Method for continuously synthesizing sodium trichloropyridinol
By using a microchannel reactor in the cyclosynthesis reaction of sodium trichloropyridinol, the temperature, pressure and flow rate are controlled, and the problem of explosion risk and temperature difficult to control in traditional cyclosynthesis reactions is solved, higher product purity and yield are achieved, and production safety is improved.
Patent Information
- Application Number
- CN202411989484.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-31
- Publication Date
- 2025-05-09
AI Technical Summary
The cyclosynthesis process of traditional sodium trichloropyridinol has problems such as explosion risk and difficult temperature control, which affects production safety and product quality.
The cyclosynthesis reaction was carried out using a microchannel reactor. By controlling the temperature at 180-200°C, the pressure at 0.4-0.8 Mpa and the flow rate at 0.5-2ml/min, the risk of the reaction process was reduced and the reaction efficiency was improved.
It effectively reduces the risk of explosion in cyclosynthesis reaction, improves the purity and yield of the product, and ensures the safety of production operations and the stability of product quality.
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Figure CN119954716A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the field of organic synthesis, and in particular relates to a preparation process of an intermediate sodium trichloropyridinol used in the synthesis of the pesticides chlorpyrifos and chlorpyrifos-methyl, and more specifically, relates to a method for continuously synthesizing sodium trichloropyridinol. Background Art
[0002] Chlorpyrifos is a broad-spectrum, highly effective, low-toxic organophosphorus insecticide. The pure product is white or light yellow granular, stable at room temperature, with a slight thiol smell, and the industrial product has a kerosene or turpentine smell. The main processed preparations of chlorpyrifos include emulsifiable concentrates, water emulsions, microemulsions, wettable powders, ultra-low volume sprays, granules, etc. The drug has contact, stomach poison and fumigation effects, and is widely used to control more than 100 types of pests such as borers, cotton bollworms, scale insects, leaf rollers, aphids, thrips, armyworms, leafhoppers and mites in rice, sugarcane, fruit trees, cotton, flowers, corn, tea, vegetables, and animal husbandry. It also has a good control effect on underground pests and livestock parasites. Because it has relatively low toxicity to humans and animals, a broad spectrum of insecticides, and excellent control effects, it is one of the important pesticides for controlling agricultural pests.
[0003] Since December 31, 2016, chlorpyrifos has been banned from use on vegetables. In addition, according to the "Complete Version of the List of Prohibited and Restricted Pesticides 2022", chlorpyrifos is also banned from use on vegetables, fruits, tea, fungi, and Chinese herbal medicines. However, chlorpyrifos plays an important role in field pest control. As a nerve agent, it effectively controls a variety of pests including underground pests, planthoppers, aphids, etc. through multiple methods such as contact, stomach poison and fumigation. It is suitable for field crops such as rice, wheat, soybeans, and cotton. It has a long lasting effect and strong compatibility. It can significantly increase crop yield and quality, while reducing the amount and cost of pesticides used. It is an indispensable pest control variety in field agricultural production.
[0004] The structure of chlorpyrifos is as follows:
[0005]
[0006] The synthesis of chlorpyrifos is mainly through the condensation reaction of 3,5,6-trichloropyridine-2-ol sodium (referred to as "trichloropyridine sodium", English abbreviation STCP) and ethyl chloride to synthesize chlorpyrifos technical drug. The reaction formula is as follows:
[0007]
[0008] In the above reaction formula, sodium trichloropyridinol is an important intermediate in the synthesis of chlorpyrifos. The main synthetic process routes of sodium trichloropyridinol include: pyridine method, trichloroacetyl chloride method, phenyl trichloroacetate method, acrylic acid method, pyridine double directional chlorination synthesis process and improved trichloroacetyl chloride method. Among them, the most industrialized production method is trichloroacetyl chloride method, and the starting raw material of this method is trichloroacetyl chloride.
[0009] The reaction process of preparing sodium trichloropyridinol by trichloroacetyl chloride method is briefly shown as follows:
[0010] (1) Addition reaction
[0011]
[0012] (2) Cyclization reaction
[0013]
[0014] (3) Alkaline hydrolysis reaction
[0015]
[0016] In the above reaction process, the product of the addition reaction is 2,2,4-trichloro-4-cyanobutyryl chloride, referred to as the adduct. The adduct undergoes a cyclization reaction to obtain a product, 3,3,5,6-tetrachloro-4,4-dihydropyridin-2-one, referred to as the cyclocompound. The cyclization reaction to prepare the cyclocompound is a violent reaction and is prone to explosion, especially when the temperature cannot be controlled.
[0017] In order to solve the danger problem in the above-mentioned cyclization reaction process, the present invention optimizes the cyclization reaction process and adopts a microchannel reactor to carry out the cyclization reaction to reduce the danger in the reaction process. Summary of the invention
[0018] In order to solve the above problems, the present invention provides a method for preparing sodium trichloropyridinol. The method comprises the following steps: a microchannel reactor is used to perform a cyclization reaction of an adduct 2,2,4-trichloro-4-cyanobutyryl chloride, and the prepared intermediate product is subjected to an alkaline hydrolysis reaction to prepare sodium trichloropyridinol. The conditions of the microchannel reaction are as follows: the temperature of the microchannel reactor is controlled at 180-200° C., the pressure of the microchannel reactor is controlled at 0.4-0.8 Mpa, and the flow rate of the intermediate product outputted from the outlet of the microchannel reactor is 0.5-2 ml / min.
[0019] The product (also called "intermediate product") of the traditional cyclization reaction (or "ring-closing reaction") is generally 3,3,5,6-tetrachloro-4,4-dihydropyridine-2-one, and then 3,3,5,6-tetrachloro-4,4-dihydropyridine-2-one is reacted with alkali solution to prepare sodium trichloropyridinol. However, the product of the cyclization reaction carried out in the above-mentioned microchannel reactor is not a single component 3,3,5,6-tetrachloro-4,4-dihydropyridine-2-one, but also contains 2,3,5,6-tetrachloropyridine (hereinafter referred to as "tetrachloropyridine"). These two products are subjected to alkaline hydrolysis reaction to prepare sodium trichloropyridinol (chemical name: sodium 3,5,6-trichloropyridine-2-ol). In the present invention, the microchannel reaction product is referred to as an "intermediate product" to simplify the understanding of the present invention, wherein the intermediate product contains two components: 3,3,5,6-tetrachloro-4,4-dihydropyridin-2-one and 2,3,5,6-tetrachloropyridine.
[0020] Preferably, in the above method, dry hydrogen chloride gas is also used in the microchannel reaction. In the microchannel reaction, 2,2,4-trichloro-4-cyanobutyryl chloride (hereinafter sometimes referred to as "adduct") is input into the liquid inlet of the microchannel reactor, and dry hydrogen chloride gas is input into the gas inlet of the microchannel reactor.
[0021] During the microchannel reaction process, the temperature and pressure of the microchannel reactor are controlled, and the flow rate of the gas-liquid mixture at the outlet of the microchannel reactor is controlled. The quality of the intermediate product and whether the raw materials are reacted completely are achieved by controlling the temperature, pressure and flow rate.
[0022] Preferably, in the above method, the temperature of the microchannel reactor is controlled at 180-190°C.
[0023] The temperature of the microchannel reactor of the present invention is controlled at a temperature suitable for the cyclization reaction. Since the microchannel reactor controls the reaction temperature in an oil bath, the oil bath temperature control enables the reaction in the microchannel reactor to obtain a sufficient temperature. The heat released after the reaction is initiated can be quickly conducted out of the microchannel reactor into the oil bath environment, thereby achieving relatively stable and accurate temperature control of the microchannel reactor. This stable and accurate temperature control is crucial to avoiding temperature runaway in high-temperature reactions, and can reduce the risk of explosion or even avoid the occurrence of explosions.
[0024] Preferably, in the above method, the pressure of the microchannel reactor is controlled at 0.4-0.6 MPa, and particularly preferably, the pressure of the microchannel reactor is controlled at 0.6 MPa.
[0025] The present invention controls the pressure of the gas-liquid mixture in the microchannel reactor to ensure the increase of mass transfer and heat transfer rate, accelerate the reaction speed, improve the reaction efficiency, ensure the balance of the reaction, and improve the yield and purity of the target product. Moreover, the pressure is fixed within a stable range to maintain the stability of the reaction conditions, reduce the reaction fluctuations and the generation of by-products caused by pressure fluctuations, thereby ensuring the stability and controllability of the reaction quality and level. The pressure control in the microchannel reactor is jointly controlled by controlling the input pressure of 2,2,4-trichloro-4-cyanobutyryl chloride, the input pressure of dry hydrogen chloride gas and the flow rate of the product outlet of the microchannel reactor, and is finally reflected in the pressure value inside the microchannel reactor.
[0026] Preferably, in the above method, the flow rate of the intermediate product output from the outlet of the microchannel reactor is 1 ml / min.
[0027] Preferably, in the above method, the 2,2,4-trichloro-4-cyanobutyryl chloride is prepared by the following method: trichloroacetyl chloride and acrylonitrile are used as raw materials, cuprous chloride is used as a catalyst, and the reaction is carried out at 80-95° C. for 9-11 hours, and then trichloroacetyl chloride and acrylonitrile are distilled off under pressure, and then dichloroethane is added, stirred thoroughly, and then filtered to filter out the filter residue cuprous chloride, and the filtrate is decompressed to distill off dichloroethane to obtain 2,2,4-trichloro-4-cyanobutyryl chloride.
[0028] Preferably, in the above method, the method of alkaline hydrolysis reaction is: adding sodium hydroxide solution and water to a reaction bottle to prepare a dilute alkaline solution, and then quickly adding the intermediate product dropwise to the dilute alkaline solution in the reaction bottle, and then adding sodium hydroxide solution dropwise after the addition, the dropping time is 1 hour, after the dropwise addition is completed, the reaction solution is added to a high-pressure reactor, the temperature is raised to 120-140°C, the pressure is 0.5Mpa, and the temperature is kept for 1 hour, and then the temperature is lowered to 25°C for suction filtration to obtain a wet product of sodium trichloropyridinol, and the product sodium trichloropyridinol is obtained after drying.
[0029] In the above alkaline hydrolysis reaction process, the reaction that occurred should be an alkaline hydrolysis process of two components, that is, 3,3,5,6-tetrachloro-4,4-dihydropyridin-2-one and 2,3,5,6-tetrachloropyridine both underwent alkaline hydrolysis reaction, and the final products were all sodium trichloropyridinol.
[0030] In the above method, the inner diameter of the microchannel of the microchannel reactor is a conventional inner diameter, that is, the inner diameter of the microchannel generally used for gas-liquid mixing or gas-liquid reaction can be used in the above method. Preferably, the inner diameter of the microchannel of the microchannel reactor is 0.5-2.0 mm. Preferably, the microchannel aperture of the microchannel reactor is 1 mm. The microchannel of this size significantly increases the heat transfer area of the reaction system in the microchannel, and the heat transfer efficiency is much higher than that of the traditional reactor. The heat exchange area of the microchannel reactor can reach 1000 times that of the ordinary kettle reactor. Through rapid heat exchange, the heat generated by the reaction can be quickly derived from the reaction system, thereby effectively avoiding the "flying temperature" phenomenon, controlling the reaction temperature within a relatively narrow temperature range, and greatly reducing the risk of unstable reaction and easy explosion in the cyclization reaction.
[0031] The present invention also provides a thin layer chromatography (TLC) method for detecting whether the raw material 2,2,4-trichloro-4-cyanobutyryl chloride is completely reacted during the cyclization reaction. The method is as follows:
[0032] At one end of the silica gel plate, called the lower end, use a pencil to gently draw a sampling dot about 5 mm away from the edge. At the other end of the silica gel plate, called the upper end, use a pencil to draw a straight line about 5 mm away from the edge, called the immersion line. During the test, use a capillary to absorb the sample and drop it on the sampling dot. Then place the silica gel plate with the upper end facing down into a wide-mouthed glass bottle filled with a developing agent, cover the bottle mouth with a rubber sheet, observe the diffusion position of the developing agent on the silica gel plate, and take out the silica gel plate when the developing agent diffuses above the sampling dot. After drying, immerse it in a beaker filled with a color developer for 3 seconds, take it out and observe to obtain the test result.
[0033] Preferably, in the above method, the developing agent is a mixture of ethyl acetate: petroleum ether = 1:8 (V / V), and the color developer is a potassium permanganate solution, which is prepared by thoroughly mixing 1.5g of potassium permanganate, 10g of potassium carbonate, 0.125g of sodium hydroxide, and 200ml of distilled water.
[0034] The above-mentioned thin layer chromatography analysis method can quickly determine whether the product of the cyclization reaction contains the raw material 2,2,4-trichloro-4-cyanobutyryl chloride, so as to determine whether the conditions of the cyclization reaction are suitable for preparing the intermediate product.
[0035] Beneficial effects of the present invention
[0036] The present invention uses a microchannel reactor to replace the reaction of a reactor, so that the raw material 2,2,4-trichloro-4-cyanobutyryl chloride can react completely, thereby improving the conversion rate of the raw material and the quality of the product. The microchannel reaction improves the safety of production operations and avoids possible explosion hazards.
[0037] In the traditional process for preparing sodium trichloropyridinol, the cyclization reaction is a violent exothermic reaction. The temperature must be raised to about 120°C to initiate the cyclization reaction. After initiation, the reaction will heat up violently, even rapidly rising to over 200°C. The temperature of such a production process is extremely difficult to control. Hydrogen chloride gas is a catalyst for the cyclization reaction. The higher the temperature, the higher the concentration of hydrogen chloride gas in the system. The higher the temperature, the faster the cyclization reaction and the higher the pressure. At the same time, due to local high temperature and extremely high temperature, some of the products of the cyclization reaction decompose into unknown impurities.
[0038] The optimal conditions for the cyclization reaction through the microchannel reactor are an outlet flow rate of 1 ml / min, an oil bath temperature of 180° C., and a pressure of 0.6 MPa. The microchannel reaction product prepared under the process conditions is used to prepare sodium trichloropyridinol. The prepared sodium trichloropyridinol is superior to the product produced in the workshop in terms of purity, content and appearance, and the yield can also be greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS
[0039] Figure 1 The figure is a schematic diagram of the results of thin layer chromatography (TLC) detection of whether the raw materials in the cyclization reaction product have been completely reacted. 1 is the color image of the reaction solution at the beginning of the cyclization reaction, 2 is the color image during the cyclization reaction, 3 is the color image of the reaction end a, 4 is the color image of the reaction end b, 5 is the sample addition point, 6 is the display image of the adduct 2,2,4-trichloro-4-cyanobutyryl chloride, 7 is the display image of 3,3,5,6-tetrachloro-4,4-dihydropyridin-2-one, and 8 is the display image of 2,3,5,6-tetrachloropyridine. The reaction end a means that the raw material 2,2,4-trichloro-4-cyanobutyryl chloride has been completely reacted, and the reaction end b means that the raw material 2,2,4-trichloro-4-cyanobutyryl chloride has not been completely reacted. DETAILED DESCRIPTION
[0040] In the following examples, the method used to detect whether the raw material 2,2,4-trichloro-4-cyanobutyryl chloride in the cyclization reaction is completely reacted is a thin layer chromatography (TLC) method. The specific operation method of the TLC method is as follows:
[0041] At one end of the silica gel plate, called the lower end, use a pencil to gently draw a sampling dot about 5 mm away from the edge. At the other end of the silica gel plate, called the upper end, use a pencil to draw a straight line about 5 mm away from the edge, called the immersion line. During the test, use a capillary to absorb the sample and drop it on the sampling dot. Then place the silica gel plate with the upper end facing down into a wide-mouthed glass bottle filled with a developing agent, cover the bottle mouth with a rubber sheet, observe the diffusion position of the developing agent on the silica gel plate, and take out the silica gel plate when the developing agent diffuses above the sampling dot. After drying, immerse it in a beaker filled with a color developer for 3 seconds, take it out and observe to obtain the test result.
[0042] The developing agent is a mixture of ethyl acetate and petroleum ether in a ratio of 1:8 (V / V). The color developer is a potassium permanganate solution, which is prepared by thoroughly mixing 1.5 g of potassium permanganate, 10 g of potassium carbonate, 0.125 g of sodium hydroxide, and 200 ml of distilled water.
[0043] The diffusion of the components in the sample determines whether the raw materials have reacted completely, that is, Figure 1 The state of reaction a in the above is still the state of reaction b, that is, Figure 1 Is it 3 or 4 in the answer?
[0044] Example 1: Microchannel Reactor
[0045] The microchannel reactor is provided with a liquid inlet, a gas inlet and a product outlet. The liquid inlet liquid inlet amount and pressure are adjustable, the gas inlet gas inlet amount and pressure are adjustable, the product flow rate of the product outlet is measurable, and the pressure in the microchannel reactor can be monitored at any time. The microchannel aperture in the microchannel reactor is 1mm. The microreactor is in an oil bath environment, the oil bath uses silicone oil, and the oil bath temperature can be adjusted to a maximum of 250°C.
[0046] Example 2: Preparation of microchannel reaction raw materials (addition reaction)
[0047] Add 800g trichloroacetyl chloride, 280g acrylonitrile and 17.5g cuprous chloride to a medium-sized reaction bottle, raise the temperature to above 95°C and start heat preservation and reflux for 9-11h. After the heat preservation is completed, evaporate the trichloroacetyl chloride and acrylonitrile under reduced pressure, then add 314g ethylene dichloride and stir thoroughly for 20min, filter the reaction liquid, and the filter residue is cuprous chloride. The filtrate is decompressed and evaporated to remove ethylene dichloride, and 2,2,4-trichloro-4-cyanobutyryl chloride (referred to as "adduct") is obtained.
[0048] Example 3: Microchannel reaction (cyclization reaction)
[0049] The adduct prepared in Example 2 and the dried hydrogen chloride gas are respectively input into the microchannel reactor, the oil bath temperature is first adjusted to control the temperature of the microchannel reactor at a certain temperature, and then the input amount of the adduct 2,2,4-trichloro-4-cyanobutyryl chloride and the input amount of the dried hydrogen chloride gas are adjusted to adjust the flow rate of the reaction product output and the pressure in the microchannel reactor, the reaction product is output to a reaction bottle with a reflux condenser for cooling, hydrogen chloride is recovered, and a microchannel reaction product is obtained. The reaction product is subjected to thin layer chromatography analysis to determine whether the product of the microchannel reaction contains the raw material 2,2,4-trichloro-4-cyanobutyryl chloride. The thin layer chromatography analysis process refers to the method described above. After completing a microchannel reaction, the microchannel reactor is cleaned, and then the next microchannel reaction is carried out according to the above process.
[0050] After TLC detection of the microchannel reaction product, if it is determined that the raw material 2,2,4-trichloro-4-cyanobutyryl chloride has reacted completely, the reaction product is subjected to the next step of alkaline hydrolysis reaction.
[0051] The raw material 2,2,4-trichloro-4-cyanobutyryl chloride prepared in Example 1 was subjected to cyclization reaction in a microchannel reactor, and the temperature of the microchannel reactor was set to three values of 160° C., 180° C., and 200° C., the outlet flow rate of the microchannel reactor was adjusted to 1-2 ml / min, and the pressure of the microchannel reactor was adjusted to 0.2-0.8 MPa. The specific reaction conditions and the corresponding product conditions are shown in Table 1 below:
[0052] Table 1 Parameters and results of microchannel reactions
[0053]
[0054] It can be seen from the microchannel reaction results in Table 1 above that controlling the temperature of the microchannel reactor at 180°C and 200°C and controlling the pressure and flow rate can allow the addition product 2,2,4-trichloro-4-cyanobutyryl chloride to react completely.
[0055] At 180°C, a flow rate of 1 ml / min and a pressure of 0.6 MPa, the adduct has completely reacted. At a flow rate of 1 ml / min and a pressure of 0.8 MPa, the adduct has completely reacted, but there are impurity spots, indicating that the cyclization reaction is a little excessive.
[0056] At 200°C, a flow rate of 1 ml / min and a pressure of 0.4 MPa, the adduct has completely reacted; at a flow rate of 2 ml / min and a pressure of 0.6 MPa, the adduct has completely reacted; at a flow rate of 2 ml / min and a pressure of 0.8 MPa, the adduct has completely reacted, but because there are additional impurity spots, it shows that the cyclization reaction is somewhat excessive.
[0057] Example 4: Preparation of sodium trichloropyridinol (alkaline hydrolysis reaction)
[0058] First, 10 g of the intermediate product sample of the complete reaction (including over-reaction) of the raw materials in Example 3 was taken.
[0059] Then, 2g of liquid alkali (32% sodium hydroxide solution) and 30g of water were added to the reaction bottle to prepare a dilute alkali solution, and then 10g of the microchannel reaction product was quickly added dropwise to the dilute alkali solution in the reaction bottle, and then 12g of liquid alkali (32% sodium hydroxide solution) was added dropwise after the addition was complete. The addition time was 1h. After the addition was completed, the reaction solution was added to a micro-autoclave, heated to 120-140°C, the pressure was 0.5Mpa, and the temperature was kept for 1h, and then cooled to 25°C for suction filtration to obtain a wet product of sodium trichloropyridinol, and the product sodium trichloropyridinol was obtained after drying. The product sodium trichloropyridinol was subjected to mass measurement, purity detection, impurity detection, and yield calculation, etc.
[0060] The intermediate products 8, 9, 11, 12 and 13 prepared in Example 3 were used to prepare sodium trichloropyridinol according to the alkaline hydrolysis reaction method. The results of measurement, detection and calculation of the prepared product sodium trichloropyridinol are shown in Table 2 below:
[0061] Table 2 Quality and yield of sodium trichloropyridinol produced from different raw materials
[0062] raw material Product purity% Tetrachloropyridine% Yield % Appearance % Intermediate 8 99.8 0.03 84.9 White solid Intermediate 9 98.5 0.01 74.7 Earthy yellow solid Intermediate 11 99.7 0.12 79.2 Off-white solid Intermediate 12 99.5 0.10 76.1 Off-white solid Intermediate 13 98.8 0.01 75.2 Earthy yellow solid
[0063] Among the various indicators of the product sodium trichloropyridinol in Table 2, the yield is calculated based on trichloroacetyl chloride, tetrachloropyridine is an impurity, and the content of other impurities can be calculated based on the purity of sodium trichloropyridinol and the content of impurity tetrachloropyridine. For example, the content of other impurities in sodium trichloropyridinol prepared by alkaline hydrolysis reaction using intermediate product 8 is 0.17%.
[0064] The traditional process is to use a reactor to control the cyclization reaction temperature to carry out the cyclization reaction. The yield of sodium trichloropyridinol is calculated based on the raw material trichloroacetyl chloride, and the yield is generally around 75%, and can reach up to 76%. The prepared sodium trichloropyridinol is an off-white solid, and the purity can generally reach 99.1%. The content of tetrachloropyridine impurities is generally around 0.06%.
[0065] It can be seen from Table 2 that compared with the traditional process, the sodium trichloropyridinol produced by the intermediate product 8 prepared by the microchannel reaction has a higher purity, a white solid appearance, a better appearance, a purity of up to 99.8%, a lower content of the impurity tetrachloropyridine, and a higher yield of sodium trichloropyridinol, which can reach 84.9%, 8 percentage points higher than the yield of the traditional process.
[0066] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent transformations made using the contents of the present invention specification, or directly or indirectly applied in related technical fields, are also included in the patent protection scope of the present invention.
Claims
1. A method for preparing sodium trichloropyridinol, the method comprising: performing a cyclization reaction of an adduct 2,2,4-trichloro-4-cyanobutyryl chloride in a microchannel reactor, performing an alkaline hydrolysis reaction on the prepared intermediate product to prepare sodium trichloropyridinol, wherein the conditions of the microchannel reaction are: the temperature of the microchannel reactor is controlled at 180-200° C., the pressure of the microchannel reactor is controlled at 0.4-0.8 MPa, and the flow rate of the intermediate product output at the outlet of the microchannel reactor is 0.5-2 ml / min.
2. The method according to claim 1, characterized in that The intermediate product contains two components: 3,3,5,6-tetrachloro-4,4-dihydropyridin-2-one and 2,3,5,6-tetrachloropyridine.
3. The method according to any one of claims 1 to 2, characterized in that: Dry hydrogen chloride gas is also used in the microchannel reaction. In the microchannel reaction, 2,2,4-trichloro-4-cyanobutyryl chloride is input into the liquid inlet of the microchannel reactor, and dry hydrogen chloride gas is input into the gas inlet of the microchannel reactor.
4. The method according to any one of claims 1 to 3, characterized in that: The temperature of the microchannel reactor is controlled at 180-190°C, and preferably, the temperature of the microchannel reactor is controlled at 180°C.
5. The method according to any one of claim 4, characterized in that: The pressure of the microchannel reactor is controlled at 0.4-0.6Mpa.
6. The method according to any one of claims 4-5, characterized in that: The flow rate of the intermediate product output from the outlet of the microchannel reactor is 1 ml / min.
7. The method according to claim 1, characterized in that 2,2,4-trichloro-4-cyanobutyryl chloride is prepared by the following method: trichloroacetyl chloride and acrylonitrile are used as raw materials, cuprous chloride is used as a catalyst, and the reaction is carried out at 80-95° C. for 9-11 hours, and then trichloroacetyl chloride and acrylonitrile are distilled off under pressure, and then dichloroethane is added, stirred thoroughly, and then filtered, and the filter residue cuprous chloride is filtered out, and the filtrate is decompressed to distill off dichloroethane to obtain 2,2,4-trichloro-4-cyanobutyryl chloride.
8. The method according to claim 1, characterized in that The method of alkaline hydrolysis reaction is as follows: sodium hydroxide solution and water are added to a reaction bottle to prepare a dilute alkaline solution, and then the intermediate product is rapidly dropped into the dilute alkaline solution in the reaction bottle, and then sodium hydroxide solution is added dropwise after the addition is completed, and the dropping time is 1 hour. After the dropping is completed, the reaction solution is added into a high-pressure reactor, the temperature is raised to 120-140° C., the pressure is 0.5 MPa, and the temperature is kept for 1 hour, and then the temperature is lowered to 25° C. for suction filtration to obtain a wet product of sodium trichloropyridinol, and the product sodium trichloropyridinol is obtained after drying.