Process for the preparation of 2,3,3',4'-diphenyl ether tetra carboxylic dianhydride

Abstract

This invention discloses a method for preparing 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride, comprising an amidation reaction of 3-chlorophthalic anhydride and aniline to obtain a first intermediate, a condensation reaction of the first intermediate with 3,4-dimethylphenol to obtain a second intermediate, and simultaneous oxidation and hydrolysis of the second intermediate with nitric acid under high temperature and high pressure to obtain 2,3,3',4'-diphenyl ether tetracarboxylic acid, followed by dehydration to anhydride to obtain 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride. The method of this invention uses an amidation reaction of aniline with 3-chlorophthalic anhydride, thus obtaining a second intermediate containing a phenyl group. This second intermediate can be simultaneously oxidized and hydrolyzed with nitric acid under high temperature and high pressure to obtain 2,3,3',4'-diphenyl ether tetracarboxylic acid. This method not only has a shorter reaction time but also avoids the environmentally unfriendly problem of using potassium permanganate oxidation. In particular, the hydrolysis reaction conditions are simpler, the reaction time is shorter, the reaction effect is better, and the product purity is higher.

Description

Technical Field

[0001] This invention belongs to the field of asymmetric dianhydride preparation technology, specifically relating to a method for preparing 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride. 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 characteristics in processing and performance, 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 monomer of diphenyl ether tetracarboxylic dianhydride, a white solid, with CAS number 50662-95-8 and molecular formula C2. 16 H6O7, with a relative content of 310.21 and a melting range of 178–182°C, is used in the field of polyimide.

[0004] The existing technologies disclose two main methods for synthesizing 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride:

[0005] I. Using 4-halophthalic anhydride, 3-halophthalic anhydride and hydroxylamine compounds as starting materials, 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride is obtained through a one-step coupling reaction in the presence of rhodium catalysts such as bis(triphenylphosphine)carbonyl rhodium chloride [see Chinese Patent Document CN115536627A].

[0006] The shortcomings of this method are: (1) Rhodium catalysts such as bis(triphenylphosphine)carbonyl rhodium chloride are expensive, resulting in high production costs and making them unsuitable for industrial production; (2) The coupling reaction inevitably generates a lot of byproducts 2,3,2',3'-diphenyl ether tetracarboxylic dianhydride and 3,4,3',4'-diphenyl ether tetracarboxylic dianhydride, resulting in low product purity.

[0007] II. Starting with 3-chlorophthalic anhydride and methylamine, the first intermediate is obtained by amidation reaction, then by condensation reaction with 3,4-dimethylphenol to obtain the second intermediate, followed by hydrolysis under strong alkaline conditions to obtain the third intermediate, then oxidized with potassium permanganate to obtain 2,3,3',4'-diphenyl ether tetracarboxylic acid, and finally dehydrated to anhydride to obtain 2,3,3',4'-diphenyl ether tetracarboxylic acid dianhydride.

[0008] The synthesis route is as follows:

[0009] .

[0010] The shortcomings of this preparation method are: (1) There are many reaction steps, requiring a total of five steps; (2) The fourth step of oxidation requires the use of potassium permanganate, which is very environmentally unfriendly; (3) The third step of hydrolysis is difficult, requiring repeated reflux and water reaction in a potassium hydroxide / ethanol / water system for 3 to 4 days. In particular, many intermediate amide compounds are difficult to hydrolyze completely, resulting in low purity of the third intermediate, which ultimately leads to low purity of the target product and low reaction yield, making it unsuitable for industrial production. Summary of the Invention

[0011] The purpose of this invention is to solve the above-mentioned problems and provide a method for preparing 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride with lower production costs, shorter reaction steps, greater environmental friendliness, and higher product purity.

[0012] The technical solution to achieve the objective of this invention is: a method for preparing 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride, comprising the following steps:

[0013] ① Starting with 3-chlorophthalic anhydride and aniline, the first intermediate N-phenyl-chlorophthalimide is obtained by amidation reaction;

[0014] ②The first intermediate obtained in step ① is condensed with 3,4-dimethylphenol to obtain the second intermediate, dimethylphenoxy-N-phenylphthalimide;

[0015] ③The second intermediate obtained in step ② is subjected to simultaneous oxidation and hydrolysis with nitric acid under high temperature and high pressure conditions to obtain 2,3,3',4'-diphenyl ether tetracarboxylic acid;

[0016] ④ Dehydrate the 2,3,3',4'-diphenyl ether tetracarboxylic acid obtained in step ③ to form an anhydride, yielding 2,3,3',4'-diphenyl ether tetracarboxylic acid dianhydride.

[0017] The specific synthesis route is as follows:

[0018] .

[0019] In step ① above, the molar ratio of 3-chlorophthalic anhydride to aniline is 1:0.95 to 1:1.2.

[0020] In step ① above, the amidation reaction is carried out in the presence of an organic solvent; the organic solvent is DMF or NMP.

[0021] In step ① above, the organic solvent is DMF (i.e., N,N-dimethylformamide), the weight ratio of 3-chlorophthalic anhydride to DMF is 1:3 to 1:5, and the amidation reaction temperature is 130 to 150°C.

[0022] In step ① above, the organic solvent is DMF, and the dehydration method of the amidation reaction is to add toluene and reflux to remove water.

[0023] In step ① above, the organic solvent is NMP (i.e., N-methylpyrrolidone), the weight ratio of 3-chlorophthalic anhydride to NMP is 1:2 to 1:4, and the amidation reaction temperature is 160 to 180°C.

[0024] In step ① above, the organic solvent is NMP, and the dehydration method for the amidation reaction is nitrogen purging to remove water.

[0025] In step ① above, the organic solvent is NMP, and the first intermediate is added directly to step ② without post-processing.

[0026] In step ② above, the molar ratio of the first intermediate to the 3,4-dimethylphenol is 1:1 to 1:3, preferably 1:1 to 1:1.2.

[0027] In step ② above, the condensation reaction is carried out in the presence of potassium carbonate; the molar ratio of the first intermediate to the potassium carbonate is 1:1 to 1:3, preferably 1:1 to 1:1.2.

[0028] In step ③ above, the molar ratio of the second intermediate to the nitric acid is 1:6 to 1:12, preferably 1:7 to 1:10.

[0029] In step ③ above, the concentration of nitric acid is 35-55 wt%.

[0030] In step ③ above, the high temperature and high pressure refer to a reaction temperature of 150-180℃ and a reaction pressure of 1.0-2.0MPa.

[0031] The dehydration to anhydride formation in step ④ above is a conventional method in this field.

[0032] The solvents used in step ④ above for dehydration to form anhydride are acetic anhydride and toluene. The weight ratio of 2,3,3',4'-diphenyl ether tetracarboxylic acid to acetic anhydride is 1:1 to 1:4, preferably 1:2 to 1:3; the weight ratio of 2,3,3',4'-diphenyl ether tetracarboxylic acid to toluene is 1:1 to 1:4, preferably 1:2 to 1:3.

[0033] The positive effects of this invention are as follows: The method of this invention uses aniline and 3-chlorophthalic anhydride for amidation reaction, thus obtaining a second intermediate containing a phenyl group. This second intermediate can be simultaneously oxidized and hydrolyzed with nitric acid under high temperature and high pressure conditions to obtain 2,3,3',4'-diphenyl ether tetracarboxylic acid. Not only are the reaction steps shorter, but the environmentally unfriendly problem of using potassium permanganate oxidation is also avoided. In particular, the hydrolysis reaction conditions are simpler, the reaction time is shorter, the reaction effect is better, and the product purity is higher. Attached Figure Description

[0034] Figure 1 The image shows the LC-MS spectrum of N-phenyl-chlorophthalimide, the first intermediate prepared in Example 1.

[0035] Figure 2 The image shows the LC-MS spectrum of the second intermediate, dimethylphenoxy-N-phenylphthalimide, prepared in Example 2.

[0036] Figure 3 The image shows the LC-MS spectrum of 2,3,3',4'-diphenyl ether tetracarboxylic acid prepared in Example 3.

[0037] Figure 4 The LC-MS spectrum of the target product 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride prepared in Example 4 after methanol preparation is shown.

[0038] Figure 5 The NMR spectrum of the target product 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride obtained in Example 4 is shown. Detailed Implementation

[0039] (Example 1)

[0040] This embodiment describes the preparation method of the first intermediate, N-phenyl-chlorophthalimide, as follows:

[0041] Add 400g of DMF to a 1L three-necked flask, then add 100g of 3-chlorophthalic anhydride (0.55mol), stir to dissolve, and add 51.0g of aniline (0.55mol) dropwise while controlling the temperature at 20-40℃. The reaction is exothermic and takes about 1 hour to complete. After the addition is complete, stir for 30 minutes, add 50g of toluene, raise the temperature to 138-140℃, reflux to remove water, and react until no more water is carried out by toluene.

[0042] After the reaction was completed, the temperature was lowered to 20-30℃, stirred for 30 min, filtered, the filter cake was washed with a small amount of toluene, and then dried under vacuum at 60-70℃ for 6 h to obtain 122.4 g of white solid first intermediate, with a yield of 86.7% and an HPLC purity of 99.6%.

[0043] The LC-MS spectrum of the first intermediate obtained in this embodiment is shown below. Figure 1 ,Depend on Figure 1 It can be seen that the molecular weight of the first intermediate is 257.9, which is consistent with N-phenyl-chlorophthalimide.

[0044] (Example 2)

[0045] This embodiment describes the preparation method of the second intermediate, dimethylphenoxy-N-phenylphthalimide, as follows:

[0046] 120.0 g of the first intermediate (0.466 mol) prepared in Example 1 was added to a 1 L three-necked flask, followed by the addition of 480 g of DMF, 60 g of toluene, 59.7 g of 3,4-dimethylphenol (0.489 mol), and 67.5 g of potassium carbonate (0.489 mol). The mixture was stirred and heated to 138–140 °C, refluxed to remove water, and reacted until no more water was carried out by toluene.

[0047] After the reaction was completed, the temperature was lowered to 40–50 °C, filtered, and the filtrate was washed with a small amount of DMF. Then, the filtrate was concentrated under reduced pressure to 200 mL at 70 °C. Then, 360 g of methanol was slowly added with stirring, and a large amount of solid precipitated out. After the addition was complete, the mixture was stirred at 20–30 °C for 30 min, filtered, and the filter cake was washed with a small amount of toluene. Then, it was dried under vacuum at 60–70 °C for 6 h to obtain 145.5 g of off-white solid second intermediate, with a yield of 91.0% and an HPLC purity of 98.2%.

[0048] The LC-MS spectrum of the second intermediate obtained in this embodiment is shown below. Figure 2 ,Depend on Figure 2 It can be seen that the molecular weight of the second intermediate is 342.9 [M+H], which is consistent with dimethylphenoxy-N-phenylphthalimide.

[0049] (Example 3)

[0050] This embodiment describes the preparation method of 2,3,3',4'-diphenyl ether tetracarboxylic acid, as detailed below:

[0051] 60.0 g of the second intermediate dimethylphenoxy-N-phenylphthalimide (0.175 mol) prepared in Example 2 was added to a 500 mL titanium high-pressure reactor, followed by 200 g of 50 wt% nitric acid aqueous solution (1.587 mol). All valves were closed, and stirring was started. The temperature was slowly increased to 160–170 °C over 3–4 h. During the heating process, the pressure of the high-pressure reactor was maintained at 1.2–1.5 MPa. The reaction was carried out under these high-temperature and high-pressure conditions for 2 h.

[0052] After the reaction was completed, the temperature was lowered to 20-30℃, the gas in the high-pressure reactor was vented, and then the reaction solution was concentrated to 90 mL under reduced pressure at 60℃. The temperature was then lowered to 5-10℃ and stirred for 2 hours. After filtration, the filtrate was collected to recover aniline. The filter cake was placed in a 500 mL three-necked flask, 240 g of purified water was added, and the temperature was raised to 90-95℃ to dissolve the solid completely. Then the temperature was slowly lowered to 5-10℃ and stirred for 2 hours, during which solid precipitated. After filtration, the filter cake was washed with a small amount of purified water and then dried under vacuum at 70-80℃ for 6 hours to obtain 44.7 g of white solid 2,3,3',4'-diphenyl ether tetracarboxylic acid, with a yield of 73.9% and an HPLC purity of 99.3%.

[0053] The LC-MS spectrum of the white solid obtained in this embodiment is shown in the figure. Figure 3 ,Depend on Figure 3 It can be seen that the molecular weight of the white solid is 345.8 [M+H], which is consistent with 2,3,3',4'-diphenyl ether tetracarboxylic acid.

[0054] (Example 4)

[0055] This embodiment describes the preparation method of the target product 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride, as detailed below:

[0056] 40.0 g of 2,3,3',4'-diphenyl ether tetracarboxylic acid prepared in Example 3 was added to a 250 mL three-necked flask, along with 80 g of acetic anhydride and 80 g of toluene. The mixture was then heated to 105–110 °C and stirred for 3–4 h, followed by cooling to 10–20 °C and stirring for 1 h. After filtration, the filter cake was washed with a small amount of toluene and then dried under vacuum at 70–80 °C for 6 h to obtain 33.9 g of the target product, 2,3,3',4'-diphenyl ether tetracarboxylic acid dianhydride, with a yield of 94.6% and an HPLC purity of 99.8%.

[0057] The LC-MS spectrum of the target product obtained in this embodiment after methanol preparation is shown below. Figure 4 ,Depend on Figure 4 It can be seen that the molecular weight of the target product is 310.7, which is consistent with 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride.

[0058] The NMR spectrum of the target product obtained in this embodiment is shown in [reference needed]. Figure 5 .

[0059] (Example 5)

[0060] This embodiment describes a one-pot method for preparing the second intermediate, dimethylphenoxy-N-phenylphthalimide, using NMP as a solvent, as detailed below:

[0061] Add 300g of NMP to a 1L three-necked flask, then add 100g of 3-chlorophthalic anhydride (0.55mol), stir to dissolve, and add 51.0g of aniline (0.547mol) dropwise while controlling the temperature at 20-40℃. The reaction is exothermic and takes about 1 hour to complete. After the addition is complete, raise the temperature to 160-170℃ and stir the reaction for 3-4 hours. During the reaction, purge with a small amount of nitrogen gas to remove water.

[0062] After the reaction is complete, the temperature is lowered to 70-80℃, and 66.8g of 3,4-dimethylphenol (0.55mol) and 75.6g of potassium carbonate (0.55mol) are added. Nitrogen gas is continuously purged to remove water, while the temperature is raised to 160-170℃ and the mixture is stirred for 5-6 hours.

[0063] After the reaction was completed, the temperature was lowered to 20–30 °C, and the mixture was filtered. The filtrate was washed with a small amount of NMP, and 480 g of methanol was slowly added dropwise to the filtrate. A solid gradually precipitated out. After the addition was complete, the mixture was stirred at 20–30 °C for 30 min, filtered, and then 600 g of methanol was added to the filter cake. The mixture was stirred at 20–30 °C for 1–2 h, filtered, and the filter cake was washed with a small amount of toluene. The mixture was then dried under vacuum at 60–70 °C for 6 h to obtain 159.4 g of a white solid, the second intermediate dimethylphenoxy-N-phenylphthalimide. The yield of the two-step reaction was 84.8%, and the HPLC purity was 97.8%.

[0064] (Example 6)

[0065] This embodiment describes the preparation method of 2,3,3',4'-diphenyl ether tetracarboxylic acid, as detailed below:

[0066] 60.0 g of the second intermediate dimethylphenoxy-N-phenylphthalimide (0.175 mol) prepared in Example 5 was added to a 500 mL titanium high-pressure reactor, followed by 180 g of 50 wt% nitric acid aqueous solution (1.428 mol). All valves were closed, and stirring was started. The temperature was slowly increased to 160-170 °C over 3-4 hours. During the heating process, the pressure of the high-pressure reactor was maintained at 1.2-1.5 MPa. The reaction was carried out under these high-temperature and high-pressure conditions for 2 hours.

[0067] After the reaction was completed, the temperature was lowered to 20-30℃, the gas in the high-pressure reactor was vented, and then the reaction solution was concentrated to 90 mL under reduced pressure at 60℃. The temperature was then lowered to 5-10℃ and stirred for 2 hours. After filtration, the filtrate was collected to recover aniline. The filter cake was placed in a 500 mL three-necked flask, 240 g of purified water was added, and the temperature was raised to 90-95℃ to dissolve the solid completely. Then the temperature was slowly lowered to 5-10℃ and stirred for 2 hours, during which solid precipitated. After filtration, the filter cake was rinsed with a small amount of purified water and then dried under vacuum at 70-80℃ for 6 hours to obtain 42.1 g of white solid 2,3,3',4'-diphenyl ether tetracarboxylic acid, with a yield of 69.6% and an HPLC purity of 99.4%.

[0068] (Example 7)

[0069] This embodiment describes the preparation method of the target product 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride, as detailed below:

[0070] 40.0 g of 2,3,3',4'-diphenyl ether tetracarboxylic acid prepared in Example 6 was added to a 250 mL three-necked flask, along with 120 g of acetic anhydride and 120 g of toluene. The mixture was then heated to 105–110 °C and stirred for 3–4 h, followed by cooling to 10–20 °C and stirring for 1 h. After filtration, the filter cake was washed with a small amount of toluene and then dried under vacuum at 70–80 °C for 6 h to obtain the target product 2,3,3',4'-diphenyl ether tetracarboxylic acid dianhydride with a yield of 95.4% and an HPLC purity of 99.8%.

Claims

1. A method for preparing 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride, comprising the following steps: ① using 3-chlorophthalic anhydride and aniline as starting materials, an amidation reaction is first performed to obtain a first intermediate, N-phenyl-chlorophthalimide; ② the first intermediate obtained in step ① is condensed with 3,4-dimethylphenol to obtain a second intermediate, dimethylphenoxy-N-phenylphthalimide; ③ the second intermediate obtained in step ② is subjected to high temperature and high pressure conditions, using... Nitric acid undergoes simultaneous oxidation and hydrolysis to yield 2,3,3',4'-diphenyl ether tetracarboxylic acid; the molar ratio of the second intermediate to the nitric acid is 1:6 to 1:12; the concentration of the nitric acid is 35 to 55 wt%; the high temperature and high pressure are a reaction temperature of 150 to 180°C and a reaction pressure of 1.0 to 2.0 MPa; ④ The 2,3,3',4'-diphenyl ether tetracarboxylic acid obtained in step ③ is dehydrated to form anhydride to obtain 2,3,3',4'-diphenyl ether tetracarboxylic acid dianhydride; The specific synthesis route is as follows: 。 2. The method for preparing 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride according to claim 1, characterized in that: In step ① above, the molar ratio of 3-chlorophthalic anhydride to aniline is 1:0.95 to 1:1.

2.

3. The method for preparing 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride according to claim 1 or 2, characterized in that: In step ① above, the amidation reaction is carried out in the organic solvent DMF; the weight ratio of the 3-chlorophthalic anhydride to the DMF is 1:3 to 1:

5.

4. The method for preparing 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride according to claim 3, characterized in that: The amidation reaction temperature is 130–150°C, and the dehydration method of the amidation reaction is to add toluene and reflux to remove water.

5. The method for preparing 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride according to claim 1 or 2, characterized in that: In step ① above, the amidation reaction is carried out in the organic solvent NMP; the weight ratio of the 3-chlorophthalic anhydride to the NMP is 1:2 to 1:

4.

6. The method for preparing 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride according to claim 5, characterized in that: The amidation reaction temperature is 160–180°C, and the dehydration method of the amidation reaction is nitrogen purging to remove water.

7. The method for preparing 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride according to claim 1 or 2, characterized in that: In step ② above, the molar ratio of the first intermediate to the 3,4-dimethylphenol is 1:1 to 1:

3.

8. The method for preparing 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride according to claim 1 or 2, characterized in that: In step ② above, the condensation reaction is carried out in the presence of potassium carbonate; the molar ratio of the first intermediate to the potassium carbonate is 1:1 to 1:3.

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