CN118026937A - Synthesis method of intermediate of haloxyfop-methyl for pesticides - Google Patents

Synthesis method of intermediate of haloxyfop-methyl for pesticides Download PDF

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Publication number
CN118026937A
CN118026937A CN202311538190.8A CN202311538190A CN118026937A CN 118026937 A CN118026937 A CN 118026937A CN 202311538190 A CN202311538190 A CN 202311538190A CN 118026937 A CN118026937 A CN 118026937A
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Prior art keywords
methyl
methyl hydrazine
acetic acid
ethyl trifluoroacetoacetate
hydrazine sulfate
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CN202311538190.8A
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Inventor
田义群
李忠
彭春雪
郑松林
胡付超
刘玉
汪倩
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Hubei Taisheng Chemical Co Ltd
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Hubei Taisheng Chemical Co Ltd
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Abstract

The invention belongs to the technical field of pesticide synthesis, and particularly relates to a synthesis method of a pyribenzoxim intermediate hydroxypyrazole. According to the method, ethyl trifluoroacetoacetate and methyl hydrazine sulfate are used as raw materials, and the key intermediate hydroxypyrazole of the fenpyrad can be obtained through heating and heat-preserving reaction, post-treatment, filtration, reduced pressure distillation, water adding crystallization, filtration and drying. The invention provides a synthesis method of a haloxyfop-methyl intermediate, which uses methyl hydrazine sulfate to replace 40% methyl hydrazine aqueous solution, avoids the dangerous characteristics of virulence, flammability, corrosiveness and the like of the 40% methyl hydrazine aqueous solution, and has the advantages of safe transportation, no potential safety hazard in the use process, mild reaction conditions, simple and feasible method and suitability for mass production.

Description

Synthesis method of intermediate of haloxyfop-methyl for pesticides
Technical Field
The invention relates to a synthesis method of a haloxyfop-R-methyl intermediate for pesticides, and belongs to the technical field of pesticide synthesis.
Background
Pyroxasulfane (Pyroxasulfone) is an isoxazole herbicide which is a white solid, odorless, and has the chemical name of 3- [5- (difluoromethoxy) -1-methyl-3- (trifluoromethyl) pyrazol-4-ylmethyl sulfonyl ] -4, 5-dihydro-5, 5-dimethyl-1, 2-isoxazole, CAS accession number 447399-55-5, molecular formula C 12H14F5N3O4 S, molecular weight 391.32, melting point 157.6 ℃, and solubility in water of: 0.17 mg/L (25 ℃ C.). The haloxyfop-R-methyl is an excellent pre-emergence soil treatment agent developed by Japanese combinatorial chemistry company in 2002, has a wide weed killing spectrum, is suitable for various crops, is widely applied to various crops such as corn, wheat, soybean, cotton, sunflower, potato, peanut and the like, has high activity and low dosage, is 8-10 times lower than that of a classic soil treatment agent chloroacetamides, has better control effect and longer duration, has strong compatibility with various herbicides, is safe to the crops, has lower biotoxicity to mammals and most of the environment, is expected to replace chloroacetamides herbicides in the future, and becomes a novel standard pole of the soil treatment agent, and has wide market prospect.
Numerous intermediates are involved in the preparation of haloxyfop-butyl, but the key intermediate is 5-hydroxy-1-methyl-3-trifluoromethyl-1H-pyrazole, 5-hydroxy-1-methyl-3-trifluoromethyl-1H-pyrazole is a white or pale yellow powder, a slight odor, CAS registry number 122431-37-2, chemical formula C 5H5F3N2 O, molecular weight: 166.10, the melting point is 177-179 ℃. In the existing synthesis method, 40% methyl hydrazine solution and ethyl trifluoroacetoacetate are adopted to react in a solvent to synthesize 5-hydroxy-1-methyl-3-trifluoromethyl-1H-pyrazole, but the 40% methyl hydrazine solution is highly toxic, inflammable, corrosive and high in risk, and general enterprises do not have purchasing qualification, and the raw materials are short in source, so that the potential safety hazard exists in the use process.
Disclosure of Invention
The invention provides a synthesis method of the key intermediate 5-hydroxy-1-methyl-3-trifluoromethyl-1H-pyrazole, which uses methyl hydrazine sulfate to replace 40% methyl hydrazine solution, so that the method not only avoids the dangerous characteristics of high toxicity, flammability, corrosiveness and the like of 40% methyl hydrazine solution, but also has the advantages of relatively low price, wide sources, safe transportation, no potential safety hazard in the use process, mild reaction conditions, simple and feasible method, and is suitable for mass production.
The invention relates to a synthesis method of a haloxyfop-R-methyl intermediate, in particular to a synthesis method of a haloxyfop-R-methyl intermediate hydroxypyrazole. According to the method, ethyl trifluoroacetoacetate and methyl hydrazine sulfate are used as raw materials, and the key intermediate hydroxypyrazole methanol of the fenpyrad can be obtained by filtering, distilling under reduced pressure, adding water for crystallization and finally drying after post-treatment.
The synthesis method of the intermediate of the penoxsulam specifically comprises the following steps:
(1) Adding solvent ethanol into a reactor, and sequentially adding sodium acetate, acetic acid and ethyl trifluoroacetoacetate under stirring; cooling to 0 ℃, adding methyl hydrazine sulfate in batches, heating to 60-90 ℃ for reaction after the addition, and preserving heat for 3-8 hours; detecting the content of the ethyl trifluoroacetoacetate serving as a raw material (the reaction is complete when the content is less than 1 percent by using an area normalization method), cooling the reaction liquid to room temperature, performing suction filtration, performing reduced pressure distillation on the filtrate to recover solvent ethanol and part of acetic acid, and stopping reduced pressure distillation when solids are separated out; cooling to room temperature, adding water into the mixture, standing the mixture, carrying out suction filtration on the mixture, washing a solid product with water, and finally drying the solid product to obtain the pyribenzoxim intermediate hydroxypyrazole.
(2) The method for synthesizing the intermediate of the metazopyr as claimed in claim 2, which is characterized in that: in the step (1), the molar ratio of sodium acetate, acetic acid, methyl hydrazine sulfate and ethyl trifluoroacetoacetate is (2.0-4.0): (1.5 to 4): (1.0 to 2.0): 1, a step of; preferably: sodium acetate, acetic acid, methyl hydrazine sulfate and ethyl trifluoroacetoacetate (2.2-3.0): (2.0 to 3.0): (1.1 to 1.5): 1.
(3) The method for synthesizing the intermediate of the metazopyr as claimed in claim 2, which is characterized in that: heating to 60-90 ℃ in the step (1), reacting, and preserving heat for 3-8 hours; preferably: the heating temperature is 70-80 ℃, and the heat preservation reaction is carried out for 5-6 hours.
Detailed Description
The synthesis method of the intermediate of the penoxsulam provided by the invention is described in detail in the following examples, but is not limited to the examples. The equipment and reagents used in the present invention are conventional commercially available products in the art, unless specifically indicated.
Example 1:
500 mL ethanol solvent was added to a 1L three-neck flask with a stirrer and thermometer, stirring was started, 45.10 g (0.55 mol,2.2 eq.) sodium acetate was added thereto, then 30.03 g (1.00 mol,4.0 eq.) acetic acid was added thereto, then 46.00 g (0.25 mol,1.0 eq.) ethyl trifluoroacetoacetate was added thereto, the temperature was lowered by an ice water bath, finally 39.64 g (0.28 mol,1.1 eq.) methyl hydrazine sulfate was added in portions, after the addition was completed, a condenser was connected, the ice-removing water bath was removed, heating was started, and the temperature was set to 80 ℃. After 5 hours of reaction under this condition, the content of ethyl trifluoroacetoacetate as a raw material in the reaction liquid was monitored by GC (the content was 0.54% by area normalization method, and the reaction was completed). The reaction solution was cooled to room temperature, then suction filtration was performed, the filtrate was distilled under reduced pressure (distillation temperature: 45 ℃ C., vacuum degree: 0.092 Mpa) to recover all ethanol and part of acetic acid, the distillation under reduced pressure was stopped when a large amount of solids were precipitated, cooled to room temperature, and then 100 mL ice water was added to stand for 1 hour. Filtering the mixture after standing, washing the solid for 3 times by using 50 mL ice water each time, and finally drying to obtain a product 33.34 g, wherein the yield is: 81.34%, purity: 98.86%.
Example 2:
350 mL ethanol solvent was added to a 1L three-neck flask with a stirrer and thermometer, stirring was started, 90.23 g (1.10 mol,2.2 eq.) sodium acetate was added thereto, 120.10 g (2.00 mol,3.0 eq.) acetic acid was then added, 92.06 g (0.50 mol,1.0 eq.) ethyl trifluoroacetoacetate was then added to the three-neck flask, the ice water bath was cooled, 79.28 g (0.55 mol,1.1 eq.) methyl hydrazine sulfate was added in portions, after the addition was completed, a condenser was connected, the ice water bath was removed, heating was started, and the temperature was set to 80 ℃. The reaction was carried out under this condition for 5.5 hours, and the content of ethyl trifluoroacetoacetate as a raw material in the reaction solution (the content was 0.17% calculated by the area normalization method) was monitored by GC, and the reaction was completed. The reaction solution was cooled to room temperature, then suction filtration was performed, the filtrate was distilled under reduced pressure (distillation temperature: 47 ℃, vacuum degree: 0.095 Mpa) to recover all ethanol and part of acetic acid, the distillation under reduced pressure was stopped when a large amount of solids were precipitated, cooled to room temperature, and then 200 mL ice water was added to stand for 1 hour. Filtering the mixture after standing, washing the solid for 3 times by using 50mL ice water each time, and finally drying to obtain a product 73.86 g, wherein the yield is: 83.94%, purity: 99.89%.
Example 3:
1500 mL ethanol solvent was added to a 5L three-neck flask with a stirrer and thermometer, stirring was started, 225.58 g (2.75 mol,2.2 eq.) sodium acetate was added thereto, 300.25 g (5.00 mol,4.0 eq.) acetic acid was then added, 230.14 g (1.25 mol,1.0 eq.) ethyl trifluoroacetoacetate was then added to the three-neck flask, the ice water bath was cooled, 198.21 g (1.38 mol,1.1 eq.) methyl hydrazine sulfate was added in portions, after the addition was completed, the condenser was connected, the ice water bath was removed, heating was started, and the temperature was set to 77 ℃. The reaction was carried out under this condition for 6 hours, and the content of ethyl trifluoroacetoacetate as a raw material in the reaction solution (the content was 0.62% by area normalization) was monitored by GC, and the reaction was completed. The reaction solution was cooled to room temperature, then suction filtration was performed, the filtrate was distilled under reduced pressure (distillation temperature: 43 ℃ C., vacuum degree: 0.085 Mpa) to recover all ethanol and part of acetic acid, the distillation under reduced pressure was stopped when a large amount of solids were precipitated, cooled to room temperature, and then 500 mL ice water was added to stand for 1 hour. Filtering the mixed solution after standing, washing the solid with 150 mL ice water for 3 times each time, and finally drying to obtain a product 175.08 g with the yield: 84.33%, purity: 99.88%.
Example 4:
2400 mL ethanol solvent is added into a 5L three-neck flask with a stirring and thermometer, stirring is started, 360.93 g (4.4 mol,2.2 eq.) sodium acetate is added into the flask, 480.40 g (8.0 mol,4.0 eq.) acetic acid is then added into the flask, 368.22 g (2.0 mol,1.0 eq.) ethyl trifluoroacetoacetate is then added into the flask, the temperature is reduced by an ice water bath, 317.13 g (2.2 mol,1.1 eq.) methyl hydrazine sulfate is finally added in batches, after the addition is completed, a condensing device is connected, the ice water bath is removed, heating is started, and the temperature is set to 80 ℃. The reaction was carried out under this condition for 6 hours, and the content of ethyl trifluoroacetoacetate as a raw material in the reaction solution (the content was 0.62% by area normalization) was monitored by GC, and the reaction was completed. The reaction solution was cooled to room temperature, then suction filtration was performed, the filtrate was distilled under reduced pressure (distillation temperature: 43 ℃ C., vacuum degree: 0.085 Mpa) to recover all ethanol and part of acetic acid, the distillation under reduced pressure was stopped when a large amount of solids were precipitated, cooled to room temperature, and then 800 mL ice water was added to stand for 1 hour. Filtering the mixed solution after standing, washing the solid with 200 mL ice water for 3 times each time, and finally drying to obtain a product 295.55 g with the yield: 87.97%, purity: 99.84%.

Claims (4)

1. A synthesis method of a haloxyfop-methyl intermediate for pesticides is characterized by comprising the following steps: adding solvent ethanol into a reactor, sequentially adding sodium acetate, acetic acid and ethyl trifluoroacetoacetate, cooling by ice water bath, adding methyl hydrazine sulfate in batches, heating to react after the addition, filtering the reaction liquid, distilling the filtrate under reduced pressure, adding water for crystallization, filtering the solid, and drying to obtain an intermediate product.
2. The method for synthesizing the intermediate of the metazopyr as claimed in claim 1, wherein the method comprises the following steps: the method comprises the following steps:
Adding solvent ethanol into a reactor, and sequentially adding sodium acetate, acetic acid and ethyl trifluoroacetoacetate under stirring; cooling to 0 ℃, adding methyl hydrazine sulfate in batches, heating to 60-90 ℃ for reaction after the addition, and preserving heat for 3-8 hours; detecting the content of the ethyl trifluoroacetoacetate serving as a raw material by GC, cooling the reaction liquid to room temperature, carrying out suction filtration, carrying out reduced pressure distillation on the filtrate to recover solvent ethanol and part of acetic acid, and stopping reduced pressure distillation when solids are separated out; cooling to room temperature, adding water into the mixture, standing the mixture, carrying out suction filtration on the mixture, washing a solid product with water, and finally drying the solid product to obtain the pyribenzoxim intermediate hydroxypyrazole.
3. The method for synthesizing the intermediate of the pyrifos-methyl according to claim 2, which is characterized in that: in the step (1), the molar ratio of sodium acetate, acetic acid, methyl hydrazine sulfate and ethyl trifluoroacetoacetate is (2.0-4.0): (1.5 to 4): (1.0 to 2.0): 1, a step of; preferably: sodium acetate, acetic acid, methyl hydrazine sulfate and ethyl trifluoroacetoacetate (2.2-3.0): (2.0 to 3.0): (1.1 to 1.5): 1.
4. The method for synthesizing the intermediate of the pyrifos-methyl according to claim 2, which is characterized in that: heating to 60-90 ℃ in the step (1), reacting, and preserving heat for 3-8 hours; preferably: the heating temperature is 70-80 ℃, and the heat preservation reaction is carried out for 5-6 hours.
CN202311538190.8A 2023-11-14 2023-11-14 Synthesis method of intermediate of haloxyfop-methyl for pesticides Pending CN118026937A (en)

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