Method for producing insecticide tolfenpyrad

Abstract

The invention provides an improved method for producing insecticide tolfenpyrad, and a hydrolysis step in the existing method is omitted in the process of synthesizing an intermediate A, so that wastewater discharge is reduced; besides, according to the method, the tolfenpyrad crystals are separated through centrifugation after crystallization, the centrifuged tolfenpyrad crystals enter the stock bin from the centrifugal machine, then the stock bin enters the dryer, and automation of the centrifugation, feeding and drying processes is achieved. The continuous process disclosed by the invention is beneficial to emission reduction and consumption reduction of the product and can relieve the environmental protection problem.

Description

Technical Field

[0001] The present invention belongs to the field of pesticides. More specifically, the present invention relates to an improved method for producing the insecticide tolfenpyrad. Background Art

[0002] Tolfenpyrad is a novel pyrazole heterocyclic acaricide. Tolfenpyrad has a broad insecticidal spectrum and has a contact-killing effect. Tolfenpyrad degrades rapidly in plants, soil, and water. Due to its protective, therapeutic, eradicative, and penetrative effects, as well as its non-mutagenic characteristics, it is a novel agricultural insecticide and acaricide with great development potential and market vitality in the pesticide industry.

[0003] The applicant's previous patent application CN118359540A disclosed a method for producing tolfenpyrad, which specifically includes the following steps: condensation reaction, cyclization reaction, methylation reaction, chlorination reaction, hydrolysis, acyl chlorination reaction, etherification reaction, hydrogenation reaction, and product synthesis to obtain the product tolfenpyrad insecticide. However, this method has more reaction steps, especially including a hydrolysis step, in which a hydrolysis reagent is added to the chlorination reaction solution for hydrolysis, and an acidic reagent is added after hydrolysis for acidification to obtain a hydrolysis reaction solution, where the hydrolysis reagent is one or a mixture of sodium hydroxide aqueous solution, potassium hydroxide aqueous solution, and water methanol, and the acidic reagent is 10% hydrochloric acid. This hydrolysis step generates a large amount of wastewater, which is not conducive to the reduction of three wastes. In addition, how to achieve a continuous production and purification process to realize the automated production of tolfenpyrad, so as to achieve the purpose of energy conservation and emission reduction, is also a problem to be solved currently. Summary of the Invention

[0004] In view of the above problems, the inventors of the present invention have conducted in-depth research and provided an improved method for producing the insecticide tolfenpyrad, which is characterized in that the hydrolysis step in the existing method is omitted during the synthesis of intermediate A in the existing method, thereby reducing wastewater discharge; in addition, in the method of the present invention, after crystallization, the tolfenpyrad crystals are separated by centrifugation, and the centrifuged tolfenpyrad crystals enter the silo from the centrifuge, and then the silo enters the dryer to realize the automation of the centrifugation, feeding, and drying processes. The continuous process of the present invention is conducive to product emission reduction and consumption reduction, which can alleviate environmental protection problems and has economic value.

[0005] Therefore, the present invention provides the following:

[0006] The present invention provides a method for producing the insecticide tolfenpyrad, which includes the following steps:

[0007] (1) Synthesize the following intermediate A

[0008]

[0009] Wherein intermediate A is synthesized through the following continuous reaction:

[0010]

[0011] Among them, the continuous reaction does not include a hydrolysis step;

[0012] (2) Synthesize the following intermediate B

[0013]

[0014] Among them, intermediate B is synthesized through the following continuous reaction:

[0015]

[0016] and

[0017] (3) React the said intermediate A and the said intermediate B to synthesize tolfenpyrad:

[0018]

[0019] In a further embodiment, after step (3), it further includes the steps of crystallizing and separating tolfenpyrad and drying it under negative pressure.

[0020] In a further embodiment, after the crystallization and separation, it further includes the steps of recovering the solvent and reusing it.

[0021] In a further embodiment, after crystallization, the tolfenpyrad crystals are separated by centrifugation, and the centrifuged tolfenpyrad crystals enter the silo from the centrifuge, and the silo then enters the dryer to realize the automation of the centrifugation, feeding and drying processes.

[0022] In a further embodiment, the mother liquor after centrifugation is directly transported by a pump into the recovery kettle.

[0023] In a further embodiment, step (1) sequentially includes a condensation reaction, a cyclization reaction, a methylation reaction, a chlorination reaction and an acyl chlorination reaction.

[0024] In a further embodiment, there is no hydrolysis reaction between the chlorination reaction and the acyl chlorination reaction in step (1).

[0025] In a further embodiment, the hydrolysis reaction is to add a hydrolysis reagent to the chlorination reaction solution for hydrolysis, and after hydrolysis, an acidic reagent is added for acidification to obtain a hydrolysis reaction solution.

[0026] In a further embodiment, step (2) sequentially includes an etherification reaction and a hydrogenation reaction.

[0027] In a further embodiment, in step (3), intermediate A and intermediate B are mixed and reacted under heating to reflux. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is the process synthesis route of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] The present invention will be further described in detail below in conjunction with the embodiments and the drawings, but the embodiments of the present invention are not limited thereto.

[0030] In a specific embodiment, the reaction equation of the present invention is as follows: Condensation station

[0031] Cyclization station

[0032] Methylation station

[0033] Chlorination process

[0034] Acyl chlorination station

[0035]

[0036] Etherification station

[0037]

[0038] Hydrogenation station

[0039]

[0040] Product synthesis station

[0041]

[0042] In the above reaction formula, step (1) of the present invention sequentially includes a condensation reaction, a cyclization reaction, a methylation reaction, a chlorination reaction, and an acyl chlorination reaction; step (2) of the present invention sequentially includes an etherification reaction and a hydrogenation reaction. For the reagents, reaction conditions, etc. used in these specific reaction steps, reference can be made to CN118359540A. The improvements (differences) of the present invention compared to CN118359540A include: (1) there is no hydrolysis reaction between the chlorination reaction and the acyl chlorination reaction in step (1); and (2) after step (3), there are also steps of crystallizing and separating tolfenpyrad, drying under negative pressure, and after the crystallization separation, there are also steps of recovering the solvent and reusing it, and after crystallization, the tolfenpyrad crystals are separated by centrifugation, and the centrifuged tolfenpyrad crystals enter the storage bin from the centrifuge, and the storage bin then enters the dryer to realize the automation of the centrifugation, feeding, and drying processes.

[0043] Example

[0044] According to the Figure 1 process flow of the present invention as shown, tolfenpyrad is synthesized.

[0045] Condensation

[0046] Put toluene and sodium ethoxide into the condensation reaction kettle, and cool down to -10°C. Start dropping, control the dropping speed so that the temperature remains at -10°C to 10°C. After the dropping is completed, add the condensation reaction liquid to the neutralization kettle for extraction and layering.

[0047] Cyclization

[0048] Cool down to 0°C in the cyclization kettle, drop hydrazine hydrate, and keep the temperature for reaction for 1 hour, and take samples for in-process control.

[0049] Methylation

[0050] Add toluene solution to the kettle, drop dimethyl sulfate, the dropping time is 2 hours, after dropping, keep the temperature for reaction for 2 hours, and take samples for analysis. After the analysis is qualified, wash with water and layer.

[0051] Chlorination process

[0052] For the materials from the previous step, heat to maintain the reflux state of the temperature, introduce chlorine gas for about 8 hours, and take samples for analysis.

[0053] Acyl chlorination

[0054] Add toluene and catalyst to the materials from the previous step, stir evenly, then drop thionyl chloride, and keep the temperature for reaction for 1 hour.

[0055] Etherification

[0056] Add toluene and p-cresol to the salification kettle, start stirring, add potassium hydroxide, add DMF, heat up to 60 - 80°C, keep the temperature for reaction at 120 - 150°C for 1 hour, and then take samples for analysis.

[0057] Hydrogenation

[0058] Open the nitrogen protection for the autoclave, add the catalyst, slowly heat to 50 - 70 °C, and react until hydrogen is no longer consumed.

[0059] After the reaction is completed, cool down, displace with nitrogen, and then take samples for analysis.

[0060] Product synthesis

[0061] Heat to reflux and react for 5 hours, then take samples for analysis. After the reaction is completed, add an aqueous solution. The aqueous layer is extracted with a solvent, and the organic layers are combined and recovered and reused under negative pressure. Add fresh solvent for crystallization and centrifugation. The tolfenpyrad crystals centrifuged out enter the silo from the centrifuge, and the silo then enters the dryer to automate the centrifugation, feeding, and drying processes.

[0062] After testing, the main technical indicators of the product are as follows:

[0063] Serial number Project name Content Remarks 1 Main content of the product 98％ 2 Appearance Off-white 3 Acetone-insoluble matter 0.15％

[0064] According to the comparative production data under parallel conditions, compared with the method of CN118359540A, since the process for synthesizing tolfenpyrad in the present invention does not include the hydrolysis reaction between the chlorination reaction and the acyl chlorination reaction, the amount of wastewater treatment is about 20% less. And at the same time, the product yield is basically equivalent (slightly reduced by about 5%). However, omitting this hydrolysis step can simplify the continuous reaction equipment, reduce costs and reduce reaction risks. In addition, the method of the present invention further includes the steps of crystallizing and separating tolfenpyrad and drying it under negative pressure. After the crystallization and separation, it further includes the steps of recovering the solvent and reusing it. And after crystallization, the tolfenpyrad crystals are separated by centrifugation, and the centrifuged tolfenpyrad crystals enter the silo from the centrifuge, and the silo then enters the dryer to automate the centrifugation, feeding, and drying processes.

[0065] Those skilled in the art should understand that although the present invention has been specifically described with reference to the above embodiments, the present invention is not limited to these specific embodiments. Based on the methods and technical solutions taught by the present invention, without departing from the spirit of the present invention, those skilled in the art can make appropriate modifications or improvements, and the equivalent implementation schemes obtained therefrom are all within the scope of the present invention.

Claims

1. A method for producing the insecticide tolfenpyrad, comprising the following steps: (1) Synthesize the following intermediate A The intermediate A is synthesized by the following continuous reactions: wherein the continuous reaction does not include a hydrolysis step; (2) Synthesize the following intermediate B The intermediate B is synthesized by the following continuous reactions: and (3) subjecting the intermediate A and the intermediate B to the following reaction to synthesize tolfenpyrad:

2. The method according to claim 1, further comprising the steps of separating the tolfenpyrad crystals and drying under negative pressure after step (3).

3. The method according to claim 2, further comprising the step of recovering and reusing the solvent after the crystallization separation.

4. The method according to claim 2 or 3, wherein the tolafenamide crystals are separated by centrifugation after crystallization, and the tolafenamide crystals centrifuged out from the centrifuge enter the silo, and the silo enters the dryer, thereby realizing the automation of the centrifugation, feeding and drying processes.

5. The method according to claim 4, wherein the mother liquor after centrifugation is directly transported into the recovery tank by a pump.

6. The method according to claim 1, wherein the step (1) comprises condensation reaction, cyclization reaction, methylation reaction, chlorination reaction and acyl chloride reaction in sequence.

7. The method according to claim 6, wherein no hydrolysis reaction is involved between the chlorination reaction and the acyl chlorination reaction in step (1).

8. The method according to claim 7, wherein the hydrolysis reaction is performed by adding a hydrolysis reagent into the chlorination reaction solution for hydrolysis, and then adding an acidic reagent for acidification to obtain a hydrolysis reaction solution.

9. The method according to claim 1, wherein the step (2) comprises an etherification reaction and a hydrogenation reaction in sequence.

10. The method according to claim 1, wherein in the step (3), intermediate A and intermediate B are mixed and reacted under heating to reflux.

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