Method for decolorizing bisphenol AF crude product without using activated carbon

Abstract

The invention discloses a method for decolorizing a bisphenol AF crude product without using activated carbon, which is characterized by comprising the following steps: dissolving the bisphenol AF crude product in an acetone-water mixed solvent, adjusting the pH value to be a weak acid reaction system, adding a reducing agent thiourea dioxide, stirring and reacting for 1-4 hours at a set temperature, cooling and filtering to obtain a decolorized crude product, and filtering to obtain the decolorized bisphenol AF crude product. And adding the decolorized crude product into a diethyl ether-dichloromethane mixed solvent, stirring for a certain time at 40 DEG C, then cooling to 5-20 DEG C by a program, crystallizing, and filtering to obtain a white solid. According to the method, thiourea dioxide is used as a reducing agent, thiourea dioxide is released in a weak acid system, benzoquinone pigments are selectively reduced, bisphenol AF with the purity of 99.7% can be obtained after recrystallization, the yield is 92.6%, the color is bright and white, reaction operation is simple, the reducing agent is cheap and easy to obtain, the yield and purity are high, the decoloration time is short, the production cost is low, and environmental protection is achieved; the generation of activated carbon solid waste in a traditional treatment method is avoided, and the economic benefit is greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of chemical technology production, and specifically relates to a method for decolorizing crude bisphenol AF without using activated carbon. Background Technology

[0002] Bisphenol AF (2,2) two (4-Hydroxyphenyl) Hexafluoropropane (HCP) is a white solid powder, insoluble in water, but soluble in methanol, ethanol, diethyl ether, acetone, etc. Its molecule contains a hexafluoroisopropyl group (HCP). This imparts higher chemical stability, hydrophobicity, and heat resistance, making it primarily used as a fluororubber vulcanization accelerator and pharmaceutical intermediate. It is widely applied in various fields such as chemical engineering, aerospace, microelectronics, and new energy. Currently, bisphenol AF is mainly synthesized from phenol and hexafluoroacetone trihydrate as raw materials, using hydrofluoric acid, heteropoly acids, and trifluoromethanesulfonic acid as catalysts.

[0003] Because an excessive amount of phenol is added during the reaction, the product remains pink or yellow even after post-treatment. Phenol is easily oxidized at high temperatures, turning pink. Chinese patent CN107619367B uses activated carbon adsorption as a traditional decolorization method, but this reduces product yield and fails to completely decolorize the product to whiten it.

[0004] Therefore, a method for decolorizing crude bisphenol AF without using activated carbon to obtain high-purity and high-whiteness bisphenol AF is urgently needed. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method for decolorizing crude bisphenol AF without using activated carbon.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0007] This invention provides a method for decolorizing crude bisphenol AF without using activated carbon, characterized by comprising the following steps: dissolving crude bisphenol AF in acetone. A water-mixed solvent was used to adjust the pH to a weakly acidic reaction system. Under nitrogen protection, the reducing agent thiourea dioxide was added. The mixture was stirred at a set temperature for a certain time, then cooled and filtered to obtain a decolorized crude product. The decolorized crude product was then added to a diethyl ether-dichloromethane mixed solvent and stirred at 40 °C for a certain time. The temperature was then gradually reduced to 5-20 °C to allow crystallization. The product was then filtered to obtain a white solid.

[0008] Preferably, the purity of the crude bisphenol AF is 80-92%.

[0009] Preferably, the volume ratio of the acetone-water mixed solvent is 2:3-7:3.

[0010] Preferably, the weak acid reaction system has a pH of 4.5 5.8.

[0011] Preferably, the amount of the reducing agent, thiourea dioxide, is 0.1-5% of the mass of the crude bisphenol AF.

[0012] Preferably, after the reducing agent, thiourea dioxide, is added, stirring and reaction are performed at 25-80 ℃, the stirring and reaction time is 1-4 h, and the stirring and reaction is performed under nitrogen protection.

[0013] Preferably, after the reaction of the reducing agent, thiourea dioxide, is completed, the temperature is lowered to 10-30 ℃ for filtration to obtain a decolorized crude product.

[0014] Preferably, in the recrystallization process, dichloromethane is added to the decolorized crude product, and the temperature is raised to 40 ℃, and then ether is added dropwise.

[0015] Preferably, in the recrystallization process, the crystallization temperature is 5-20 ℃.

[0016] Preferably, the temperature lowering rate when the temperature is lowered to 5-20 ℃ is 0.3 ℃ / min.

[0017] Preferably, the volume ratio of the ether-dichloromethane mixed solvent is 1:3-1:10.

[0018] Compared with the prior art, the present application has the following beneficial effects:

[0019] In the present application, thiourea dioxide is used as a reducing agent, and thiourea dioxide is released in a weak acid system to selectively reduce quinone pigments. After recrystallization, bisphenol AF with a purity of 99.7% and a yield of 92.6% is obtained, and the color is bright white, the reaction operation is simple, the reducing agent is cheap and easy to obtain, the yield and purity are high, the decolorization time is short, the production cost is low, and the environment is protected. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 FIG. 4 is an HPLC chromatogram of bisphenol AF after decolorization and recrystallization purification. DETAILED DESCRIPTION

[0021] The preferred embodiments of the present application are described below, and it should be understood that the preferred embodiments described herein are only used to illustrate and explain the present application, and are not used to limit the present application.

[0022] Example 1

[0023] Under nitrogen protection, phenol and hexafluoroacetone trihydrate were used as raw materials, the molar ratio of which was 2:1, and the mixture was heated to 150℃ for 3 hours under the catalysis of trifluoromethanesulfonic acid to generate bisphenol AF crude product with a purity of 92%.

[0024] 100 g of bisphenol AF crude product was added into 800 mL of acetone-water mixed solvent (7:3 / v:v) to adjust the pH to 5.5 5.8, 0.5 g of sulfourea dioxide was added, and the mixture was reacted at 65℃ for 2 hours under nitrogen protection. After cooling to 25℃, the mixture was filtered to obtain 98 g of decolorized crude product.

[0025] 98 g of the decolorized crude product was dissolved in 475 mL of dichloromethane, and the solution was heated to 40℃. Ethyl ether (total amount 158 mL) was added dropwise until the solution became turbid. The solution was cooled to 5℃ at a rate of 0.3℃ per minute, and then filtered to obtain 92.6 g of needle-shaped crystals with a purity of 99.7%. The crystals were bright white (the HPLC chromatogram of purified bisphenol AF is shown in 5℃ (0.3℃ per minute), and then filtered to obtain 92.6 g of needle-shaped crystals with a purity of 99.7%. The crystals were bright white (the HPLC chromatogram of purified bisphenol AF is shown in Figure 1 ).

[0026] Examples 2-6 and Comparative Examples 1-6

[0027] The preparation method and purification method of Examples 2-6 and Comparative Examples 1-6 were basically the same as those of Example 1, except that the amount of sulfourea dioxide, the reducing agent, was different, which was represented by A, and A represented the mass percentage of the reducing agent based on the raw material.

[0028] Table 1: Color of BPAF crystals after reduction under different conditions.

[0029]

[0030] According to the external standard method, the yield of the product and the purity of the product were calculated based on the peak area of the corresponding product. The optimal purity of the purified bisphenol AF reached 99.7%, and the yield reached 92.6%.

[0031] Finally, it should be noted that the above description is only a preferred embodiment of the present application and is not intended to limit the present application. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent replacements to some technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for decolorizing crude bisphenol AF without using activated carbon, characterized in that, Includes the following steps: Crude bisphenol AF was dissolved in an acetone-water mixture, and the pH was adjusted to a weakly acidic reaction system. Under nitrogen protection, the reducing agent thiourea dioxide was added, and the reaction was carried out with stirring at a set temperature for 1 to 4 hours. After cooling, the mixture was filtered to obtain a decolorized crude product. The decolorized crude product was added to an ether-dichloromethane mixture and stirred at 40 °C for a certain time. Then, the temperature was gradually reduced to 5 to 20 °C to allow crystallization, and the product was filtered to obtain a white solid.

2. The method for decolorizing crude bisphenol AF without using activated carbon according to claim 1, characterized in that, The purity of the crude bisphenol AF is 80-92%.

3. The method for decolorizing crude bisphenol AF without using activated carbon according to claim 1, characterized in that, The volume ratio of the acetone-water mixed solvent is 2:3 to 7:

3.

4. The method for decolorizing crude bisphenol AF without using activated carbon according to claim 1, characterized in that, The weak acid reaction system has a pH of 4.

5. 5.

8.

5. The method for decolorizing crude bisphenol AF without using activated carbon according to claim 1, characterized in that, The amount of the reducing agent thiourea dioxide is 0.1-5% of the crude bisphenol AF.

6. The method for decolorizing crude bisphenol AF without using activated carbon according to claim 1, characterized in that, After adding the reducing agent thiourea dioxide, the mixture was stirred at 25-80 °C for 1-4 h under nitrogen protection.

7. The method for decolorizing crude bisphenol AF without using activated carbon according to claim 1, characterized in that, After the reaction with the reducing agent thiourea dioxide is completed, the temperature is lowered to 10-30℃ and filtered to obtain the decolorized crude product.

8. The method for decolorizing crude bisphenol AF without using activated carbon according to claim 1, characterized in that, During recrystallization, dichloromethane is added to the decolorized crude product, the temperature is raised to 40 °C, and then diethyl ether is added dropwise.

9. The method for decolorizing crude bisphenol AF without using activated carbon according to claim 1, characterized in that, During recrystallization, the crystallization temperature is 5~20 ℃, and the cooling rate from 40 ℃ to 5~20 ℃ is 0.3 ℃ / min.

10. A method for decolorizing crude bisphenol AF without using activated carbon according to claim 1, characterized in that, The volume ratio of the diethyl ether-dichloromethane mixed solvent is 1:3 to 1:10.

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