A synthesis process of clothianidin

Abstract

The present invention relates to the technical field of insecticides, and specifically discloses a synthesis process of clothianidin. The specific process includes the following steps: Synthesis: Add water into a reaction kettle, then put nitroguanidine and monomethylamine solution, and slowly raise the temperature of the reaction kettle to 40-43 °C and keep it warm for 1.5-2 h. After the heat preservation is completed, when the reaction solution is sampled and analyzed without nitroguanidine, continue the heat preservation reaction for 0.5 h, and then make the clothianidin filter cake through neutralization, filtration, recrystallization, centrifugation, drying, substitution, filtration, desolvation, crystallization, centrifugation and drying and packaging of the materials. The present invention obtains methylguanidine by the processes of synthesis, neutralization, filtration, recrystallization, centrifugation and drying of water, synthesis mother liquor, nitroguanidine and monomethylamine solution, and then uses carbon tetrachloride, methylguanidine, potassium carbonate, tetrabutylammonium bromide and dichloromethylthiophene as solvents for substitution reaction. After the reaction, clothianidin is prepared through filtration, desolvation, crystallization, centrifugation and drying processes, thus opening up a new synthesis method.

Description

Technical Field

[0001] The present invention belongs to the technical field of insecticides, and specifically relates to a synthesis process of clothianidin. Background Art

[0002] Clothianidin is a neonicotinoid insecticide. Its action is similar to that of nicotinic acetylcholine receptors, and it has contact, stomach poison, and systemic activities. It is mainly used as an insecticide for controlling pests such as aphids, leafhoppers, thrips, and planthoppers of Hemiptera, Coleoptera, Diptera, and certain Lepidoptera on rice, vegetables, fruit trees, and other crops. It has the advantages of high efficiency, broad spectrum, low dosage, low toxicity, long-lasting efficacy, no phytotoxicity to crops, safe use, and no cross-resistance with conventional pesticides. It has excellent systemic and penetration effects, and is another variety to replace highly toxic organophosphorus pesticides. Its structure is novel and special, and its performance is more excellent compared with traditional neonicotinoid insecticides;

[0003] The preparation method disclosed in Patent Publication No. CN107163000B for clothianidin is to add 1,5-dimethyl-2-nitroimino-hexahydro-1,3,5-triazine, 2-chloro-5-(chloromethyl)thiazole, and an acid-binding agent into a reaction solvent for a condensation reaction to obtain a reaction solution; (1) The reaction solvent includes dimethyl carbonate, methyl isobutyl ketone, ethyl acetate, or dichloroethane; (2) Water is added to the reaction solution obtained in step (1) to dissolve the salt generated by the condensation reaction; (3) Phosphotungstic acid is added to the reaction solution treated in step (2) for a synthesis reaction, filtered, and the filter residue is dried to obtain clothianidin;

[0004] Although the steps of this preparation method are simple, the water, solvent, and reactants in the preparation process are not effectively utilized, seriously reducing the reuse rate of each substance and increasing the production cost at the same time;

[0005] During the preparation process, pollutants are easily generated, mainly waste gas, waste water, and waste residue. If not properly treated, it is extremely easy to cause harm to nature. Therefore, there is an urgent need to invent a synthesis process of clothianidin to solve the above-mentioned problems. Summary of the Invention

[0006] The purpose of the present invention is to provide a synthesis process of clothianidin, which solves the problems of material waste, low reuse rate, and serious pollution mentioned above.

[0007] To solve the above technical problems, the present invention provides a synthesis process of clothianidin. The specific synthesis process includes the following steps:

[0008] S1. Synthesis: Add water into a reaction kettle, then put nitroguanidine and monomethylamine solution, and slowly raise the temperature of the reaction kettle to 40 - 43 °C and keep it warm for 1.5 - 2 h. After the heat preservation is completed, when the reaction solution is sampled and analyzed without nitroguanidine, continue the heat preservation reaction for 0.5 h, and the reaction ends;

[0009] S2. Neutralization: Prepare 70% sulfuric acid by evaporating water and cool it to 25 - 30 °C for standby; transfer the reacted reaction solution to the neutralization kettle, turn on the chilled water in the interlayer of the neutralization kettle, cool the temperature of the reaction solution to 20 °C, drop the standby 70% dilute sulfuric acid into the neutralization kettle until the pH = 7 - 8, continue to cool to 15 - 20 °C after neutralization and then discharge the material;

[0010] S3. Filtration: Evenly distribute the material discharged from the neutralization kettle on the filter cloth through the distributor in the filter, filter to obtain methylguanidine, send the filtered filtrate and spray water into the filtrate tank in the wastewater workshop for negative pressure concentration treatment, the evaporated water after concentration treatment can be used for preparing sulfuric acid in S2 after filtration, the centrifuged synthetic mother liquor after concentration enters the reaction kettle for recycling, and the centrifuged wastewater is pumped into the wastewater workshop for treatment;

[0011] S4. Recrystallization: Pulp the filter cake and then transfer it to the refining kettle, add evaporated water to it, turn on the stirrer, heat the refining kettle to 75 - 80 °C, wait until the material is completely dissolved, put it into the filter, and fill the filter with compressed air to press the material into the crystallization kettle for cooling;

[0012] S5. Centrifugation: Feed the cooled material into the centrifuge for centrifugation, the centrifuged water is pumped into the centrifugal low - level tank, part of it is transported through the pipeline to the filter to replace the spray water for spraying the filter cake, and the other part is transported through the pipeline to the reaction kettle to replace water for use;

[0013] S6. Drying: Open the feeding port of the primary dryer to add the centrifuged material into the dryer, and at the same time input air into the dryer, control the inlet air temperature of the primary dryer at 140 °C, heat the air, mix the centrifuged material with the hot air, and separate it through the cyclone separator in the dryer, the separated material enters the dryer from the feeding port of the secondary dryer, mixes with the hot air and is separated through the cyclone separator in the dryer, control the inlet air temperature of the secondary dryer at 120 °C, after secondary drying, obtain methylguanidine, detect the moisture content of the dried material, and use it after passing the detection, weighing and packing;

[0014] S7. Substitution: Put dichloromethylthiazole into the high - temperature dissolution tank to melt it into a liquid, and transfer it to the high - level tank for standby;

[0015] Inject the solvent carbon tetrachloride into the feeding kettle, and add methylguanidine, acid-binding agent and catalyst with qualified water content in S6. Then press the materials in the feeding kettle into the reaction kettle with nitrogen. Put dichloromethylthiophene into the reaction kettle from the high-level tank for reaction. Slowly raise the temperature of the reaction kettle to 110 °C, keep it warm for 10 - 12 h, then take a sample for testing. After passing the test, the reaction ends, and the reaction solution is cooled to 25 - 30 °C. The reaction solution contains crude clothianidin, potassium chloride generated by the reaction, tetrabutylammonium bromide, acid-binding agent and solvent carbon tetrachloride;

[0016] S8, Filtration: Pump the cooled reaction solution into the filter to filter out the filter residue and filtrate. The filter residue contains potassium chloride generated in S7 and the unreacted acid-binding agent. Pump the filtered filter residue into the receiving tank, add an appropriate amount of steam condensate to dissolve it in the receiving tank, add hydrochloric acid to neutralize the dissolved solution, and introduce hydrogen chloride gas to react with the neutralized solution to obtain a potassium chloride solution. Transport the potassium chloride solution to the drying kettle for drying. After drying, obtain potassium chloride, cool it and package it for storage;

[0017] S9, Solvent Removal: Preheat the filtrate in S8 through the inlet tower preheater, and then pump it into the solvent removal tower. Control the temperature when pumping in the filtrate to be 75 °C. After pumping in the filtrate, control the temperature of the bottom of the solvent removal tower to be 85 - 90 °C to remove the solvent in the filtrate. The solvent removal time is 1 - 1.5 h, and collect the solvent into the recycled solvent tank. Conduct component detection on the solvent in the recycled solvent tank. After the detection meets the usage standard, pump it into the substitution feeding kettle for recycling;

[0018] S10, Crystallization: After solvent removal is completed, the materials in the solvent removal tower enter the crystallization kettle for cooling. Control the temperature of the first-stage crystallization kettle to be 55 - 60 °C, and the crystallization time to be 1.5 - 2 h. The materials flow from the first-stage crystallization kettle into the second-stage crystallization kettle through the overflow channel, and then control the temperature of the second-stage crystallization kettle to be below 25 °C for crystallization. After crystallization is completed, transport it to the crystallization tank for standby.

[0019] S11, Centrifugation, Drying and Packaging:

[0020] Pump the materials in the crystallization tank into the centrifuge through a pump, and centrifuge through the centrifuge. The centrifuged solvent is pumped back into the first-stage crystallization kettle for continuous crystallization to obtain clothianidin. The centrifuged materials are sent into a double-cone dryer for drying. During drying, continuously fill nitrogen into the double-cone dryer, and at the same time control the pressure of the double-cone dryer to be -0.07 mpa and the temperature to be 85 °C. After drying for 1.5 - 2 h, the double-cone dryer stops heating up to obtain a clothianidin filter cake. After the temperature of the filter cake drops to 40 °C, weigh it and package it for storage.

[0021] Further, the thickness of the guanidine formate distributed on the filter cloth in S3 is 2-3 cm. The filter uses a vacuum mechanism to extract the moisture in the guanidine formate on the filter cloth to obtain a filter cake. The nozzles in the filter spray the filter cake to wash away the salt in the filter cake.

[0022] Further, the concentrated residue obtained by the negative pressure concentration treatment in S3 is cooled and crystallized to precipitate ammonium sulfate and methylammonium sulfate. The ammonium sulfate is separated by a centrifuge and packaged and stored in the warehouse.

[0023] Further, the filter is one of a bag filter or a screen filter.

[0024] Further, the cooling temperature of the crystallization kettle in S4 is 20-25 °C.

[0025] Further, the water content of the guanidine formate in S6 is <0.1%.

[0026] Further, the catalyst in S7 is tetrabutylammonium bromide, and the acid-binding agent is potassium carbonate.

[0027] Further, the solvents removed in S9 include carbon tetrachloride and a small amount of tetrabutylammonium bromide.

[0028] Further, the synthesis principle of clothianidin:

[0029]

[0030] The present invention obtains guanidine formate by a process of synthesis, neutralization, filtration, recrystallization, centrifugation and drying of water, synthetic mother liquor, nitroguanidine and monomethylamine solution, and then uses carbon tetrachloride, guanidine formate, potassium carbonate, tetrabutylammonium bromide and dichloromethylthiophene as solvents for substitution reaction. After the reaction, clothianidin is prepared by filtration, desolvation, crystallization, centrifugation and drying processes. The synthetic process uses a new combination of components for synthesis, thus opening up a new synthetic method;

[0031] During the synthesis process, the wastewater is concentrated and crystallized to obtain evaporation water that can be used to prepare sulfuric acid; the centrifugate containing methylammonium sulfate is transported to the reaction kettle to replace the water used in the synthesis of the reaction kettle; a small part of the centrifugal water obtained after centrifugation after recrystallization is transported to the filter to replace the spray water in the filter to spray the filter cake, and most of it is transported to the reaction kettle to replace the water used in the synthesis; the components of the solvent after desolvation in the desolvation tower are detected. If the detection meets the use standard, it is pumped into the substitution feeding kettle for recycling. The synthetic process of this application effectively improves the recycling rate of resources, thus effectively saving production costs;

[0032] The synthesis process acidifies waste salts potassium chloride and potassium carbonate during synthesis, and introduces hydrogen chloride gas to obtain potassium chloride. After drying and packaging the potassium chloride, the waste salts are effectively treated, and available substances are also obtained, avoiding waste of effective substances. Description of the Drawings

[0033] Figure 1 It is the overall synthesis process flow chart of the synthesis process of clothianidin of the present invention. Detailed Embodiments

[0034] The technical solutions in the embodiments of the invention will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0035] A synthesis process of clothianidin of the present invention, the specific synthesis process includes the following steps:

[0036] Synthesis: Add 3t of water into the reaction kettle, then put in 3.5t of nitroguanidine and 2.2t of monomethylamine solution, and slowly raise the temperature of the reaction kettle to 42 °C and keep it warm for 2h. After the heat preservation is completed, when the reaction solution is sampled and analyzed without nitroguanidine, continue the heat preservation reaction for 0.5h, and the reaction ends;

[0037] Neutralization: Prepare 70% sulfuric acid with evaporated water and cool it to 30 °C for standby; transfer the completed reaction solution to the neutralization kettle, turn on the chilled water in the interlayer of the neutralization kettle, cool the temperature of the reaction solution to 20 °C, and drop the standby 70% dilute sulfuric acid into the neutralization kettle to neutralize to pH = 8. After the neutralization is completed, continue to cool to 18 °C and then discharge the material;

[0038] Filtration: The material discharged from the neutralization kettle is evenly distributed on the filter cloth through the distributor in the filter, and methylguanidine is filtered out. The thickness of the methylguanidine is 3cm. The moisture in the methylguanidine on the filter cloth is extracted by a vacuum mechanism to obtain a filter cake, and the filter cake is sprayed with water to wash the salt in the filter cake. The filtrate and the spraying water after filtration by the filter enter the synthesis low-level pool. The wastewater in the synthesis low-level pool will be sent to the filtrate pool in the wastewater workshop for negative pressure concentration treatment. The evaporated water after concentration treatment can be used for the above-mentioned step of preparing sulfuric acid after filtration. The concentrated residue is cooled and crystallized to precipitate ammonium sulfate and methylamine sulfate. The ammonium sulfate is separated by a centrifuge and packaged and stored in the warehouse. The centrifugal synthesis mother liquor containing methylamine sulfate enters the reaction kettle for recycling, and the centrifuged wastewater is sent to the wastewater workshop for treatment;

[0039] Recrystallization: Put the filter cake into the pulping tank, add evaporation water to the pulping tank for pulping. After pumping the slurry into the refining kettle, inject 2.7 t of evaporation water into it, start stirring, and heat up the refining kettle to 78 °C. After the material is completely dissolved, put it into a filter. Here, the filter is preferably a cloth bag filter. Charge compressed air into the cloth bag filter to press the material into the crystallization kettle for cooling. The cooling temperature of the crystallization kettle is 25 °C;

[0040] Centrifugation: Feed the cooled material into a centrifuge for centrifugation. The centrifuged water is pumped into the low-level centrifugation tank. Part of it is transported through a pipeline to the filter to replace the spray water for spraying the filter cake, and the other part is transported through a pipeline to the reaction kettle to replace water for use;

[0041] Drying: Input air into the dryer, control the inlet air temperature of the first-stage dryer at 140 °C, heat the air, open the feeding port of the first-stage dryer to add the centrifuged material into the dryer to mix with the hot air and separate it through the cyclone separator in the dryer. The separated material enters the dryer from the feeding port of the second-stage dryer to mix with the hot air and separate it through the cyclone separator in the dryer. The inlet air temperature of the second-stage dryer is controlled at 120 °C. After secondary drying, guanylthiourea is obtained. Detect the water content of the dried material. The detected water content of guanylthiourea < 0.1%. After passing the detection, weigh and pack it for standby;

[0042] Substitution: Put dichloromethylthiazole into a high-temperature dissolution tank to melt it into a liquid, and pump it into the high-level tank for standby;

[0043] Inject 2.5 t of the solvent carbon tetrachloride into the feeding kettle, and add 1.18 t of guanylthiourea, 1.63 t of potassium carbonate, and 45 kg of tetrabutylammonium bromide. Use nitrogen to press the materials in the feeding kettle into the reaction kettle. Put 1.65 t of dichloromethylthi from the high-level tank in the reaction kettle for reaction. Slowly raise the temperature of the reaction kettle to 110 °C, keep it warm for 11 h and then take a sample for detection. After passing the detection, the reaction ends, and cool the reaction solution to 30 °C. The reaction solution contains crude clothianidin, the generated potassium chloride, tetrabutylammonium bromide, acid-binding agent, and the solvent carbon tetrachloride;

[0044] Filtration: Pump the cooled reaction solution into a filter. Here, the filter is preferably a screen filter. Filter out the filter residue of potassium chloride and the unreacted acid-binding agent generated in the above steps. The filter residue is waste salt. Pump the filtered waste salt into the receiving tank, add an appropriate amount of steam condensate to dissolve it in the receiving tank, add hydrochloric acid to the dissolved solution for neutralization, and introduce hydrogen chloride gas to react with the neutralized solution. The reaction obtains a potassium chloride solution. Transport the potassium chloride solution to the drying kettle for drying. After drying, potassium chloride is obtained, cooled and packaged and stored in the warehouse;

[0045] Desolventization: The filtrate filtered out in the above steps is preheated through an inlet tower preheater and then pumped into a desolventization tower. The filtrate contains ammonium sulfate and methylammonium sulfate. The temperature when pumping in the filtrate is controlled at 75°C. After pumping in the filtrate is completed, the temperature of the bottom of the desolventization tower is controlled at 88°C to remove the solvent in the filtrate. The desolventization time is 1.5 h, and the solvent is collected in a recycled solvent tank. The removed solvent contains carbon tetrachloride and a small amount of tetrabutylammonium bromide. The components of the solvent in the recycled solvent tank are detected. After the detection meets the use standard, it is pumped into a substitution feeding kettle for recycling;

[0046] Crystallization: After desolventization is completed, the materials in the desolventization tower enter a crystallization kettle for cooling. The temperature of the first-stage crystallization kettle is controlled at 58°C, and the crystallization time is 2 h. The materials flow from the first-stage crystallization kettle into the second-stage crystallization kettle through an overflow channel, and then the temperature of the second-stage crystallization kettle is controlled below 25°C for crystallization. After crystallization is completed, it is transported to a crystallization tank for standby.

[0047] Centrifugal drying and packaging:

[0048] The materials in the crystallization tank are pumped into a centrifuge through a pump and centrifuged by the centrifuge. The centrifuged solvent is pumped back into the first-stage crystallization kettle for continuous crystallization. Clothianidin is obtained after crystallization. The centrifuged materials are sent into a double-cone dryer for drying. Nitrogen is continuously filled into the double-cone dryer during drying. At the same time, the pressure of the double-cone dryer is controlled at -0.07 mpa and the temperature is 85°C. After drying for 1.5 h, the double-cone dryer stops heating up to obtain a clothianidin filter cake. After the temperature of the filter cake drops to 40°C, it is weighed and packaged and stored in the warehouse.

[0049] Synthesis principle of clothianidin:

[0050]

[0051] The above-disclosed is only a preferred embodiment of the present invention. Of course, the scope of the rights of the present invention cannot be limited by this. Therefore, equivalent changes made according to the claims of the present invention still fall within the scope covered by the present invention.

Claims

1. A synthetic process for clothianidin, characterized in that, The specific synthesis process includes the following steps: S1, synthesis: water is added to a reaction kettle, and then nitroguanidine and monomethylamine solution are added, and the temperature of the reaction kettle is slowly raised to 40-43°C, and the temperature is kept for 1.5-2h. After the temperature is kept, the reaction solution is sampled and analyzed for the absence of nitroguanidine, and the temperature is kept for 0.5h, and the reaction is terminated; S2, neutralization: 70% sulfuric acid is prepared with evaporated water and cooled to 25-30°C for standby use; the reaction solution after the reaction is transferred to the neutralization kettle, the chilled water in the neutralization kettle interlayer is opened, the temperature of the reaction solution is cooled to 20°C, and 70% dilute sulfuric acid for standby use is dripped into the neutralization kettle to neutralize to PH=7-8, and after the neutralization is completed, the temperature is further lowered to 15-20°C before discharging; S3, filtration: the material discharged from the neutralization kettle is evenly distributed on the filter cloth through the distributor in the filter, and methylguanidine is obtained by filtration. The filtrate and spray water after filtration are sent to the filtrate pool of the wastewater workshop for negative pressure concentration treatment. The evaporated water after the concentration treatment can be used for preparing sulfuric acid in S2 after filtration. The centrifugal synthesis mother liquor after concentration enters the reactor for recycling, and the waste water after centrifugation is sent to the wastewater workshop for treatment; S4, recrystallization: after beating the filter cake, put it into the refining kettle, add evaporated water, start stirring, and heat the refining kettle to 75-80 ° C. After the material is completely dissolved, put it into the filter, and fill the filter with compressed air to press the material into the crystallization kettle for cooling; S5, centrifugation: the cooled material is put into the centrifuge for centrifugation, and the centrifugal water after centrifugation is pumped into the centrifugal low-level tank. A part of it is transported to the filter through the pipeline to replace the spray water to spray the filter cake, and the other part is transported to the reactor through the pipeline to replace the water; S6, drying: open the feeding port of the primary dryer to add the centrifugal material to the dryer, and input air into the dryer at the same time, control the air inlet temperature of the primary dryer at 140 ° C, heat the air, mix the centrifugal material with the hot air, and separate it through the cyclone separator in the dryer, the separated material enters the dryer from the feeding port of the secondary dryer, mixes with the hot air and is separated through the cyclone separator in the dryer, the air inlet temperature of the secondary dryer is controlled at 120 ° C, and after secondary drying, guanidine is obtained, and the moisture content of the dried material is tested, and the qualified materials are weighed and packaged for standby use; S7, substitution: put dichloromethylthiazole into a high-temperature dissolving tank to melt it into liquid, and pump it into a high-level tank for standby use; The solvent carbon tetrachloride is injected into the feeding kettle, and the methylguanidine with qualified water content in S6, the acid binding agent and the catalyst are added, the catalyst is tetrabutylammonium bromide, the acid binding agent is potassium carbonate, and the materials in the feeding kettle are pressed into the reactor with nitrogen, and dichloromethylthiophene is added from the high-level tank of the reactor for reaction, and the temperature of the reactor is slowly raised to 110°C, and then the temperature is kept for 10-12 hours and then sampling is carried out for detection. After the detection is qualified, the reaction is terminated, and the reaction liquid is cooled to 25-30°C, and the reaction liquid contains the crude clothianidin, potassium chloride generated by the reaction, tetrabutylammonium bromide, the acid binding agent and the solvent carbon tetrachloride; S8. Filtration: Pump the cooled reaction solution into a filter to filter out the filter residue and filtrate. The filter residue contains potassium chloride generated in S7 and the acid-binding agent that did not participate in the reaction. Transfer the filtered filter residue into a receiving tank, add an appropriate amount of steam condensate to dissolve it in the receiving tank, add hydrochloric acid to neutralize the dissolved solution, and introduce hydrogen chloride gas to react with the neutralized solution to obtain a potassium chloride solution. Transport the potassium chloride solution to a drying kettle for drying. After drying, obtain potassium chloride, cool it and package it for storage in the warehouse. S9. Solvent Removal: Preheat the filtrate in S8 through a feed tower preheater, and then pump it into a solvent removal tower. Control the temperature of the filtrate when pumping it in to be 75 °C. After pumping in the filtrate, control the temperature of the bottom of the solvent removal tower to be 85 - 90 °C to remove the solvent in the filtrate. The solvent removal time is 1 - 1.5 h, and collect the solvent into a recycled solvent tank. Conduct a component detection on the solvent in the recycled solvent tank. After the detection meets the usage standard, pump it into a substitution feeding kettle for recycling. S10. Crystallization: After the solvent removal is completed, the material in the solvent removal tower enters a crystallization kettle for cooling. Control the temperature of the first-stage crystallization kettle to be 55 - 60 °C, and the crystallization time to be 1.5 - 2 h. The material flows from the first-stage crystallization kettle into the second-stage crystallization kettle through an overflow channel, and then control the temperature of the second-stage crystallization kettle to be below 25 °C for crystallization. After crystallization is completed, transport it to a crystallization tank for standby. S11. Centrifugation, Drying and Packaging: Pump the material in the crystallization tank into a centrifuge through a pump, and centrifuge it through the centrifuge. The separated solvent is pumped back into the first-stage crystallization kettle for continuous crystallization to obtain clothianidin. The centrifuged material is sent into a double-cone dryer for drying. During drying, continuously fill nitrogen into the double-cone dryer, and at the same time control the pressure of the double-cone dryer to be -0.07 mpa and the temperature to be 85 °C. After drying for 1.5 - 2 h, the double-cone dryer stops heating up to obtain a clothianidin filter cake. After the temperature of the filter cake drops to 40 °C, weigh it and package it for storage in the warehouse.

2. The synthetic process for clothianidin according to claim 1, characterized in that, In S3, the thickness of the methylguanidine distributed on the filter cloth is 2 - 3 cm. The filter uses a vacuum mechanism to extract the moisture in the methylguanidine on the filter cloth to obtain a filter cake. The nozzles in the filter spray the filter cake to wash away the salt in the filter cake.

3. The synthetic process for clothianidin according to claim 1, characterized in that, In S3, ammonium sulfate and methylammonium sulfate are precipitated after the negative pressure concentration residue is cooled and crystallized. Ammonium sulfate is separated by centrifugation and packaged for storage in the warehouse.

4. The synthetic process for clothianidin according to claim 1, characterized in that, The filter is one of a bag filter or a screen filter.

5. The synthetic process for clothianidin according to claim 1, characterized in that, In S4, the cooling temperature of the crystallization kettle is 20 - 25 °C.

6. The synthetic process for clothianidin according to claim 1, characterized in that, In S6, the water content of the methylguanidine < 0.1%.

7. The synthetic process for clothianidin according to claim 1, characterized in that, In S9, the removed solvent contains carbon tetrachloride and a small amount of tetrabutylammonium bromide.

8. The synthetic process for clothianidin according to claim 1 or 7, characterized in that, The synthesis principle of clothianidin:

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