An apparatus and method for the continuous synthesis of 2,6-dichloro-4-trifluoromethylaniline

Abstract

This invention belongs to the field of chemical process technology, specifically relating to an apparatus and method for the continuous synthesis of 2,6-dichloro-4-trifluoromethylaniline. Using 2-chloro-N,N-dimethyl-4-(trifluoromethyl)aniline or N,N-dimethyl-4-(trifluoromethyl)aniline as raw material, and chlorine gas as the chlorinating agent, the chlorination reaction on the benzene ring is carried out in a packed static tubular reactor, followed by the chlorination reaction of the methyl group on the side chain in a photocatalytic reactor. Finally, alkali solution is added to obtain 2,6-dichloro-4-trifluoromethylaniline, with a yield of approximately 97% and a purity of approximately 98%. This invention uses a continuous process instead of a batch method to synthesize 2,6-dichloro-4-trifluoromethylaniline, thereby enhancing mass and heat transfer capabilities, making the reaction process safer and more efficient, reducing raw material costs, and minimizing the generation of byproducts, ultimately enabling industrial-scale production.

Description

Technical Field

[0001] This invention belongs to the field of chemical process technology, specifically relating to an apparatus and method for the continuous synthesis of 2,6-dichloro-4-trifluoromethylaniline. Background Technology

[0002] 2,6-Dichloro-4-trifluoromethylaniline is commonly used as a raw material and intermediate in pesticide production, primarily for the synthesis of fluorinated organic pesticides such as fipronil and lambda-cyhalothrin. It is widely used in agriculture to control various weeds, fungi, and pests, and can also be used as a reservoir stabilizer to improve oil well production and extend well lifespan.

[0003] There are many existing methods for synthesizing 2,6-dichloro-4-trifluoromethylaniline. One method uses 4-chlorotrifluorotoluene or 3,4-dichlorotrifluorotoluene as raw materials, and obtains N,N-dimethyl-4-(trifluoromethyl)aniline or N,N-dimethyl-2-chloro-4-(trifluoromethyl)aniline through a dimethyl amination reaction. Then, 2,6-dichloro-4-trifluoromethylaniline is obtained through chlorination and alkaline hydrolysis.

[0004] US Patent Application US5401882 describes a method for obtaining 2,6-dichloro-4-fluoromethyl-N,N-dimethylaniline using N,N-dimethylformamide as a methylating agent, followed by chlorination under ultraviolet light and treatment with sodium hydroxide to obtain 2,6-dichloro-4-trifluoromethylaniline. However, this method is a batch reaction. Due to the low penetration of ultraviolet light, insoluble substances generated during the reaction affect the light exposure, resulting in a slow reaction rate in the later stages, requiring up to 6 hours of reaction time. Furthermore, the reaction exhibits low selectivity, low yield, and low product content, making it unsuitable for industrial-scale production. Chinese Patent Application CN1468838A discloses a method using azobisisobutyronitrile (AIBN) as an initiator instead of ultraviolet light for side-chain methyl chlorination, followed by hydrolysis to obtain 2,6-dichloro-4-trifluoromethylaniline. This method incorporates expensive AIBN, leading to high production costs and the introduction of unnecessary impurities due to AIBN decomposition, resulting in low product purity. Furthermore, the crude product obtained by this method still needs to be further refined, resulting in high production losses and low efficiency. Similarly, Wu Tianquan et al. published an article on "Synthesis of 2,6-dichloro-4-trifluoromethylaniline", in which N,N-dimethyl-4-(trifluoromethyl)aniline was subjected to photoradical reaction and chlorination reaction under ultraviolet light and catalyst to obtain 2,6-dichloro-4-trifluoromethylaniline. This method requires the introduction of excessive chlorine gas, resulting in large amounts of waste pollution. Moreover, the preferred reaction time is as long as 20 hours or more, resulting in low production efficiency (Wu Tianquan, Hu Aixi. Synthesis of 2,6-dichloro-4-trifluoromethylaniline [J], Journal of Natural Science of Hunan Normal University, 2007, 30(4):77-80).

[0005] In summary, existing technologies suffer from problems such as long reaction times, low product content, low production efficiency, and high costs. There is an urgent need for a device and method for the continuous synthesis of 2,6-dichloro-4-trifluoromethylaniline to shorten reaction time, increase product content and production efficiency, reduce production costs, and thus be suitable for industrial-scale production. Summary of the Invention

[0006] To address the aforementioned problems in the existing technology, this invention provides an apparatus and method for the continuous synthesis of 2,6-dichloro-4-trifluoromethylaniline. This invention features short reaction time, low cost, safe operation, high product content, high production efficiency, and ease of industrial production.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] An apparatus for continuous production of 2,6-dichloro-4-trifluoromethylaniline includes an aniline raw material tank 1, a chlorine gas cylinder 2, a transfer pump 3, a first preheating pipe 4, a first flow meter 5, a packed tubular reactor 6, a first reactor 7, a second flow meter 8, an outlet control valve 9, a gas-liquid separator 10, a storage tank 11, a transfer pump 12, a second preheating pipe 13, a photocatalytic reactor 14, an outlet control valve 15, a gas-liquid separator 16, and a storage tank 17. The raw material tank 1 is connected to the inlet of the transfer pump 3, and the outlet of the transfer pump 3 is connected to the inlet of the first preheating pipe 4. The chlorine gas cylinder 2 is connected to the first flow meter 5. The outlet of the first preheating pipe 4 and the first flow meter 5 are respectively connected to the inlet of the packed static tubular reactor 6. The inlet and outlet of the first reactor 7 are respectively connected to the outlet of the packed tubular reactor 6 and the gas-liquid separator 10. 0. A gas-liquid separator 10 is provided with an outlet pipe on its upper side, and an outlet control valve 9 is provided on the outlet pipe. The lower end of the gas-liquid separator 10 is connected to the storage tank 11 through a pipe. A discharge control valve is provided on the pipe between the gas-liquid separator 10 and the storage tank 11. The outlet of the storage tank 11 is connected to the inlet of the conveying pump 12. The inlet of the second preheating pipe 13 is connected to the outlet of the conveying pump 12. The chlorine cylinder 2 is connected to the second flow meter 8. The outlet of the second flow meter 8 and the outlet of the second preheating pipe 13 are both connected to the inlet of the photocatalytic reactor 14. The outlet of the photocatalytic reactor 14 is connected to the gas-liquid separator 16. A gas-liquid separator 16 is provided with an outlet pipe on its upper side, and an outlet control valve 15 is provided on the outlet pipe. The lower end of the gas-liquid separator 16 is connected to the storage tank 17 through a pipe. A discharge control valve is provided on the pipe between the gas-liquid separator 16 and the storage tank 17.

[0009] A temperature sensor T1 is installed between the first preheating pipe 4 and the packed tubular reactor 6; a temperature sensor T2 and a pressure sensor P1 are installed between the tubular reactor 6 and the first reactor 7; a pressure sensor P2 is installed between the gas-liquid separator 10 and the gas outlet control valve 9; a temperature sensor T3 is installed between the second preheating pipe 13 and the photocatalytic reactor 14; a temperature sensor T4 and a pressure sensor P3 are installed between the photocatalytic reactor 14 and the gas-liquid separator 16; and a pressure sensor P4 is installed between the gas-liquid separator 16 and the gas outlet control valve 15.

[0010] The first preheating tube 4, the packed tubular reactor 6, the first reactor 7, and the second preheating tube 13 are all made of polytetrafluoroethylene, while the photocatalytic reactor 14 is made of silicon dioxide.

[0011] A method for synthesizing 2,6-dichloro-4-trifluoromethylaniline using the aforementioned continuous synthesis apparatus includes dissolving aniline raw materials in an organic solvent, preheating them via a first preheating tube 4, and then conveying them to a packed tubular reactor 6. Simultaneously, chlorine gas from gas cylinder 2 is conveyed to this reactor. After the two react and mix, the mixture enters a first reactor 7 and is finally conveyed to a gas-liquid separator 10. The gas from the reaction products enters the upper outlet pipe of the gas-liquid separator 10 and is controlled by the outlet gas control system. The liquid phase product is discharged through valve 9. After being preheated by the second preheating pipe 13 via the transfer pump 12 from the lower outlet of the gas-liquid separator 10, it is then mixed with chlorine gas supplied by the second flow meter 8 in the photocatalytic reactor 14 and enters the gas-liquid separator 16. The gas in the reaction product enters the upper gas outlet pipe from the upper outlet of the gas-liquid separator 16 and is discharged by the gas outlet control valve 15. The liquid phase product flows into the storage tank 17 from the lower outlet of the gas-liquid separator 10. Finally, after adding alkaline solution, the final product 2,6-dichloro-4-trifluoromethylaniline is obtained.

[0012] The mass ratio of aniline raw material to organic solvent is 1:5 to 1:20, the molar ratio of aniline raw material to chlorine gas transported to the static tubular reactor is 1:1 to 1:3, the molar ratio of aniline raw material to chlorine gas transported to the photocatalytic reactor is 1:2 to 1:4, and the molar ratio of aniline raw material to alkali is 1:2 to 1:5.

[0013] The aniline raw material is 2-chloro-N,N-dimethyl-4-(trifluoromethyl)aniline or N,N-dimethyl-4-(trifluoromethyl)aniline.

[0014] The organic solvent is one or more of chloroform, dichlorobenzene, and tetrachloroethylene.

[0015] The alkaline solution is one or more of sodium hydroxide, potassium hydroxide, and sodium bicarbonate solutions.

[0016] When the aniline raw material is 2-chloro-N,N-dimethyl-4-(trifluoromethyl)aniline, the molar ratio of 2-chloro-N,N-dimethyl-4-(trifluoromethyl)aniline to chlorine gas transported to the static tubular reactor is 1:1 to 1:1.2; when the aniline raw material is N,N-dimethyl-4-(trifluoromethyl)aniline, the molar ratio of N,N-dimethyl-4-(trifluoromethyl)aniline to chlorine gas transported to the static tubular reactor is 1:2 to 1:2.2.

[0017] The temperature of the raw material liquid in the first preheating tube is 30-60℃, the residence time of the reaction liquid in the first reactor is 2-15 min, the temperature of the reaction liquid in the second preheating tube is 40-60℃, the pressure of chlorine gas entering the pipeline is 0.03-0.8 MPa, the residence time of the reaction liquid in the photocatalytic reactor is 5-40 min, and the temperature for photocatalytic reaction is 40-60℃.

[0018] The light source in the photocatalytic reactor can be one or more of LED lamps, mercury lamps, and ultraviolet lamps, with a wavelength of 200-500 nm, preferably 300-450 nm, and a light intensity of 10-100%.

[0019] While the existing technology US5401882A allows for halogenation and side-chain methyl halogenation under ultraviolet light irradiation, the reaction process suffers from slow reaction rates in the later stages due to the influence of insoluble substances on the light and the attenuation of ultraviolet light in a batch reactor, making industrial production difficult. The inventors have creatively used a continuous reaction device for photocatalytic reaction, which allows the light source to remain stable during the reaction, thus ensuring the continuity of the reaction. Through long-term research, the inventors discovered that aniline raw materials easily generate dichloro intermediate compounds during the chlorination process in a batch reactor, which then react with moisture in the air to produce insoluble substances, resulting in high impurity content and unstable yield and purity of the chlorinated product. The inventors unexpectedly discovered in experiments that when using a continuous reaction device, the stability of photocatalytic chlorination is significantly improved, the impurity problem is solved, and the product purity is greatly increased. This may be because the reaction conditions avoid contact with moisture, and the optimal reaction temperature and stable light intensity in the photocatalytic reactor improve the selectivity and production efficiency of the reaction.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] (1) This invention uses 2-chloro-N,N-dimethyl-4-(trifluoromethyl)aniline or N,N-dimethyl-4-(trifluoromethyl)aniline as raw materials to synthesize 2,6-dichloro-4-trifluoromethylaniline through a continuous process, which reduces the generation of by-products and can directly obtain high-purity products without distillation. The final product yield reaches more than 97%, and the product content reaches more than 98%.

[0022] (2) The present invention uses a packed tubular reactor to carry out the chlorination reaction on the benzene ring. Through continuous operation, the gas and liquid phases are mixed efficiently and quickly, which shortens the reaction time, improves the mass and heat transfer efficiency, and can quickly remove the heat of reaction, solving the problem of excessive temperature caused by heat release during the batch reaction process, thereby improving the selectivity, safety and production efficiency of the reaction.

[0023] (3) The present invention uses a photocatalytic reactor to carry out the methyl chlorination reaction on the side chain, which can complete the reaction in a short time and obtain a high content of product. This overcomes the disadvantages of weak light transmittance and long reaction time in batch reactors, and finally realizes industrial production. Attached Figure Description

[0024] Figure 1 This is a diagram of the reaction apparatus for the continuous synthesis of 2,6-dichloro-4-trifluoromethylaniline according to the present invention.

[0025] Among them, 1-raw material tank, 2-gas cylinder, 3-transfer pump, 4-first preheating pipe, 5-first flow meter, 6-packed reactor, 7-first reactor, 8-second flow meter, 9-outlet control valve, 10-gas-liquid separator, 11-storage tank, 12-transfer pump, 13-second preheating pipe, 14-photocatalytic reactor, 15-outlet control valve, 16-gas-liquid separator, 17-storage tank Detailed Implementation

[0026] The invention will now be described in further detail with reference to the accompanying drawings.

[0027] This invention uses 2-chloro-N,N-dimethyl-4-(trifluoromethyl)aniline or N,N-dimethyl-4-(trifluoromethyl)aniline as raw materials, employs chlorine gas as the chlorinating agent, and carries out the chlorination reaction on the benzene ring in a packed tubular reactor, followed by the chlorination reaction of the methyl group on the side chain in a photocatalytic reactor. Finally, an alkaline solution is added to obtain 2,6-dichloro-4-trifluoromethylaniline. By using this continuous reaction apparatus, the reaction process is made safer and more efficient, and the generation of byproducts is reduced, ultimately enabling industrial-scale production.

[0028]

[0029] Where R represents Cl and H.

[0030] Example 1

[0031] 10.0 g of 2-chloro-N,N-dimethyl-4-(trifluoromethyl)aniline (0.04 mol) was dissolved in 100 mL of chloroform, and the resulting 2-chloro-N,N-dimethyl-4-(trifluoromethyl)aniline solution was placed in a raw material tank. This solution was preheated in a preheating tube via a plunger pump and then transferred to a packed static tubular reactor at a preheating temperature of 40°C. Chlorine gas (0.044 mol) was supplied to the reactor via a gas mass flow meter at a pressure of 0.2 MPa. After the two reactants collided and mixed, the mixture was then transferred to a time-delay reactor for a further reaction, with a residence time of 5 min. The reaction products were then separated by a gas-liquid separator, with the gas exiting from the upper outlet of the separator. The liquid phase product is discharged through the gas outlet control valve in the pipeline. After being preheated by the second preheating pipe through the lower outlet of the gas-liquid separator, the liquid phase product is discharged through the gas outlet control valve. The liquid phase product is discharged through the lower outlet of the gas-liquid separator through the transfer pump into the storage tank. The liquid phase product is discharged through the gas outlet control valve. The liquid phase product is discharged through the lower outlet of the gas-liquid separator into the storage tank through the transfer pump. 6.4g of 50% sodium hydroxide solution is added and stirred to obtain 9.12g of the final product 2,6-dichloro-4-trifluoromethylaniline. The content of the product is 98.1% and the yield is 97.2% by gas chromatography analysis.

[0032] Example 2

[0033] 10.0 g of 2-chloro-N,N-dimethyl-4-(trifluoromethyl)aniline (0.04 mol) was dissolved in 100 mL of tetrachloroethylene to obtain a solution of 2-chloro-N,N-dimethyl-4-(trifluoromethyl)aniline, which was then placed in a raw material tank. This solution was preheated in a preheating tube via a plunger pump and then transferred to a packed dynamic tubular reactor at a preheating temperature of 45°C. Chlorine gas (0.048 mol) was supplied to the reactor via a gas mass flow meter at a pressure of 0.3 MPa. After the two reactants collided and mixed, the mixture continued to react in a time-delay reactor for 5 minutes. The reaction products were then separated by a gas-liquid separator, with the gas exiting from the upper outlet of the separator into the upper part of the reactor. The gas phase product is discharged through the gas outlet pipeline and the gas outlet control valve. The liquid phase product enters the second preheating pipe through the lower outlet of the gas-liquid separator via a transfer pump and is preheated at a temperature of 50°C. Then, it passes through the photocatalytic reactor and reacts with chlorine gas (0.092 mol) supplied by a gas mass flow meter at a temperature of 50°C for 5 minutes and a pressure of 0.1 MPa. The light source used in the photocatalytic process is a mercury lamp with a wavelength of 360 nm. After passing through the gas-liquid separator, the gas in the reaction product enters the upper gas outlet pipeline through the upper outlet of the gas-liquid separator and is discharged through the gas outlet control valve. The liquid phase product enters the storage tank through the lower outlet of the gas-liquid separator via a transfer pump. 7 g of 50% sodium hydroxide solution is added and stirred to obtain 9.08 g of the final product 2,6-dichloro-4-trifluoromethylaniline. Gas chromatography analysis shows that the content is 98.3% and the yield is 97.0%.

[0034] Example 3

[0035] 10.0 g of N,N-dimethyl-4-(trifluoromethyl)aniline (0.05 mol) was dissolved in 100 mL of chloroform to obtain a solution of 2-chloro-N,N-dimethyl-4-(trifluoromethyl)aniline, which was placed in a raw material tank. This solution was preheated in a preheating tube via a plunger pump and then transferred to a packed static tubular reactor at a preheating temperature of 40°C. Chlorine gas (0.105 mol) was supplied to the reactor via a gas mass flow meter at a pressure of 0.2 MPa. After the two reactants collided and mixed, the mixture continued to react in a time-delay reactor for 4 minutes. The gas from the reaction products then entered the upper outlet pipe of the gas-liquid separator. The liquid phase product is discharged through the outlet control valve. After preheating in the second preheating pipe via the lower outlet of the gas-liquid separator, the liquid phase product is discharged through the transfer pump. The preheating temperature is 55℃. Then, it is mixed with chlorine gas (0.105 mol) supplied by the gas mass flow meter in the photocatalytic reactor. The temperature is 55℃, the residence time is 10 min, and the pressure is 0.1 MPa. The light source used in the photocatalytic process is an ultraviolet lamp with an illumination wavelength of 360 nm. After passing through the gas-liquid separator, the gas in the reaction product enters the upper outlet pipe through the upper outlet of the gas-liquid separator and is discharged through the outlet control valve. The liquid phase product enters the storage tank through the lower outlet of the gas-liquid separator via the transfer pump. 11.22 g of 50% potassium hydroxide solution is added and stirred to obtain 11.4 g of the final product 2,6-dichloro-4-trifluoromethylaniline. Gas chromatography analysis shows that the content is 98.2% and the yield is 97.4%.

[0036] Example 4

[0037] 2.0 kg of N,N-dimethyl-4-(trifluoromethyl)aniline (10 mol) was dissolved in 20 L of dichlorobenzene to obtain a solution of 2-chloro-N,N-dimethyl-4-(trifluoromethyl)aniline, which was then placed in a raw material tank. This solution was preheated in a preheating tube via a plunger pump and then transferred to a packed dynamic tubular reactor at a preheating temperature of 40°C. Chlorine gas (21 mol) was supplied to the reactor via a gas mass flow meter at a pressure of 0.2 MPa. After the two reactants collided and mixed, the mixture continued to react in a time-delay reactor for 4 minutes. The reaction products were then separated by a gas-liquid separator, with the gas exiting from the upper outlet into the upper gas outlet pipe. The liquid phase product is discharged through the outlet control valve and then enters the second preheating pipe through the lower outlet of the gas-liquid separator via a transfer pump. After preheating, the temperature is 55℃. Then, it passes through the photocatalytic reactor and reacts with chlorine gas (22 mol) supplied by a gas mass flow meter. The temperature is 55℃, the residence time is 8 min, and the pressure is 0.1 MPa. The light source used in the photocatalytic process is an LED lamp with a wavelength of 406 nm. After passing through the gas-liquid separator, the gas in the reaction product enters the upper outlet pipe through the upper outlet of the gas-liquid separator and is discharged through the outlet control valve. The liquid phase product enters the storage tank through the lower outlet of the gas-liquid separator via a transfer pump. 3.36 kg of 50% sodium bicarbonate solution is added and stirred to obtain 2.28 kg of the final product 2,6-dichloro-4-trifluoromethylaniline. Gas chromatography analysis shows that the content is 98.2% and the yield is 97.5%.

[0038] Comparative Example 1

[0039] Referring to the intermittent method reported in patent CN1468838A, 2,6-dichloro-4-trifluoromethylaniline was synthesized from 2-chloro-N,N-dimethyl-4-(trifluoromethyl)aniline. 10 g of 2-chloro-N,N-dimethyl-4-(trifluoromethyl)aniline was dissolved in 100 mL of chloroform. 0.06 mol of Cl2 was bubbled through the solution at 50 °C, and the reaction was allowed to proceed for 3 hours. The reaction solution was then cooled to 10 °C, and 0.092 mol of Cl2 was bubbled through the solution. The mixture was then irradiated with a UV lamp (wavelength 365 nm) for 50 min. The chloroform was evaporated, and 7 g of 50% sodium hydroxide aqueous solution was added dropwise. The mixture was refluxed for 3 hours to obtain 6.64 g of the final product, 2,6-dichloro-4-trifluoromethylaniline. Gas chromatography analysis showed a purity of 90% and a yield of 65%.

Claims

1. An apparatus for the continuous production of 2,6-dichloro-4- trifluoromethylaniline, characterized in that: The reactor includes an aniline raw material tank 1, a chlorine gas cylinder 2, a transfer pump 3, a first preheating pipe 4, a first flow meter 5, a packed tubular reactor 6, a first reactor 7, a second flow meter 8, an outlet control valve 9, a gas-liquid separator 10, a storage tank 11, a transfer pump 12, a second preheating pipe 13, a photocatalytic reactor 14, an outlet control valve 15, a gas-liquid separator 16, and a storage tank 17. The raw material tank 1 is connected to the inlet of the transfer pump 3, and the outlet of the transfer pump 3 is connected to the inlet of the first preheating pipe 4. The chlorine gas cylinder 2 is connected to the first flow meter 5. The outlet of the first preheating pipe 4 and the first flow meter 5 are respectively connected to the inlet of the packed static tubular reactor 6. The inlet and outlet of the first reactor 7 are respectively connected to the outlet of the packed tubular reactor 6 and the gas-liquid separator 10. The gas-liquid separator 10 has a [missing information - likely a design feature or structure]. The gas outlet pipeline is equipped with a gas outlet control valve 9. The lower end of the gas-liquid separator 10 is connected to the storage tank 11 via a pipeline. A discharge control valve is installed on the pipeline between the gas-liquid separator 10 and the storage tank 11. The outlet of the storage tank 11 is connected to the inlet of the conveying pump 12. The inlet of the second preheating pipe 13 is connected to the outlet of the conveying pump 12. The chlorine cylinder 2 is connected to the second flow meter 8. The outlet of the second flow meter 8 and the outlet of the second preheating pipe 13 are both connected to the inlet of the photocatalytic reactor 14. The outlet of the photocatalytic reactor 14 is connected to the gas-liquid separator 16. A gas outlet pipeline is provided on the upper side of the gas-liquid separator 16. A gas outlet control valve 15 is installed on the gas outlet pipeline. The lower end of the gas-liquid separator 16 is connected to the storage tank 17 via a pipeline. A discharge control valve is installed on the pipeline between the gas-liquid separator 16 and the storage tank 17.

2. The apparatus according to claim 1, characterized in that: A temperature sensor T1 is installed between the first preheating pipe 4 and the packed tubular reactor 6; a temperature sensor T2 and a pressure sensor P1 are installed between the tubular reactor 6 and the first reactor 7; a pressure sensor P2 is installed between the gas-liquid separator 10 and the gas outlet control valve 9; a temperature sensor T3 is installed between the second preheating pipe 13 and the photocatalytic reactor 14; a temperature sensor T4 and a pressure sensor P3 are installed between the photocatalytic reactor 14 and the gas-liquid separator 16; and a pressure sensor P4 is installed between the gas-liquid separator 16 and the gas outlet control valve 15.

3. The apparatus according to claim 1, characterized in that: The first preheating tube 4, the packed tubular reactor 6, the first reactor 7, and the second preheating tube 13 are all made of polytetrafluoroethylene, while the photocatalytic reactor 14 is made of silicon dioxide.

4. A method for synthesizing 2,6-dichloro-4-trifluoromethylaniline using the continuous synthesis apparatus for 2,6-dichloro-4-trifluoromethylaniline according to any one of claims 1 to 3, characterized in that, Aniline raw materials are dissolved in an organic solvent, preheated by the first preheating tube 4, and then transported to the packed tubular reactor 6. At the same time, chlorine gas from gas cylinder 2 is transported to the reactor. After the two collide and mix, they enter the first reactor 7 and are finally transported to the gas-liquid separator 10. The gas in the reaction product enters the upper gas outlet pipeline from the upper outlet of the gas-liquid separator 10 and is discharged by the gas outlet control valve 9. The liquid product enters the second preheating tube 13 from the lower outlet of the gas-liquid separator 10 via the transfer pump 12, is preheated, and then reacts and mixes with chlorine gas transported by the second flow meter 8 in the photocatalytic reactor 14 before entering the gas-liquid separator 16. The gas in the reaction product enters the upper gas outlet pipeline from the upper outlet of the gas-liquid separator 16 and is discharged by the gas outlet control valve 15. The liquid product flows into the storage tank 17 from the lower outlet of the gas-liquid separator 10. Finally, after adding alkaline solution and reacting, the final product 2,6-dichloro-4-trifluoromethylaniline is obtained.

5. The method according to claim 4, characterized in that: The mass ratio of aniline raw material to organic solvent is 1:5 to 1:20; the molar ratio of aniline raw material to chlorine gas transported to the static tubular reactor is 1:1 to 1:3; the molar ratio of aniline raw material to chlorine gas transported to the photocatalytic reactor is 1:2 to 1:4; and the molar ratio of aniline raw material to alkali is 1:2 to 1:

5.

6. The method according to claim 4, characterized in that: The aniline raw material is 2-chloro-N,N-dimethyl-4-(trifluoromethyl)aniline or N,N-dimethyl-4-(trifluoromethyl)aniline.

7. The method according to claim 4, characterized in that: The organic solvent is one or more of chloroform, dichlorobenzene, and tetrachloroethylene.

8. The method according to claim 4, characterized in that: The alkaline solution is one or more of sodium hydroxide, potassium hydroxide, and sodium bicarbonate solutions.

9. The method according to claim 4, characterized in that: The temperature of the raw material liquid in the first preheating tube is 30-60℃, the residence time of the reaction liquid in the first reactor is 2-15 min, the temperature of the reaction liquid in the second preheating tube is 40-60℃, the pressure of chlorine gas entering the pipeline is 0.03-0.8 MPa, the residence time of the reaction liquid in the photocatalytic reactor is 5-40 min, and the temperature for photocatalytic reaction is 40-60℃.

10. The method according to claim 4, characterized in that: The light source in the photocatalytic reactor can be one or more of LED lamps, mercury lamps, and ultraviolet lamps, with a wavelength of 200-500 nm and a light intensity of 10-100%.

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