,3',4'-biphenyltetracarboxylic dianhydride prepared in Example 1 of the present invention. Detailed implementation manners

[0026] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments may be combined with each other.

[0027] The present invention will be described in detail below with reference to the drawings and in combination with embodiments.

[0028] Example 1

[0029] (I) Preparation of CT-XO (catalyst)

[0030] After grinding indium nitrate and molybdenum chloride in a mortar, 95.41 g and 173.32 g were respectively weighed and added to 3700 g of dimethyl sulfoxide, and ultrasonic treatment was carried out for 2 h to make them disperse evenly; then 200 g of melamine and 333.44 g of cyclohexane-1,4-dicarboxaldehyde were added to the above system, the temperature was raised to 150 °C, and the reaction was kept for 72 h under vigorous stirring. A large amount of gray solid precipitated out. After cooling to room temperature, the solid was filtered and vacuum dried at 120 °C for 24 h to obtain 650.76 g of self-made catalyst CT-XO.

[0031] (II) Synthesis of α-BPDA

[0032] 100 g of 2,3,3',4'-tetramethylbiphenyl and 120 g of CT-XO catalyst were added to 1500 g of deionized water, air was introduced, the pressure was maintained at 2.2 MPa, the temperature was raised to 50 °C, and the reaction was kept for 36 h. After the reaction was completed, the temperature was lowered to room temperature, and the catalyst was filtered off. 15 g of activated carbon was added to the filtrate, stirred at room temperature for 1 h, filtered, and the filtrate changed from dark brown to colorless and transparent. Then 2250 g of o-dichlorobenzene was added to the filtrate, the temperature was raised to 130 °C, water was refluxed and removed, solids gradually precipitated in the system, and it was kept for 13 h until no more water was distilled out. After the temperature was lowered to room temperature, the solid was filtered and vacuum dried at 130 °C for 24 h to obtain 121.34 g of 2,3,3',4'-biphenyltetracarboxylic dianhydride, with a molar yield of 86.74%, a purity of 99.90%, and YI = 0.89.

[0033] Example 2

[0034] 100 g of 2,3,3',4'-tetramethylbiphenyl and 100 g of CT-XO catalyst were added to 2000 g of deionized water. Air was introduced, and the pressure was maintained at 1.8 MPa. The temperature was raised to 60 °C, and the reaction was carried out under insulation for 40 h. After the reaction, the temperature was lowered to room temperature, and the catalyst was removed by filtration. 10 g of activated carbon was added to the filtrate, and it was stirred at room temperature for 1 h. After filtration, the filtrate changed from dark brown to colorless and transparent. Then, 2000 g of o-xylene was added to the filtrate, and the temperature was raised to 110 °C. Water was removed by reflux. Solids gradually precipitated in the system. It was kept for 18 h until no more water was distilled out. The temperature was lowered to room temperature. After the solids were filtered, they were dried in vacuo at 130 °C for 24 h to obtain 112.57 g of 2,3,3',4'-biphenyltetracarboxylic dianhydride, with a molar yield of 80.47%, a purity of 99.73%, and YI = 1.23.

[0035] Example 3

[0036] (I) Regeneration of CT-XO

[0037] The filtered catalyst CT-XO in Example 1 was added to 1200 g of deionized water and soaked at 80 °C for 24 h. After filtration, it was dried in vacuo at 110 °C for 12 h to obtain the regenerated catalyst CT-XO-recovered.

[0038] 100 g of 2,3,3',4'-tetramethylbiphenyl and CT-XO-recovered were added to 1500 g of deionized water. Air was introduced, and the pressure was maintained at 2.2 MPa. The temperature was raised to 50 °C, and the reaction was carried out under insulation for 36 h. After the reaction, the temperature was lowered to room temperature, and the catalyst was removed by filtration. 15 g of activated carbon was added to the filtrate, and it was stirred at room temperature for 1 h. After filtration, the filtrate changed from dark brown to colorless and transparent. Then, 2250 g of o-dichlorobenzene was added to the filtrate, and the temperature was raised to 130 °C. Water was removed by reflux. Solids gradually precipitated in the system. It was kept for 13 h until no more water was distilled out. The temperature was lowered to room temperature. After the solids were filtered, they were dried in vacuo at 130 °C for 24 h to obtain 111.13 g of 2,3,3',4'-biphenyltetracarboxylic dianhydride, with a molar yield of 79.44%, a purity of 99.74%, and YI = 1.09.

[0039] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

[0040] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation method of 2,3,3',4'-biphenyltetracarboxylic dianhydride, which is characterized in that: It includes the following steps: S1: Add 2,3,3',4'-tetramethylbiphenyl and a catalyst into deionized water, introduce air, and react under certain temperature and pressure; S2: After the reaction ends, cool it to room temperature, add activated carbon for decolorization, add a solvent to the filtrate after decolorization, and form an anhydride at high temperature; lower the temperature to precipitate a white solid, and the solid is dried to obtain 2,3,3',4'-biphenyltetracarboxylic dianhydride; The preparation method of the catalyst includes the following steps: After grinding indium nitrate and molybdenum chloride, add them to dimethyl sulfoxide and disperse evenly by ultrasonic wave, then add melamine and cyclohexane-1,4-dialdehyde to the above system, react at high temperature, after the reaction ends, cool it to room temperature, and the solid obtained after filtration is dried in vacuum to obtain the catalyst.

2. The preparation method of 2,3,3',4'-biphenyltetracarboxylic dianhydride according to claim 1, which is characterized in that: The mass ratio of the catalyst, deionized water, and 2,3,3',4'-tetramethylbiphenyl is 0.8 - 1.5:10 - 30:

1.

3. The preparation method of 2,3,3',4'-biphenyltetracarboxylic dianhydride according to claim 2, which is characterized in that: The temperature in step S1 is 40 - 70 °C.

4. The preparation method of 2,3,3',4'-biphenyltetracarboxylic dianhydride according to claim 2, which is characterized in that: The pressure in step S1 is 1 - 3 MPa.

5. The preparation method of 2,3,3',4'-biphenyltetracarboxylic dianhydride according to claim 2, which is characterized in that: The reaction time in step S1 is 24 - 48 h.

6. The preparation method of 2,3,3',4'-biphenyltetracarboxylic dianhydride according to claim 1, which is characterized in that: The solvent in step S2 is one or more of benzene, toluene, o-xylene, and o-dichlorobenzene.

7. The preparation method of 2,3,3',4'-biphenyltetracarboxylic dianhydride according to claim 6, which is characterized in that: The solvent in step S2 is o-dichlorobenzene.

8. The preparation method of 2,3,3',4'-biphenyltetracarboxylic dianhydride according to claim 6, which is characterized in that: The mass ratio of the solvent and the filtrate in step S2 is 1.2 - 2:

1.

9. The preparation method of 2,3,3',4'-biphenyltetracarboxylic dianhydride according to claim 1, which is characterized in that: The temperature for forming an anhydride in step S2 is 110 - 140 °C.

10. The preparation method of 2,3,3',4'-biphenyltetracarboxylic dianhydride according to claim 1, which is characterized in that: The molar ratio of indium nitrate, molybdenum chloride, dimethyl sulfoxide, cyclohexane-1,4-dialdehyde, and melamine is 0.1 - 0.3:0.3 - 0.5:20 - 40:1 - 2:

1.

11. The preparation method of 2,3,3',4'-biphenyltetracarboxylic dianhydride according to claim 1, which is characterized in that: The temperature of the high-temperature reaction is 130 - 160 °C.

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