Synthesis method of pyroxasulfone

Abstract

The invention discloses a method for synthesizing pyroxasulfone, which comprises the following steps: by taking a raw material A and air as raw materials, carrying out oxidation reaction under the catalysis of a Fe (III) catalyst to obtain pyroxasulfone. The method has the advantages of mild reaction conditions, high yield, less three wastes, avoidance of hydrogen peroxide use and storage reactions, low cost and suitableness for industrial production.

Description

Technical Field

[0001] The invention relates to a synthesis method of sulfonepyraclostrobin, in particular to a synthesis method of sulfonepyraclostrobin with simple synthesis process and simple operation, belonging to the technical field of organic synthesis. Background Art

[0002] Sulfonepyrazol was developed by Kumizu Chemical Co., Ltd. of Japan. Its chemical name is: 3-[5-(difluoromethoxy)-1-methyl-3-(trifluoromethyl)pyrazol-4-ylmethylsulfonyl]-4,5-dihydro-5,5-dimethyl-1,2-isoxazole, and it has the following structure: Sulfonepyraclostrobin can be used as a pre-emergence soil treatment agent in most crop fields. After application, it is absorbed by the young roots and shoots of weeds, inhibiting the early growth of seedlings, destroying meristems and coleoptiles, and is a serious potential inhibitor of the biosynthesis of VLCFA (very long side-chain fatty acids) (C20-C30) in plants.

[0003] The synthesis of sulfonepyraclostrobin is reported in the following prior art: Patent CN102666503A discloses that hydrogen peroxide can be used for oxidation reaction, as follows: Patent CN116761802A reports a method of oxidation using an oxidant, hydrogen peroxide, as follows: In the preparation methods of sulfonepyraclostrobin reported in the literature, most of the processes use hydrogen peroxide for oxidation reaction. However, due to the easy decomposition of hydrogen peroxide, there are safety risks in storage and use. In recent years, accidents involving hydrogen peroxide have occurred frequently, so the selection of a safer oxidation method is urgently needed. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention provides a method for synthesizing sulfonepyraclostrobin. The method uses air as an oxidant and undergoes an oxidation reaction under the catalysis of a catalyst to synthesize sulfonepyraclostrobin. The method has mild reaction conditions, high safety, low cost, and less three wastes, and is suitable for industrial production.

[0005] The specific technical solutions of the present invention are as follows: A method for synthesizing sulfonepyraclostrobin, comprising taking raw material A and air as raw materials, and subjecting raw material A and air to oxidation reaction under the catalysis of Fe (III) catalyst to obtain sulfonepyraclostrobin; the reaction formula is as follows: In the above synthesis method, raw material A is used as an intermediate, air is used as an oxidant, and an oxidation reaction is carried out under the catalysis of an Fe(III) catalyst to obtain sulfonepyraclostrobin. Raw material A can be purchased from the market, or can also be synthesized by itself according to the method reported in the prior art.

[0006] Furthermore, in the above-mentioned synthesis method, the Fe(III) catalyst is a trivalent iron salt, and optional ones include Fe(NO3)3·9H2O, Fe(NO3)3, Fe(OAc)3, FeCl3, Fe2(SO4)3, FeBr3, etc. The catalyst can be one or two or more.

[0007] Furthermore, in the above synthesis method, the molar ratio of raw material A to Fe(III) catalyst is 1:1% to 15%, for example, 1:1%, 1:2%, 1:3%, 1:4%, 1:5%, 1:6%, 1:7%, 1:8%, 1:9%, 1:10%, 1:11%, 1:12%, 1:13%, 1:14%, and 1:15%.

[0008] Furthermore, in the above synthesis method, during the reaction, air is introduced into the system until the pressure is maintained at 0.11 to 0.3 MPa. For example, the pressure during the reaction can be 0.11 MPa, 0.12 MPa, 0.13 MPa, 0.14 MPa, 0.15 MPa, 0.16 MPa, 0.17 MPa, 0.18 MPa, 0.19 MPa, 0.20 MPa, 0.21 MPa, 0.22 MPa, 0.23 MPa, 0.24 MPa, 0.25 MPa, 0.26 MPa, 0.27 MPa, 0.28 MPa, 0.29 MPa, or 0.30 MPa.

[0009] Furthermore, in the above-mentioned synthesis method, the reaction is carried out in a solvent, and the solvent acts as a reaction medium. The solvent is at least one of acetic acid, chloroacetic acid, trifluoroacetic acid, difluoroacetic acid, and propionic acid, and the amount of the solvent is adjusted as needed.

[0010] Furthermore, in the above synthesis method, the reaction temperature is 60° C. to 100° C., for example, 60° C., 65° C., 70° C., 75° C., 80° C., 85° C., 90° C., 95° C., 100° C., preferably 75 to 85° C. At this reaction temperature, the raw material A can react rapidly with air in the presence of a catalyst, and the reaction time is less than 4 hours, for example, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 3.9h, and the reaction can generally be completed in about 3 hours.

[0011] Furthermore, in the above-mentioned synthesis method, the specific reaction steps are: during the reaction, raw material A, catalyst, and solvent are mixed, and then air is introduced, and the temperature is raised to the reaction temperature for reaction. After the reaction is completed, hot filtration is performed to separate, the mother liquor is collected, water is added to cool and crystallize, and centrifugation is performed to obtain the product. The present invention has simple post-processing, is easy to operate, and the obtained product has high purity and high yield.

[0012] The present invention provides a new method for synthesizing sulfonepyraclostrobin, which directly reacts raw material A, a catalyst and air to obtain sulfonepyraclostrobin in one step. Compared with the existing synthesis method using chemical oxidants such as hydrogen peroxide, the present invention has the following advantages: (1) The present invention has fewer reaction steps, faster reaction speed, simple synthesis process, mild reaction conditions, fewer side reactions, and improved reaction selectivity, reaction yield, and product purity through the selection of process conditions. It has been verified that under the preferred process conditions, the product yield is above 93% and the purity can reach above 98%; (2) The product obtained by the present invention is easy to separate, and the post-treatment is simple and extensive, which is suitable for large-scale production; (3) The three wastes generated in the synthesis process of the present invention are small, easy to handle, and environmentally friendly; (4) The present invention innovatively uses air catalysis to carry out oxidation in the preparation process of sulfonepyraclostrobin, avoiding the use of easily decomposable hydrogen peroxide, improving the safety of the process, reducing costs, and achieving intrinsic safety. DETAILED DESCRIPTION

[0013] The technical scheme of the present invention is further described below in conjunction with specific embodiments, but the present invention is not limited to the following embodiments. Unless otherwise specified, the raw materials used in the present invention can be purchased on the market. Alternatively, they can be synthesized by themselves according to the methods reported in the prior art.

[0014] Unless otherwise specified, the following concentrations are all mass percentages.

[0015] In the following examples, the calculation formula for yield is: yield = (product mass * product purity / product molecular weight) / product theoretical molar amount * 100%.

[0016] Example 1 Under room temperature conditions, 20 ml of acetic acid, 5.0 g (content 87%) raw material A and 0.737 g catalyst Fe(NO3)3·9H2O were added to the reactor with stirring; air was introduced into the reactor to maintain the pressure at 0.15 MPa, the temperature was raised to 80°C for reaction, and the reaction was kept warm for 3.0 hours. After HPLC detection showed that the reaction was complete, the reaction solution was first hot filtered, the filtrate was collected, and then 20 g of water was dropwise added to the filtrate, and the temperature was slowly decreased to 5°C for crystallization. After the temperature was decreased to 1 hour, the crystal was kept warm for 1 hour, and 4.62 g of white solid was obtained by filtration. The purity was 98.4% as determined by HPLC, and the yield was 96% based on raw material A.

[0017] Example 2 At room temperature, 20 ml of trifluoroacetic acid, 5.0 g (content 87%) raw material A and 0.439 g catalyst Fe(NO3)3 were added to the reactor with stirring; air was introduced into the reactor to maintain the pressure at 0.25 MPa, the temperature was raised to 75°C for reaction, and the reaction was kept warm for 3.0 hours. After HPLC detection showed that the reaction was complete, the reaction solution was first hot filtered, the filtrate was collected, and then 20 g of water was added dropwise to the filtrate, and the temperature was slowly decreased to 5°C for crystallization. The temperature was kept warm for 1 hour to grow the crystals, and 4.61 g of white solid was obtained by filtration. The purity was 98.3% as determined by HPLC, and the yield was 95.7% based on raw material A.

[0018] Example 3 At room temperature, 20 ml of acetic acid, 5.0 g (content 87%) raw material A and 0.439 g catalyst Fe(NO3)3 were added to the reactor with stirring; air was introduced into the reactor to maintain the pressure at 0.2 MPa, the temperature was raised to 95°C for reaction, and the reaction was kept warm for 3.0 hours. After HPLC detection showed that the reaction was complete, the reaction solution was first hot filtered, the filtrate was collected, and then 20 g of water was dropwise added to the filtrate, and the temperature was slowly decreased to 5°C for crystallization. The temperature was kept warm for 1 hour to grow the crystals, and 4.57 g of white solid was obtained by filtration. The purity was 98.1% as determined by HPLC, and the yield was 94.7% based on raw material A.

[0019] Example 4 Under room temperature conditions, 20 ml of acetic acid, 5.0 g (content 87%) raw material A and 0.244 g catalyst Fe(NO3)3·9H2O were added to the reactor with stirring; air was introduced into the reactor to maintain the pressure at 0.15 MPa, the temperature was raised to 85°C for reaction, and the reaction was kept warm for 3.0 hours. After HPLC detection showed that the reaction was complete, the reaction solution was first hot filtered, the filtrate was collected, and then 20 g of water was dropwise added to the filtrate, and the temperature was slowly decreased to 5°C for crystallization. After the temperature was decreased to 1 hour, the crystal was kept warm for 1 hour, and 4.62 g of white solid was obtained by filtration. The purity was 98.3% as determined by HPLC, and the yield was 95.9% based on raw material A.

[0020] Example 5 The method of Example 1 was used to prepare pyraclostrobin, except that the reaction solvent was 20 ml of chloroacetic acid, the reaction pressure was 0.14 MPa, and the other steps were unchanged. The purity was 98.1% after testing, and the yield was 94.5% based on the raw material A.

[0021] Example 6 The method of Example 1 was used to prepare sulfonepyraclostrobin, except that the catalyst used was 0.001 mol of ferric acetate, the reaction pressure was 0.18 MPa, and the other steps remained unchanged. The purity was 98% after testing, and the yield was 93.5% based on the raw material A.

[0022] Example 7 The method of Example 1 was used to prepare pyraclostrobin, except that the reaction temperature was 70° C., the reaction pressure was 0.25 MPa, and the other steps remained unchanged. The purity was 98.1% after testing, and the yield was 95.5% based on the raw material A.

[0023] Example 8 The method of Example 1 was used to prepare sulfonepyraclostrobin, except that the reaction temperature was 80°C, the reaction catalyst was 0.001 mol ferric bromide, and the other steps were unchanged. The purity was 98.1% after testing, and the yield was 93.5% based on the raw material A.

[0024] Comparative Example 1 The method of Example 1 was used to prepare pyraclostrobin, except that no catalyst was added, the reaction temperature was 80° C., and the other steps were unchanged. After 3 h of reaction, the raw material did not react. After the reaction was extended for 12 h, there was still no reaction, and the experiment was stopped.

[0025] The present invention has been described in detail through preferred embodiments. However, through the study of the foregoing, changes and additions to the various embodiments are also obvious to those of ordinary skill in the art. The applicant intends that all these changes and additions fall within the scope of protection of the claims of the present invention. The terms used herein are only for illustration of specific embodiments and are not intended to limit the present invention. Unless otherwise defined, all terms (including technical terms and scientific terms) used herein are the same as those understood by those of ordinary skill in the art to which the present invention belongs. Any modification and improvement of this product, and the replacement and use of similar or similar substances within the scope or category of the patent, are all within the scope of protection of the present invention.

Claims

1. A method for synthesizing sulfonepyraclostrobin, characterized in that: Using raw material A and air as raw materials, an oxidation reaction occurs under the catalysis of Fe (III) catalyst to obtain sulfonepyraclostrobin; the reaction formula is as follows: 。 2. The synthesis method according to claim 1, characterized in that: The Fe(III) catalyst is a trivalent iron salt.

3. The synthesis method according to claim 2, characterized in that: The Fe(III) catalyst is at least one of Fe(NO3)3·9H2O, Fe(NO3)3, Fe(OAc)3, FeCl3, Fe2(SO4)3, and FeBr3.

4. The synthesis method according to claim 1, 2 or 3, characterized in that: The molar ratio of raw material A to Fe(III) catalyst is 1:1% to 15%.

5. The synthesis method according to claim 1, 2 or 3, characterized in that: During the reaction, the air pressure in the system is 0.11-0.3 MPa.

6. The synthesis method according to claim 1, 2 or 3, characterized in that: The reaction temperature is 60-100°C.

7. The synthesis method according to claim 6, characterized in that: The reaction time is less than 4h.

8. The synthesis method according to claim 1, 2 or 3, characterized in that: The reaction is carried out in a solvent.

9. The synthesis method according to claim 8, characterized in that: The solvent is at least one of acetic acid, chloroacetic acid, trifluoroacetic acid, difluoroacetic acid and propionic acid.

10. The synthesis method according to claim 8, characterized in that: During the reaction, raw material A, catalyst and solvent are mixed, then air is introduced and the temperature is raised to the reaction temperature to react.

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