4, 4, 4apos; synthesis method of-bis (4-aminophenoxy) biphenyl

Abstract

The invention discloses a synthesis method of 4, 4 '-bis (4-aminophenoxy) biphenyl, which comprises the following steps: (1) carrying out salt forming reaction on p-aminophenol and inorganic strong alkali to obtain a suspension containing p-aminophenol salt; the salt forming reaction is carried out in the presence of sodium hydrosulfite; and (2) reacting the p-aminophenol suspension obtained in the step (1) with 4, 4 '-dihalogenated biphenyl to obtain 4, 4'-bis (4-aminophenoxy) biphenyl. The method provided by the invention not only avoids the problem of high production cost caused by the need of a noble metal catalyst for catalytic hydrogenation in the prior art, but also avoids the problems of more three wastes and environmental unfriendliness in the prior art, and has the advantages of low production cost, high safety, environmental friendliness and suitability for industrial mass production.

Description

Technical Field

[0001] This invention belongs to the field of organic synthesis technology, specifically relating to a method for synthesizing 4,4'-bis(4-aminophenoxy)biphenyl. Background Technology

[0002] Polyimide, as a special engineering material, has been widely used in aerospace, microelectronics, nanotechnology, liquid crystals, separation membranes, lasers, and other fields. In the 1960s, countries around the world listed the research, development, and utilization of polyimide as one of the most promising engineering plastics of the 21st century. Due to its outstanding performance and synthesis characteristics, its huge application prospects, whether as a structural material or a functional material, have been fully recognized.

[0003] 4,4'-Bis(4-aminophenoxy)biphenyl is a symmetrical diphenyl ether diamine monomer, CAS number 13080-85-8, with the molecular formula C4. 24 H 20 N2O2, with a relative molecular weight of 368.43, is a white powder with a melting range of 197–200°C. It is mainly used in the field of polyimide.

[0004] Currently, the methods for synthesizing 4,4'-bis(4-aminophenoxy)biphenyl are basically as follows: 4,4'-dihydroxybiphenyl is first reacted with 4-chloronitrobenzene to obtain 4,4'-bis(4-nitrophenoxy)biphenyl [see Non-Patent Literature 1, 2 and Patent Literature 2], and then further reduced to obtain 4,4'-bis(4-aminophenoxy)biphenyl [see Non-Patent Literature 1, 2 and Patent Literature 1, 2].

[0005] The synthesis route is as follows: .

[0006] The shortcomings of this synthetic route are: (1) The reduction system used in Non-Patent Literature 1 is palladium on carbon / hydrazine hydrate, which has the disadvantages of high toxicity of raw materials, difficulty in recycling and treating waste gas and wastewater, high pollution of three wastes, and unfriendly to the environment; (2) The reduction system used in Non-Patent Literature 2 and Patent Literature 1 and 2 is precious metal catalyst / hydrogen, which has the disadvantages of high reaction pressure, poor safety, high price of precious metal catalyst, and high production cost.

[0007] Non-patent literature 1: Synthesis of 4,4'-bis(4-aminophenoxy)biphenyl and its surface properties of polyimide film, Yu Xinhai, Insulating Materials, Vol. 41, No. 2, 2008, pp. 10-14.

[0008] Non-Patent Literature 2: Synthesis of 4,4'-bis(4-aminophenoxy)biphenyl, Cao Longhai et al., Heilongjiang Science, No. 10, 2013, pp. 24-25.

[0009] Patent Document 1: Chinese Patent Document CN103450037A, Publication Date: December 18, 2013.

[0010] Patent Document 2: Chinese Patent Document CN105294461A, Publication Date: February 3, 2016. Summary of the Invention

[0011] The purpose of this invention is to solve the above-mentioned problems by providing a method for synthesizing 4,4'-bis(4-aminophenoxy)biphenyl, which solves the problems of high production cost, poor safety and environmental unfriendliness of the prior art.

[0012] The technical solution to achieve the objective of this invention is: a method for synthesizing 4,4'-bis(4-aminophenoxy)biphenyl, comprising the following steps: ① A salt-forming reaction is carried out between p-aminophenol and an inorganic strong base to obtain a suspension containing p-aminophenol salt; the salt-forming reaction is carried out in the presence of sodium hydrosulfite. ② The suspension of p-aminophenol salt obtained in step ① is reacted with 4,4'-dihalobiphenyl to obtain 4,4'-bis(4-aminophenoxy)biphenyl.

[0013] The applicant discovered that the yield and purity of the product obtained by reacting p-aminophenol with an inorganic strong base first to form a salt, followed by reaction with 4,4'-dihalobiphenyl, were both low. The main reason was that p-aminophenol was easily oxidized to form impurities such as aminophenoxazine derivatives, even under nitrogen protection, which severely affected the product yield and purity. Through extensive experimentation, the applicant found that introducing sodium hydrosulfite could effectively prevent the occurrence of related side reactions, greatly improving the product yield and purity.

[0014] In step ① above, the amount of sodium hydrosulfite used is 1% to 3% of the weight of p-aminophenol.

[0015] In step ① above, the inorganic strong base is sodium hydroxide or potassium hydroxide; the molar ratio of p-aminophenol to the inorganic strong base is 1:1 to 1:1.02.

[0016] In step ① above, the salt formation reaction is carried out in the presence of an organic solvent; the organic solvent is toluene or xylene; the weight ratio of p-aminophenol to the organic solvent is 1:8 to 1:10.

[0017] In step ① above, the salt formation reaction is carried out in toluene solvent at a reaction temperature of 110–120°C, and the dehydration method is to remove water by reflux of toluene.

[0018] In step ① above, the salt formation reaction is carried out in xylene solvent at a reaction temperature of 140–150°C, and the dehydration method is nitrogen purging to remove water.

[0019] In step ② above, the 4,4'-dihalobiphenyl is 4,4'-difluorobiphenyl, 4,4'-dichlorobiphenyl, or 4,4'-dibromobiphenyl; the molar ratio of the 4,4'-dihalobiphenyl to the p-aminophenol is 1:1.8 to 1:2.2.

[0020] The reaction in step ② above is carried out in the presence of a polar solvent; the organic solvent is N,N-dimethylformamide or N,N-dimethylacetamide; the amount of the polar solvent is 5 to 15% of the weight of the p-aminophenol.

[0021] In step ② above, the reaction temperature is 100-110℃ and the reaction time is 5-6h.

[0022] The positive effects of this invention are: (1) The method of the present invention avoids the problem of high production cost caused by the use of precious metal catalysts for catalytic hydrogenation in the prior art, and also avoids the problem of excessive waste and environmental unfriendliness in the prior art. It has the advantages of low production cost, high safety, more environmental friendliness and suitability for large-scale industrial production.

[0023] (2) The method of the present invention can effectively prevent the occurrence of related side reactions by introducing sodium hydrosulfite, and greatly improve the yield and purity of the product. Attached Figure Description

[0024] Figure 1 This is the LC-MS spectrum of the final product obtained in Example 1. Detailed Implementation

[0025] (Example 1) The reaction formula for the synthesis of 4,4'-bis(4-aminophenoxy)biphenyl in this embodiment is as follows: .

[0026] The specific method is as follows: ① Under nitrogen protection, 400g of toluene was added to a 2L four-necked flask, followed by 50g of p-aminophenol (0.46mol). After stirring evenly, 18.4g of sodium hydroxide (0.46mol), 1g of sodium hydrosulfite, and 50g of toluene were added. A reflux separator was set up and the temperature was raised to 110-120℃ for reflux reaction. During the reaction, the water produced was continuously carried out by the toluene under reflux, and a large amount of white solid was produced. The reflux state was maintained for 2-3 hours until no water was carried out by the toluene. The temperature was then lowered to obtain a toluene suspension of sodium p-aminophenol, which was ready for use.

[0027] ② Under nitrogen protection, 5g of N,N-dimethylformamide and 43.5g of 4,4'-difluorobiphenyl (0.23mol) were added to the suspension obtained in step ①. The temperature was slowly raised to 100-110℃ and the reaction was maintained for 5-6 hours. Samples were taken to monitor the raw material p-aminophenol content, which was less than 1%. The temperature was then lowered to 80-90℃, and 250g of purified water was added. The mixture was stirred for another 0.5 hours, allowed to stand and separate into layers, and the lower aqueous phase was removed. Another 250g of purified water was added to the organic phase, and the mixture was stirred at 80-90℃ for another 0.5 hours. The mixture was allowed to stand and separate into layers, and the lower aqueous phase was removed. The organic phase was cooled to 0-5℃, filtered, and the filter cake was washed with a small amount of frozen toluene. The wet product was placed in an oven and vacuum dried at 60-70℃ for 6 hours to obtain 79.6g of white crystalline powder 4,4'-bis(4-aminophenoxy)biphenyl, with a yield of 94.3% and an HPLC purity of 99.6%.

[0028] The LC-MS spectrum of the final product obtained in this embodiment is shown in the appendix. Figure 1 ,Depend on Figure 1 It can be seen that the molecular weight of the final product is 368.2, which is consistent with 4,4'-bis(4-aminophenoxy)biphenyl.

[0029] (Comparative Example 1) The difference between this comparative example and Example 1 is that 1g of sodium hydrosulfite was not added in step ①, resulting in 69.6g of 4,4'-bis(4-aminophenoxy)biphenyl with a yield of 82.5% and an HPLC purity of 95.7%.

[0030] (Examples 2-3) The synthesis methods of 4,4'-bis(4-aminophenoxy)biphenyl in each embodiment are basically the same as those in Example 1, except for the types of 4,4'-dihalobiphenyl, as shown in Table 1.

[0031] Table 1 Example 1 Example 2 Example 3 4,4'-Dihalobiphenyl 43.5 g of 4,4'-difluorobiphenyl (0.23 mol) 51.0 g of 4,4'-dichlorobiphenyl (0.23 mol) 71.3 g of 4,4'-dibromobiphenyl (0.23 mol) product 79.6g 79.7g 79.5g yield 94.3% 94.4% 94.2% purity 99.6% 99.5% 99.8%

Claims

1. A method for synthesizing 4,4'-bis(4-aminophenoxy)biphenyl, characterized in that... It includes the following steps: ① A salt-forming reaction is carried out between p-aminophenol and an inorganic strong base to obtain a suspension containing p-aminophenol salt; the salt-forming reaction is carried out in the presence of sodium hydrosulfite; ② The suspension of p-aminophenol salt obtained in step ① is reacted with 4,4'-dihalobiphenyl to obtain 4,4'-bis(4-aminophenoxy)biphenyl.

2. The method for synthesizing 4,4'-bis(4-aminophenoxy)biphenyl according to claim 1, characterized in that: In step ① above, the amount of sodium hydrosulfite used is 1% to 3% of the weight of p-aminophenol.

3. The method for synthesizing 4,4'-bis(4-aminophenoxy)biphenyl according to claim 1 or 2, characterized in that: In step ① above, the inorganic strong base is sodium hydroxide or potassium hydroxide; the molar ratio of p-aminophenol to the inorganic strong base is 1:1 to 1:1.

02.

4. The method for synthesizing 4,4'-bis(4-aminophenoxy)biphenyl according to claim 1 or 2, characterized in that: In step ① above, the salt formation reaction is carried out in the presence of an organic solvent; the organic solvent is toluene or xylene; the weight ratio of p-aminophenol to the organic solvent is 1:8 to 1:

10.

5. The method for synthesizing 4,4'-bis(4-aminophenoxy)biphenyl according to claim 4, characterized in that: In step ① above, the salt formation reaction is carried out in toluene solvent at a reaction temperature of 110-120°C, and the dehydration method is to remove water by reflux of toluene.

6. The method for synthesizing 4,4'-bis(4-aminophenoxy)biphenyl according to claim 4, characterized in that: In step ① above, the salt formation reaction is carried out in xylene solvent at a reaction temperature of 140–150°C, and the dehydration method is nitrogen purging to remove water.

7. The method for synthesizing 4,4'-bis(4-aminophenoxy)biphenyl according to claim 1 or 2, characterized in that: In step ② above, the 4,4'-dihalobiphenyl is 4,4'-difluorobiphenyl, 4,4'-dichlorobiphenyl, or 4,4'-dibromobiphenyl; the molar ratio of the 4,4'-dihalobiphenyl to the p-aminophenol is 1:1.8 to 1:2.

2.

8. The method for synthesizing 4,4'-bis(4-aminophenoxy)biphenyl according to claim 1 or 2, characterized in that: The reaction in step ② above is carried out in the presence of N,N-dimethylformamide; the amount of N,N-dimethylformamide used is 5 to 15% of the weight of p-aminophenol.

9. The method for synthesizing 4,4'-bis(4-aminophenoxy)biphenyl according to claim 1, characterized in that: In step ② above, the reaction temperature is 100-110℃ and the reaction time is 5-6h.

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