Purification method of 4, 4 '-dichlorodiphenyl sulfone mixture

Abstract

The invention discloses a purification method of a 4, 4 '-dichlorodiphenyl sulfone mixture, and belongs to the technical field of organic synthesis, 2, 4'-dichlorodiphenyl sulfone generates 2-hydroxy-4 '-chlorodiphenyl sulfone sodium salt under an alkaline condition by controlling reaction conditions, and then the 2-hydroxy-4'-chlorodiphenyl sulfone sodium salt is removed by a water washing method to realize purification of 4, 4 '-dichlorodiphenyl sulfone.

Description

Technical Field

[0001] This invention belongs to the field of organic synthesis technology, specifically a method for purifying a mixture of 4,4'-dichlorodiphenyl sulfone. Background Technology

[0002] 4,4'-Dichlorodiphenyl sulfone is a major raw material for manufacturing engineering plastics such as polysulfone and polyethersulfone; it is also an intermediate in pharmaceuticals, dyes and pesticides, and has wide applications in engineering plastics and fine chemicals.

[0003] Currently, industrialized preparation methods mainly include the sulfur trioxide method, the chlorosulfonic acid method, and the sulfoxide oxidation method. The sulfur trioxide method uses sulfur trioxide, dimethyl sulfate, and chlorobenzene as raw materials. Its advantages are short reaction time, good product quality, and high yield. Its disadvantages are the high toxicity of the reactants and the complexity of the process. The chlorosulfonic acid method involves reacting p-chlorobenzenesulfonic acid with chlorobenzene under aluminum trichloride catalysis. Its advantages are a relatively mature process and good product quality. Its disadvantages are the complexity of the process, the need for multiple production equipment, high cost, and the environmental pollution caused by the hydrogen chloride gas generated during production. The sulfoxide oxidation method first uses sulfoxide and chlorobenzene to prepare 4,4'-dichlorodiphenyl sulfoxide under aluminum trichloride catalysis, and then prepares 4,4'-dichlorodiphenyl sulfone from 4,4'-dichlorodiphenyl sulfoxide. Its advantages are simple process, short reaction time, low temperature, and high product quality. Its disadvantage is the environmental pollution caused by the hydrogen chloride gas generated during production. Regardless of the method used, due to the selectivity of the reaction, 4,4'-dichlorodiphenyl sulfone will contain 2,4'-dichlorodiphenyl sulfone. In existing technologies, 4,4'-dichlorodiphenyl sulfone containing 2,4'-dichlorodiphenyl sulfone can be recrystallized in solvents such as trichloroethylene and chlorobenzene to obtain 4,4'-dichlorodiphenyl sulfone with higher purity. However, 2,4'-dichlorodiphenyl sulfone and 4,4'-dichlorodiphenyl sulfone will exist in a certain proportion in the recrystallization mother liquor, and cannot be further purified by recrystallization. The remaining mixture of 4,4'-dichlorodiphenyl sulfone, 2,4'-dichlorodiphenyl sulfone, and 4,4'-dichlorodiphenyl sulfone must mostly be disposed of as hazardous waste, resulting in resource waste and increasing the production cost of 4,4'-dichlorodiphenyl sulfone. Alternatively, 4,4'-dichlorodiphenyl sulfone and 2,4'-dichlorodiphenyl sulfone can be converted into 4,4'-dihydroxydiphenyl sulfone and 2,4'-dihydroxydiphenyl sulfone, and then separated by the difference in the solubility of their monosodium salts. However, this method has the problems of cumbersome operation, harsh process conditions and large amount of waste. Summary of the Invention

[0004] To address the above problems, the present invention aims to provide a method for purifying a mixture of 4,4'-dichlorodiphenyl sulfone.

[0005] To achieve the above objectives, the present invention employs the following technical solution: A method for purifying a mixture of 4,4'-dichlorodiphenyl sulfone involves adding a mixture of 2,4'-dichlorodiphenyl sulfone and 4,4'-dichlorodiphenyl sulfone to a reaction vessel, adding an alkaline solution to react, and finally rinsing with pure water and drying to obtain 4,4-dichlorodiphenyl sulfone.

[0006] Specifically, the following steps are included: 1) Add the mixture of 2,4'-dichlorodiphenyl sulfone and 4,4'-dichlorodiphenyl sulfone to a reaction vessel, stir and mix evenly, then add alkaline solution, heat to 160~180℃, and react for 4~8 hours to obtain the reaction solution; 2) Cool the reaction solution obtained in step 1) to 110~150℃, separate it, wash the obtained filter cake with pure water, and dry it to obtain 4,4-dichlorodiphenyl sulfone.

[0007] The alkaline solution mentioned in step 1) is an aqueous solution of sodium hydroxide with a mass concentration of 5-10%.

[0008] The molar ratio of 2,4'-dichlorodiphenyl sulfone to the base in step 1) is 1:2~2.4.

[0009] The separation temperature mentioned in step 2) is 110~150℃.

[0010] The temperature of the pure water mentioned in step 2) is 80~100℃.

[0011] Preferably, the alkaline solution in step 1) is an aqueous solution of sodium hydroxide with a mass concentration of 8%.

[0012] Preferably, the molar ratio of 2,4'-dichlorodiphenyl sulfone to the base in step 1) is 1:2.2.

[0013] Preferably, the separation temperature in step 2) is 120°C.

[0014] Preferably, the temperature of the pure water in step 2) is 90°C.

[0015] The synthetic route for the sodium salt of 2-hydroxy-4'-chloro-diphenyl sulfone of this invention is as follows: .

[0016] The present invention has the following advantages over the prior art: The purification method for the 4,4'-dichlorodiphenyl sulfone mixture of the present invention utilizes the characteristics of the weak α-chlorine electron cloud density and stronger electrophilic substitution ability on the benzene ring of 2,4'-dichlorodiphenyl sulfone to achieve the conversion of 2,4'-dichlorodiphenyl sulfone into sodium salt of 2-hydroxy-4'-chloro-diphenyl sulfone that dissolves in the aqueous phase, while 4,4'-dichlorodiphenyl sulfone does not participate in the reaction, thereby achieving efficient separation of 2,4'-dichlorodiphenyl sulfone and 4,4'-dichlorodiphenyl sulfone.

[0017] The purification method of the present invention for the 4,4'-dichlorodiphenyl sulfone mixture further purifies 4,4'-dichlorodiphenyl sulfone from the mixture of 2,4'-dichlorodiphenyl sulfone and 4,4'-dichlorodiphenyl sulfone. The preparation method of the present invention further reduces the cost of producing 4,4'-dichlorodiphenyl sulfone, is environmentally friendly to equipment, has simple post-processing, high production efficiency, and is green and environmentally friendly. Attached Figure Description

[0018] Figure 1 The high-performance liquid chromatogram of 4,4'-dichlorodiphenyl sulfone prepared in Example 1 of this invention. Detailed Implementation

[0019] To better understand the technical solution of the present invention, the following detailed embodiments further illustrate the above-mentioned content of the present invention. However, this should not be construed as limiting the scope of the above-mentioned subject matter of the present invention to the following examples. All technologies implemented based on the above-mentioned content of the present invention fall within the scope of the present invention.

[0020] The mixture of 2,4'-dichlorodiphenyl sulfone and 4,4'-dichlorodiphenyl sulfone described in this invention is prepared by concentrating the obtained reaction solution to a concentration of 28%~30% of 4,4'-dichlorodiphenyl sulfone in the reaction solution, cooling and crystallizing to obtain pure 4,4'-dichlorodiphenyl sulfone and crystallization mother liquor, and then concentrating the crystallization mother liquor to obtain the mixture.

[0021] Example 1: 574.32 g of a mixture of 2,4'-dichlorodiphenyl sulfone and 4,4'-dichlorodiphenyl sulfone was added to a reaction vessel, wherein the concentration ratio of 4,4'-dichlorodiphenyl sulfone to 2,4'-dichlorodiphenyl sulfone was 1:1. After stirring and mixing evenly, 1100 g of an 8% sodium hydroxide aqueous solution was added, and the mixture was heated to 170°C and reacted for 6 hours to obtain a reaction solution. The reaction solution was then cooled to 120°C, separated, and the resulting filter cake was washed with 90°C pure water and dried to obtain 4,4-dichlorodiphenyl sulfone. Its liquid chromatogram is shown below. Figure 1 As shown, the yield was 98.7% and the purity was 99.8%.

[0022] Example 2: 574.32 g of a mixture of 2,4'-dichlorodiphenyl sulfone and 4,4'-dichlorodiphenyl sulfone was added to a reaction vessel, wherein the concentration ratio of 4,4'-dichlorodiphenyl sulfone to 2,4'-dichlorodiphenyl sulfone was 1:9. After stirring and mixing evenly, 2880 g of a 5% sodium hydroxide aqueous solution was added, and the mixture was heated to 160°C and reacted for 4 h to obtain a reaction solution. The reaction solution was then cooled to 110°C, separated, and the resulting filter cake was washed with 80°C pure water and dried to obtain 4,4-dichlorodiphenyl sulfone with a yield of 97.9% and a purity of 99.1%.

[0023] Example 3: 2871.6g of a mixture of 2,4'-dichlorodiphenyl sulfone and 4,4'-dichlorodiphenyl sulfone was added to a reaction vessel, wherein the concentration ratio of 4,4'-dichlorodiphenyl sulfone to 2,4'-dichlorodiphenyl sulfone was 3:7. After stirring and mixing evenly, 9800g of a 6% sodium hydroxide aqueous solution was added, and the mixture was heated to 165°C and reacted for 5 hours to obtain a reaction solution. The reaction solution was then cooled to 120°C and separated. The resulting filter cake was washed with 85°C pure water and dried to obtain 4,4-dichlorodiphenyl sulfone, with a yield of 98.5% and a purity of 99.6%.

[0024] Example 4: 574.32 g of a mixture of 2,4'-dichlorodiphenyl sulfone and 4,4'-dichlorodiphenyl sulfone was added to a reaction vessel, wherein the concentration ratio of 4,4'-dichlorodiphenyl sulfone to 2,4'-dichlorodiphenyl sulfone was 9:1. After stirring and mixing evenly, 251 g of a 7% sodium hydroxide aqueous solution was added, and the mixture was heated to 170°C and reacted for 6 h to obtain a reaction solution. The reaction solution was then cooled to 130°C, separated, and the resulting filter cake was washed with 90°C pure water and dried to obtain 4,4-dichlorodiphenyl sulfone with a yield of 98.7% and a purity of 99.5%.

[0025] Example 5: 574.32 g of a mixture of 2,4'-dichlorodiphenyl sulfone and 4,4'-dichlorodiphenyl sulfone was added to a reaction vessel, wherein the concentration ratio of 4,4'-dichlorodiphenyl sulfone to 2,4'-dichlorodiphenyl sulfone was 8:2. After stirring and mixing evenly, 410 g of a 9% sodium hydroxide aqueous solution was added, and the mixture was heated to 175°C and reacted for 7 h to obtain a reaction solution. The reaction solution was then cooled to 140°C, separated, and the resulting filter cake was washed with 95°C pure water and dried to obtain 4,4-dichlorodiphenyl sulfone with a yield of 98.7% and a purity of 99.4%.

[0026] Example 6: 574.32 g of a mixture of 2,4'-dichlorodiphenyl sulfone and 4,4'-dichlorodiphenyl sulfone was added to a reaction vessel, wherein the concentration ratio of 4,4'-dichlorodiphenyl sulfone to 2,4'-dichlorodiphenyl sulfone was 1:1. After stirring and mixing evenly, 960 g of a 10% sodium hydroxide aqueous solution was added, and the mixture was heated to 180°C and reacted for 8 hours to obtain a reaction solution. The reaction solution was then cooled to 150°C, separated, and the resulting filter cake was washed with 100°C pure water and dried to obtain 4,4-dichlorodiphenyl sulfone with a yield of 98.1% and a purity of 99.1%.

[0027] In a comparative example, 574.32 g of a mixture of 4,4'-dichlorodiphenyl sulfone and 2,4'-dichlorodiphenyl sulfone was added to a reaction vessel, wherein the concentration ratio of 4,4'-dichlorodiphenyl sulfone to 2,4'-dichlorodiphenyl sulfone was 1:1. Then, 800 g of a 20% sodium hydroxide solution was added to the reaction vessel. The temperature inside the reaction vessel was raised to 230°C and maintained at this temperature for 7 hours. After the reaction was completed, the reaction solution was cooled to 85°C and filtered to obtain 4,4'-dichlorodiphenyl sulfone with a yield of 110% and a purity of 55%.

[0028] While the specific embodiments of the present invention have been described above, they are not intended to limit the scope of protection of the present invention. Based on the technical solutions of the present invention, various modifications or variations that can be made by those skilled in the art without creative effort are still within the scope of protection of the present invention.

Claims

1. A method for purifying a 4,4'-dichlorodiphenyl sulfone mixture, characterized by: A mixture of 2,4'-dichlorodiphenyl sulfone and 4,4'-dichlorodiphenyl sulfone is added into a reaction kettle, and then a lye is added for reaction, and finally, the reaction liquid is washed with pure water, dried to obtain 4,4-dichlorodiphenyl sulfone.

2. The purification method of a 4,4'-dichlorodiphenyl sulfone mixture according to claim 1, characterized by: Specifically comprising the following steps: 1) A mixture of 2,4'-dichlorodiphenyl sulfone and 4,4'-dichlorodiphenyl sulfone is added into a reaction kettle, and then a lye is added for reaction, and finally, the reaction liquid is washed with pure water, dried to obtain 4,4-dichlorodiphenyl sulfone. 2) The reaction liquid prepared in step 1) is cooled to 110-150°C, separated, and the obtained filter cake is washed with pure water, dried to obtain 4,4-dichlorodiphenyl sulfone.

3. The method of purifying a 4,4'-dichlorodiphenyl sulfone mixture according to claim 2, wherein: The lye in step 1) is a sodium hydroxide aqueous solution with a mass concentration of 5-10%.

4. The method of purifying a 4,4'-dichlorodiphenyl sulfone mixture according to claim 2, wherein: The molar ratio of 2,4'-dichlorodiphenyl sulfone to the lye in step 1) is 1:2-2.

4.

5. The method of purifying a 4,4'-dichlorodiphenyl sulfone mixture according to claim 2, wherein: The separation temperature in step 2) is 110-150°C.

6. The method of purifying a 4,4'-dichlorodiphenyl sulfone mixture according to claim 2, wherein: The temperature of the pure water in step 2) is 80-100°C.

7. The method of purifying a 4,4'-dichlorodiphenyl sulfone mixture according to claim 2, wherein: The lye in step 1) is a sodium hydroxide aqueous solution with a mass concentration of 8%.

8. The method of purifying a 4,4'-dichlorodiphenyl sulfone mixture according to claim 2, wherein: The molar ratio of 2,4'-dichlorodiphenyl sulfone to the lye in step 1) is 1:2.

2.

9. The method of purifying a 4,4'-dichlorodiphenyl sulfone mixture according to claim 2, wherein: The separation temperature in step 2) is 120°C.

10. The method of purifying a 4,4'-dichlorodiphenyl sulfone mixture according to claim 2, wherein: The temperature of the pure water in step 2) is 90°C.

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