Method for synthesizing m-chloroperoxybenzoic acid by multi-stage series circulating tube type continuous reactor

Abstract

The invention provides a method for synthesizing m-chloroperoxybenzoic acid by a multi-stage series circulating tube type continuous reactor, and belongs to the technical field of chemical production. According to the method, m-chlorobenzoyl chloride, hydrogen peroxide, inorganic alkali and inorganic acid are used as raw materials, sulfate is used as a stabilizer, and the raw materials are simultaneously and continuously fed into a multi-stage series circulating tube type continuous reactor for a synthetic reaction under the condition of a solvent. The yield of the m-chloroperoxybenzoic acid can reach 95% or above, and compared with an existing process, the yield is increased by 17-20%; according to the invention, an intermittent / semi-intermittent kettle type process is improved into a continuous circulating pipe type process, so that the automatic and continuous production level is improved.

Description

Technical Field

[0001] This invention relates to the field of chemical production technology, and in particular to a method for synthesizing m-chloroperoxybenzoic acid using a multi-stage series circulating tubular continuous reactor. Background Technology

[0002] m-Cloroperoxybenzoic acid is a commonly used oxidant in organic synthesis. It is widely used in cyclization reactions, such as the steric reaction of carbon-carbon double bonds; Baeyer-Villiger oxidation reactions, such as the reaction of carbonyl compounds with peroxy acids to form esters; it can also be used as an oxidant in the synthesis of pharmaceuticals, pesticides and other fine chemical products.

[0003] In existing technologies, m-chloroperoxybenzoic acid is mainly produced by m-chlorobenzoyl chloride, hydrogen peroxide, and potassium hydroxide in a solvent environment using a batch / semi-batch process. The specific method is as follows: CN1322713A uses water, solvent, sodium hydroxide, 35% hydrogen peroxide, and catalyst as a base, followed by the dropwise addition of m-chlorobenzoyl chloride, and finally the addition of 20% hydrochloric acid to adjust the pH to 4-5. This process uses excessive solvent, employs a semi-batch production method, has a long residence time, and carries a high potential safety risk. He Wei et al. from the School of Biotechnology and Pharmaceutical Engineering at Nanjing University of Technology dissolved 30% hydrogen peroxide and potassium peroxide in distilled water, then added m-chlorobenzoyl chloride at low temperature. The reaction mixture was then rapidly stirred at 20°C for 30 minutes, followed by acidification of the two-phase fluid to pH 4.0. This process uses excessive amounts of solvent, hydrogen peroxide, and potassium peroxide, and yields a low product yield. The above processes suffer from low reaction yields and excessive solvent usage.

[0004] Therefore, how to synthesize m-chloroperoxybenzoic acid using a multi-stage series circulating tubular continuous reactor is a technical problem that needs to be solved. Summary of the Invention

[0005] The purpose of this invention is to provide a method for synthesizing m-chloroperoxybenzoic acid using a multi-stage series circulating tubular continuous reactor, in order to solve the technical problems of low reaction yield and excessive solvent usage in existing processes.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for synthesizing m-chloroperoxybenzoic acid using a multi-stage series circulating tubular continuous reactor, comprising the following steps: Solution A is prepared by dissolving m-chlorobenzoyl chloride in a solvent, and solution B is prepared by mixing hydrogen peroxide, inorganic base and stabilizer. Solution A and solution B are simultaneously and continuously fed into a multi-stage series circulating tubular continuous reactor system for synthesis reaction; The multi-stage series circulating tubular continuous reactor system comprises at least three circulating tubular continuous reactors connected in series; an inorganic acid is added to the penultimate stage reactor of the multi-stage series circulating tubular continuous reactor system for neutralization reaction; dichloromethane and water are added to the last stage reactor for water washing, and the synthesized target product is continuously collected from the outlet to a collection tank.

[0007] Furthermore, the synthesis reaction temperature in each stage of the circulating tubular reactor is independently -20~10℃, and the average residence time is 5~200min.

[0008] Furthermore, the concentration of intermediate chlorobenzoyl chloride in solution A is 55~85 wt.%, and the solvent contains one or more of dichloromethane, dichloroethane, methanol, tetrahydrofuran, and dioxane.

[0009] Furthermore, solution B is prepared by premixing hydrogen peroxide, inorganic alkali, and stabilizer in a tubular reactor. The inorganic alkali includes sodium hydroxide and / or potassium hydroxide; the stabilizer includes magnesium sulfate and / or sodium sulfate. The concentration of hydrogen peroxide in solution B is 30~50 wt.%, the concentration of inorganic alkali is 35~55 wt.%, and the stabilizer accounts for 1~10‰ of the total mass fraction of solution B.

[0010] Furthermore, the temperature of the tubular reactor is controlled at -10~10℃, and the residence time is 1~30min.

[0011] Furthermore, the flow rate of solution A is 800~1100 mL / h, and the flow rate of solution B is 1300~1600 mL / h.

[0012] Furthermore, the molar ratio of intermediate benzoyl chloride in solution A to hydrogen peroxide in solution B is 2-6; the molar ratio of intermediate benzoyl chloride in solution A to inorganic base in solution B is 2-8.

[0013] Furthermore, the inorganic acid comprises one or more of sulfuric acid, hydrochloric acid, and phosphoric acid, the concentration of the inorganic acid is 10-50 wt.%, and the flow rate of the inorganic acid is 1500-2000 mL / h.

[0014] Furthermore, the amount of dichloromethane added is 0.2 to 3 times the total mass of solution A and solution B, and the amount of water added is 0.5 to 10 times the total mass of solution A and solution B.

[0015] The beneficial effects of this invention are: The continuous production process of m-chloroperoxybenzoic acid of the present invention adopts a continuous circulating tubular method, which improves production efficiency and reaction safety compared with existing processes, and meets the requirements of green, safe and efficient production. The yield of m-chloroperoxybenzoic acid of the present invention can reach more than 95%, which is 17-20% higher than that of existing processes. The present invention improves the batch / semi-batch batch reactor process into a continuous circulating tubular process, thereby improving the level of automated continuous production.

[0016] In summary, the method of this invention solves the problems of excessive by-products, low production efficiency, and poor safety associated with traditional batch reactor processes. Using a continuous production process simplifies production equipment, improves reaction selectivity, thereby increasing production efficiency and reducing production costs. Simultaneously, the continuous production process enhances the inherent safety of the reaction process. Using this method, the purity of the product m-chloroperoxybenzoic acid can reach over 95%, with a yield exceeding 95%. This process utilizes a multi-stage continuous circulating tubular reactor for engineering scale-up, offering advantages such as high heat and mass transfer efficiency, stable temperature control, high production efficiency, and high safety, meeting national requirements for green, safe, and environmentally friendly chemical enterprises. Attached Figure Description

[0017] Figure 1 This is a flow chart of the reaction apparatus of the present invention; Among them, 1-m-chlorobenzoyl chloride storage tank; 2-solvent storage tank; 3-hydrogen peroxide storage tank; 4-alkali solution storage tank; 5-dilute acid storage tank; 6-dichloromethane storage tank; 7-pure water storage tank; 8-discharge receiving tank; 9-acyl chloride solution mixing vessel; 10-first-stage tubular reactor; 11-first-stage tubular reactor; 12-second-stage circulating tubular reactor; 13-third-stage circulating tubular reactor.

[0018] Figure 2 This is a schematic diagram of the structure of a circulating tubular continuous reactor; the circulating tubular reactor includes 14-power chamber, 15-heat exchange tube, 16-first feed inlet, 17-second feed inlet, 18-overflow outlet, 19-drain outlet, 20-pressure balance outlet, and 21-thermometer. Detailed Implementation

[0019] This invention provides a method for synthesizing m-chloroperoxybenzoic acid using a multi-stage series circulating tubular continuous reactor, comprising the following steps: Solution A is prepared by dissolving m-chlorobenzoyl chloride in a solvent, and solution B is prepared by mixing hydrogen peroxide, inorganic base and stabilizer. Solution A and solution B are simultaneously and continuously fed into a multi-stage series circulating tubular continuous reactor system for synthesis reaction; The multi-stage series circulating tubular continuous reactor system comprises at least three circulating tubular continuous reactors connected in series; an inorganic acid is added to the penultimate stage reactor of the multi-stage series circulating tubular continuous reactor system for neutralization reaction; dichloromethane and water are added to the last stage reactor for water washing, and the synthesized target product is continuously collected from the outlet to a collection tank.

[0020] In this invention, the circulating tubular continuous reactor is provided with a power chamber 14 and a heat exchange tube 15. The power chamber 14 is provided with a propulsion agitator, a first feed inlet 16, a second feed inlet 17, an overflow outlet 18, and a pressure balance outlet 20.

[0021] The heat exchange tube 15 adopts a shell-and-tube structure and is vertically installed in the shell. Process heat exchange is achieved through the heat exchange medium in the shell. The two heat exchange tubes are connected by a circulation pipeline. The bottom of the lower circulation pipeline is provided with a drain port 19. The thermometers 21 are provided in both the upper and lower pipelines.

[0022] In this invention, the synthesis reaction temperature in each stage of the circulating tubular reactor is independently -20~10℃, preferably -10~5℃, and more preferably -5~0℃; the average residence time is 5~200min, preferably 5~60min, and more preferably 5~20min.

[0023] In this invention, the average residence time of the material in the single-stage reactor should be adjusted by regulating the feed flow rate, and the complete conversion of the raw material m-chlorobenzoyl chloride in the first-stage reactor should be ensured to meet the reaction safety requirements and prevent material overheating and cross-contamination in the event of thermal runaway. Preferably, the raw material m-chlorobenzoyl chloride is completely converted in the first-stage reactor.

[0024] In this invention, the reaction equations involved in the synthesis process are as follows: H₂O₂ + KOH = K₂O₂ + 2H₂O .

[0025] In this invention, in the multi-stage series circulating tubular continuous reactor, hydrogen peroxide, inorganic alkali, and stabilizer are premixed in the tubular reactor and connected to the inlet of the multi-stage series circulating tubular continuous reactor system via pipelines to the raw material solution storage tank. The outlet of the multi-stage series circulating tubular continuous reactor system is connected to the feed receiving tank via pipelines. Dilute acid is added in the penultimate reactor for neutralization; dichloromethane and water are introduced into the last reactor for washing. The multi-stage series circulating tubular continuous reactor system consists of at least three circulating tubular reactors connected in series. Each circulating tubular reactor consists of two shell-and-tube reactors, a dynamic stirring chamber, and connecting pipelines. The tube side of the shell-and-tube reactor contains the reaction system feed liquid, and the shell side contains the heat exchange medium. The specific surface area of ​​the tube side should be greater than 150 m². 2 / m 3 The feed circulation is a stirred propulsion circulation. To ensure the mixing effect, the tube circulation rate should be higher than the liquid holdup per minute. The characteristics of the continuous circulation tubular reactor are described in detail in (CN113121356A).

[0026] The circulating tubular reactor has a tubular structure inside and uses an upper overflow method to transport materials to the subsequent reactors; When the multi-stage series-connected circulating tubular reactor system consists of at least two circulating tubular reactors connected in series, each subsequent stage of reactor can be a batch overflow reactor.

[0027] Pumps equipped with flow meters are installed on the pipelines connecting each raw material storage tank to the multi-stage series circulating tubular continuous reactor system.

[0028] In this invention, the concentration of intermediate benzoyl chloride in solution A is 55-85 wt.%, preferably 60-80 wt.%, and more preferably 70-80 wt.%; the solvent contains one or more of dichloromethane, dichloroethane, methanol, tetrahydrofuran, and dioxane, preferably dichloromethane.

[0029] In this invention, solution B is prepared by premixing hydrogen peroxide, inorganic alkali, and stabilizer in a tubular reactor. The inorganic alkali includes sodium hydroxide and / or potassium hydroxide, preferably potassium hydroxide; the stabilizer includes magnesium sulfate and / or sodium sulfate, preferably magnesium sulfate. The concentration of hydrogen peroxide in solution B is 30-50 wt.%, preferably 40-50 wt.%, and more preferably 45-50 wt.%; the concentration of inorganic alkali is 35-55 wt.%, preferably 45-55 wt.%; and the stabilizer accounts for 1-10‰ of the total mass fraction of solution B, preferably 1-5‰, and more preferably 2-4‰.

[0030] In this invention, the temperature of the tubular reactor is controlled at -10~10℃, preferably -10~0℃, and more preferably -8~-5℃; the residence time is 1~30min, preferably 1~15min, and more preferably 5~10min.

[0031] In this invention, the flow rate of solution A is 800~1100mL / h, preferably 900~1050mL / h, and more preferably 950~1000mL / h; the flow rate of solution B is 1300~1600mL / h, preferably 1350~1500mL / h, and more preferably 1400~1450mL / h.

[0032] In this invention, the molar ratio of intermediate benzoyl chloride in solution A to hydrogen peroxide in solution B is 2-6, preferably 2-4; the molar ratio of intermediate benzoyl chloride in solution A to inorganic base in solution B is 2-8, preferably 2-5, and more preferably 3-4.

[0033] In this invention, the inorganic acid comprises one or more of sulfuric acid, hydrochloric acid, and phosphoric acid, and the concentration of the inorganic acid is 10-50 wt.%, preferably 20-40 wt.%, more preferably 25-30 wt.%; the flow rate of the inorganic acid is 1500-2000 mL / h, preferably 1600-1800 mL / h, more preferably 1650-1700 mL / h.

[0034] In this invention, the amount of dichloromethane added is 0.2 to 3 times the total mass of solution A and solution B, preferably 1 to 2 times; the amount of water added is 0.5 to 10 times the total mass of solution A and solution B, preferably 1 to 9 times, and more preferably 2 to 8 times.

[0035] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0036] Example 1

[0037] In this embodiment, the multi-stage series circulating tubular continuous reactor system is formed by three circulating tubular reactors connected in series.

[0038] Specific reaction steps: m-Chlorobenzoyl chloride was dissolved in dioxane to prepare a 58.7% (w / w) solution A. 50% hydrogen peroxide, 42% potassium hydroxide aqueous solution, and 0.1% (w / w) magnesium sulfate pentahydrate were premixed in a single-stage tubular reactor to prepare solution B. The temperature of the tubular reactor was controlled at -5 to 0℃, and the residence time was 5 min. Solutions A and B were precooled to -5℃ respectively. Then, the two solutions were simultaneously and continuously pumped into the second circulating tubular reactor of a multi-stage series circulating tubular continuous reactor system. The flow rate of solution A was controlled at 1002 mL / h, and the flow rate of solution B was controlled at 1441 mL / h. The reaction temperature was controlled at -5 to 0℃. The reaction mixture then overflowed into the second circulating tubular reactor. Simultaneously, 30% sulfuric acid was continuously introduced into the second-stage reactor at a flow rate of 1603 mL / h. The material overflowing from the second-stage reactor was introduced into the third-stage reactor, where dichloromethane and water were simultaneously introduced at a flow rate of 600 mL / h and 1000 mL / h, respectively. Once the reaction system was stable, the product solution was started to be received.

[0039] The feed solution was continuously received for 2 hours, and samples were collected for analysis, indicating complete conversion of the raw material. After extraction, washing with water, and drying, 759.3 g of m-chloroperoxybenzoic acid was finally obtained, with a content of 95.3% and a yield of 93.8% (see Table 1).

[0040] Example 2

[0041] The continuous production process of m-chloroperoxybenzoic acid involves constructing a reaction system according to the method described in Example 1. In this example, the multi-stage series circulating tubular continuous reactor system is formed by three circulating tubular reactors connected in series.

[0042] Specific reaction steps: Dissolve m-chlorobenzoyl chloride in methanol to prepare solution A with a mass fraction of 83.9%; premix 50% hydrogen peroxide, 42% potassium hydroxide aqueous solution and 0.1% magnesium sulfate pentahydrate in a single-stage tubular reactor to prepare solution B. The temperature of the tubular reactor is controlled at -5~0℃, the residence time is 5min, and solutions A and B are precooled to -5℃ respectively; then, the two solutions are simultaneously and continuously fed into the second circulating tubular reactor of the multi-stage series circulating tubular continuous reactor system by pumps. The flow rate of solution A was controlled at 824 mL / h, and the flow rate of solution B was controlled at 1441 mL / h. The reaction temperature was controlled at -5 to 0℃. The reaction solution was then sequentially introduced into the second circulating tubular reactor via overflow. Simultaneously, 30% sulfuric acid was continuously introduced into the second-stage reactor at a flow rate of 1603 mL / h. The material overflowing from the second-stage reactor was introduced into the third-stage reactor, where dichloromethane and water were simultaneously introduced at a flow rate of 600 mL / h and 1000 mL / h, respectively. Once the reaction system was stable, the product solution was started to be received.

[0043] The feed solution was continuously received for 2 hours, and samples were collected for analysis, indicating complete conversion of the raw materials. After extraction, washing with water, and drying, the received post-reaction feed solution finally yielded 745.6 g of m-chloroperoxybenzoic acid with a content of 93.8% and a yield of 92.1% (see Table 1).

[0044] Example 3

[0045] The continuous production process of m-chloroperoxybenzoic acid is carried out by constructing a reaction system according to the method described in Example 1. The multi-stage series circulating tubular continuous reactor system in this example is formed by three circulating tubular reactors connected in series, and each reactor has a volume of 1 L.

[0046] Specific reaction steps: Dissolve m-chlorobenzoyl chloride in THF to prepare a solution A with a mass fraction of 74.9%; premix 50% hydrogen peroxide, 42% potassium hydroxide aqueous solution and 0.1% magnesium sulfate pentahydrate in a single-stage tubular reactor to prepare solution B. The temperature of the tubular reactor is controlled at -5~0℃, the residence time is 5min, and solutions A and B are precooled to -5℃ respectively; then, the two solutions are simultaneously and continuously fed into the second circulating tubular reactor of the multi-stage series circulating tubular continuous reactor system by pumps. The flow rate of solution A was controlled at 1067 mL / h, and the flow rate of solution B was controlled at 1441 mL / h. The reaction temperature was controlled at -5 to 0℃. The reaction solution was then sequentially introduced into the second circulating tubular reactor via overflow. Simultaneously, 30% sulfuric acid was continuously introduced into the second-stage reactor at a flow rate of 1603 mL / h. The material overflowing from the second-stage reactor was introduced into the third-stage reactor, where dichloromethane and water were simultaneously introduced at a flow rate of 600 mL / h and 1000 mL / h, respectively. Once the reaction system was stable, the product solution was started to be received.

[0047] The feed solution was continuously received for 2 hours, and samples were collected for analysis, indicating complete conversion of the raw materials. After extraction, washing with water, and drying, the received post-reaction feed solution finally yielded 743.5 g of m-chloroperoxybenzoic acid with a content of 96.2% and a yield of 94.2% (see Table 1).

[0048] Example 4

[0049] The continuous production process of m-chloroperoxybenzoic acid is carried out by constructing a reaction system according to the method described in Example 1. The multi-stage series circulating tubular continuous reactor system in this example is formed by three circulating tubular reactors connected in series, and each reactor has a volume of 1 L.

[0050] Specific reaction steps: Dissolve m-chlorobenzoyl chloride in THF to prepare a 74.5% (w / w) solution A; premix 50% hydrogen peroxide, 42% potassium hydroxide aqueous solution, and 0.1% (w / w) magnesium sulfate pentahydrate in a single-stage tubular reactor to prepare solution B. The temperature of the tubular reactor is controlled at -5~0℃, the residence time is 5min, and solutions A and B are precooled to -5℃ respectively; then, the two solutions are simultaneously and continuously fed into the second circulating tubular reactor of the multi-stage series circulating tubular continuous reactor system using pumps. The flow rate of solution A was controlled at 967 mL / h, and the flow rate of solution B was controlled at 1441 mL / h. The reaction temperature was controlled at -5 to 0℃. The reaction solution was then sequentially introduced into the second circulating tubular reactor via overflow. Simultaneously, 30% sulfuric acid was continuously introduced into the second-stage reactor at a flow rate of 1603 mL / h. The material overflowing from the second-stage reactor was introduced into the third-stage reactor, where dichloromethane and water were simultaneously introduced at a flow rate of 600 mL / h and 1000 mL / h, respectively. Once the reaction system was stable, the product solution was started to be received.

[0051] The feed solution was continuously received for 2 hours, and samples were collected for analysis, indicating complete conversion of the raw materials. After extraction, washing with water, and drying, the received post-reaction feed solution finally yielded 758.5 ​​g of m-chloroperoxybenzoic acid with a purity of 95.9% and a yield of 95.8% (see Table 1).

[0052] Example 5

[0053] The continuous production process of m-chloroperoxybenzoic acid is carried out by constructing a reaction system according to the method described in Example 1. The multi-stage series circulating tubular continuous reactor system in this example is formed by three circulating tubular reactors connected in series, and each reactor has a volume of 1 L.

[0054] Specific reaction steps: Dissolve m-chlorobenzoyl chloride in 1,2-dichloroethane to prepare a 70.4% (w / w) solution A; premix 50% hydrogen peroxide, 42% potassium hydroxide aqueous solution, and 0.1% (w / w) magnesium sulfate pentahydrate in a single-stage tubular reactor to prepare solution B. The temperature of the tubular reactor is controlled at -5~0℃, and the residence time is 5min. Precool solutions A and B to -5℃ respectively; then, pump the two solutions simultaneously and continuously into the second circulating tubular reactor of the multi-stage series circulating tubular continuous reactor system. The flow rate of solution A was controlled at 1055 mL / h, and the flow rate of solution B was controlled at 1441 mL / h. The reaction temperature was controlled at -5 to 0℃. The reaction solution was then sequentially introduced into the second circulating tubular reactor via overflow. Simultaneously, 30% sulfuric acid was continuously introduced into the second-stage reactor at a flow rate of 1603 mL / h. The material overflowing from the second-stage reactor was introduced into the third-stage reactor, where dichloromethane and water were simultaneously introduced at a flow rate of 600 mL / h and 1000 mL / h, respectively. Once the reaction system was stable, the product solution was started to be received.

[0055] The feed solution was continuously received for 2 hours, and samples were collected for analysis, indicating complete conversion of the raw materials. After extraction, washing with water, and drying, the received post-reaction feed solution finally yielded 753.8 g of m-chloroperoxybenzoic acid with a purity of 95.8% and a yield of 95.1% (see Table 1).

[0056] Comparative Example

[0057] The semi-batch reactor process for producing m-chloroperoxybenzoic acid involves sequentially adding 35g of hydrogen peroxide and 18g of dioxane into a reactor, starting stirring, and cooling the jacket with ice-salt water. Once the temperature reaches below -5°C, 0.008g of magnesium sulfate heptahydrate is added, followed by the dropwise addition of a prepared alkaline solution over approximately 60 minutes while maintaining the temperature below 5°C. The mixture is then kept at this temperature for another 30 minutes, maintaining the reaction temperature between -5°C and 0°C. 20g of m-chlorobenzoyl chloride is slowly added dropwise over approximately 2 hours, maintaining the reaction temperature between -5°C and 0°C for 1 hour. Then, 30wt.% sulfuric acid at 0°C is rapidly added to adjust the pH to below 1, followed by the addition of 60g of water and stirring for 60 minutes. Finally, 12g of dichloromethane is added and stirred until the supernatant is clear. The mixture is allowed to stand, separated, filtered, washed with water, and dried. The final product obtained is 17.9g of dried m-chloroperoxybenzoic acid with a purity of 80% and a yield of 75%.

[0058] Table 1 Results of the Third-Order Continuous Reaction Test

[0059] As can be seen from the above embodiments, the present invention provides a method for synthesizing m-chloroperoxybenzoic acid using a multi-stage series circulating tubular continuous reactor. As shown in Table 1, the m-chloroperoxybenzoic acid production process of the present invention adopts a continuous circulating tubular method, which improves production efficiency and reaction safety compared to existing processes, meeting the requirements of green, safe, and efficient production. The yield of m-chloroperoxybenzoic acid in the present invention can reach over 95%, which is 17-20% higher than that of existing processes. The present invention improves the batch / semi-batch reactor process to a continuous circulating tubular process, enhancing the level of automated and continuous production.

[0060] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for synthesizing m-chloroperoxybenzoic acid using a multi-stage series circulating tubular continuous reactor, characterized in that, Includes the following steps: Solution A is prepared by dissolving m-chlorobenzoyl chloride in a solvent, and solution B is prepared by mixing hydrogen peroxide, inorganic base and stabilizer. Solution A and solution B are simultaneously and continuously fed into a multi-stage series circulating tubular continuous reactor system for synthesis reaction; The multi-stage series circulating tubular continuous reactor system comprises at least three circulating tubular continuous reactors connected in series; an inorganic acid is added to the penultimate stage reactor of the multi-stage series circulating tubular continuous reactor system for neutralization reaction; dichloromethane and water are added to the last stage reactor for water washing, and the synthesized target product is continuously collected from the outlet to a collection tank.

2. The method for synthesizing m-chloroperoxybenzoic acid in a multi-stage series circulating tubular continuous reactor according to claim 1, characterized in that, The synthesis reaction temperature in each stage of the circulating tubular reactor is independently -20~10℃, and the average residence time is 5~200min.

3. The method for synthesizing m-chloroperoxybenzoic acid in a multi-stage series circulating tubular continuous reactor according to claim 1 or 2, characterized in that, The concentration of intermediate benzoyl chloride in solution A is 55~85 wt.%, and the solvent contains one or more of dichloromethane, dichloroethane, methanol, tetrahydrofuran, and dioxane.

4. The method for synthesizing m-chloroperoxybenzoic acid in a multi-stage series circulating tubular continuous reactor according to claim 3, characterized in that, Solution B is prepared by premixing hydrogen peroxide, inorganic alkali, and stabilizer in a tubular reactor. The inorganic alkali includes sodium hydroxide and / or potassium hydroxide; the stabilizer includes magnesium sulfate and / or sodium sulfate. The concentration of hydrogen peroxide in solution B is 30~50 wt.%, the concentration of inorganic alkali is 35~55 wt.%, and the stabilizer accounts for 1~10‰ of the total mass fraction of solution B.

5. The method for synthesizing m-chloroperoxybenzoic acid in a multi-stage series circulating tubular continuous reactor according to claim 4, characterized in that, The temperature of the tubular reactor is controlled at -10~10℃, and the residence time is 1~30min.

6. The method for synthesizing m-chloroperoxybenzoic acid using a multi-stage series circulating tubular continuous reactor according to claim 1, 2, or 5, characterized in that, The flow rate of solution A is 800~1100 mL / h, and the flow rate of solution B is 1300~1600 mL / h.

7. The method for synthesizing m-chloroperoxybenzoic acid in a multi-stage series circulating tubular continuous reactor according to claim 6, characterized in that, The molar ratio of intermediate benzoyl chloride in solution A to hydrogen peroxide in solution B is 2-6; the molar ratio of intermediate benzoyl chloride in solution A to inorganic base in solution B is 2-8.

8. The method for synthesizing m-chloroperoxybenzoic acid in a multi-stage series circulating tubular continuous reactor according to claim 7, characterized in that, The inorganic acid comprises one or more of sulfuric acid, hydrochloric acid, and phosphoric acid, the concentration of the inorganic acid is 10-50 wt.%, and the flow rate of the inorganic acid is 1500-2000 mL / h.

9. The method for synthesizing m-chloroperoxybenzoic acid in a multi-stage series circulating tubular continuous reactor according to claim 1, 7, or 8, characterized in that, The amount of dichloromethane added is 0.2 to 3 times the total mass of solution A and solution B, and the amount of water added is 0.5 to 10 times the total mass of solution A and solution B.

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