Preparation method of 5-hydroxyisophthalic acid

Abstract

The invention discloses a preparation method of 5-hydroxyisophthalic acid, which comprises the following steps: by taking sodium 5-sulfoisophthalic acid or potassium 5-sulfoisophthalic acid as a raw material, reacting in an aqueous solution of NaOH or KOH, acidifying with diluted hydrochloric acid, and post-treating to obtain the target product 5-hydroxyisophthalic acid. The reaction of the isophthalic acid-5-sodium sulfonate or the isophthalic acid-5-potassium sulfonate in an aqueous solution of NaOH or KOH is carried out in a tubular reactor. Compared with a route in the prior art, the process route provided by the invention has the advantages of easiness in operation, high yield, low cost, small wastewater amount and the like.

Description

Technical Field

[0001] The invention relates to a method for preparing 5-hydroxyisophthalic acid, and belongs to the technical field of compound preparation. Background Art

[0002] 5-Hydroxyisophthalic acid (5-Hydroxyisophthalic acid), the structural formula is as follows:

[0003]

[0004] This compound is a commonly used chemical intermediate, and currently has the following preparation methods:

[0005] The synthetic route of Chinese patent CN106831397A is as follows:

[0006]

[0007] The process uses 5-bromoisophthalic acid as raw material, and hydrolyzes it in a liquid alkali aqueous solution with cuprous oxide as catalyst for 20 hours, and then acidifies it with dilute hydrochloric acid to obtain the product with a yield of 86%. Since the starting raw material 5-bromoisophthalic acid is relatively expensive, the hydrolysis reaction time is relatively long, and the manufacturing cost is relatively high.

[0008] The synthetic route of U.S. Patent US2756149 is as follows:

[0009]

[0010] The route is to add a mixture of sodium hydroxide and potassium hydroxide into a stainless steel cup, heat it to 220°C to melt, then add potassium 5-sulfonate of isophthalic acid, control the temperature at 215-235°C, vigorously stir for 30 minutes, cool and add water at the end of the reaction, acidify with hydrochloric acid to obtain a crude product, and then recrystallize with water to obtain the product with a yield of 81.5%.

[0011] The raw material 5-potassium sulfonate isophthalic acid used in this route is easy to obtain and cheap, but the process uses a large amount of mixed alkali, 41 times (molar ratio) of the starting raw material. The reaction mixture is viscous, difficult to stir, and has uneven temperature, and the yield is not high. At the same time, a large amount of high-salt wastewater is produced, making it difficult to scale up production. Summary of the invention

[0012] The technical problem to be solved by the present invention is to provide a new method for preparing 5-hydroxyisophthalic acid.

[0013] In order to solve the above technical problems, the present invention discloses a preparation method of 5-hydroxyisophthalic acid, wherein the preparation method uses sodium 5-sulfonate isophthalic acid or potassium 5-sulfonate isophthalic acid as a raw material, reacts in an aqueous solution of NaOH or KOH, and then acidifies with dilute hydrochloric acid and post-processes to obtain the target product 5-hydroxyisophthalic acid, wherein the reaction of sodium 5-sulfonate isophthalic acid or potassium 5-sulfonate isophthalic acid in an aqueous solution of NaOH or KOH is carried out in a tubular reactor. The post-processing is filtering and recrystallization in sequence. The reaction equation is as follows:

[0014]

[0015] Furthermore, the reaction temperature is 200-300°C, preferably 220-250°C.

[0016] Furthermore, the molar ratio of NaOH or KOH to sodium 5-sulfoisophthalate or potassium 5-sulfoisophthalate is 4 to 40:1, preferably 7 to 11:1.

[0017] Furthermore, in the aqueous solution of NaOH or KOH, the mass amount of water is 10% to 200% of the mass amount of NaOH or KOH, preferably 50%.

[0018] Furthermore, the residence time of the reaction raw materials in the pipeline of the tubular reactor is 0.25 to 20 hours, preferably 40 to 60 minutes. The residence time is controlled by adjusting the feed rate according to the volume of the pipeline reactor.

[0019] Furthermore, the tubular reactor is a dynamic tubular reactor, the reaction raw materials are continuously fed using a slurry pump, and the reaction products are continuously discharged.

[0020] The preparation method of the present invention has the following advantages: the target product content in the product is >99.0%, and the molar yield can be as high as 96.6%. Compared with the US patent US2756149, it has the following advantages:

[0021] 1. In US2756149, KOH / NaOH mixed alkali is used as the reaction medium, and the amount is large. If the amount is reduced, stirring is impossible. The present invention uses an aqueous solution of NaOH (KOH) as the reaction medium, and the amount of alkali is greatly reduced. Since water is added, the solubility of the material is increased, stirring is easy, and the temperature is easy to control.

[0022] 2. US2756149 is a batch reaction at normal pressure, with low output and difficult operation. The present invention uses a dynamic tubular reactor to achieve continuous production, with low equipment investment, high output and low production cost.

[0023] In general, the process route of the present invention has the advantages of easy operation, high yield, low cost, and less wastewater compared to the route in the prior art. DETAILED DESCRIPTION

[0024] The present invention is further explained below in conjunction with the examples. The following examples are only used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0025] Example 1: Synthesis of 5-hydroxyisophthalic acid

[0026] In a stainless steel container, add NaOH and water, stir and dissolve, then add 5-sodium sulfoisophthalate, and continue stirring until the material becomes a slurry. NaOH: water: 5-sodium sulfoisophthalate = 8:8.8:1 (molar ratio).

[0027] In a 2000mL dynamic tubular reactor, the temperature was set to 230°C, and the prepared slurry liquid was fed at a rate of 40mL / min using a slurry pump. After 50 minutes, the reaction liquid was collected from the back pressure valve of the dynamic tubular reactor, acidified to pH <3.0 with 7wt% hydrochloric acid, cooled to a temperature <20°C, and the crude product was filtered out. The crude product was recrystallized with water to obtain 176.27g of 5-hydroxyisophthalic acid with a content of 99.5wt%, and a product molar yield of 96.3%.

[0028] Example 2: Synthesis of 5-hydroxyisophthalic acid

[0029] In a stainless steel container, add NaOH and water, stir and dissolve, then add 5-sodium sulfoisophthalate, and continue stirring until the material becomes a slurry. NaOH: water: 5-sodium sulfoisophthalate = 5:5.6:1 (molar ratio).

[0030] In a 2000mL dynamic tubular reactor, the temperature was set to 230°C, and the prepared slurry liquid was fed at a rate of 40mL / min using a slurry pump. After 50 minutes, the reaction liquid was collected from the back pressure valve of the dynamic tubular reactor, acidified to pH <3.0 with 7wt% dilute hydrochloric acid, cooled to a temperature <20°C, filtered out the crude product, and recrystallized with water to obtain 163.9g of 5-hydroxyisophthalic acid with a content of 95wt% and a product molar yield of 85.5%.

[0031] Example 3: Synthesis of 5-hydroxyisophthalic acid

[0032] In a stainless steel container, add NaOH and water, stir and dissolve, then add 5-sodium sulfoisophthalate, and continue stirring until the material becomes a slurry. NaOH: water: 5-sodium sulfoisophthalate = 11:12.2:1 (molar ratio).

[0033] In a 2000mL dynamic tubular reactor, the temperature was set to 230°C, and the prepared slurry liquid was fed at a rate of 40mL / min using a slurry pump. After 50 minutes, the reaction liquid was collected from the back pressure valve of the dynamic tubular reactor, acidified to pH <3.0 with 7wt% hydrochloric acid, cooled to a temperature <20°C, and the crude product was filtered out. The crude product was recrystallized with water to obtain 175.24g of 5-hydroxyisophthalic acid with a content of 99.3wt% and a product molar yield of 95.6%.

[0034] Example 4: Synthesis of 5-hydroxyisophthalic acid

[0035] In a stainless steel container, add KOH and water, stir and dissolve, then add potassium 5-sulfoisophthalate, and continue stirring until the material becomes a slurry. KOH: water: sodium 5-sulfoisophthalate = 8:12.5:1 (molar ratio).

[0036] In a 2000mL dynamic tubular reactor, the temperature was set to 230°C, and the prepared slurry liquid was fed at a rate of 40mL / min using a slurry pump. After 50 minutes, the reaction liquid was collected from the back pressure valve of the dynamic tubular reactor, acidified to pH <3.0 with 7wt% hydrochloric acid, cooled to a temperature <20°C, and the crude product was filtered out. The crude product was recrystallized with water to obtain 176.46 g of 5-hydroxyisophthalic acid with a content of 99.6wt% and a product molar yield of 96.5%.

[0037] Example 5: Synthesis of 5-hydroxyisophthalic acid

[0038] In a stainless steel container, add NaOH and water, stir and dissolve, then add 5-sodium sulfoisophthalate, and continue stirring until the material becomes a slurry. NaOH: water: 5-sodium sulfoisophthalate = 8:8.8:1 (molar ratio).

[0039] In a 2000mL dynamic tubular reactor, the temperature was set to 230°C, and the prepared slurry liquid was fed at a rate of 80mL / min using a slurry pump. After 25 minutes, the reaction liquid was collected from the back pressure valve of the dynamic tubular reactor, acidified to pH <3.0 with 7wt% hydrochloric acid, cooled to a temperature <20°C, and the crude product was filtered out. The crude product was recrystallized with water to obtain 160.2g of 5-hydroxyisophthalic acid with a content of 93.0wt%, and a product molar yield of 81.1%.

[0040] Example 6: Synthesis of 5-hydroxyisophthalic acid

[0041] In a stainless steel container, add NaOH and water, stir and dissolve, then add 5-sodium sulfoisophthalate, and continue stirring until the material becomes a slurry. NaOH: water: 5-sodium sulfoisophthalate = 8:8.8:1 (molar ratio).

[0042] In a 2000mL dynamic tubular reactor, the temperature was set to 230°C, and the prepared slurry liquid was fed at a rate of 20mL / min using a slurry pump. After 100 minutes, the reaction liquid was collected from the back pressure valve of the dynamic tubular reactor, acidified to pH <3.0 with 7wt% hydrochloric acid, cooled to a temperature <20°C, and the crude product was filtered out. The crude product was recrystallized with water to obtain 176.4g of 5-hydroxyisophthalic acid with a content of 99.2wt% and a product molar yield of 96.1%.

[0043] Example 7: Synthesis of 5-hydroxyisophthalic acid

[0044] In a stainless steel container, add NaOH and water, stir and dissolve, then add 5-sodium sulfoisophthalate, and continue stirring until the material becomes a slurry. NaOH: water: 5-sodium sulfoisophthalate = 8:8.8:1 (molar ratio).

[0045] In a 2000mL dynamic tubular reactor, the temperature was set to 200°C, and the prepared slurry liquid was fed at a rate of 40mL / min using a slurry pump. After 50 minutes, the reaction liquid was collected from the back pressure valve of the dynamic tubular reactor, acidified to pH <3.0 with 7wt% hydrochloric acid, cooled to a temperature <20°C, and the crude product was filtered out. The crude product was recrystallized with process water to obtain 128.5g of 5-hydroxyisophthalic acid with a content of 71.1wt%, and the product molar yield was 50.1%.

[0046] Example 8: Synthesis of 5-hydroxyisophthalic acid

[0047] In a stainless steel container, add NaOH and water, stir and dissolve, then add 5-sodium sulfoisophthalate, and continue stirring until the material becomes a slurry. NaOH: water: 5-sodium sulfoisophthalate = 8:8.8:1 (molar ratio).

[0048] In a 2000mL dynamic tubular reactor, the temperature was set to 250°C, and the prepared slurry liquid was fed at a rate of 40mL / min using a slurry pump. After 50 minutes, the reaction liquid was collected from the back pressure valve of the dynamic tubular reactor, acidified to pH <3.0 with 7wt% hydrochloric acid, cooled to a temperature <20°C, and the crude product was filtered out. The crude product was recrystallized with process water to obtain 177g of 5-hydroxyisophthalic acid with a content of 99.4wt% and a product molar yield of 96.6%.

[0049] In Examples 1-8, the feed amount of 5-sodium sulfoisophthalate or 5-potassium sulfoisophthalate is 1 mol, and the molar yield of the product is calculated according to the molar amount of 5-sodium sulfoisophthalate or 5-potassium sulfoisophthalate used. The mass concentration of the dilute hydrochloric acid used is not higher than 20wt%.

Claims

1. A method for preparing 5-hydroxyisophthalic acid, characterized in that: The preparation method uses sodium 5-sulfoisophthalic acid or potassium 5-sulfoisophthalic acid as a raw material, reacts in an aqueous solution of NaOH or KOH, and then acidifies with dilute hydrochloric acid and post-treats to obtain the target product 5-hydroxyisophthalic acid. The reaction of sodium 5-sulfoisophthalic acid or potassium 5-sulfoisophthalic acid in the aqueous solution of NaOH or KOH is carried out in a tubular reactor.

2. The method for preparing 5-hydroxyisophthalic acid according to claim 1, wherein: The reaction temperature is 200-300°C.

3. The method for preparing 5-hydroxyisophthalic acid according to claim 2, characterized in that: The reaction temperature is 220-250°C.

4. The method for preparing 5-hydroxyisophthalic acid according to claim 1, characterized in that: The molar ratio of NaOH or KOH to sodium 5-sulfoisophthalic acid or potassium 5-sulfoisophthalic acid is 4 to 40:

1.

5. The method for preparing 5-hydroxyisophthalic acid according to claim 4, characterized in that: The molar ratio of NaOH or KOH to sodium 5-sulfoisophthalic acid or potassium 5-sulfoisophthalic acid is 7 to 11:

1.

6. The method for preparing 5-hydroxyisophthalic acid according to claim 1, characterized in that: In the aqueous solution of NaOH or KOH, the mass amount of water is 10% to 200% of the mass amount of NaOH or KOH.

7. The method for preparing 5-hydroxyisophthalic acid according to claim 7, characterized in that: In the aqueous solution of NaOH or KOH, the mass amount of water is 50% of the mass amount of NaOH or KOH.

8. The method for preparing 5-hydroxyisophthalic acid according to claim 1, characterized in that: The residence time of the reaction raw materials in the pipeline of the tubular reactor is 0.25 to 20 hours.

9. The method for preparing 5-hydroxyisophthalic acid according to claim 8, characterized in that: The residence time of the reaction raw materials in the pipeline of the tubular reactor is 40 to 60 minutes.

10. The method for preparing 5-hydroxyisophthalic acid according to claim 1, characterized in that: The tubular reactor is a dynamic tubular reactor, the reaction raw materials are continuously fed using a slurry pump, and the reaction products are continuously discharged.

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