Synthesis method of 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride

Abstract

The invention discloses a synthetic method for 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 obtaining a first intermediate through an asymmetric etherification reaction; 2. hydrolyzing the first intermediate to obtain a second intermediate; 3. dehydrating the second intermediate to an anhydride to obtain 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride; and the asymmetric etherification reaction being carried out in the presence of a catalyst, sodium nitrite. The method of the present invention requires only three-step reaction, a shorter synthetic route, and reaction raw materials are cheap and readily available, with higher reaction safety, especially a shorter hydrolysis reaction time, a more thorough reaction, and a higher yield, making it more suitable for industrialized mass production.

Description

Technical Field

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

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

[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 synthesis methods of 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride disclosed in the prior art mainly include the following three methods:

[0005] 1. Using 3-chlorophthalic anhydride and methylamine as starting materials, an amidation reaction is first performed to obtain a first intermediate, which is then condensed with 3,4-dimethylphenol to obtain a second intermediate. This is then hydrolyzed under strong alkaline conditions to obtain a third intermediate, which is then oxidized with potassium permanganate to obtain 2,3,3',4'-diphenylether tetracarboxylic acid, and finally dehydrated to anhydride to obtain 2,3,3',4'-diphenylether tetracarboxylic dianhydride.

[0006] The synthetic route is as follows:

[0007] .

[0008] 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 with water in a potassium hydroxide / ethanol / water system for 3 to 4 days. In particular, many intermediate amide compounds are difficult to completely hydrolyze, resulting in low purity of the third intermediate, and ultimately low purity of the target product and reaction yield, making it unsuitable for industrial production.

[0009] 2. Chinese patent document CN115536627A discloses a method for obtaining 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride by a one-step coupling reaction using 4-halogenated phthalic anhydride, 3-halogenated phthalic anhydride and a hydroxylamine compound as starting materials in the presence of a rhodium catalyst such as bis(triphenylphosphine)carbonyl rhodium chloride.

[0010] The shortcomings of this method are: (1) Rhodium catalysts such as bis(triphenylphosphine)carbonyl rhodium chloride are expensive, resulting in high production costs and unsuitable for industrial production; (2) The coupling reaction inevitably produces 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.

[0011] 3. Chinese patent document CN117820271A discloses a method using 3-chlorophthalic anhydride and aniline as starting materials, first 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 simultaneously undergoing oxidation and hydrolysis with nitric acid under 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.

[0012] The synthetic route is as follows:

[0013] .

[0014] 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

[0015] The purpose 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.

[0016] The technical solution 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, first subjecting the starting materials to an asymmetric etherification reaction to obtain a first intermediate; ② hydrolyzing the first intermediate to obtain a second intermediate; and ③ dehydrating the second intermediate to obtain anhydride to obtain 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride.

[0017] The synthetic route is as follows:

[0018] .

[0019] 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.

[0020] 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.

[0021] The sodium nitrite is preferably added in 3 to 5 times.

[0022] 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); and the weight ratio of the N-methyl-4-nitrophthalimide to the first solvent is 1:4 to 1:8.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] In the above step ③, the reaction temperature for dehydration to anhydride is 90-120°C.

[0029] The present invention has the positive effects that the method of the present invention only requires 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

[0030] Figure 1 This is the LC-MS spectrum of the first intermediate obtained in step ① of Example 1.

[0031] Figure 2 This is the LC-MS spectrum of the second intermediate obtained in step ② of Example 1.

[0032] 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.

[0033] Figure 4 This is the carbon NMR spectrum of the final product obtained in step ③ of Example 1. DETAILED DESCRIPTION

[0034] (Example 1)

[0035] The synthetic method of 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride of the present embodiment comprises the following steps:

[0036] ① Add 480 mL of N-methylpyrrolidone to a 1 L three-necked flask, then add 100 g of N-methyl-4-nitrophthalimide (0.485 mol) and 84 g of 3-nitrophthalonitrile (0.485 mol), then heat to 75-80 ° C, stir until completely dissolved, add 5.6 g of sodium nitrite (0.08 mol) and 100 mL of toluene, heat to 140-142 ° C, reflux with water for 3 hours, then add 5.6 g of sodium nitrite (0.08 mol), continue to keep warm and reflux with water for 3 hours, then add 5.6 g of sodium nitrite (0.08 mol), continue to keep warm and reflux with water for 3 hours.

[0037] After the reaction is completed, the temperature is lowered to 50-60°C, and the toluene is recovered by concentration under reduced pressure. The temperature is then raised to 130-140°C, and the N-methylpyrrolidone is recovered by concentration under reduced pressure until the volume of the reaction solution is 200-220 mL. The temperature is then 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 dried in an oven at 70-80°C under reduced pressure for 8 h to obtain 128.3 g of a light brown first intermediate with a yield of 87.2% and an HPLC purity of 90.8%.

[0038] The LC-MS spectrum of the first intermediate prepared in this example is shown in Figure 1 ,Depend on Figure 1It can be seen that the molecular weight of the compound is 303.1 [MH], which is basically consistent with the first intermediate.

[0039] ② Add 60 g of the first intermediate (0.198 mol) obtained in step ① to 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 autoclave pressure reaches 0.5-0.6 MPa. React at this high temperature and high pressure for 12 h.

[0040] After the reaction, the temperature was lowered to 65-75°C, the pressure was released, the lid of the kettle was opened, 3 g of activated carbon was added and stirred for 30 min, filtered, and the filtrate was collected in a 500 mL three-necked flask. The temperature was controlled at 65-75°C, 36 wt% hydrochloric acid was slowly added dropwise to adjust the pH to 3-4, and stirring was continued for 1 h. The filter cake was rinsed with a small amount of water, and then 300 mL of water was added. The temperature was raised to 65-75°C and stirred for 1 h. The filter cake was rinsed with a small amount of water and placed in an oven at 70-80°C and dried under reduced pressure 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%.

[0041] 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.

[0042] 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 for 3-4 h.

[0043] After the reaction, the temperature was lowered to 10-20°C, stirred for 1 hour, and 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 41.7 g of the final product with a yield of 93.1% and an HPLC purity of 99.6%.

[0044] The LC-MS spectrum of the final product prepared in this example after using methanol for sample preparation is shown in FIG. 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 that of 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride.

[0045] The carbon NMR spectrum of the final product obtained in this example is shown in Figure 4 .

[0046] (Example 2)

[0047] The synthetic method of 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride of the present embodiment comprises the following steps:

[0048] ① Add 550 mL of N,N-dimethylformamide to a 1 L three-necked flask, then add 100 g of N-methyl-4-nitrophthalimide (0.485 mol) and 86 g of 3-nitrophthalonitrile (0.497 mol), then heat to 70-75 ° C, stir until completely dissolved, add 7.0 g of sodium nitrite (0.10 mol) and 100 mL of toluene, heat to 137-139 ° C, reflux with water for 3 hours, then add 7.0 g of sodium nitrite (0.10 mol), continue to keep warm and reflux with water for 3 hours, then add 7.0 g of sodium nitrite (0.10 mol), continue to keep warm and reflux with water for 3 hours.

[0049] After the reaction, the temperature was lowered to 50-60°C, and the toluene was recovered by concentrating under reduced pressure. The temperature was then raised to 100-110°C, and the N,N-dimethylformamide was recovered by concentrating under reduced pressure until the volume of the reaction solution was 200-220 mL. The temperature was lowered to 70-80°C, 320 mL of water was added, and the mixture was stirred for 1 h. The mixture was filtered, and the filter cake was rinsed with a small amount of water and dried in an oven at 70-80°C 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%.

[0050] ② Add 60 g of the first intermediate (0.198 mol) obtained in step ① to a 500 mL stainless steel autoclave, followed by 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 point, the autoclave pressure reaches 0.5-0.6 MPa. React at this high temperature and high pressure for 12 h.

[0051] After the reaction, the temperature was lowered to 65-75°C, the pressure was released, the lid of the reactor was opened, 3 g of activated carbon was added and stirred for 30 min, filtered, and the filtrate was collected in a 500 mL three-necked flask. The temperature was controlled at 65-75°C and 98 wt% sulfuric acid was slowly added dropwise to adjust the pH to 3-4. Stirring was continued for 1 h, filtered, and the filter cake was rinsed with a small amount of water. Then, 300 mL of water was added, the temperature was raised to 65-75°C and stirred for 1 h, filtered, and the filter cake was rinsed with a small amount of water. It was placed in an oven at 70-80°C and dried under reduced pressure 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%.

[0052] 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 for 3-4 h.

[0053] After the reaction, the temperature was lowered to 10-20°C, stirred for 1 hour, and 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'-diphenylether tetracarboxylic dianhydride, comprising the following steps: ① using N-methyl-4-nitrophthalimide and 3-nitrophthalonitrile as starting materials, first subjecting the starting materials to an asymmetric etherification reaction to obtain a first intermediate; the asymmetric etherification reaction is carried out in the presence of a catalyst, sodium nitrite; ② hydrolyzing the first intermediate to obtain a second intermediate; ③ dehydrating the second intermediate to obtain anhydride to obtain 2,3,3',4'-diphenylether tetracarboxylic dianhydride; the synthesis route is as follows: 。 2. The synthetic method of 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride according to claim 1, wherein: 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, wherein: In the above step ①, 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, wherein: 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; and the weight ratio of the N-methyl-4-nitrophthalimide to the organic 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 synthetic method of 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 synthetic method of 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 synthetic method of 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 synthetic method of 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, wherein: In the above step ③, the reaction temperature for dehydration to anhydride is 90-120°C.

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