Continuous flow synthesis method of 4, 4 '-dichlorodiphenyl sulfone

Abstract

The invention discloses a continuous flow synthesis method of 4, 4 '-dichlorodiphenyl sulfone, and belongs to the field of organic chemical synthesis. The continuous flow synthesis method comprises the following steps: S1, adding sulfuryl chloride into a catalyst, and pre-dissolving to obtain a sulfuryl chloride solution of the catalyst; s2, conveying chlorobenzene to the silicon carbide microchannel reactor by adopting a first feeding pump, conveying the sulfuryl chloride solution to the reactor by adopting a second feeding pump, and reacting the reaction solution at the temperature of 20-60 DEG C; and S3, receiving the material at the outlet of the silicon carbide microchannel reactor into a reaction container filled with water, carrying out hydrolysis reaction, standing for layering after hydrolysis is completed, collecting an oil phase, cooling to 0-10 DEG C, separating out crystals, filtering, washing, and drying to obtain the 4, 4 '-dichlorodiphenyl sulfone. The method realizes continuous preparation of DDS through one-step liquid phase reaction, has the advantages of easily available raw materials, short process flow, controllable reaction process, high production efficiency and the like, has the yield of 94% or more and the purity of 99.8% or more, and effectively solves the problems of long production period, low yield and the like in the prior art.

Description

Technical Field

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

[0002] 4,4'-Dichlorodiphenyl sulfone (DDS) is an important aromatic sulfone compound, a white crystalline solid (melting point 148~149 ℃). It is widely used in the fine chemical industry as a core monomer for synthesizing high-performance engineering plastics such as polysulfone (PSU) and polyethersulfone (PES), and as a raw material for the leprosy drug 4,4'-diaminodiphenyl sulfone. With the increasing demand for polysulfone resins in high-end fields such as medical, electronics, and aerospace, the market demand for DDS continues to expand, and the requirements for the efficiency, safety, and high purity of its synthesis process are becoming increasingly stringent.

[0003] Currently, the traditional processes for industrial-scale production of DDS mainly include the chlorosulfonic acid method, the sulfuric acid method, and the thionyl chloride oxidation method. The chlorosulfonic acid method uses chlorobenzene and chlorosulfonic acid as raw materials, and the product quality is relatively good. However, the sulfonating agent chlorosulfonic acid is highly hazardous, inconvenient to transport and store, and has high production costs and large amounts of waste. The sulfuric acid method uses high-concentration fuming sulfuric acid or liquid sulfur trioxide and chlorobenzene as raw materials. The cost is relatively low, but the reaction temperature is high, the time is long, there are many side reactions, and the conversion rate and product quality are not good. The thionyl chloride oxidation method requires Friedel-Crafts reaction to generate 4,4'-dichlorodiphenyl sulfoxide, and then oxidation with hydrogen peroxide. The yield is relatively high, but the purity is low. The reaction cycle is long, the solvent consumption is large, and the wastewater discharge is large.

[0004] In recent years, a series of improved technologies have emerged in related fields to address the pain points of traditional processes. For example, patent CN120865037A discloses a method for continuous production of DDS using a silicon carbide microchannel reactor, employing thionyl chloride, chlorobenzene, and aluminum chloride as raw materials, and achieving continuous production through a dual-reactor series connection. However, this process requires two-step reactions (acylation + oxidation), resulting in high equipment and solvent costs. Patent CN119241401A proposes a method for synthesizing ultra-high purity DDS, achieving a purity of ≥99.98% through dichlorodiphenyl sulfoxide purification-methanol system oxidation-xylene recrystallization. However, this process is intermittent, with a complex route and high production costs, making it unsuitable for large-scale applications.

[0005] In summary, existing DDS synthesis processes (including traditional processes and improved technologies) still suffer from the following core problems: First, the catalyst is prone to water absorption and deactivation, leading to unstable catalytic efficiency; second, the reaction modes are mostly batch or semi-continuous, resulting in long production cycles and low efficiency; third, the hydrolysis method is unreasonable, with long low-temperature hydrolysis times and high energy consumption; fourth, the product yield (≤92%) and purity (≤99.5%) are difficult to simultaneously meet the requirements of high-end applications; and fifth, the reactor material compatibility is insufficient, resulting in short equipment lifespan under highly corrosive systems. Therefore, developing a continuous flow DDS synthesis process that is short in process, highly efficient, safe and environmentally friendly, and produces stable product quality has become an urgent technical challenge to be solved in this field. Summary of the Invention

[0006] To overcome the above-mentioned defects of the prior art, the present invention provides a continuous flow synthesis method for 4,4'-dichlorodiphenyl sulfone. Through catalyst pre-dissolution treatment, application of silicon carbide microchannel reactor, optimization of reverse hydrolysis process and precise parameter matching, a high-yield and high-purity continuous production of DDS is achieved. Moreover, this method has a short process flow, low production cost and convenient product post-processing.

[0007] The continuous flow synthesis method for 4,4'-dichlorodiphenyl sulfone includes the following steps: S1. Add thioyl chloride to the catalyst, stir at 25~70 ℃ for 2~4 h, and cool to room temperature to obtain a thioyl chloride solution of the catalyst; S2. Chlorobenzene is fed to the silicon carbide microchannel reactor using a first feed pump, and the thiocyanate solution obtained in step S1 is fed to the silicon carbide microchannel reactor using a second feed pump. The reaction solution is reacted at a temperature of 20~60 °C. S3. The material from the outlet of the silicon carbide microchannel reactor is received into a reaction vessel containing water for hydrolysis. After hydrolysis, the material is allowed to stand and separate into layers. The oil phase is collected and cooled to 0~10℃ to precipitate crystals. The material is then filtered, washed, and dried to obtain 4,4'-dichlorodiphenyl sulfone.

[0008] In a preferred embodiment, the catalyst in step S1 is selected from anhydrous aluminum chloride, titanium tetrachloride, anhydrous ferric chloride, or anhydrous zinc chloride.

[0009] In a preferred embodiment, the mass ratio of thiocyanate chloride to catalyst in step S1 is 1:1 to 1.6.

[0010] In the preferred embodiment, the chlorobenzene described in step S2 is dehydrated by a desiccant before use.

[0011] In a further preferred embodiment, the desiccant is selected from anhydrous magnesium sulfate, anhydrous sodium sulfate, or anhydrous calcium chloride.

[0012] In a preferred embodiment, the volumetric flow rate ratio of the first feed pump and the second feed pump in step S2 is 3.2 to 6:1.

[0013] In the preferred embodiment, the reaction temperature in step S2 is 30~50 °C.

[0014] In a preferred embodiment, the residence time of the reaction solution in the microchannel reactor in step S2 is 8-11 minutes. The present invention can control the residence time of the reaction solution in the reactor by adjusting the flow rate of the feed pump.

[0015] In the preferred embodiment, the volumetric flow rate of the first feed pump in step S2 is controlled at 900~1200 mL / min; the volumetric flow rate of the second feed pump in step S2 is controlled at 200~280 mL / min.

[0016] In the preferred embodiment, the hydrolysis reaction in step S3 specifically involves controlling the mass ratio of water to chlorobenzene in the reaction vessel to be 1:1.5~2. After the material is received, the temperature is raised to 70~90 ℃ and stirred for 1~2 h. Through the hydrolysis reaction, the catalyst and unreacted sulfuryl chloride are separated from the oil phase, thereby achieving the purpose of purifying 4,4'-dichlorodiphenyl sulfone.

[0017] In the preferred embodiment, the washing described in step S3 specifically involves: controlling the solid-liquid ratio to be 1:1.5~2, adding water to the filtered solid, heating to 70~90 ℃ and stirring for 0.5~1 h, then filtering again to obtain the solid.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The present invention adopts a liquid-phase reaction method in which the catalyst is dissolved in thioyl chloride and then mixed with chlorobenzene. This method can avoid the catalyst from absorbing water and becoming deactivated during the addition process, and can also make the catalyst and raw materials more uniformly mixed and the reaction more complete.

[0019] 2. Compared with other sulfuryl chloride processes, this invention improves the low-temperature hydrolysis step in the post-treatment, combining hydrolysis and high-temperature dissolution into one step. Firstly, it makes the process more continuous, reducing the hydrolysis reaction time and equipment costs. Secondly, the hydrolysis involves adding the reaction solution to water, rather than adding water to the reaction solution in the traditional method, making the degree and temperature of hydrolysis more controllable and reducing the risk of reactor rupture. Thirdly, the temperature inside the hydrolysis reactor rises gradually and slowly, and the hydrogen chloride gas produced by hydrolysis is released steadily, resulting in less chlorobenzene being carried away, thus reducing not only the amount of pollutants in the tail gas but also the consumption of chlorobenzene.

[0020] 3. By using a microchannel reactor, this invention achieves the continuous synthesis of 4,4'-dichlorodiphenyl sulfone. This process is simple to operate, highly efficient, significantly reduces reaction time, and is controllable, thus improving production efficiency and the feasibility of large-scale production. The obtained product has a purity of over 99.8% and a yield exceeding 94%. Detailed Implementation

[0021] The technical solution of the present invention will be further described and illustrated below through examples. All raw materials used in the examples are commercially available or prepared using conventional methods.

[0022] Example 1 A continuous flow synthesis method for 4,4'-dichlorodiphenyl sulfone includes the following steps: S1. Add 6.5 kg of anhydrous aluminum chloride to a 20 L glass reactor, slowly add 6 kg of thiocyanate chloride, stir at 60 °C for 2 h to completely dissolve the anhydrous aluminum chloride, and cool to room temperature to obtain a thiocyanate chloride solution. S2. Add 40 kg of chlorobenzene treated with a desiccant to a 50 L glass reactor. Use a 12 L silicon carbide microchannel reactor. The first feed pump delivers chlorobenzene to the silicon carbide microchannel reactor at a volumetric flow rate of 1000 mL / min (mass flow rate of 1110 g / min). The second feed pump delivers the thiocyanate solution obtained in step S1 to the silicon carbide microchannel reactor at a volumetric flow rate of 200 mL / min (mass flow rate of 350 g / min). The residence time of the reaction solution in the silicon carbide microchannel reactor is 10 min. The feeding time is 30 min. The reaction temperature is 40 ℃. In step S2, 4,4'-dichlorodiphenyl sulfone is directly synthesized in one step, and the reaction formula is shown in formula (I): Equation (I); S3. The material from the outlet of the silicon carbide microchannel reactor is received into a 100 L glass reactor containing 20 kg of water. The mixture is heated to 80 °C and stirred for 1 h to carry out a hydrolysis reaction. After standing and separating into layers, the oil phase (i.e., the chlorobenzene phase) is collected and cooled to 0~10 °C, precipitating a large amount of white solid. The solid is filtered out, 20 kg of water is added, and the mixture is heated to 80 °C and stirred for 0.5 h. It is then filtered and dried again to obtain 9.70 kg of 4,4'-dichlorodiphenyl sulfone.

[0023] The purity of the obtained 4,4'-dichlorodiphenyl sulfone was 99.87% as determined by liquid chromatography, and the yield was calculated to be 96.2% (actual product mass / theoretical product mass * 100%).

[0024] Example 2 A continuous flow synthesis method for 4,4'-dichlorodiphenyl sulfone is basically the same as that in Example 1, except that the reaction temperature in step S2 is 30 °C.

[0025] The yield of 4,4'-dichlorodiphenyl sulfone was 9.57 kg. The purity of the sulfone was 99.83% as determined by liquid chromatography, and the yield was calculated to be 95.1%.

[0026] Example 3 A continuous flow synthesis method for 4,4'-dichlorodiphenyl sulfone includes the following steps: S1. Add 7.11 kg of anhydrous aluminum chloride to a 20 L glass reactor, slowly add 6 kg of sulfuryl chloride, stir at 60 °C for 2 h to completely dissolve the anhydrous aluminum chloride, and cool to room temperature to obtain a sulfuryl chloride solution. S2. Add 40 kg of chlorobenzene treated with a desiccant to a 50 L glass reactor. Use a 12 L silicon carbide microchannel reactor. The first feed pump delivers chlorobenzene to the silicon carbide microchannel reactor at a volumetric flow rate of 993 mL / min (mass flow rate of 1102 g / min). The second feed pump delivers the thiocyanate solution obtained in step S1 to the silicon carbide microchannel reactor at a volumetric flow rate of 207 mL / min (mass flow rate of 364 g / min). The residence time of the reaction solution in the silicon carbide microchannel reactor is 10 min, the feeding time is 30.3 min, and the reaction temperature is 40 ℃. S3. The material from the outlet of the silicon carbide microchannel reactor is received into a 100 L glass reactor containing 20 kg of water. The mixture is heated to 80 °C and stirred for 1 h to carry out a hydrolysis reaction. After standing and separating into layers, the oil phase (i.e., the chlorobenzene phase) is collected and cooled to 0~10 °C, resulting in the precipitation of a large amount of white solid. The solid is filtered out, 20 kg of water is added, and the mixture is heated to 80 °C and stirred for 0.5 h. The mixture is then filtered again and dried to obtain 9.71 kg of 4,4'-dichlorodiphenyl sulfone.

[0027] The purity of the obtained 4,4'-dichlorodiphenyl sulfone was 99.85% as determined by liquid chromatography, and the yield was calculated to be 96.5%.

[0028] Example 4 A continuous flow synthesis method for 4,4'-dichlorodiphenyl sulfone includes the following steps: S1. Add 6.5 kg of anhydrous aluminum chloride to a 20 L glass reactor, slowly add 6 kg of thiocyanate chloride, stir at 60 °C for 2 h to completely dissolve the anhydrous aluminum chloride, and cool to room temperature to obtain a thiocyanate chloride solution. S2. Add 40 kg of chlorobenzene treated with a desiccant to a 50 L glass reactor. Use a 12 L silicon carbide microchannel reactor. The first feed pump delivers chlorobenzene to the silicon carbide microchannel reactor at a volumetric flow rate of 1136 mL / min (mass flow rate of 1261 g / min). The second feed pump delivers the thiocyanate solution obtained in step S1 to the silicon carbide microchannel reactor at a volumetric flow rate of 200 mL / min (mass flow rate of 350 g / min). The residence time of the reaction solution in the silicon carbide microchannel reactor is 9 min, the feeding time is 30 min, and the reaction temperature is 40 ℃. S3. The silicon carbide microchannel reaction outlet material is received into a 100 L glass reactor containing 20 kg of water, heated to 80 ℃ and stirred for 1 h to carry out hydrolysis reaction. After standing and separating into layers, the oil phase, i.e. the chlorobenzene phase, is collected and cooled to 0~10 ℃, and a large amount of white solid is precipitated. The solid is filtered out, 20 kg of water is added, and the temperature is raised to 80 ℃ and stirred for 0.5 h. It is filtered and dried again to obtain 9.54 kg of 4,4'-dichlorodiphenyl sulfone.

[0029] The purity of the obtained 4,4'-dichlorodiphenyl sulfone was 99.80% as determined by liquid chromatography, and the yield was calculated to be 94.8%.

[0030] Example 5 A continuous flow synthesis method for 4,4'-dichlorodiphenyl sulfone includes the following steps: S1. Add 9.02 kg of titanium tetrachloride to a 20 L glass reactor, slowly add 6 kg of thioyl chloride, stir at 25 ℃ for 2 h to mix evenly, and then cool to room temperature to obtain a thioyl chloride solution. S2. Add 40 kg of chlorobenzene treated with a desiccant to a 50 L glass reactor. Use a 12 L silicon carbide microchannel reactor. The first feed pump delivers chlorobenzene to the silicon carbide microchannel reactor at a volumetric flow rate of 963 mL / min (mass flow rate of 1068 g / min). The second feed pump delivers the thiocyanate solution obtained in step S1 to the silicon carbide microchannel reactor at a volumetric flow rate of 237 mL / min (mass flow rate of 403 g / min). The residence time of the reaction solution in the silicon carbide microchannel reactor is 10 min, the feeding time is 31.3 min, and the reaction temperature is 40 ℃. S3. The material from the outlet of the silicon carbide microchannel reactor is received into a 100 L glass reactor containing 20 kg of water. The mixture is heated to 80 °C and stirred for 1 h to carry out a hydrolysis reaction. After standing and separating into layers, the oil phase (i.e., the chlorobenzene phase) is collected and cooled to 0-10 °C, resulting in the precipitation of a large amount of white solid. The solid is filtered out, 20 kg of water is added, and the mixture is heated to 80 °C and stirred for 0.5 h. It is then filtered and dried again to obtain 9.56 kg of 4,4'-dichlorodiphenyl sulfone.

[0031] The purity of the obtained 4,4'-dichlorodiphenyl sulfone was 99.83% as determined by liquid chromatography, and the yield was calculated to be 95.2%.

[0032] Example 6 A continuous flow synthesis method for 4,4'-dichlorodiphenyl sulfone includes the following steps: S1. Add 8.64 kg of anhydrous ferric chloride to a 20 L glass reactor, slowly add 6 kg of thiocyanate chloride, stir at 60 °C for 2 h to completely dissolve the ferric chloride, and cool to room temperature to obtain a thiocyanate chloride solution. S2. Add 40 kg of chlorobenzene treated with a desiccant to a 50 L glass reactor. Use a 12 L silicon carbide microchannel reactor. The first feed pump delivers chlorobenzene to the silicon carbide microchannel reactor at a volumetric flow rate of 980 mL / min (mass flow rate of 1087 g / min). The second feed pump delivers the thiocyanate solution obtained in step S1 to the silicon carbide microchannel reactor at a volumetric flow rate of 220 mL / min (mass flow rate of 401 g / min). The residence time of the reaction solution in the silicon carbide microchannel reactor is 10 min, the feeding time is 30.75 min, and the reaction temperature is 40 ℃. S3. The material from the outlet of the silicon carbide microchannel reactor is received into a 100 L glass reactor containing 20 kg of water. The mixture is heated to 80 °C and stirred for 1 h to carry out a hydrolysis reaction. After standing and separating into layers, the oil phase (i.e., the chlorobenzene phase) is collected and cooled to 0~10 °C, precipitating a large amount of white solid. The solid is filtered out, 20 kg of water is added, and the mixture is heated to 80 °C and stirred for 0.5 h. It is then filtered and dried again to obtain 9.48 kg of 4,4'-dichlorodiphenyl sulfone.

[0033] The purity of the obtained 4,4'-dichlorodiphenyl sulfone was 99.81% as determined by liquid chromatography, and the yield was calculated to be 94.3%.

[0034] Comparative Example 1 A method for synthesizing 4,4'-dichlorodiphenyl sulfone includes the following steps: 5.46 kg of anhydrous aluminum chloride and 33.3 kg of chlorobenzene treated with a desiccant were added to a 100 L glass reactor. 5.05 kg of sulfuryl chloride was slowly added under stirring, with the reaction temperature controlled at 40 °C. The addition was completed in 2 h, and the reaction continued for 4 h. Then, 20 kg of water was slowly added, the temperature was raised to 80 °C, and the mixture was stirred for 1 h. The aqueous phase was separated, and the chlorobenzene phase was cooled to 0-10 °C, precipitating a large amount of white solid. The solid was filtered off, 20 kg of water was added, and the temperature was raised to 80 °C and stirred for 0.5 h. The mixture was filtered again and dried to obtain 9.08 kg of 4,4'-dichlorodiphenyl sulfone.

[0035] The purity of the obtained 4,4'-dichlorodiphenyl sulfone was 99.53% as determined by liquid chromatography, and the yield was calculated to be 90.5%.

[0036] To more clearly demonstrate the specific parameters of the process implementation of the present invention, the reaction conditions and yields of each embodiment and comparative example are listed in Table 1 below.

[0037] Table 1. Reaction conditions and yields of the examples and comparative examples

[0038] Note: The total amount of thiocyanate added is 5.05 kg.

[0039] It should be understood that the above embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

Claims

1. A continuous flow synthesis method for 4,4'-dichlorodiphenyl sulfone, characterized in that, Includes the following steps: S1. Add thioyl chloride to the catalyst, stir at 25~70 ℃ for 2~4 h, and cool to room temperature to obtain a thioyl chloride solution of the catalyst; S2. Chlorobenzene is fed to the silicon carbide microchannel reactor using a first feed pump, and the thiocyanate solution obtained in step S1 is fed to the silicon carbide microchannel reactor using a second feed pump. The reaction solution is reacted at a temperature of 20~60 °C. S3. The material from the outlet of the silicon carbide microchannel reactor is received into a reaction vessel containing water for hydrolysis. After hydrolysis, the material is allowed to stand and separate into layers. The oil phase is collected and cooled to 0~10 ℃ to precipitate crystals. The material is then filtered, washed, and dried to obtain 4,4'-dichlorodiphenyl sulfone.

2. The continuous flow synthesis method of 4,4'-dichlorodiphenyl sulfone according to claim 1, characterized in that, The catalyst mentioned in step S1 is selected from anhydrous aluminum chloride, titanium tetrachloride, anhydrous ferric chloride, or anhydrous zinc chloride.

3. The continuous flow synthesis method of 4,4'-dichlorodiphenyl sulfone according to claim 1, characterized in that, The mass ratio of thiocyanate chloride to catalyst in step S1 is 1:1 to 1.

6.

4. The continuous flow synthesis method of 4,4'-dichlorodiphenyl sulfone according to claim 1, characterized in that, The chlorobenzene described in step S2 is dehydrated by a desiccant before use.

5. The continuous flow synthesis method of 4,4'-dichlorodiphenyl sulfone according to claim 4, characterized in that, The desiccant is selected from anhydrous magnesium sulfate, anhydrous sodium sulfate, or anhydrous calcium chloride.

6. The continuous flow synthesis method of 4,4'-dichlorodiphenyl sulfone according to claim 1, characterized in that, The volumetric flow rate ratio of the first feed pump and the second feed pump mentioned in step S2 is 3.2~6:

1.

7. The continuous flow synthesis method of 4,4'-dichlorodiphenyl sulfone according to claim 1, characterized in that, The reaction temperature in step S2 is 30~50 ℃; the residence time of the reaction solution in the microchannel reactor in step S2 is 8~11 min.

8. The continuous flow synthesis method of 4,4'-dichlorodiphenyl sulfone according to claim 1, characterized in that, The volumetric flow rate of the first feed pump in step S2 is controlled at 900~1200 mL / min; the volumetric flow rate of the second feed pump in step S2 is controlled at 200~280 mL / min.

9. The continuous flow synthesis method of 4,4'-dichlorodiphenyl sulfone according to claim 1, characterized in that, The hydrolysis reaction described in step S3 is specifically as follows: the mass ratio of water to chlorobenzene in the reaction vessel is controlled to be 1:1.5~2. After the material is received, the temperature is raised to 70~90 ℃ and stirred for 1~2 h.

10. The continuous flow synthesis method of 4,4'-dichlorodiphenyl sulfone according to claim 1, characterized in that, The washing process described in step S3 is as follows: control the solid-liquid ratio to be 1:1.5~2, add water to the filtered solid, heat to 70~90 ℃ and stir for 0.5~1 h, then filter again to obtain the solid.

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