Synthesis method of pyroxasulfone

Abstract

The invention belongs to the technical field of organic synthesis of pesticides, and discloses a synthesis method of pyroxasulfone. The synthesis method of pyroxasulfone comprises the following steps: taking an intermediate A as shown in a formula (I) and a sulfonating agent, and adding a catalyst for reaction to obtain an intermediate B as shown in a formula (II); taking the intermediate B and an intermediate C as shown in a formula (III), and reacting under an alkaline condition to obtain pyroxasulfone. According to the synthesis method of pyroxasulfone, reaction steps are reduced, and the process duration and the production period of pyroxasulfone are greatly shortened; the used raw materials are low in cost and easy to obtain, the reaction conditions are mild, and oxidants such as hydrogen peroxide are not needed; meanwhile, few three wastes are generated in the technological process, and the method is environmentally friendly, is suitable for green large-scale production, and is a green synthesis method which is efficient, environmentally friendly and easy to control.

Description

Technical Field

[0001] The invention relates to the technical field of organic synthesis of pesticides, and in particular to a method for synthesizing pyraclostrobin. Background Art

[0002] Sulfonepyraclostrobin is a pre-emergence soil treatment agent developed by Kuibo Chemical Co., Ltd., which shows significant advantages and wide applicability in the agricultural field. Sulfonepyraclostrobin can be safely used in a variety of crop fields such as corn, cotton, peanuts, wheat, sunflowers, etc.; due to its broad spectrum of weed control, high activity, low dosage, and good safety, it is considered to be the best agent for controlling resistant weeds such as rigid ryegrass in countries such as Australia. With the continuous advancement of agricultural technology and the growing demand for efficient and environmentally friendly herbicides, sulfonepyraclostrobin has gradually replaced widely used chloroacetamide herbicides such as acetochlor and isopropylamine. Its excellent performance and advantages make it an important force in the herbicide market, and it is expected to bring greater benefits and higher quality to agricultural production.

[0003] The synthesis of sulfonepyraclostrobin is a complicated process. In the existing synthesis method, sulfonepyraclostrobin is obtained by oxidation of intermediate I (3-[(5-difluoromethoxy-1-methyl-3-trifluoromethylpyrazol-4-yl)-methylthio]-4,5-dihydro-5,5-dimethyl-1,2-isoxazole) with an oxidant (see the reaction flow diagram). Figure 1 ), and the synthesis of intermediate I is the key step of the whole process, which is mainly composed of isoxazole ring fragments and pyrazole ring fragments. According to the difference between the intermediate isoxazole ring fragments and the pyrazole ring fragments, the synthesis method of intermediate I has the following four synthesis methods:

[0004] (1) [5,5-dimethyl-(4,5-dihydroisoxazol-3-yl)]thiocarboxamidine hydrochloride is prepared by reacting thiourea, 3-chloro-5,5-dimethyl-4,5-dihydroisoxazole and hydrochloric acid, and then reacting with N-methyl-3-trifluoromethyl-4-chloromethyl-5-difluoromethoxypyrazole in an alkaline environment to generate intermediate I, which is then oxidized to obtain sulfonepyraclostrobin (see the schematic diagram of the reaction flow chart). Figure 2 ). However, this route uses 3-chloro-5,5-dimethyl-4,5-dihydroisoxazole to catalyze salt formation with thiourea and inorganic acid to prepare [5,5-dimethyl-(4,5-dihydroisoxazol-3-yl)]thiocarboxamidine hydrochloride. On the one hand, it requires the use of multiple solvents, which is complicated to operate and difficult to recover and apply the solvent. On the other hand, in order to increase the reaction rate, a large amount of hydrochloric acid is added to this method, which is not conducive to large-scale industrial production.

[0005] (2) 3-chloro-5,5-dimethyl-4,5-dihydroisoxazole and sodium methyl mercaptan aqueous solution are used as raw materials, reacted in DMF at room temperature, extracted, dried, concentrated, and then oxidized with hydrogen peroxide or m-chloroperbenzoic acid, and then N-methyl-3-trifluoromethyl-4-bromomethyl-5-difluoromethoxypyrazole is added with a mixed solution of thiourea and hydrochloric acid in ethanol as a solvent, and stirred at room temperature to obtain intermediate I, which is oxidized to obtain sulfonepyraclostrobin (see the schematic diagram of the reaction flow chart). Figure 3 ). The reaction conditions of this route are mild and the intermediates are highly active. However, expensive NBS is used as a bromination reagent in the synthesis process, which improves the reaction activity but greatly increases the cost of raw materials. In addition, this route has problems such as too long synthesis steps, low method yield, and many subsequent reaction by-products that are difficult to separate, making it unsuitable for industrial production.

[0006] (3) N-methyl-3-trifluoromethyl-4-chloromethyl-5-difluoromethoxypyrazole reacts with potassium thioacetate in ethanol as solvent, and then directly reacts with 3-chloro-5,5-dimethyl-4,5-dihydroisoxazole to obtain intermediate I, which is then oxidized to obtain sulfonepyraclostrobin (see the schematic diagram of the reaction flow chart). Figure 4 ). The potassium thioacetate used in this route is a non-industrial reagent, and the yield and purity are low due to the limitations of reaction conditions and reaction mechanism during the combination with the pyrazole ring fragment, which affects the yield and quality of the final product sulfonepyraclostrobin.

[0007] (4) N-methyl-3-trifluoromethyl-4-bromomethyl-5-difluoromethoxypyrazole and sodium hydrosulfide remove one molecule of sodium chloride in an alkaline environment to generate a thiol-containing compound, which is then reacted with 3-chloro-5,5-dimethyl-4,5-dihydroisoxazole to obtain intermediate I, which is then oxidized to obtain sulfonepyraclostrobin (see the schematic diagram of the reaction flow). Figure 5 ). The thiol compound generated during the synthesis of this route is easily oxidized, resulting in a low yield during its combination with the isoxazole fragment; at the same time, the thiol compound generated has an unpleasant odor and toxicity, which can easily cause adverse effects on the production environment and operators, and there are great challenges in industrial production.

[0008] In summary, the above-mentioned different sulfonepyraclostrobin synthesis methods all generally have the problems of cumbersome synthesis steps, low reaction yield, high raw material cost or difficulty in synthesis, and are not conducive to industrial production. At the same time, in the oxidation process of intermediate I (sulfonepyraclostrobin key intermediate) to synthesize sulfonepyraclostrobin, it is easy to generate sulfoxide impurities that cannot be completely oxidized, resulting in a significant decrease in product yield and insufficient purity. Therefore, it is urgent to develop a more efficient, stable, green and environmentally friendly and easy-to-control sulfonepyraclostrobin synthesis method. Summary of the invention

[0009] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a method for synthesizing pyraclostrobin.

[0010] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0011] In a first aspect, the present invention provides a method for synthesizing sulfonepyraclostrobin, comprising the following steps:

[0012] (1) taking an intermediate A represented by formula (I) and a sulfonating agent, adding a catalyst to react, and obtaining an intermediate B represented by formula (II);

[0013] (2) taking the intermediate B and the intermediate C shown in formula (III), reacting them under alkaline conditions to obtain sulfonepyraclostrobin shown in formula (IV);

[0014]

[0015] In the formula (I) or (III), the X and / or the Y is a halogen or an organic sulfonate group.

[0016] In the synthesis method of sulfonepyraclostrobin of the present invention, a special sulfonating agent and intermediate A are used to remove one molecule of aldehyde under the action of a catalyst to synthesize intermediate B in one step (see the schematic diagram of the reaction mechanism Figure 7 ), and then react with intermediate C to synthesize a high-purity sulfonepyraclostrobin finished product. The synthesis method of the present invention reduces the reaction steps, greatly shortens the process time of sulfonepyraclostrobin, and the raw materials used are cheap and easy to obtain, the reaction conditions are mild, the process safety is good, no oxidants such as hydrogen peroxide are needed, the three wastes generated are small, and the wastewater does not contain oxidants, the post-treatment is simpler, and it is environmentally friendly and suitable for green large-scale production.

[0017] The purity of the sulfonepyraclostrobin synthesized by the method of the present invention is as high as 99%, and the sulfonepyraclostrobin finished product does not contain sulfoxide impurities or the content thereof is extremely low, thereby further improving the product yield and purity.

[0018] As a preferred embodiment of the synthesis method of sulfonepyraclostrobin of the present invention, the halogen is any one of chlorine, bromine and iodine; and the organic sulfonate group is a methanesulfonate group or a p-toluenesulfonate group.

[0019] In the synthesis method of sulfonepyraclostrobin of the present invention, the X substituent of the intermediate A is any one of chlorine, bromine, iodine, methanesulfonate and p-toluenesulfonate; the Y substituent of the intermediate C is any one of chlorine, bromine, iodine, methanesulfonate and p-toluenesulfonate.

[0020] As a preferred embodiment of the synthesis method of sulfonepyraclostrobin of the present invention, the structural formula of the sulfonating agent is:

[0021]

[0022] In the formula, M is any one of sodium, potassium, lithium, cesium, calcium, zinc and magnesium; and Z is any one of a hydroxyl group, an ether group and a C1-C8 ester group.

[0023] Preferably, the ether group is any one of a silyl ether group, a methyl ether group, and a benzyl ether group.

[0024] Preferably, the M is sodium; and the Z is hydroxyl.

[0025] As a preferred embodiment of the synthesis method of sulfonepyraclostrobin of the present invention, the catalyst is an iodine catalyst; the iodine catalyst is potassium iodide and / or sodium iodide.

[0026] Preferably, the iodine catalyst is potassium iodide.

[0027] As a preferred embodiment of the method for synthesizing sulfonepyraclostrobin of the present invention, in step (1), a solvent is further added to the reaction; the solvent is at least one of diethyl ether, tetrahydrofuran, chloroform, dichloromethane, dichloroethane, acetone, acetonitrile, N,N-dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone, and 1,4-dioxane.

[0028] Preferably, the solvent is dimethyl sulfoxide.

[0029] Preferably, the mass ratio of the intermediate A to the solvent is 1:(1-10).

[0030] Further preferably, the mass ratio of the intermediate A to the solvent is 1:(3-8).

[0031] More preferably, the mass ratio of the intermediate A to the solvent is 1:5.

[0032] As a preferred embodiment of the synthesis method of sulfonepyraclostrobin of the present invention, in step (1), the molar ratio of the intermediate A to the sulfonating agent is 1:(0.5-5); the molar ratio of the intermediate A to the catalyst is 1:(0.05-0.5).

[0033] Preferably, the molar ratio of the intermediate A to the sulfonating agent is 1:(1-3); the molar ratio of the intermediate A to the catalyst is 1:(0.08-0.2).

[0034] Further preferably, the molar ratio of the intermediate A to the sulfonating agent is 1:2; the molar ratio of the intermediate A to the catalyst is 1:0.1.

[0035] As a preferred embodiment of the synthesis method of sulfonepyraclostrobin of the present invention, in step (2), the alkaline condition is achieved by adding a base; the base is at least one of sodium carbonate, potassium carbonate, cesium carbonate, sodium bicarbonate, potassium bicarbonate, sodium hydroxide, potassium hydroxide, calcium hydroxide, lithium hydroxide, ammonia water, triethylamine, N,N-diisopropylethylamine, pyridine, ammonium bicarbonate, and sodium acetate.

[0036] Preferably, the base is potassium carbonate.

[0037] Preferably, the molar ratio of the intermediate A, intermediate C and base is 1:(1-3):(3-5).

[0038] Further preferably, the molar ratio of the intermediate A, intermediate C and base is 1:2:4.

[0039] As a preferred embodiment of the method for synthesizing sulfonepyraclostrobin of the present invention, in step (1), the reaction temperature is 0°C to 50°C, and the reaction time is 12h to 24h.

[0040] Preferably, in step (1), the reaction temperature is 25° C. and the reaction time is 18 h.

[0041] As a preferred embodiment of the method for synthesizing sulfonepyraclostrobin of the present invention, in step (2), the reaction temperature is 0°C to 50°C, and the reaction time is 1h to 24h.

[0042] Preferably, in step (2), the reaction temperature is 25° C. and the reaction time is 3 h.

[0043] Compared with the prior art, the beneficial effects of the present invention are as follows: first, the synthesis method of sulfonepyraclostrobin of the present invention reduces the reaction steps, greatly shortening the process time and production cycle of sulfonepyraclostrobin; second, the raw materials used in the synthesis method of the present invention are cheap and easily available, the reaction conditions are mild, and there is no need to use oxidants such as hydrogen peroxide, which not only improves the process safety of sulfonepyraclostrobin production, but also makes the generated waste free of oxidants, reducing the difficulty and cost of wastewater treatment; at the same time, the amount of three wastes (waste gas, wastewater and solid waste) generated in the entire process is small, which is environmentally friendly and suitable for green large-scale production; in addition, the synthesis method of the present invention will not generate excessive sulfoxide impurities in the sulfonepyraclostrobin finished product due to incomplete oxidation, further improving the product yield and purity. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a schematic diagram of the reaction process of sulfonepyraclostrobin, the background technology of the present invention;

[0045] Figure 2 It is a schematic diagram of the reaction process of sulfonepyraclostrobin, the background technology of the present invention;

[0046] Figure 3 It is a schematic diagram of the reaction process of sulfonepyraclostrobin, the background technology of the present invention;

[0047] Figure 4 It is a schematic diagram of the reaction process of sulfonepyraclostrobin, the background technology of the present invention;

[0048] Figure 5 It is a schematic diagram of the reaction process of sulfonepyraclostrobin, the background technology of the present invention;

[0049] Figure 6 is the structural formula of sulfonepyraclostrobin of the present invention;

[0050] Figure 7 Schematic diagram of the reaction mechanism of sulfonepyraclostrobin of the present invention;

[0051] Figure 8 This is a schematic diagram of the reaction process of sulfonepyraclostrobin according to an embodiment of the present invention;

[0052] Fig. 9 This is the HPLC spectrum of sulfonepyraclostrobin in Example 1 of the present invention;

[0053] Fig.10 This is the HPLC spectrum of sulfonepyraclostrobin in Example 2 of the present invention;

[0054] Fig.11 This is the HPLC spectrum of sulfonepyraclostrobin in Example 3 of the present invention;

[0055] Fig.12 The HPLC spectrum of sulfonepyraclostrobin of comparative example 1 of the present invention is shown in FIG. DETAILED DESCRIPTION

[0056] To better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments. It should be understood by those skilled in the art that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0057] The following is an elaboration in conjunction with specific embodiments to illustrate the practical effects of the solutions of the present invention.

[0058] Unless otherwise specified, the experimental methods used in the examples are all conventional methods; the materials, reagents, equipment, etc. used, unless otherwise specified, can be obtained from commercial sources.

[0059] The raw materials used in the following examples and comparative examples are described as follows, but are not limited to these materials:

[0060] Sodium formaldehyde sulfoxylate dihydrate, purchased from Anaiji;

[0061] 3-Bromo-5,5-dimethyl-4,5-dihydroisoxazole, CAS No.: 882697-80-5, purity: 97%, purchased from Bitartrate;

[0062] N-methyl-3-trifluoromethyl-4-chloromethyl-5-difluoromethoxypyrazole, CAS No.: 656825-76-2, purity: 98%, purchased from Bitartrum;

[0063] N-methyl-3-trifluoromethyl-4-bromomethyl-5-difluoromethoxypyrazole, CAS No.: 656825-78-4, purchased from Capot Chemical Co., Ltd.;

[0064] 3-Chloro-5,5-dimethyl-4,5-dihydroisoxazole and 3-[(5-difluoromethoxy-1-methyl-3-trifluoromethylpyrazol-4-yl)-methylthio]-4,5-dihydro-5,5-dimethyl-1,2-isoxazole were prepared by referring to the method of Chinese invention patent document CN111393427B.

[0065] Example 1: Synthesis of sulfonepyraclostrobin

[0066] (1) Add 138.1 g (1.0 mol) of sodium formaldehyde sulfoxylate dihydrate, 16.6 g (0.1 mol) of potassium iodide and 300 ml of DMSO into a reaction flask and stir at 23°C for 0.5 h. Slowly drop 67 g (0.50 mol) of 3-chloro-5,5-dimethyl-4,5-dihydroisoxazole into the reaction flask and continue stirring at 23°C for 8 h.

[0067] (2) After the sample is tested and found to be qualified, 276.4 g (2.0 mol) of potassium carbonate is added and stirred at 23° C. for 0.5 h, and 264.6 g (1.0 mol) of N-methyl-3-trifluoromethyl-4-chloromethyl-5-difluoromethoxypyrazole is added dropwise. After the addition, the mixture is reacted at 23° C. for 3 h.

[0068] (3) Add salt water and ethyl acetate to the reaction solution, separate the phases, extract the aqueous phase with ethyl acetate, dry, and concentrate to obtain a crude product, which is recrystallized to obtain sulfonepyraclostrobin with a yield of 94.6% and a purity of 99.91%, including 0.01% sulfoxide impurity.

[0069] The data of the nuclear magnetic resonance hydrogen spectrum of the obtained product sulfonepyraclostrobin are as follows:

[0070] 1 H NMR (400 MHz, CDCl 3 )δ:6.83(t,J=71.9Hz,1H),4.60(s,2H),3.88(s,3H),3.11(s,2H),1.52(s,6H).

[0071] Example 2: Synthesis of sulfonepyraclostrobin

[0072] (1) Add 116 g (0.84 mol) of sodium formaldehyde sulfoxylate dihydrate, 13.9 g (0.08 mol) of potassium iodide and 270 ml of DMSO into a reaction flask and stir at 23°C for 0.5 h. Slowly drop 74.8 g (0.42 mol) of 3-bromo-5,5-dimethyl-4,5-dihydroisoxazole into the reaction flask and continue stirring at 23°C for 8 h.

[0073] (2) After the sample was tested and found to be qualified, 232.2 g (1.68 mol) of potassium carbonate was added and stirred at 23° C. for 0.5 h, and 259.6 g (0.84 mol) of N-methyl-3-trifluoromethyl-4-bromomethyl-5-difluoromethoxypyrazole was added dropwise. After the addition, the mixture was reacted at 23° C. for 3 h.

[0074] (3) Add salt water and ethyl acetate to the reaction solution, separate the phases, extract the aqueous phase with ethyl acetate, dry, and concentrate to obtain a crude product, which is recrystallized to obtain sulfonepyraclostrobin. The yield is 95.7%, the purity is 99.88%, and no sulfoxide impurity is detected.

[0075] Example 3: Synthesis of sulfonepyraclostrobin

[0076] (1) Add 69 g (0.5 mol) of sodium formaldehyde sulfoxylate dihydrate, 22 g (0.55 mol) of sodium hydroxide and 200 g of water into a reaction flask, and cool the resulting clear solution to below 3°C. Add 43.2 g (0.55 mol) of acetyl chloride dropwise. After the addition is complete, heat the resulting concentrated slurry to room temperature and continue stirring for 3 h. Filter the solid, wash the solid with a saturated saline solution and ethyl acetate, filter and dry in a vacuum oven at 45°C for 18 h to obtain the target compound 1-(acetoxy)-sodium methanesulfinate as a white solid.

[0077] (2) 70.5 g (0.44 mol) of sodium 1-(acetoxy)-methanesulfinate, 7 g (0.04 mol) of potassium iodide and 100 ml of THF were added to a reaction flask and stirred at 35° C. for 0.5 h. 39.2 g (0.22 mol) of 3-bromo-5,5-dimethyl-4,5-dihydroisoxazole was slowly dripped into the reaction flask and stirred at 35° C. for 8 h.

[0078] (3) After the sample is tested and found to be qualified, 40 g (1.0 mol) of sodium hydroxide and 100 g of water are added and stirred at 35° C. for 2 h, and 68 g (0.84 mol) of N-methyl-3-trifluoromethyl-4-bromomethyl-5-difluoromethoxypyrazole is added dropwise. After the addition, the mixture is reacted at 35° C. for 3 h.

[0079] (4) Add salt water and ethyl acetate to the reaction solution, separate the phases, extract the aqueous phase with ethyl acetate, dry, and concentrate to obtain a crude product, which is recrystallized to obtain sulfonepyraclostrobin with a yield of 94.2% and a purity of 99.57%, including 0.01% sulfoxide impurity.

[0080] Example 4: Synthesis of sulfonepyraclostrobin

[0081] The only difference between the synthesis method of sulfonepyraclostrobin described in this embodiment and that in Example 1 is that the molar ratio of 3-chloro-5,5-dimethyl-4,5-dihydroisoxazole to sodium formaldehyde sulfoxylate dihydrate is 1:1, the yield of sulfonepyraclostrobin is 81.2%, and the purity is 97.6%.

[0082] Example 5: Synthesis of sulfonepyraclostrobin

[0083] The only difference between the synthesis method of sulfonepyraclostrobin described in this embodiment and that in Example 1 is that the molar ratio of 3-chloro-5,5-dimethyl-4,5-dihydroisoxazole to sodium formaldehyde sulfoxylate dihydrate is 1:3, the yield of sulfonepyraclostrobin is 93.5%, and the purity is 98.1%.

[0084] Example 6: Synthesis of sulfonepyraclostrobin

[0085] The only difference between the synthesis method of sulfonepyraclostrobin described in this embodiment and that in Example 1 is that the molar ratio of 3-chloro-5,5-dimethyl-4,5-dihydroisoxazole to sodium formaldehyde sulfoxylate dihydrate is 1:5, the yield of sulfonepyraclostrobin is 90.9%, and the purity is 98.5%.

[0086] Example 7: Synthesis of sulfonepyraclostrobin

[0087] The only difference between the synthesis method of sulfonepyraclostrobin described in this embodiment and that in Example 1 is that the molar ratio of 3-chloro-5,5-dimethyl-4,5-dihydroisoxazole to sodium formaldehyde sulfoxylate dihydrate is 1:0.5, the yield of sulfonepyraclostrobin is 47.6%, and the purity is 93.8%.

[0088] Example 8: Synthesis of sulfonepyraclostrobin

[0089] The only difference between the synthesis method of sulfonepyraclostrobin described in this embodiment and that in Example 1 is that the molar ratio of 3-chloro-5,5-dimethyl-4,5-dihydroisoxazole to potassium carbonate is 1:3, the yield of sulfonepyraclostrobin is 92.6%, and the purity is 99.1%.

[0090] Example 9: Synthesis of sulfonepyraclostrobin

[0091] The only difference between the synthesis method of sulfonepyraclostrobin described in this example and that in Example 1 is that the molar ratio of 3-chloro-5,5-dimethyl-4,5-dihydroisoxazole to potassium carbonate is 1:5, the yield of sulfonepyraclostrobin is 92.2%, and the purity is 98.9%.

[0092] Comparative Example 1: Synthesis of sulfonepyraclostrobin

[0093] (1) At 25°C, 25 g (0.07 mol) of intermediate I (3-[(5-difluoromethoxy-1-methyl-3-trifluoromethylpyrazol-4-yl)-methylthio]-4,5-dihydro-5,5-dimethyl-1,2-isoxazole, purity 97.8%) was dissolved in 60 mL of methanol, and then 1.2 g of sodium tungstate dihydrate (3.5 mmol) and 0.5 mL of concentrated sulfuric acid (98%, 7 mmol) were added to the reaction, and finally 26 g of hydrogen peroxide (31%, 0.21 mol) was added dropwise. After the addition was completed, stirring was continued at 25°C for 5 hours, and the reaction was monitored by liquid phase;

[0094] (2) After the reaction is completed, 20 mL of water is added to the reaction mixture and stirring is continued at 0°C. The product is precipitated and finally filtered and the filter cake is washed twice with 20 mL of cold methanol to obtain a white solid of sulfonepyraclostrobin with a yield of 76% and a purity of 92.73%, of which the sulfoxide impurity is 4.55%.

[0095] The specific reaction chemical formula is shown below:

[0096]

[0097] Comparative Example 2: Synthesis of sulfonepyraclostrobin

[0098] The only difference between the synthesis method of sulfonepyraclostrobin described in this comparative example and that in Example 1 is that the molar ratio of 3-chloro-5,5-dimethyl-4,5-dihydroisoxazole to sodium formaldehyde sulfoxylate dihydrate is 1:8, the yield of sulfonepyraclostrobin is 74.7%, and the purity is 89.9%.

[0099] Comparative Example 3: Synthesis of sulfonepyraclostrobin

[0100] The only difference between the synthesis method of sulfonepyraclostrobin described in this comparative example and that in Example 1 is that the molar ratio of 3-chloro-5,5-dimethyl-4,5-dihydroisoxazole to potassium carbonate is 1:1, the yield of sulfonepyraclostrobin is 72.8%, and the purity is 91.3%.

[0101] Comparative Example 4: Synthesis of sulfonepyraclostrobin

[0102] The only difference between the synthesis method of sulfonepyraclostrobin described in this comparative example and that in Example 1 is that the molar ratio of 3-chloro-5,5-dimethyl-4,5-dihydroisoxazole to potassium carbonate is 1:8, the yield of sulfonepyraclostrobin is 71.5%, and the purity is 87.5%.

[0103] It can be seen from the above examples that the yield of the synthesis method of sulfonepyraclostrobin of the present invention is greater than 94%, the purity of the obtained sulfonepyraclostrobin is greater than 99%, and the content of sulfoxide impurities in the finished product is low. However, the test results of sulfonepyraclostrobin obtained by oxidation of intermediate I with an oxidant in Comparative Example 1 show that the sulfoxide impurities in the sulfonepyraclostrobin obtained by this method are high and the yield is low.

[0104] The synthesis method of sulfonepyraclostrobin of the present invention reduces the reaction steps, greatly shortens the process time and production cycle of sulfonepyraclostrobin; the raw materials used are cheap and easily available, the reaction conditions are mild, and there is no need to use oxidants such as hydrogen peroxide; at the same time, less three wastes are generated in the process, which is friendly to the environment, the obtained product has high yield and high purity, is suitable for green large-scale production, and is an efficient, environmentally friendly and easy-to-control green synthesis method.

[0105] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A method for synthesizing sulfonepyraclostrobin, characterized in that: The following steps are involved: (1) taking an intermediate A represented by formula (I) and a sulfonating agent, adding a catalyst to react, and obtaining an intermediate B represented by formula (II); (2) taking the intermediate B and the intermediate C shown in formula (III), reacting them under alkaline conditions to obtain sulfonepyraclostrobin shown in formula (IV); Wherein, X and / or Y in the formula (I) or (III) is a halogen or an organic sulfonate group.

2. The method for synthesizing sulfonepyraclostrobin according to claim 1, characterized in that: The halogen is any one of chlorine, bromine and iodine; the organic sulfonate group is a methanesulfonate group or a p-toluenesulfonate group.

3. The method for synthesizing sulfonepyraclostrobin according to claim 1, characterized in that: The structural formula of the sulfonating agent is: In the formula, M is any one of sodium, potassium, lithium, cesium, calcium, zinc and magnesium; and Z is any one of hydroxyl, ether and C1-C8 ester.

4. The method for synthesizing sulfonepyraclostrobin according to claim 1, characterized in that: The catalyst is an iodine catalyst; the iodine catalyst is potassium iodide and / or sodium iodide.

5. The method for synthesizing sulfonepyraclostrobin according to claim 1, characterized in that: In step (1), a solvent is further added to the reaction; the solvent is at least one of diethyl ether, tetrahydrofuran, chloroform, dichloromethane, dichloroethane, acetone, acetonitrile, N,N-dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone, and 1,4-dioxane.

6. The method for synthesizing sulfonepyraclostrobin according to claim 5, characterized in that: The mass ratio of the intermediate A to the solvent is 1:(1-10).

7. The method for synthesizing sulfonepyraclostrobin according to claim 1, characterized in that: In step (1), the molar ratio of the intermediate A to the sulfonating agent is 1:(0.5-5); the molar ratio of the intermediate A to the catalyst is 1:(0.05-0.5).

8. The method for synthesizing sulfonepyraclostrobin according to claim 7, characterized in that: The molar ratio of the intermediate A to the sulfonating agent is 1:(1-3); the molar ratio of the intermediate A to the catalyst is 1:(0.08-0.2).

9. The method for synthesizing sulfonepyraclostrobin according to claim 1, characterized in that: In step (2), the alkaline condition is achieved by adding a base; the base is at least one of sodium carbonate, potassium carbonate, cesium carbonate, sodium bicarbonate, potassium bicarbonate, sodium hydroxide, potassium hydroxide, calcium hydroxide, lithium hydroxide, ammonia water, triethylamine, N,N-diisopropylethylamine, pyridine, ammonium bicarbonate, and sodium acetate.

10. The method for synthesizing sulfonepyraclostrobin according to claim 9, characterized in that: The molar ratio of the intermediate B, the intermediate C and the base is 1:(1-3):(3-5).

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