Synthesis method of ultra-high-purity 4, 4 '-dichlorodiphenyl sulfone

Abstract

The invention discloses a synthesis method of ultra-high-purity 4, 4 '-dichlorodiphenyl sulfone, which comprises the following steps: 1) preparing a 4, 4'-dichlorodiphenyl sulfoxide crude product; 2) mixing the 4, 4 '-dichlorodiphenyl sulfoxide crude product with methanol, heating and refluxing, and after the refluxing is finished, cooling and centrifugally filtering to obtain a 4, 4'-dichlorodiphenyl sulfoxide refined product; 3) mixing the 4, 4 '-dichlorodiphenyl sulfoxide fine product, methanol, ammonium metatungstate and sodium carbonate, heating and dissolving, dropwise adding hydrogen peroxide to carry out oxidation reaction, and after the reaction is finished, cooling and centrifugally filtering to obtain a 4, 4'-dichlorodiphenyl sulfone crude product; and 4) mixing the 4, 4 '-dichlorodiphenyl sulfone crude product with xylene, heating and dissolving, decolorizing, filtering, cooling and crystallizing, centrifuging and drying to obtain the ultra-high-purity 4, 4'-dichlorodiphenyl sulfone. The purity of the prepared 4, 4 '-dichlorodiphenyl sulfone can reach 99.98% or above, the content of 4, 4'-dichlorodiphenyl sulfoxide is 2 ppm or below, organic solvent residues are 10 ppm or below, and the requirements of related application fields needing high-purity products can be met.

Description

Technical Field

[0001] The invention belongs to the technical field of synthesis of special engineering plastic polysulfone resin monomers, and in particular relates to a method for synthesizing ultra-high purity 4,4'-dichlorodiphenyl sulfone. Background Art

[0002] 4,4'-Dichlorodiphenyl sulfone is an important monomer for synthesizing polysulfone, polyethersulfone and polyphenylsulfone resins. At present, the existing methods for synthesizing 4,4'-dichlorodiphenyl sulfone at home and abroad include chlorosulfonic acid method, sulfuric acid method, sulfur trioxide method, etc., but these synthesis methods are difficult to ensure the ultra-high purity of 4,4'-dichlorodiphenyl sulfone, and thus cannot meet the needs of application fields that require high-purity products. For example, the purity of 4,4'-dichlorodiphenyl sulfone synthesized by the existing synthesis method is about 99.90%, and the residual 4,4'-dichlorodiphenyl sulfoxide is above 100ppm. When it is used to prepare polysulfone resins, the residual 4,4'-dichlorodiphenyl sulfoxide seriously affects the yellowness, stability and other qualities of the polysulfone resins. In addition, in polysulfone resins, because it does not participate in polymerization, it is easy to precipitate, which restricts the application of polysulfone resins in high-end fields such as medical treatment (such as hemodialysis membranes). Summary of the invention

[0003] The purpose of the present invention is to provide a high-yield and green method for synthesizing ultra-high-purity 4,4'-dichlorodiphenyl sulfone in view of the problems existing in the prior art. The purity of the 4,4'-dichlorodiphenyl sulfone prepared by the synthesis method can reach 99.98% or more, and the content of 4,4'-dichlorodiphenyl sulfoxide is below 2ppm.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] The method for synthesizing the ultra-high purity 4,4'-dichlorodiphenyl sulfone provided by the present invention comprises the following steps:

[0006] 1) preparing crude 4,4'-dichlorodiphenyl sulfoxide;

[0007] 2) mixing the crude 4,4'-dichlorodiphenyl sulfoxide obtained in step 1) with methanol, then heating and refluxing, and after the reflux is completed, cooling, centrifuging and filtering to obtain a fine product of 4,4'-dichlorodiphenyl sulfoxide;

[0008] 3) Mixing the 4,4'-dichlorodiphenyl sulfoxide obtained in step 2), methanol, ammonium metatungstate and sodium carbonate, and then heating to dissolve, and after complete dissolution, adding hydrogen peroxide dropwise to carry out oxidation reaction, and after the reaction is completed, cooling and centrifugation to obtain a crude 4,4'-dichlorodiphenyl sulfone;

[0009] 4) The crude 4,4'-dichlorodiphenyl sulfone obtained in step 3) is mixed with xylene, and then heated to dissolve. After the dissolution is completed, decolorization, filtration, cooling and crystallization, centrifugation, and drying are performed to obtain the ultra-high purity 4,4'-dichlorodiphenyl sulfone.

[0010] Preferably, in step 1), the method for preparing crude 4,4'-dichlorodiphenyl sulfoxide comprises the following steps:

[0011] S1. Chlorobenzene and anhydrous aluminum chloride are mixed, stirred and dispersed, and thionyl chloride is added dropwise at a set temperature. After the addition is completed, the reaction is continued by keeping warm. After the reaction is completed, the temperature is raised to dissolve to obtain a chlorobenzene solution containing 4,4'-dichlorodiphenyl sulfoxide;

[0012] S2. Add the chlorobenzene solution containing 4,4'-dichlorodiphenyl sulfoxide obtained in step S1 into water, heat it for hydrolysis, release aluminum chloride, then distill off chlorobenzene under normal pressure, cool, centrifuge and wash with water to obtain a crude 4,4'-dichlorodiphenyl sulfoxide.

[0013] Furthermore, in step S1, the set temperature and the temperature for continued reaction after the addition of thionyl chloride are 20°C-60°C; the dropping speed of thionyl chloride is 3-5 drops / second, and the reaction is continued for 45-60 minutes after the addition of thionyl chloride is completed.

[0014] Furthermore, in step S1, the temperature of the heating and dissolving is 110°C-120°C, so that the by-product hydrogen chloride can fully overflow.

[0015] Furthermore, in step S2, the temperature of the hydrolysis is 40-50°C, and the time is 60-80 minutes; the distillation of chlorobenzene is a normal pressure water entrainment distillation, and the chlorobenzene is completely recovered for reuse, and the distillation end temperature is 110°C-120°C.

[0016] Preferably, in step 2), the temperature of the reflux is 115-120°C, and the reflux time is not less than 30 minutes, the purpose of which is to fully dissolve the by-products in 4,4'-dichlorodiphenyl sulfoxide in methanol and remove them, which is conducive to a more complete subsequent oxidation reaction. In step 2), methanol is used as an organic solvent, which has good solubility, is volatile, has low toxicity, a boiling point of 64.8°C, a low distillation recovery temperature, low energy consumption, and a high recovery rate.

[0017] Preferably, in step 3), the amount of methanol is 4.0-5.0 times the weight of 4,4'-dichlorodiphenyl sulfoxide; the amount of ammonium metatungstate is 1.5-2.0% of the weight of 4,4'-dichlorodiphenyl sulfoxide; the amount of sodium carbonate is 10-12% of the weight of 4,4'-dichlorodiphenyl sulfoxide; the mass concentration of hydrogen peroxide is 35%, and its amount is 0.5-0.6 times the weight of 4,4'-dichlorodiphenyl sulfoxide.

[0018] In step 3) of the present invention, weakly acidic ammonium metatungstate is used as a catalyst. With ammonium metatungstate solution as a raw material, a metatungstic acid solution is formed in the reaction, and hydrogen peroxide generates oxygen ions under acidic conditions and oxidizes 4,4'-dichlorodiphenyl sulfoxide to obtain a crude 4,4'-dichlorodiphenyl sulfone. In addition, sodium carbonate can neutralize metatungstate to obtain sodium metatungstate, and a solvent extraction method using sodium metatungstate solution as a raw material is used to obtain an ammonium metatungstate solution, and then ammonium metatungstate is obtained by evaporation and crystallization, thereby realizing the recycling of the catalyst.

[0019] Preferably, in step 3), the temperature of the heating and dissolving is 50-55°C; the dripping speed of the hydrogen peroxide is 3-5 drops / second; the temperature of the oxidation reaction is 70-75°C, and the time is 1-1.5h.

[0020] Preferably, in step 4), the amount of xylene used is 2.5-3.0 times the weight of the crude 4,4'-dichlorodiphenyl sulfone, the temperature for heating and dissolving is 90°C-95°C; activated carbon is added for decolorization, and the amount of activated carbon used is 0.3-0.5% of the weight of the crude 4,4'-dichlorodiphenyl sulfone; and the crystallization temperature is below 30°C.

[0021] Further preferably, the xylene is a mixture of o-xylene, p-xylene and m-xylene, wherein the volume ratio of o-xylene, p-xylene and m-xylene is 6:3:1. Compared with the crystallization using a single toluene solvent, the xylene mixed solvent used in the present invention is more conducive to the growth of 4,4'-dichlorodiphenyl sulfone crystals, with less impurity inclusion and less organic residue. When it is used to prepare polysulfone, polyethersulfone, polyphenylsulfone resin, etc., it is more conducive to the control of polymerization degree, and the resin quality is better and more stable.

[0022] Beneficial effects of the present invention:

[0023] 1) The reaction system of methanol, ammonium metatungstate, sodium carbonate and hydrogen peroxide adopted in the present invention abandons the large-scale use of acetic acid and sulfuric acid in the traditional method and solves the problem of non-recyclability, reduces equipment corrosion and environmental pollution, changes the acidic environment oxidation to the alkaline environment oxidation, and improves the oxidation conversion rate. In the crude 4,4'-dichlorodiphenyl sulfone obtained under the reaction system conditions, the content of 4,4'-dichlorodiphenyl sulfoxide is less than 0.2%, and the purity of 4,4'-dichlorodiphenyl sulfone is greater than 99.80%.

[0024] 2) The present invention adopts unique oxidation technology and crystallization technology to synthesize ultra-high purity 4,4'-dichlorodiphenyl sulfone, wherein the purity of 4,4'-dichlorodiphenyl sulfone can reach 99.98% or above, the content of 4,4'-dichlorodiphenyl sulfoxide is below 2ppm, and the residual organic solvent is below 10ppm, meeting the most stringent requirements in the world.

[0025] 3) The present invention not only solves the problem of relatively high residual 4,4'-dichlorodiphenyl sulfoxide in the finished product, but also completely solves the high stability and reliability problems of polysulfone polymerization, and makes the polysulfone resin reach advanced levels in terms of molecular weight distribution, molecular weight size, and monomer residue, solving the problem of high-end application of polysulfone resin! BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a liquid chromatography analysis chart of the crude 4,4'-dichlorodiphenyl sulfoxide obtained in Example 1;

[0027] Figure 2 This is a liquid chromatography analysis chart of the crude 4,4'-dichlorodiphenyl sulfone obtained in Example 1;

[0028] Figure 3 This is a liquid chromatography analysis chart of the ultra-high purity 4,4'-dichlorodiphenyl sulfone product obtained in Example 1;

[0029] Figure 4 This is a liquid chromatography analysis chart of the crude 4,4'-dichlorodiphenyl sulfone obtained in Comparative Example 1.

[0030] Figure 5 This is a liquid chromatography analysis chart of the finished 4,4'-dichlorodiphenyl sulfone obtained in Comparative Example 1. DETAILED DESCRIPTION

[0031] In order to better understand the present invention, the content of the present invention is further explained below in conjunction with specific examples, but the content of the present invention is not limited to the following embodiments.

[0032] Example 1

[0033] 1) 40g of chlorobenzene and 10g of anhydrous aluminum chloride were mixed, stirred and dispersed, and 7.5g of thionyl chloride was added dropwise at a rate of 3 drops / second at 35°C. After the addition was completed, the mixture was kept warm and reacted for 50 minutes. After the reaction was completed, the mixture was heated to 115°C to dissolve, thereby obtaining a chlorobenzene solution containing 4,4'-dichlorodiphenyl sulfoxide;

[0034] 2) slowly adding the chlorobenzene solution containing 4,4'-dichlorodiphenyl sulfoxide into tap water, heating to 40-45°C for hydrolysis for 1 hour to release aluminum chloride, and then distilling out chlorobenzene with atmospheric pressure water, the distillation end temperature is 115°C, cooling, centrifuging, and washing with water to obtain a crude 4,4'-dichlorodiphenyl sulfoxide;

[0035] 3) Mix 35 g of crude 4,4'-dichlorodiphenyl sulfoxide with 200 g of methanol, then heat to 115-120° C. and reflux for 45 min. After reflux, cool and centrifuge to obtain 30 g of refined 4,4'-dichlorodiphenyl sulfoxide;

[0036] 4) Mix 30g of 4,4'-dichlorodiphenyl sulfoxide, 120g of methanol, 0.5g of ammonium metatungstate, and 3g of sodium carbonate, then heat to 50°C. After the solid is completely dissolved, begin to drip 15g of 35% hydrogen peroxide. After 15 minutes of dripping, keep warm and continue to react for 1.5 hours. During the insulation process, the temperature is maintained at 70-75°C. After the reaction is completed, a large amount of solid precipitates when the water bath is cooled to 20°C, then cool to 10°C in an ice bath, filter, wash with methanol and water until the solid is neutral (there is moisture on the surface of the solid), drain with a circulating water pump, and then dry to obtain a crude 4,4'-dichlorodiphenyl sulfone, weighing 27.5g. The components and contents of crude 4,4'-dichlorodiphenyl sulfone were detected by LC-20AT liquid chromatograph. The content of 4,4'-dichlorodiphenyl sulfone and 4,4'-dichlorodiphenyl sulfoxide were 99.83% and 0.17%, respectively. Figure 2 As shown in FIG. 1 , the conversion rate of the oxidation reaction is calculated to be 92%.

[0037] The synthetic route involved in this step is:

[0038]

[0039] 5) Add 11g of crude 4,4'-dichlorodiphenyl sulfone to 27.5g of a xylene mixture (the volume ratio of o-xylene, p-xylene and m-xylene is 6:3:1), heat to 90°C to dissolve, keep warm for 2h, add 0.055g of activated carbon for decolorization, then cool to below 30°C with circulating water and cooling water for crystallization, centrifuge, drain, and dry to obtain an ultra-high purity 4,4'-dichlorodiphenyl sulfone product. The sample was taken and measured by LC-20AT liquid chromatograph. The purity of the ultra-high purity 4,4'-dichlorodiphenyl sulfone product was 99.986%, and the content of 4,4'-dichlorodiphenyl sulfoxide was 0.014%. For details, see Figure 3 shown.

[0040] Comparative Example 1

[0041] Compared with Example 1, the difference of this comparative example is mainly that step 4) is different. Specifically:

[0042] 1) 40g of chlorobenzene and 10g of anhydrous aluminum chloride were mixed, stirred and dispersed, and 7.5g of thionyl chloride was added dropwise at a rate of 3 drops / second at 35°C. After the addition was completed, the mixture was kept warm and reacted for 50 minutes. After the reaction was completed, the mixture was heated to 115°C to dissolve, thereby obtaining a chlorobenzene solution containing 4,4'-dichlorodiphenyl sulfoxide;

[0043] 2) slowly adding the chlorobenzene solution containing 4,4'-dichlorodiphenyl sulfoxide into tap water, heating to 40-45°C for hydrolysis for 1 hour to release aluminum chloride, and then distilling out chlorobenzene with atmospheric pressure water, the distillation end temperature is 115°C, cooling, centrifuging, and washing with water to obtain a crude 4,4'-dichlorodiphenyl sulfoxide;

[0044] 3) Mix 35 g of crude 4,4'-dichlorodiphenyl sulfoxide with 200 g of methanol, then heat to 115-120° C. and reflux for 45 min. After reflux, cool and centrifuge to obtain 30 g of refined 4,4'-dichlorodiphenyl sulfoxide;

[0045] 4) Add 30g of 4,4'-dichlorodiphenyl sulfoxide, 120g of chlorobenzene, 5g of acetic acid, and 3g of concentrated sulfuric acid to the reaction bottle in sequence, and heat to 45-50°C. After the solid is completely dissolved, 20g of 35% hydrogen peroxide is added dropwise. After 15 minutes of addition, the reaction is continued for 2 hours. During the insulation process, the temperature is maintained at 50-55°C. After the reaction is completed, a large amount of solid is precipitated when the water bath is cooled to 20°C, and then the ice bath is cooled to 10°C for filtration, washed with methanol and water until the solid is neutral (there is moisture on the surface of the solid), and then dried with a circulating water pump to obtain a crude 4,4'-dichlorodiphenyl sulfone, weighing 26.8g. The components and contents of crude 4,4'-dichlorodiphenyl sulfone were detected by LC-20AT liquid chromatograph. The content of 4,4'-dichlorodiphenyl sulfone and 4,4'-dichlorodiphenyl sulfoxide were 99.67% and 0.32%, respectively. Figure 4 As shown in FIG. 1 , the conversion rate of the oxidation reaction is calculated to be 89.4%.

[0046] The synthetic route involved in this step is:

[0047]

[0048] 5) Add 10.72g of crude 4,4'-dichlorodiphenyl sulfone to 26.8g of a xylene mixture (the volume ratio of o-xylene, p-xylene and m-xylene is 6:3:1), heat to 90°C to dissolve, keep warm for 1.5h, add 0.053g of activated carbon for decolorization, then cool to below 30°C with circulating water and cooling water for crystallization, centrifuge, drain, and dry to obtain a finished 4,4'-dichlorodiphenyl sulfone. The purity of the finished 4,4'-dichlorodiphenyl sulfone was measured by LC-20AT liquid chromatograph to be 99.939%, and the content of 4,4'-dichlorodiphenyl sulfoxide was 0.0601%, see Figure 5 shown.

Claims

1. A method for synthesizing ultra-high purity 4,4'-dichlorodiphenyl sulfone, comprising the following steps: 1) preparing crude 4,4'-dichlorodiphenyl sulfoxide; 2) mixing the crude 4,4'-dichlorodiphenyl sulfoxide obtained in step 1) with methanol, and then heating and refluxing. After the reflux is completed, cooling and centrifugal filtration are performed to obtain a refined 4,4'-dichlorodiphenyl sulfoxide; 3) Mixing the 4,4'-dichlorodiphenyl sulfoxide obtained in step 2), methanol, ammonium metatungstate and sodium carbonate, and then heating to dissolve, and after complete dissolution, adding hydrogen peroxide dropwise to carry out oxidation reaction, and after the reaction is completed, cooling and centrifugation to obtain a crude 4,4'-dichlorodiphenyl sulfone; 4) The crude 4,4'-dichlorodiphenyl sulfone obtained in step 3) is mixed with xylene, and then heated to dissolve. After the dissolution is completed, decolorization, filtration, cooling and crystallization, centrifugation, and drying are performed to obtain the ultra-high purity 4,4'-dichlorodiphenyl sulfone.

2. The synthesis method according to claim 1, characterized in that In step 1), the method for preparing crude 4,4'-dichlorodiphenyl sulfoxide comprises the following steps: S1. Chlorobenzene and anhydrous aluminum chloride are mixed, stirred and dispersed, and thionyl chloride is added dropwise at a set temperature. After the addition is completed, the reaction is continued by keeping warm. After the reaction is completed, the temperature is raised to dissolve to obtain a chlorobenzene solution containing 4,4'-dichlorodiphenyl sulfoxide; S2. Add the chlorobenzene solution containing 4,4'-dichlorodiphenyl sulfoxide obtained in step S1 into water, heat it for hydrolysis, release aluminum chloride, then distill off chlorobenzene under normal pressure, cool, centrifuge and wash with water to obtain a crude 4,4'-dichlorodiphenyl sulfoxide.

3. The synthesis method according to claim 2, characterized in that In step S1, the set temperature and the temperature for heat preservation and continued reaction after the addition of thionyl chloride are 20° C.-60° C.; the dropping speed of thionyl chloride is 3-5 drops / second, and the reaction is continued for 45-60 minutes after the addition of thionyl chloride is completed.

4. The synthesis method according to claim 2, characterized in that In step S1, the temperature of the heating and dissolving is 110°C-120°C.

5. The synthesis method according to claim 2, characterized in that In step S2, the temperature of the hydrolysis is 40-50°C, and the time is 60-80 minutes; the distillation of chlorobenzene is a distillation with water entrained at normal pressure, and the chlorobenzene is completely recovered for reuse, and the end temperature of the distillation is 110°C-120°C.

6. The synthesis method according to claim 1, characterized in that In step 2), the temperature of the reflux is 115-120° C., and the reflux time is not less than 30 min.

7. The synthesis method according to claim 1, characterized in that In step 3), the amount of methanol is 4.0-5.0 times the weight of 4,4'-dichlorodiphenyl sulfoxide; the amount of ammonium metatungstate is 1.5-2.0% of the weight of 4,4'-dichlorodiphenyl sulfoxide; the amount of sodium carbonate is 10-12% of the weight of 4,4'-dichlorodiphenyl sulfoxide; the mass concentration of hydrogen peroxide is 35%, and its amount is 0.5-0.6 times the weight of 4,4'-dichlorodiphenyl sulfoxide.

8. The synthesis method according to claim 1, characterized in that In step 3), the temperature of the heating and dissolving is 50-55° C.; the dripping speed of the hydrogen peroxide is 3-5 drops / second; the temperature of the oxidation reaction is 70-75° C., and the time is 1-1.5 hours.

9. The synthesis method according to claim 1, characterized in that In step 4), the amount of xylene used is 2.5-3.0 times the weight of the crude 4,4'-dichlorodiphenyl sulfone, the temperature for heating and dissolving is 90°C-95°C; activated carbon is added for decolorization, and the amount of activated carbon used is 0.3-0.5% of the weight of the crude 4,4'-dichlorodiphenyl sulfone; the crystallization temperature is below 30°C.

10. The synthesis method according to claim 1 or 9, characterized in that: In step 4), the xylene is a mixture of o-xylene, p-xylene and m-xylene, wherein the volume ratio of o-xylene, p-xylene and m-xylene is 6:3:1.

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