2, 3, 3apos; , 4apos; synthesis method of-diphenyl ether tetracarboxylic dianhydride

Abstract

The invention discloses a synthesis method of 2, 3, 3 ', 4'-diphenyl ether tetracarboxylic dianhydride, which comprises the following steps: (1) by taking N-methyl-4-nitrophthalimide and 3-nitrophthalonitrile as initial raw materials, carrying out asymmetric etherification reaction to obtain a first intermediate; (2) hydrolyzing the first intermediate to obtain a second intermediate; (3) dehydrating the second intermediate into anhydride to obtain 2, 3, 3 ', 4'-diphenyl ether tetracarboxylic dianhydride; the asymmetric etherification reaction is carried out in the presence of a catalyst sodium nitrite. According to the method, only three-step reaction is needed, the synthetic route is short, the reaction raw materials are low in price and easy to obtain, the reaction safety is high, especially the hydrolysis reaction time is short, the reaction is more thorough, the yield is higher, and the method is more suitable for large-scale industrial production.

Description

Technical Field

[0001] The invention belongs to the technical field of asymmetric dianhydride synthesis, and specifically relates to a method for synthesizing 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride. Background Art

[0002] As a special engineering material, polyimide has been widely used in aviation, aerospace, microelectronics, nano, liquid crystal, separation membrane, laser and other fields. In the 1960s, all countries listed the research, development and utilization of polyimide as one of the most promising engineering plastics in the 21st century. Due to its outstanding characteristics in processing and performance, its huge application prospects have been fully recognized, whether as a structural material or as a functional material.

[0003] 2,3,3',4'-Diphenyl ether tetracarboxylic dianhydride is an asymmetric diphenyl ether tetracarboxylic dianhydride monomer, white solid, CAS number 50662-95-8, molecular formula C 16 H6O7, relative weight is 310.21, melting range is 178~182℃, used in polyimide field.

[0004] The prior art discloses the following three methods for synthesizing 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride: 1. Using 3-chlorophthalic anhydride and methylamine as starting materials, firstly undergo an amidation reaction to obtain a first intermediate, then undergo a condensation reaction with 3,4-dimethylphenol to obtain a second intermediate, then hydrolyze under strong alkaline conditions to obtain a third intermediate, then oxidize with potassium permanganate to obtain 2,3,3',4'-diphenyl ether tetracarboxylic acid, and finally dehydrate to anhydride to obtain 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride.

[0005] The synthetic route is as follows: .

[0006] The shortcomings of this method are: (1) there are many reaction steps, a total of five steps are required; (2) the fourth step oxidation reaction requires the use of potassium permanganate, which is very environmentally unfriendly; (3) the third step hydrolysis reaction is relatively difficult and requires repeated reflux and water reaction in a potassium hydroxide / ethanol / water system for 3 to 4 days. In particular, there are many intermediate amide compounds that are difficult to completely hydrolyze, resulting in a lower purity of the third intermediate, and ultimately resulting in a lower purity of the target product and a lower reaction yield, which is not suitable for industrial production.

[0007] 2. Chinese patent document CN115536627A discloses a method of using 4-halogenated phthalic anhydride, 3-halogenated phthalic anhydride and hydroxylamine compound as starting materials, in the presence of rhodium catalysts such as bis(triphenylphosphine)carbonyl rhodium chloride, to obtain 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride through a one-step coupling reaction.

[0008] The disadvantages of this method are: (1) Rhodium catalysts such as bis(triphenylphosphine)carbonyl rhodium chloride are expensive, resulting in high production costs and being unsuitable for industrial production; (2) The coupling reaction will inevitably generate a large amount of by-products 2,3,2',3'-diphenyl ether tetracarboxylic dianhydride and 3,4,3',4'-diphenyl ether tetracarboxylic dianhydride, resulting in low product purity.

[0009] 3. Chinese patent document CN117820271A discloses a method using 3-chlorophthalic anhydride and aniline as starting materials, firstly undergoing an amidation reaction to obtain a first intermediate N-phenyl-chlorophthalimide, then undergoing a condensation reaction with 3,4-dimethylphenol to obtain a second intermediate dimethylphenoxy-N-phenylphthalimide, then undergoing an oxidation and hydrolysis reaction with nitric acid at high temperature and high pressure conditions to obtain 2,3,3',4'-diphenyl ether tetracarboxylic acid, and finally dehydrating to anhydride to obtain 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride.

[0010] The synthetic route is as follows: .

[0011] The shortcomings of this method are: (1) the reaction steps are still relatively large, requiring a total of four steps; (2) the yield of the first three steps is less than 60%; (3) the third step uses nitric acid to simultaneously carry out oxidation and hydrolysis reactions under high temperature and high pressure conditions, which is less safe. Summary of the invention

[0012] The object of the present invention is to solve the above problems and provide a method for synthesizing 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride with shorter reaction steps, higher safety and higher product purity.

[0013] The technical scheme for achieving the purpose of the present invention is: a method for synthesizing 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride, comprising the following steps: ① using N-methyl-4-nitrophthalimide and 3-nitrophthalonitrile as starting materials, firstly subjecting the first intermediate to an asymmetric etherification reaction; ② hydrolyzing the first intermediate to obtain a second intermediate; ③ dehydrating the second intermediate to obtain anhydride to obtain 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride.

[0014] The synthetic route is as follows: .

[0015] In the above step ①, the molar ratio of the N-methyl-4-nitrophthalimide to the 3-nitrophthalonitrile is 1:0.95 to 1:1.2.

[0016] In the above step ①, the asymmetric etherification reaction is carried out in the presence of a catalyst, sodium nitrite; the molar ratio of the N-methyl-4-nitrophthalimide to the sodium nitrite is 1:0.3 to 1:1.

[0017] The sodium nitrite is preferably added in 3 to 5 times.

[0018] In the above step ①, the asymmetric etherification reaction is carried out in the presence of an organic solvent; the organic solvent is N-methylpyrrolidone (NMP), N,N-dimethylformamide (DMF) or N,N-dimethylacetamide (DMAc); the weight ratio of the N-methyl-4-nitrophthalimide to the first solvent is 1:4 to 1:8.

[0019] In the above step ①, the asymmetric etherification reaction is carried out in the presence of toluene at a reaction temperature of 135-155°C.

[0020] In the above step ②, the hydrolysis is carried out in the presence of an alkaline catalyst; the alkaline catalyst is sodium hydroxide or potassium hydroxide; and the molar ratio of the first intermediate to the alkaline catalyst is 1:5 to 1:10.

[0021] In the above step ②, the hydrolysis is carried out in the presence of a mixed solvent; the mixed solvent is water + alcohol solvent; the weight ratio of the first intermediate to the water is 1:2 to 1:5; the weight ratio of the first intermediate to the alcohol solvent is 1:1 to 1:4; the alcohol solvent is preferably ethanol or isopropanol.

[0022] In the above step ②, the hydrolysis is carried out under high temperature and high pressure conditions; the high temperature is 130-160° C., and the high pressure is 0.3-0.8 MPa.

[0023] In the above step ③, the dehydration to anhydride is carried out in acetic anhydride + toluene; the weight ratio of the second intermediate to the acetic anhydride is 1:1 to 1:4; the weight ratio of the second intermediate to the toluene is 1:1 to 1:4.

[0024] In the above step ③, the reaction temperature for dehydration to anhydride is 90-120°C.

[0025] The present invention has the positive effects that the method of the present invention only needs three steps of reaction, the synthesis route is short, the reaction raw materials are cheap and easily available, the reaction safety is high, especially the hydrolysis reaction time is short, the reaction is more thorough, the yield is higher, and it is more suitable for large-scale industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is the LC-MS spectrum of the first intermediate obtained in step ① of Example 1.

[0027] Figure 2 This is the LC-MS spectrum of the second intermediate obtained in step ② of Example 1.

[0028] Figure 3 This is the LC-MS spectrum of the final product obtained in step ③ of Example 1 after using methanol for sample preparation.

[0029] Figure 4 This is the carbon NMR spectrum of the final product obtained in step ③ of Example 1. DETAILED DESCRIPTION

[0030] (Example 1) The synthetic method of 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride of the present embodiment comprises the following steps: ① Add 480mL of N-methylpyrrolidone to a 1L three-necked flask, then add 100g of N-methyl-4-nitrophthalimide (0.485mol) and 84g of 3-nitrophthalonitrile (0.485mol), then heat to 75-80℃, stir until completely dissolved, add 5.6g of sodium nitrite (0.08mol) and 100mL of toluene, heat to 140-142℃, reflux with water for 3h, then add 5.6g of sodium nitrite (0.08mol), continue to keep warm and reflux with water for 3h, then add 5.6g of sodium nitrite (0.08mol), continue to keep warm and reflux with water for 3h.

[0031] After the reaction is completed, the temperature is lowered to 50-60°C, and the toluene is recovered by concentrating under reduced pressure. The temperature is then raised to 130-140°C, and the N-methylpyrrolidone is recovered by concentrating under reduced pressure until the volume of the reaction solution is 200-220 mL. The temperature is lowered to 70-80°C, 300 mL of water is added, and the mixture is stirred for 1 h. The filter cake is rinsed with a small amount of water, and then placed in an oven at 70-80°C and dried under reduced pressure for 8 h to obtain 128.3 g of a light brown first intermediate with a yield of 87.2% and a HPLC purity of 90.8%.

[0032] The LC-MS spectrum of the first intermediate prepared in this example is shown in Figure 1 ,Depend on Figure 1 It can be seen that the molecular weight of the compound is 303.1 [MH], which is basically consistent with the first intermediate.

[0033] ② Add 60 g of the first intermediate (0.198 mol) obtained in step ① into a 500 mL stainless steel autoclave, then add 47.3 g of sodium hydroxide (1.18 mol), 180 mL of water and 120 mL of ethanol, seal the autoclave, and heat to 140-150° C. with stirring. At this time, the pressure of the autoclave reaches 0.5-0.6 MPa, and react for 12 hours at this high temperature and high pressure.

[0034] After the reaction is completed, the temperature is lowered to 65-75°C, the pressure is released, the lid of the kettle is opened, 3 g of activated carbon is added and stirred for 30 min, filtered, the filtrate is collected in a 500 mL three-necked flask, the temperature is controlled at 65-75°C, 36 wt% hydrochloric acid is slowly added dropwise to adjust the pH to 3-4, stirring is continued for 1 h, filtered, the filter cake is rinsed with a small amount of water, and then 300 mL of water is added, the temperature is raised to 65-75°C, stirred for 1 h, filtered, the filter cake is rinsed with a small amount of water, and placed in a 70-80°C oven under reduced pressure and dried for 8 h to obtain 50.7 g of a white second intermediate with a yield of 74.0% and an HPLC purity of 99.2%.

[0035] The LC-MS spectrum of the second intermediate prepared in this example is shown in Figure 2 ,Depend on Figure 2 It can be seen that the molecular weight of the second intermediate is 346.0 [MH], which is consistent with 2,3,3',4'-diphenyl ether tetracarboxylic acid.

[0036] ③ Add 50 g of the second intermediate (0.144 mol) obtained in step ② into a 500 mL three-necked flask, then add 100 g of acetic anhydride and 100 g of toluene, stir and heat to 105-110°C and react for 3-4 hours.

[0037] After the reaction, the temperature was lowered to 10-20°C, stirred for 1 hour, filtered, the filter cake was rinsed with a small amount of toluene, placed in an oven at 70-80°C and dried under reduced pressure for 7 hours to obtain 41.7 g of the final product with a yield of 93.1% and a HPLC purity of 99.6%.

[0038] The LC-MS spectrum of the final product prepared in this example after using methanol for sample preparation is shown in Figure 3 ,Depend on Figure 3 It can be seen that the molecular weight of the final product is 309.0, which is basically consistent with 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride.

[0039] The carbon NMR spectrum of the final product obtained in this example is shown in Figure 4 .

[0040] (Example 2) The synthetic method of 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride of the present embodiment comprises the following steps: ① Add 550mL of N,N-dimethylformamide to a 1L three-necked flask, then add 100g of N-methyl-4-nitrophthalimide (0.485mol) and 86g of 3-nitrophthalonitrile (0.497mol), then heat to 70-75℃, stir until completely dissolved, add 7.0g of sodium nitrite (0.10mol) and 100mL of toluene, heat to 137-139℃, reflux with water for 3h, then add 7.0g of sodium nitrite (0.10mol), continue to keep warm and reflux with water for 3h, then add 7.0g of sodium nitrite (0.10mol), continue to keep warm and reflux with water for 3h.

[0041] After the reaction is completed, the temperature is lowered to 50-60°C, and the toluene is recovered by concentrating under reduced pressure. The temperature is then raised to 100-110°C, and the N,N-dimethylformamide is recovered by concentrating under reduced pressure until the volume of the reaction solution is 200-220 mL. The temperature is lowered to 70-80°C, 320 mL of water is added, and the mixture is stirred for 1 h. The filter cake is rinsed with a small amount of water, and then placed in an oven at 70-80°C and dried under reduced pressure for 8 h to obtain 125.0 g of a light brown first intermediate with a yield of 85.0% and an HLLC purity of 91.4%.

[0042] ② Add 60 g of the first intermediate (0.198 mol) obtained in step ① into a 500 mL stainless steel autoclave, then add 65.2 g of potassium hydroxide (1.16 mol), 180 mL of water and 120 mL of isopropanol, seal the autoclave, and heat to 140-150° C. with stirring. At this time, the pressure in the autoclave reaches 0.5-0.6 MPa, and react for 12 hours at this high temperature and high pressure.

[0043] After the reaction is completed, the temperature is lowered to 65-75°C, the pressure is released, the lid of the kettle is opened, 3 g of activated carbon is added and stirred for 30 min, filtered, the filtrate is collected in a 500 mL three-necked flask, the temperature is controlled at 65-75°C, 98 wt% sulfuric acid is slowly added dropwise to adjust the pH to 3-4, stirring is continued for 1 h, filtered, the filter cake is rinsed with a small amount of water, and then 300 mL of water is added, the temperature is raised to 65-75°C, stirred for 1 h, filtered, the filter cake is rinsed with a small amount of water, and placed in a 70-80°C oven for reduced pressure drying for 8 h to obtain 51.3 g of a white second intermediate with a yield of 74.9% and an HPLC purity of 99.0%.

[0044] ③ Add 50 g of the second intermediate (0.144 mol) obtained in step ② into a 500 mL three-necked flask, then add 100 g of acetic anhydride and 100 g of toluene, stir and heat to 105-110°C and react for 3-4 hours.

[0045] After the reaction, the temperature was lowered to 10-20°C, stirred for 1 hour, filtered, the filter cake was rinsed with a small amount of toluene, and dried under reduced pressure in an oven at 70-80°C for 7 hours to obtain 41.1 g of the final product with a yield of 91.7% and an HPLC purity of 99.5%.

Claims

1. A method for synthesizing 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride, comprising the following steps: ① using N-methyl-4-nitrophthalimide and 3-nitrophthalonitrile as starting materials, first subjecting the first intermediate to an asymmetric etherification reaction; ② hydrolyzing the first intermediate to obtain a second intermediate; ③ dehydrating the second intermediate to obtain anhydride to obtain 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride.

2. The synthetic method of 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride according to claim 1, characterized in that: In the above step ①, the molar ratio of the N-methyl-4-nitrophthalimide to the 3-nitrophthalonitrile is 1:0.95 to 1:1.

2.

3. The synthetic method of 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride according to claim 1, characterized in that: In the above step ①, the asymmetric etherification reaction is carried out in the presence of a catalyst, sodium nitrite; the molar ratio of the N-methyl-4-nitrophthalimide to the sodium nitrite is 1:0.3 to 1:

1.

4. The synthetic method of 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride according to claim 1, characterized in that: In the above step ①, the asymmetric etherification reaction is carried out in the presence of an organic solvent; the organic solvent is N-methylpyrrolidone, N,N-dimethylformamide or N,N-dimethylacetamide; the weight ratio of the N-methyl-4-nitrophthalimide to the first solvent is 1:4 to 1:

8.

5. The synthetic method of 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride according to claim 4, characterized in that: In the above step ①, the asymmetric etherification reaction is carried out in the presence of toluene at a reaction temperature of 135-155°C.

6. The method for synthesizing 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride according to claim 1, characterized in that: In the above step ②, the hydrolysis is carried out in the presence of an alkaline catalyst; the alkaline catalyst is sodium hydroxide or potassium hydroxide; and the molar ratio of the first intermediate to the alkaline catalyst is 1:5 to 1:

10.

7. The method for synthesizing 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride according to claim 1, characterized in that: In the above step ②, the hydrolysis is carried out in the presence of a mixed solvent; the mixed solvent is water + alcohol solvent; the weight ratio of the first intermediate to the water is 1:2 to 1:5; the weight ratio of the first intermediate to the alcohol solvent is 1:1 to 1:4; the alcohol solvent is ethanol or isopropanol.

8. The method for synthesizing 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride according to claim 1, characterized in that: In the above step ②, the hydrolysis is carried out under high temperature and high pressure conditions; the high temperature is 130-160° C., and the high pressure is 0.3-0.8 MPa.

9. The method for synthesizing 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride according to claim 1, characterized in that: In the above step ③, the dehydration to anhydride is carried out in acetic anhydride + toluene; the weight ratio of the second intermediate to the acetic anhydride is 1:1 to 1:4; the weight ratio of the second intermediate to the toluene is 1:1 to 1:

4.

10. The method for synthesizing 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride according to claim 1, characterized in that: In the above step ③, the reaction temperature for dehydration to anhydride is 90-120°C.

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