Method and system for continuously synthesizing 2, 4-dichloroacetophenone

Abstract

The invention discloses a method and system for continuously synthesizing 2, 4-dichloroacetophenone, and the method for continuously synthesizing 2, 4-dichloroacetophenone comprises the following steps: S1, mixing m-dichlorobenzene and a catalyst to form a turbid liquid, and continuously inputting the turbid liquid into a tubular reactor; s2, enabling gas-phase acetyl chloride to pass through a micro-interface generator to form micron-sized microbubbles, continuously inputting the micron-sized microbubbles into a tubular reactor, and carrying out mixed reaction on the micron-sized microbubbles and the turbid liquid to obtain a mixed reaction liquid; and S3, continuously inputting the mixed reaction liquid and water into a hydrolysis reactor, and carrying out hydrolysis and separation to obtain 2, 4-dichloroacetophenone. According to the invention, the traditional kettle type stirring reaction is changed into micro-interface reaction, and the mass transfer area and the total mass transfer rate among multiple phases can be multiplied, so that the reaction rate is greatly improved, the side reaction is effectively controlled, and meanwhile, the product yield, the reaction safety and the like are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of fine chemicals, and particularly relates to a method and system for continuously synthesizing 2,4-dichloroacetophenone. BACKGROUND

[0002] 2,4-dichloroacetophenone is an important fine chemical intermediate, which is widely used in the fields of pesticides, medicines and the like, such as synthesis of low-toxic, broad-spectrum fungicide propiconazole, and can also be used for synthesis of antifungal drugs such as ketoconazole.

[0003] The method for industrial production of 2,4-dichloroacetophenone mainly uses m-dichlorobenzene, aluminum trichloride and acetyl chloride as raw materials, and is synthesized by a pot type batch method through a Friedel-Crafts acylation reaction. This process has problems of uneven mixing, poor selectivity, low yield and the like. Therefore, it is necessary to explore a synthesis process with small amplification effect and high product yield.

[0004] Patent CN111116336A discloses a synthesis method of 2,4-dichloroacetophenone. The invention uses m-dichlorobenzene and acetyl chloride as raw materials to synthesize 2,4-dichloroacetophenone crude product through an electrophilic substitution reaction in a Cl-FeCl3 ionic liquid medium, and then extracts 2,4-dichloroacetophenone with cyclohexane, and high-content product is obtained after the solvent is distilled out under reduced pressure. The process is simple and easy to operate, and the Cl-FeCl3 ionic liquid used can be recycled after simple treatment. However, the process uses solvent extraction of crude product, which is easy to cause solvent residue and affect product yield. At the same time, acetyl chloride is excessive, which is difficult to recover and will also increase the cost of raw materials.

[0005] Patent CN113354520B discloses a synthesis method of 2,4-dichloroacetophenone. The invention uses aluminum hydroxide and concentrated hydrochloric acid as raw materials to react, and then obtains fresh aluminum trichloride after toluene azeotropic dehydration, and then reacts with m-dichlorobenzene and acetyl chloride to obtain 2,4-dichloroacetophenone. The obtained synthesis liquid is treated to obtain high-content 2,4-dichloroacetophenone, and the water layer is treated to obtain aluminum hydroxide and then reused. However, the process has many procedures and is complex to operate, which is easy to cause high production cost and is not conducive to enterprise scale production.

[0006] Patent CN113620797B discloses a method for preparing 2,4-dichloroacetophenone. The invention uses m-dichlorobenzene, aluminum trichloride and amide additive as raw materials, and adds acetyl bromide to synthesize the target product. The process uses amide additive to promote the dissolution of aluminum trichloride, trying to achieve the effect of homogeneous reaction; and the use of acetyl bromide effectively reduces the activity of the electrophilic reagent, which can improve the selectivity of the raw materials. The process uses high-priced raw materials, which increases the production cost, and the generated amide wastewater is difficult to treat, which further increases the production cost.

[0007] Therefore, there is an urgent need for an efficient method suitable for industrial production of 2,4-dichloroacetophenone. SUMMARY

[0008] The present application aims at the deficiencies of the prior synthesis process, and provides a method and system for continuously synthesizing 2,4-dichloroacetophenone, which has the advantages of continuous stability, high efficiency, high product content and yield, and convenient industrial implementation.

[0009] The present application provides a method for continuously synthesizing 2,4-dichloroacetophenone, comprising the following steps:

[0010] S1, mixing meta-dichlorobenzene and a catalyst to form a suspension, and continuously inputting the suspension into a tubular reactor;

[0011] S2, continuously inputting gaseous acetyl chloride into a micro-interface generator to form micron-sized micro-bubbles, and then continuously inputting the micro-bubbles into the tubular reactor to mix and react with the suspension to obtain a mixed reaction liquid;

[0012] S3, continuously inputting the mixed reaction liquid and water into a hydrolysis reactor to perform hydrolysis and separation, and obtaining 2,4-dichloroacetophenone.

[0013] Compared with the currently widely used kettle batch process, the present application uses a continuous reactor, has the effect of continuous stability and high efficiency, and uses a micro-interface reactor for gaseous bubble feeding. The micro-interface reactor uses micro-interface strengthening reaction technology to enhance the mass transfer efficiency of multiphase reaction. By enhancing the interface mass transfer, the micro-interface replaces the traditional reactor's millimeter-centimeter macro-interface, which can improve the reaction rate by several times or even dozens of times, effectively control the side reaction, and improve the yield of the product and the safety of the reaction, etc.

[0014] The micro-bubbles enter from the bottom of the tubular reactor, and the suspension can also enter from the bottom at the same time. Such a setting can increase the gas-liquid contact efficiency and enhance the reaction effect.

[0015] In the present application, the main reaction of meta-dichlorobenzene and acetyl chloride to synthesize 2,4-dichloroacetophenone is chemical reaction formula 1: .

[0016] The side reaction equation in the acylation reaction of meta-dichlorobenzene and acetyl chloride is chemical reaction formula 2: .

[0017] Further, in step S1, the feeding temperature of the gaseous acetyl chloride is 115-120℃; the molar ratio of the acetyl chloride to the meta-dichlorobenzene is 1:1.05-1.3; and the molar ratio of the acetyl chloride to the catalyst is 1:1.05-1.2.

[0018] Further, the particle size of the catalyst is less than or equal to 100 μm; the catalyst is one or more of zinc chloride, ferric chloride and aluminum chloride, and preferably, the catalyst is aluminum chloride.

[0019] Further, the particle size of the micro-bubbles is less than or equal to 100 μm, and preferably, the particle size is 30-100 μm.

[0020] Further, in step S2, the reaction temperature of the mixing reaction is 90-110 ℃, the absolute pressure of the reaction is 0.3-0.55 MPa, and the reaction residence time is 30-60 seconds.

[0021] Further, the tubular reactor is a shell-and-tube reactor.

[0022] The present application synthesizes 2,4-dichloroacetophenone product under positive pressure condition, which is beneficial to the generated hydrogen chloride dissolved in liquid phase, avoids subsequent hydrolysis, and adds hydrochloric acid to destroy the stable complex formed by the product and the catalyst, reduces the loss of raw materials, and simplifies the operation process.

[0023] Further, in step S3, the hydrolysis is specifically: the mixing reaction liquid and water are continuously input into a micro-channel reactor to perform a hydrolysis reaction, and after the hydrolysis, a water-oil two-phase mixture is formed, the volume ratio of the mixing reaction liquid to water is 1:3.5-4; the temperature of the hydrolysis reaction is 70-85 ℃, and the residence time of the hydrolysis reaction is 10-30 seconds; and the separation is one or more of delamination treatment, distillation or rectification.

[0024] The micro-channel reactor is used as a hydrolysis equipment, which has good heat transfer efficiency, high mass transfer efficiency and large specific surface area, and can complete the hydrolysis reaction in a very short time, thereby effectively improving the production efficiency.

[0025] After the hydrolysis, a water-oil two-phase mixture is formed, and further separation is performed to obtain 2,4-dichloroacetophenone, wherein the separation mode can be distillation, rectification or the like to obtain 2,4-dichloroacetophenone product; or after the hydrolysis, extraction, delamination, and then distillation, rectification or the like can be performed to obtain 2,4-dichloroacetophenone product. The separation mode of the present application is not limited thereto, as long as the water-oil two-phase mixture formed after the hydrolysis can be separated into 2,4-dichloroacetophenone product.

[0026] The present application also provides a system for continuously synthesizing 2,4-dichloroacetophenone, which is used to implement the method for continuously synthesizing 2,4-dichloroacetophenone as described above, and comprises:

[0027] A liquid phase feeding unit is used to transport the suspension formed by the m-dichlorobenzene and the catalyst;

[0028] a gas phase feed unit for feeding the gas phase acetyl chloride;

[0029] a micro-interface generating unit, the gas phase feed unit being in communication with the micro-interface generating unit, so that the gas phase acetyl chloride forms micro-bubbles of micron size through the micro-interface generating unit;

[0030] a main reaction unit, the main reaction unit being in communication with the liquid phase feed unit and the micro-interface generating unit respectively, so that the suspension and the micro-bubbles are mixed and reacted in the main reaction unit;

[0031] a post-treatment unit, the post-treatment unit being in communication with the main reaction unit, for hydrolyzing and separating the mixed reaction liquid after the mixed reaction.

[0032] Further, the micro-interface generating unit comprises at least one micro-interface generator.

[0033] Further, the micro-interface generating unit is arranged at the bottom of the main reaction unit.

[0034] Further, the entrance of the micro-interface generating unit into the main reaction unit is located at the bottom of the main reaction unit.

[0035] Further, the main reaction unit comprises at least one tubular reactor.

[0036] Further, the tubular reactor is a column tubular reactor.

[0037] Further, the post-treatment unit comprises a hydrolysis unit and a separation unit, the hydrolysis unit being in communication with the main reaction unit, for hydrolyzing the mixed reaction liquid after the mixed reaction, and the separation unit being in communication with the hydrolysis unit, for separating the mixed liquid flowed out of the hydrolysis unit.

[0038] Further, the hydrolysis unit comprises at least one micro-channel reactor.

[0039] Compared with the prior art, the present application has the following advantages:

[0040] 1. Compared with the currently generally used kettle batch process, the present application adopts continuous acylation reaction and hydrolysis reaction, and has the advantages of continuous stability, high efficiency and suitability for industrial implementation.

[0041] 2. The present application changes the traditional kettle stirring reaction into micro-interface reaction, which can multiply the mass transfer area and total mass transfer rate between multiple phases, thereby greatly improving the reaction rate, effectively controlling the side reaction, and improving the product yield and the safety of the reaction, etc. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1A process flow diagram of the continuous synthesis of 2,4-dichloroacetophenone provided by the present application.

[0043] Figure 2 A system schematic diagram of the continuous synthesis of 2,4-dichloroacetophenone provided by the present application.

[0044] Figure 3 Another system schematic diagram of the continuous synthesis of 2,4-dichloroacetophenone provided by the present application. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is further described in detail below in combination with embodiments and drawings. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application.

[0046] The present application provides a method and system for continuously synthesizing 2,4-dichloroacetophenone to solve the problems of low production efficiency and low product yield in the existing synthesis of 2,4-dichloroacetophenone.

[0047] Specifically, as shown in Figure 1 The present application provides a method for continuously synthesizing 2,4-dichloroacetophenone, comprising the following steps:

[0048] S1, mixing meta-dichlorobenzene and a catalyst to form a suspension, and continuously inputting the suspension into a tubular reactor;

[0049] S2, continuously inputting gaseous acetyl chloride into the tubular reactor after forming micron-sized micro-bubbles through a micro-interface generator to mix and react with the suspension to obtain a mixed reaction liquid;

[0050] S3, continuously inputting the mixed reaction liquid and water into a hydrolysis reactor to perform hydrolysis and separation to obtain 2,4-dichloroacetophenone.

[0051] The meta-dichlorobenzene and the catalyst are usually mixed and stirred into a suspension in a certain proportion, and are continuously input into the tubular reactor. The gaseous acetyl chloride is continuously input into the tubular reactor after forming micron-sized micro-bubbles through a micro-interface generator. The suspension and the micro-bubbles mix and react in the tubular reactor. The mixing reaction is an acylation reaction, and the tail gas produced is mainly hydrogen chloride (HCl) gas. The liquid after the reaction and water are continuously input into a hydrolysis reactor to perform a hydrolysis reaction. The water-oil two-phase mixed liquid after the hydrolysis is separated by a layering device to obtain a 2,4-dichloroacetophenone solution. The tubular reactor can be a column tubular reactor or other types of tubular reactors. The micro-interface generator can be arranged inside or outside the tubular reactor, which is not limited here. The inlet of the micro-interface generator into the tubular reactor is preferably at the bottom of the tubular reactor.

[0052] In an optional embodiment of the present application, as shown in Figure 2 the present application provides a system for continuously synthesizing 2,4-dichloroacetophenone, comprising:

[0053] a liquid-phase feeding unit for conveying a suspension of meta-dichlorobenzene and a catalyst;

[0054] a gas-phase feeding unit for conveying a gas-phase acetyl chloride;

[0055] a micro-interface generating unit, the gas-phase feeding unit being in communication with the micro-interface generating unit, so that the gas-phase acetyl chloride forms micro-sized micro-bubbles through the micro-interface generating unit;

[0056] a main reaction unit, the main reaction unit being in communication with the liquid-phase feeding unit and the micro-interface generating unit respectively, so that the suspension and the micro-bubbles are mixed and reacted in the main reaction unit;

[0057] a post-processing unit, which is in communication with the main reaction unit, for hydrolyzing and separating the mixed reaction liquid after the mixing and reaction.

[0058] In an optional embodiment of the present application, the micro-interface generating unit comprises at least one micro-interface generator, and preferably, the micro-interface generating unit is arranged at the bottom of the main reaction unit.

[0059] In an optional embodiment of the present application, the main reaction unit comprises at least one tubular reactor, and preferably, the tubular reactor is a column tubular reactor.

[0060] The micro-interface generating unit can be arranged inside or outside the main reaction unit, which is not limited herein. The inlet of the micro-interface generating unit into the main reaction unit is preferably at the bottom of the main reaction unit.

[0061] In another optional embodiment of the present application, as shown in Figure 3 the post-processing unit comprises a hydrolysis unit and a separation unit, the hydrolysis unit being in communication with the main reaction unit for hydrolyzing the mixed reaction liquid after the mixing and reaction, and the separation unit being in communication with the hydrolysis unit for separating the mixed liquid flowing out of the hydrolysis unit.

[0062] In an optional embodiment of the present application, the hydrolysis unit comprises at least one micro-channel reactor.

[0063] In order for those skilled in the art to better understand the present application, the present application is described in detail below with specific examples.

[0064] The micro-channel reactor used in the examples and comparative examples of the present application is a CS series micro-channel reactor produced by Shandong Haomai Company, has ten reaction modules with heart-shaped structure in series, and the material used is Hastelloy C276; the volume of the kettle reactor is 5L.

[0065] Example 1

[0066] (1) 9.2 mol / h of aluminum trichloride with a number average particle size of 50 microns and 9.6 mol / h of m-dichlorobenzene were mixed and stirred to form a suspension;

[0067] (2) The suspension in (1) was continuously fed into the tubular reactor. At the same time, 8 mol / h of gaseous acetyl chloride with a temperature of 115°C was input into the tubular reactor through a micro-interface generator at the bottom of the tubular reactor to form bubbles with a diameter of 50-60 microns, and then the bubbles were mixed with the suspension at 100°C and an absolute pressure of 0.45 MPa in the tubular reactor for 45 seconds;

[0068] (3) The mixed reaction liquid after reaction in (2) was continuously fed into the micro-channel reactor with deionized water at a volume ratio of 1:3.8, and hydrolysis was carried out at 75°C for 20 seconds. Then the water-oil two-phase mixture after reaction was separated by a layering device to obtain a 2,4-dichloroacetophenone solution. After the device was stable, 1 h of material was collected, and the mass of the crude 2,4-dichloroacetophenone was 1762.2 g with a content of 82.37%, and the calculated product yield was 96.00%.

[0069] Comparative Example 1

[0070] (1) In the reaction kettle, 9.2 mol of aluminum trichloride with a number average particle size of 1000 microns and 9.6 mol of m-dichlorobenzene were mixed and stirred to form a mixed liquid. The material in the kettle was heated to 50°C, and 8 mol of acetyl chloride liquid was added dropwise into the kettle, and the dropwise time was controlled for 3 h. After the dropwise addition was completed, the material in the kettle was heated to 100°C and kept for 2 h. At this time, the acylation reaction was completed.

[0071] (2) The obtained mixed reaction liquid was mixed with 3.8 times the volume of deionized water and 0.03 times the volume of 30% hydrochloric acid at one time in the hydrolysis kettle, and the mixed reaction liquid after reaction in (1) was slowly added dropwise into the hydrolysis kettle. The total dropwise time was 4 h at 75°C. The water-oil two-phase mixture after reaction was separated by a layering device to obtain a 2,4-dichloroacetophenone solution. The mass of the crude 2,4-dichloroacetophenone was 1755.48 g with a content of 75.23%, and the calculated product yield was 87.35%.

[0072] Comparative Example 2

[0073] (1) In a reaction kettle, 9.2 mol of aluminum trichloride with a number average particle size of 50 microns and 9.6 mol of m-dichlorobenzene were mixed and stirred to form a mixed solution. The material in the kettle was warmed to 100°C, and 8 mol of gaseous acetyl chloride with a temperature of 115°C was added to the kettle, and the reaction time was controlled to be 45 s. At this time, the acylation reaction was completed.

[0074] (2) The obtained reaction after mixing reaction liquid was added to the hydrolysis kettle in one time, and the volume of deionized water was 3.8 times that of the reaction after mixing reaction liquid. The reaction after mixing reaction liquid was quickly dropped into the hydrolysis kettle, and the total dropping time was 20 s at 75°C. The water-oil two-phase mixture formed after the reaction was separated by a layer separator to obtain a 2,4-dichloroacetophenone solution. The total mass of the crude 2,4-dichloroacetophenone obtained was 1755.48 g, and the content was only 10.60%. The calculated product yield was 10.21%.

[0075] Comparative Example 3

[0076] (1) 9.2 mol / h of aluminum trichloride with a number average particle size of 1000 microns and 9.6 mol / h of m-dichlorobenzene were mixed and fully stirred to form a suspension, and a small part of the aluminum trichloride settled at the bottom of the solution;

[0077] (2) The suspension in (1) was continuously transported to a shell-and-tube reactor. At the same time, 8 mol / h of gaseous acetyl chloride with a temperature of 115°C was continuously input into the shell-and-tube reactor through a micro-interface generator at the bottom of the shell-and-tube reactor to form 50-60 micron bubbles, and then mixed with the suspension at 100°C and an absolute pressure of 0.45 MPa for 45 seconds;

[0078] (3) The reaction after mixing reaction liquid in (2) was continuously transported to a micro-channel reactor with deionized water at a volume ratio of 1:3.8, and reacted at 75°C for 20 s. Then the water-oil two-phase mixture formed after the reaction was separated by a layer separator to obtain a 2,4-dichloroacetophenone solution. After the device was running stably, 1 h of material was collected, and the mass of the crude 2,4-dichloroacetophenone obtained was 1426.2 g, and the content was 62.50%. The calculated product yield was 58.95%.

[0079] Comparative Example 4

[0080] (1) 9.2 mol / h of aluminum trichloride with a number average particle size of 50 microns and 9.6 mol / h of m-dichlorobenzene were mixed and fully stirred to form a suspension;

[0081] (2) The suspension in (1) was continuously transported to a shell-and-tube reactor, and 8 mol / h of gaseous acetyl chloride with a temperature of 115°C was continuously bubbled into the shell-and-tube reactor through a multi-hole distributor in a conventional bubble-type tubular reactor, and then mixed with the suspension at 100°C and an absolute pressure of 0.45 MPa for 45 seconds.

[0082] (3) The mixed reaction liquid after reaction in (2) and deionized water were continuously transported into the micro-channel reactor at a volume ratio of 1:3.8, and reacted at 75°C for 20s. The water-oil two-phase mixture formed after the reaction was separated by a layer separator to obtain a 2,4-dichloroacetophenone solution. After the device was stable, 1h of material was collected, and the crude product of 2,4-dichloroacetophenone was obtained with a mass of 1668.1g and a content of 60.54%, and the calculated product yield was 66.79%.

[0083] Comparative Example 5

[0084] (1) 9.2mol / h of aluminum trichloride with a number average particle size of 50 microns and 9.6mol / h of m-dichlorobenzene were mixed and stirred to form a suspension;

[0085] (2) The suspension in (1) was continuously transported into a tubular reactor, and 8mol / h of gaseous acetyl chloride with a temperature of 115°C was continuously input into the tubular reactor after forming 50-60 micron bubbles through a micro-interface generator at the bottom of the tubular reactor, and mixed with the suspension at 100°C and an absolute pressure of 0.45MPa for 45s;

[0086] (3) The volume of deionized water 3.8 times the volume of the mixed reaction liquid collected for 1h after reaction was added to the hydrolysis kettle at one time, and the mixed reaction liquid collected for 1h after reaction was slowly added to the hydrolysis kettle, and the total drop time was 4h at 75°C. The water-oil two-phase mixture formed after the reaction was separated by a layer separator to obtain a 2,4-dichloroacetophenone solution. The crude product of 2,4-dichloroacetophenone was obtained with a mass of 1754.6g and a content of 82.12%, and the calculated product yield was 95.30%.

[0087] The 2,4-dichloroacetophenone product content and yield data of each example and comparative example are shown in Table 1. The 2,4-dichloroacetophenone content refers to the mass percentage content of 2,4-dichloroacetophenone in the 2,4-dichloroacetophenone product, and the yield refers to the yield of 2,4-dichloroacetophenone.

[0088] Table 1 Product content and yield of each example and comparative example

[0089] From the data of the above examples and comparative examples, compared with Example 1, Comparative Example 1 uses the traditional kettle reaction process, and not only has a long reaction time, but also has poor mixing uniformity, large particle size and other factors, resulting in low reaction yield and poor synthesis effect. Comparative Example 2 uses a kettle reaction process, and selects the same catalyst particle size, raw material ratio, reaction residence time, etc. as Example 1, but due to the slow reaction rate of the kettle and the slow hydrolysis rate of the intermediate state, the reaction effect is very poor, the yield is only about 10%, a large amount of m-dichlorobenzene does not participate in the reaction, and most of the acetyl chloride is hydrolyzed, resulting in a decrease in product yield. Compared with Example 1, Comparative Example 3 uses aluminum trichloride with a larger average particle size as the catalyst, and part of the aluminum trichloride settles at the bottom of the suspension liquid and cannot be transported to the tube reactor, resulting in a decrease in the molar ratio of aluminum trichloride to other reactants, which leads to a decrease in product yield. Compared with Example 1, Comparative Example 4 uses a bubble tube reactor for reaction and uses a conventional bubble method to introduce acetyl chloride. Due to the slow reaction rate, a large amount of acetyl chloride and m-dichlorobenzene does not react completely and enters the hydrolysis process, resulting in a large amount of acetyl chloride being hydrolyzed, which leads to a decrease in product yield. In Comparative Example 5, the traditional kettle hydrolysis method is used for hydrolysis, which takes as long as 4 hours to complete the hydrolysis, and the hydrolysis time is longer, which is much lower than the hydrolysis rate using a microchannel reactor.

[0090] The present application is described in detail in the specification, but the present application is not limited to the specific details in the above embodiments. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, and these simple modifications all belong to the protection scope of the present application.

[0091] In addition, it should be noted that each specific technical feature described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, various possible combinations are not described again in the present application.

Claims

1. A method for the continuous synthesis of 2,4-dichloroacetophenone, characterized in that, The method comprises the following steps: S1, mixing meta-dichlorobenzene and a catalyst to form a suspension, and continuously feeding the suspension into a tubular reactor; S2, continuously feeding gaseous acetyl chloride into the tubular reactor through a micro-interface generator to form micron-sized micro-bubbles, and mixing the micro-bubbles with the suspension to obtain a mixed reaction liquid; S3, continuously feeding the mixed reaction liquid and water into a hydrolysis reactor to perform hydrolysis and separation, and obtaining 2,4-dichloroacetophenone.

2. The method according to claim 1, wherein: the feeding temperature of the gaseous acetyl chloride is 115-120°C; the molar ratio of the acetyl chloride to the meta-dichlorobenzene is 1:1.05-1.3; the molar ratio of the acetyl chloride to the catalyst is 1:1.05-1.

2.

3. The method of claim 1, wherein, the particle size of the catalyst is less than or equal to 100 μm; the catalyst is one or more of zinc chloride, ferric chloride and aluminum chloride, and preferably, the catalyst is aluminum chloride.

4. The method of claim 1, wherein, the particle size of the micro-bubbles is less than or equal to 100 μm, and preferably, the particle size is 30-100 μm.

5. The method of claim 1, wherein, in step S2, the reaction temperature of the mixing reaction is 90-110°C, the absolute pressure is 0.3-0.55 MPa, and the reaction residence time is 30-60 seconds.

6. The method of claim 1, wherein, the tubular reactor is a shell-and-tube reactor.

7. The method according to any one of claims 1 to 6, characterized in that, in step S3, the hydrolysis is specifically: continuously feeding the mixed reaction liquid and water into a micro-channel reactor to perform a hydrolysis reaction, and forming a water-oil two-phase mixture after the hydrolysis; the volume ratio of the mixed reaction liquid to water is 1:3.5-4, the hydrolysis reaction temperature is 70-85°C, and the hydrolysis reaction residence time is 10-30 seconds; the separation is one or more of layering, distillation and rectification.

8. A system for the continuous synthesis of 2,4-dichloroacetophenone, characterized in that, The system for implementing the method for continuously synthesizing 2,4-dichloroacetophenone according to any one of claims 1-7 comprises: a liquid-phase feeding unit for feeding the suspension of the meta-dichlorobenzene and the catalyst; a gas-phase feeding unit for feeding the gaseous acetyl chloride; a micro-interface generating unit, which is in communication with the gas-phase feeding unit, so that the gaseous acetyl chloride forms micron-sized micro-bubbles through the micro-interface generating unit; a main reaction unit, which is in communication with the liquid-phase feeding unit and the micro-interface generating unit respectively, so that the suspension and the micro-bubbles perform a mixing reaction in the main reaction unit; a post-processing unit, which is in communication with the main reaction unit, for performing hydrolysis and separation on the mixed reaction liquid after the mixing reaction.

9. The system according to claim 8, wherein: the micro-interface generating unit comprises at least one micro-interface generator, and preferably, the micro-interface generating unit is arranged at the bottom of the main reaction unit; the main reaction unit comprises at least one tubular reactor, and preferably, the tubular reactor is a shell-and-tube reactor.

10. The system according to any one of claims 8 and 9, characterized in that, The post-processing unit comprises a hydrolysis unit and a separation unit; the hydrolysis unit is communicated with the main reaction unit and used for hydrolyzing the mixed reaction liquid after mixing reaction; the separation unit is communicated with the hydrolysis unit and used for separating the mixed liquid flowed out from the hydrolysis unit. Preferably, the hydrolysis unit comprises at least one micro-channel reactor.

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