Preparation method of kresoxim-methyl

Abstract

The invention relates to the technical field of chemical production, and particularly discloses a preparation method of kresoxim-methyl. According to the method, the crystallization mother liquor of (E)-2-(2 '-bromomethyl phenyl)-methoxyiminoacetic acid methyl ester is taken as a raw material, and the content of impurities in the crystallization mother liquor is effectively reduced through hydrogen peroxide oxidation impurity removal, so that a reaction system for subsequently preparing kresoxim-methyl is relatively pure, and the treatment difficulty after reaction is reduced; then, a quaternary ammonium salt catalyst is selected as a catalyst for the condensation reaction, and a reaction solvent is replaced by a polar solvent, so that the selectivity and the conversion rate of the condensation reaction can be effectively improved, side reactions are reduced, and the yield and the purity of kresoxim-methyl are improved. According to the method, resource utilization of the crystallization mother liquor is achieved, raw material consumption is reduced, waste emission is reduced, meanwhile, the trend of global green chemistry and sustainable development is met, and a powerful guarantee is provided for long-term stable development of enterprises.

Description

Technical Field

[0001] The invention relates to the technical field of chemical production, and in particular to a method for preparing kresoxim-methyl. Background Art

[0002] Kresoxim-methyl, also known as phenoxystrobin and phenoxythrin, has the chemical name (E)-2-methoxyimino-[2'-(o-methylphenoxymethyl)phenyl]acetic acid methyl ester and the English name Kresoxim-methyl. It is the earliest commercially developed methoxyacrylate fungicide variety. It has the advantages of strong systemicity, high activity and long lasting effect. It has excellent prevention and control effects on various fungal diseases such as powdery mildew, rust and downy mildew. It has been widely used in agricultural production and the market demand continues to grow.

[0003] At present, there are many studies on the process of synthesizing kresoxim-methyl, including (E)-2-(2'-halogenated methylphenyl)-methoxyiminoacetic acid methyl ester process, phthalide process, o-halogenated methyl halogenated benzene process, 3-isochromanone process, etc. Among them, the o-halogenated methyl halogenated benzene process is relatively complicated and has a low yield, which is not suitable for industrial production; the 3-isochromanone process has a high raw material price and a generally low conversion rate, and has weak market competitiveness; the (E)-2-(2'-halogenated methylphenyl)-methoxyiminoacetic acid methyl ester process, especially the condensation reaction of (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester with o-cresol, has a high conversion rate, but the process steps are complicated, and a high content of dibrominated impurities will be produced during the bromination process, which is difficult to separate. Therefore, the phthalide process is the mainstream production process for synthesizing kresoxim-methyl at present. This process route does not require expensive bromination reagents, and at the same time, there is no problem of generating dihalogenated byproducts during the benzyl halogenation process. However, the main disadvantage of this process is that the raw material methoxyamine hydrochloride is expensive, resulting in high costs. Therefore, it is necessary to develop a more economical and simpler process for producing kresoxim-methyl. Summary of the invention

[0004] Aiming at the problems of high production cost, complicated operation steps, low yield and purity of products in the existing method for synthesizing kresoxim-methyl, the present invention provides a method for preparing kresoxim-methyl.

[0005] In order to solve the above technical problems, the technical solution provided by the present invention is:

[0006] A method for preparing kresoxim-methyl, wherein the reaction raw material is the crystallization mother liquor of (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester obtained by separating (E)-2-(2'-methylphenyl)-methoxyiminoacetic acid methyl ester through bromination reaction, and the preparation method comprises the following steps:

[0007] Step a, removing the solvent from the crystallization mother liquor of (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester, adding alkyl halide to dissolve, then adding hydrogen peroxide to carry out oxidation reaction, standing and separating the liquids to obtain a first oil phase; adding a reducing substance to the first oil phase to remove residual hydrogen peroxide, then removing the solvent again, adding a polar solvent to dissolve, to obtain a pretreatment liquid,

[0008] Step b, adding o-methylphenol, alkali and quaternary ammonium salt catalyst to the pretreatment liquid, heating to carry out condensation reaction, desolventizing the reaction liquid, then adding alkyl halide and water to dissolve, adjusting the pH of the system to weak alkalinity, standing and separating the liquids to obtain a second oil phase;

[0009] Step c, adding mesoporous activated carbon to the second oil phase for decolorization, solid-liquid separation, desolventizing the obtained filtrate, adding an alcohol solvent to dissolve, cooling and crystallizing to obtain kresoxim-methyl.

[0010] In actual production, the conversion rate of the reaction of (E)-2-(2'-methylphenyl)-methoxyiminoacetic acid methyl ester as raw material and (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester through catalytic bromination is high, and a high content of the product remains in the crystallization mother liquor after the product is separated (the content of the product in the mother liquor accounts for about 15%-25% of the theoretical output). If it is directly discarded, it will not only cause a waste of resources, but also increase the cost of environmental protection treatment. If it is used as a resource, the problem is that the crystallization mother liquor after the product is separated is not only dark in color, but also contains more impurities, such as (E)-2-(2',2'-dibromomethylphenyl)-methoxyiminoacetic acid methyl ester and (E)-2-(2'-methylphenyl)-methoxyiminoacetic acid methyl ester, because the properties of the impurities are similar to (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester, they dissolve in each other and are difficult to separate by conventional extraction or crystallization means.

[0011] Specifically, the crystallization mother liquor of (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester described in the present invention mainly contains the product (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester, the reaction raw materials (E)-2-(2'-methylphenyl)-methoxyiminoacetic acid methyl ester, (E)-2-(2',2'-dibromomethylphenyl)-methoxyiminoacetic acid methyl ester (referred to as dibromo product), solvent, catalyst azobisisobutyronitrile and a small amount of other impurities.

[0012] Compared with the prior art, the method for preparing kresoxim-methyl provided by the invention uses the crystallization mother liquor of (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester as a raw material, removes impurities by oxidation with hydrogen peroxide, and effectively reduces the content of impurities in the crystallization mother liquor, so that the reaction system for preparing kresoxim-methyl in the subsequent step is relatively pure, and the difficulty of post-reaction treatment is reduced; then, by selecting a quaternary ammonium salt catalyst as a catalyst for the condensation reaction, and replacing the reaction solvent with a polar solvent, the selectivity and conversion rate of the condensation reaction can be effectively improved, the occurrence of side reactions can be reduced, and the yield and purity of kresoxim-methyl can be improved; finally, after adding a halogenated alkane and water to the reaction solution for extraction and desalination, mesoporous activated carbon is added and the temperature is reduced for crystallization to further remove impurities, thereby ensuring the purity of the prepared kresoxim-methyl.

[0013] The invention uses the crystallization mother liquor of (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester as a raw material, and prepares high-value kresoxim-methyl through the above process, thereby realizing the resource utilization of the crystallization mother liquor of (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester, reducing the consumption of raw materials and the discharge of wastes, and also conforming to the trend of global green chemistry and sustainable development, and providing a strong guarantee for the long-term stable development of enterprises.

[0014] It should be noted that the preparation process of the crystallization mother liquor of (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester in the present invention can be a conventional process in the art. As long as (E)-2-(2'-methylphenyl)-methoxyiminoacetic acid methyl ester is used as a raw material, catalytic halogenation, crystallization and separation are performed to obtain the crystallization mother liquor of (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester, it can be used as the reaction raw material for preparing kresoxim-methyl in the present invention.

[0015] Specifically, it can be synthesized and separated by referring to "Study on the Synthesis Process of (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester" ("Fine Chemical Intermediates" published in 2016).

[0016] Furthermore, in step a, the alkyl halide is one or both of dichloromethane and dichloroethane.

[0017] Furthermore, in step a, the amount of the alkyl halide added is 0.75-1 times the mass of the crystallization mother liquor of (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester.

[0018] The preferred alkyl halide is used as a solvent, which can fully dissolve (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester and is beneficial to improving the efficiency of the subsequent static separation.

[0019] Furthermore, in step a, the molar ratio of H2O2 in the hydrogen peroxide to (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester in the crystallization mother liquor of (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester is 0.05:1-0.25:1.

[0020] Furthermore, in step a, the temperature of the oxidation reaction is 20°C-40°C, and the time is 1h-2h.

[0021] By using hydrogen peroxide to pre-oxidize the crystallization mother liquor at a specific temperature, most of the colored impurities in the crystallization mother liquor can be oxidized and removed, thereby improving the purity of the crystallization mother liquor.

[0022] Furthermore, in step a, the reducing substance is a sodium sulfite solution with a mass concentration of 8%-12%.

[0023] It should be noted that the amount of the reducing substance added is based on the amount by which the KI-starch test paper does not turn blue.

[0024] Furthermore, in step a, the polar solvent is at least one of N,N-dimethylformamide, acetonitrile or dimethyl sulfoxide, preferably N,N-dimethylformamide or acetonitrile.

[0025] Furthermore, in step a, the amount of the polar solvent added is 0.6-0.7 times the mass of the crystallization mother liquor of (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester.

[0026] Furthermore, in step b, the base is at least one of sodium methoxide, potassium carbonate, potassium methoxide, sodium ethoxide, potassium ethoxide or sodium carbonate, preferably sodium methoxide or potassium carbonate.

[0027] Furthermore, in step b, the quaternary ammonium salt catalyst is at least one of tetrabutylammonium bromide, benzyltriethylammonium chloride, dodecyltrimethylammonium chloride or hexadecyltrimethylammonium chloride, preferably tetrabutylammonium bromide or dodecyltrimethylammonium chloride.

[0028] The preferred polar solvent and catalyst can improve the selectivity and conversion rate of the condensation reaction, thereby improving the yield and purity of kresoxim-methyl and reducing the difficulty of post-processing.

[0029] Furthermore, in step b, the alkyl halide is one or both of dichloromethane and dichloroethane.

[0030] Furthermore, in step b, the temperature of the condensation reaction is 30°C-60°C.

[0031] The condensation reaction is terminated when the content of (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester in the system is less than 0.5%.

[0032] Furthermore, in step b, the weak alkalinity refers to a pH of 8-9.

[0033] Furthermore, in step b, the molar ratio of the o-methylphenol, the base, the quaternary ammonium salt catalyst and the (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester in the crystallization mother liquor of the (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester is (1-1.5):(0.75-1.5):(0.01-0.1):1.

[0034] Furthermore, in step b, the amount of the alkyl halide added is 3-6 times the mass of the (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester in the crystallization mother liquor of the (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester.

[0035] Furthermore, in step b, the amount of water added is 0.8-2.5 times the mass of (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester in the crystallization mother liquor of (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester.

[0036] It should be noted that in step b, alkyl halide is added to the aqueous phase obtained by standing and separating the liquids for extraction, and the oil phase obtained by the extraction and the oil phase obtained by standing and separating the liquids are combined to obtain a second oil phase.

[0037] Furthermore, in step c, the amount of mesoporous activated carbon added is 0.2%-1% of the mass of the second oil phase.

[0038] It should be noted that mesoporous activated carbon refers to activated carbon with a pore size between 2-50nm.

[0039] Furthermore, in step c, the bleaching temperature is 35°C-70°C, and the bleaching time is 0.5h-1h.

[0040] Selecting mesoporous activated carbon for decolorization at a specific temperature can further remove impurities such as colored substances in the reaction system and improve the purity of kresoxim-methyl.

[0041] Furthermore, in step c, the alcohol solvent is at least one of methanol or ethanol.

[0042] Furthermore, in step c, the amount of the alcohol solvent added is 3-5 times the mass of the (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester in the (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester reaction solution.

[0043] Furthermore, in step c, the dissolving temperature is 40°C-80°C.

[0044] Furthermore, in step c, a programmed cooling method is adopted, the temperature is lowered to -10°C-10°C at a rate of 10°C / h-15°C / h, and the temperature is kept for crystallization for 1h-2h.

[0045] The preferred crystallization solvent and crystallization conditions can make the impurities such as the raw material ((E)-2-(2'-methylphenyl)-methoxyiminoacetic acid methyl ester) and the dibromo compound ((E)-2-(2',2'-dibromomethylphenyl)-methoxyiminoacetic acid methyl ester) always dissolved in the system during the crystallization process without precipitation, and ensure that the kresoxim-methyl crystals are crystallized at a moderate speed, reduce the impurity inclusion in the crystals, and thus help to improve the yield and purity of the prepared kresoxim-methyl

[0046] As a specific embodiment of the present invention, the method for preparing kresoxim-methyl provided by the present invention further comprises step d: adding the kresoxim-methyl into an alcohol solvent for dissolution, cooling and crystallizing, solid-liquid separation, washing, and drying to obtain refined kresoxim-methyl.

[0047] Furthermore, in step d, the alcohol solvent is at least one of methanol or ethanol.

[0048] Furthermore, in step d, the mass ratio of the alcohol solvent to kresoxim-methyl is 2.8:1-3.3:1.

[0049] Furthermore, in step d, a programmed cooling method is adopted, the temperature is lowered to -10°C-10°C at a rate of 10°C / h-15°C / h, and the temperature is kept for crystallization for 1h-2h.

[0050] The preferred recrystallization conditions can further improve the purity of the prepared kresoxim-methyl.

[0051] It should be noted that, in each step of the present invention, the solvent in each system is removed by decompression desolventizing method.

[0052] The invention uses the crystallization mother liquor of (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester as a raw material, carries out condensation reaction with o-methylphenol and alkali under specific catalyst conditions after oxidation and impurity removal, replaces the solvent, adds mesoporous activated carbon for impurity removal, and the like, so as to prepare high-purity kresoxim-methyl with a high yield, realizes resource utilization of the crystallization mother liquor, reduces raw material consumption, thereby significantly reducing the cost of raw materials, and significantly reduces the increase of environmental protection costs caused by treating the crystallization mother liquor as hazardous waste, conforms to the trend of global green chemistry and sustainable development, has high economic and environmental benefits, and has extremely high promotion and application value. DETAILED DESCRIPTION

[0053] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0054] The crystallization mother liquor of (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester used in the following examples and comparative examples was prepared with reference to "Study on the Synthesis Process of (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester" (Fine Chemical Intermediates published in 2016), and the specific steps are as follows:

[0055] In a 1000mL four-necked bottle, add 87.2g (0.4mol) (E)-2-(2'-methylphenyl)-methoxyiminoacetic acid methyl ester, 400mL chlorobenzene, 64.2g (0.22mol) 1,3-dibromo-5,5-dimethylhydantoin and 6.6g azobisisobutyronitrile, mix well, heat to 60°C and keep the reaction for 2h, cool down, add 200g water for washing, add anhydrous sodium sulfate for drying, and desolventize under reduced pressure to obtain a yellow oil.

[0056] Add 200 mL of isopropyl ether to the above oil, stir to dissolve, cool to -5°C, stir to crystallize for 2 hours, filter to obtain (E)-2-(2',2'-dibromomethylphenyl)-methoxyiminoacetic acid methyl ester and crystallization mother liquor. Repeat the above experiment for 10 batches to prepare the crystallization mother liquor of (E)-2-(2',2'-dibromomethylphenyl)-methoxyiminoacetic acid methyl ester.

[0057] According to external standard quantification, the content of (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester in the crystallization mother liquor was 14.1%, the content of (E)-2-(2'-methylphenyl)-methoxyiminoacetic acid methyl ester was 6.3%, and the content of (E)-2-(2',2'-dibromomethylphenyl)-methoxyiminoacetic acid methyl ester was 5.5%.

[0058] Example 1

[0059] A method for preparing kresoxim-methyl comprises the following steps:

[0060] Step a, add the above 400g crystallization mother liquor into the reactor, wherein the mother liquor contains 0.197mol of (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester, 0.122mol of (E)-2-(2'-methylphenyl)-methoxyiminoacetic acid methyl ester, and 0.060mol of (E)-2-[(2',2'-dibromomethyl)phenyl]-methoxyiminoacetic acid methyl ester, desolventize the crystallization mother liquor at 60°C and -0.095MPa to remove the fraction, add 300g of dichloroethane to dissolve, and obtain a dark blue solution. Control the feed liquid temperature at 25°C, dropwise add 6g of 28% hydrogen peroxide (0.049mol), stir for 2h, stand for phase separation, and add the obtained oil 5 g (0.004 mol) of a sodium sulfite solution with a mass concentration of 10% was added to the phase, and the phases were allowed to stand for phase separation. The fractions without distillation were removed by decompression at 60°C and -0.095 MPa. 270 g of N,N-dimethylformamide, 30.0 g of o-methylphenol (content 99%, 0.275 mol), and 5.3 g of dodecyltrimethylammonium chloride (content 98%, 0.0197 mol) were added. The feed liquid temperature was controlled at 30°C. 49.6 g of sodium methoxide-methanol solution (content 30%, 0.276 mol) was added dropwise under stirring. After the addition was completed, the temperature was kept constant until the content of (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester was less than 0.5%, and the reaction was stopped to obtain a reaction solution.

[0061] Step b, the reaction solution is desolventized at 90 ° C and -0.095 MPa until no fraction is produced, 140 g of water and 282 g of dichloroethane are added, stirred, heated to 70 ° C, adjusted to 8-9 after dissolving, stirred for 0.5 h, re-measured pH is 8-9, allowed to stand for phase separation, 85 g of dichloroethane is added to the aqueous phase for extraction, the extract phase and the oil phase are combined, 4.4 g of mesoporous wood activated carbon is added, stirred at 60 ° C for decolorization for 0.5 h, filtered, the filtrate is distilled under reduced pressure at 70 ° C and -0.095 MPa until no fraction is produced, 200 g of methanol is added, the temperature is raised to 60 ° C, stirred to dissolve, cooled to -10 ° C at a rate of 15 ° C / h, stirred for crystallization for 1 h, filtered, washed with -10 ° C methanol until the filter cake is off-white, and 70.2 g of crude product of kystrobin is obtained;

[0062] Step c, adding 200g of methanol to the above-mentioned crude product of oxathiocarb, heating to 60°C, stirring to dissolve, cooling to 0°C at a rate of 15°C / h, stirring and crystallizing for 1h, filtering, eluting with 0°C methanol until the filter cake is white, and drying to obtain 59.7g of oxathiocarb product, with a total yield of 95.2% and a content of 98.3%.

[0063] Example 2

[0064] A method for preparing kresoxim-methyl comprises the following steps:

[0065] Step a, add the above 400g crystallization mother liquor into the reactor, wherein the mother liquor contains 0.197mol of (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester, 0.122mol of (E)-2-(2'-methylphenyl)-methoxyiminoacetic acid methyl ester, and 0.060mol of (E)-2-[(2',2'-dibromomethyl)phenyl]-methoxyiminoacetic acid methyl ester, desolventize the crystallization mother liquor under reduced pressure at 60°C and -0.095MPa until no fraction is extracted, add 300g of dichloroethane to dissolve, and obtain a dark blue solution, control the feed liquid temperature at 40°C, add 4.8g of 28% mass concentration of hydrogen peroxide (0.039mol) dropwise, and stir for 1h, The mixture was allowed to stand for phase separation, 5 g (0.004 mol) of a sodium sulfite solution with a mass concentration of 10% was added to the obtained oil phase, the mixture was allowed to stand for phase separation, and the mixture was desolventized at 60°C and -0.095 MPa until no fraction was recovered, 250 g of N,N-dimethylformamide, 25.8 g of o-methylphenol (content 99%, 0.236 mol), and 3.3 g (0.010 mol) of tetrabutylammonium bromide were added, the feed liquid temperature was controlled at 50°C, and 24.7 g of potassium carbonate (content 99%, 0.177 mol) was added under stirring. After the addition was completed, the temperature was kept constant until the content of (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester was less than 0.5%, and the reaction was stopped to obtain a reaction liquid;

[0066] Step b, desolventizing the reaction solution at 90°C and -0.095MPa until no fraction is produced, adding 45.2g of water and 169.2g of dichloroethane, stirring, heating to 70°C, adjusting the pH to 8-9 after dissolving, stirring for 0.5h, retesting the pH to be 8-9, standing for phase separation, adding 100g of dichloroethane to the aqueous phase for extraction, combining the extract phase and the oil phase, adding 2.0g of mesoporous wood activated carbon, stirring and decolorizing at 60°C for 1h, filtering, and distilling the filtrate under reduced pressure at 70°C and -0.095MPa until no fraction is produced, adding 250g of methanol, heating to 60°C, stirring to dissolve, cooling to 5°C at a rate of 15°C / h, stirring and crystallizing for 1h, filtering, washing with 5°C methanol until the filter cake is off-white, and obtaining 61.8g of crude product of kystrobin;

[0067] Step c, adding 200g of methanol to the above-mentioned crude product of oxathiocarb, heating to 60°C, stirring to dissolve, cooling to -5°C at a rate of 15°C / h, stirring and crystallizing for 1h, filtering, eluting with -5°C methanol until the filter cake is white, and drying to obtain 53.1g of oxathiocarb product, with a total yield of 84.5% and a content of 98.1%.

[0068] Example 3

[0069] A method for preparing kresoxim-methyl comprises the following steps:

[0070] Step a, add the above 400g crystallization mother liquor into the reactor, wherein the mother liquor contains 0.197mol of (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester, 0.122mol of (E)-2-(2'-methylphenyl)-methoxyiminoacetic acid methyl ester, and 0.060mol of (E)-2-[(2',2'-dibromomethyl)phenyl]-methoxyiminoacetic acid methyl ester, desolventize the crystallization mother liquor under the conditions of 60°C and -0.095MPa, remove the fraction without fraction, add 350g of dichloromethane to dissolve, and obtain a dark blue solution, control the feed liquid temperature at 35°C, add 1.2g of 28% mass concentration of hydrogen peroxide (0.0098mol) dropwise, stir for 2h, and stand for phase separation, 3.5 g (0.0028 mol) of a sodium sulfite solution with a mass concentration of 10% was added to the obtained oil phase, and the phases were allowed to stand for phase separation. The fractions were removed by desolventizing at 40° C. and -0.09 MPa, and 270 g of acetonitrile, 23.7 g (content 99%, 0.217 mol) of o-methylphenol, and 0.65 g (content 98%, 0.0024 mol) of dodecyltrimethylammonium chloride were added. The feed liquid temperature was controlled at 40° C., and 53.2 g (content 30%, 0.295 mol) of sodium methoxide-methanol solution was added dropwise under stirring. After the addition was completed, the temperature was kept constant until the content of (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester was less than 0.5%, and the reaction was stopped to obtain a reaction liquid.

[0071] Step b, the reaction solution is desolventized at 80 ° C and -0.095 MPa until no fraction is produced, 70 g of water and 300 g of dichloromethane are added, stirred, heated to 38 ° C, adjusted to 8-9 after dissolving, stirred for 0.5 h, re-measured pH is 8-9, allowed to stand for phase separation, 100 g of dichloromethane is added to the aqueous phase for extraction, the extract phase and the oil phase are combined, 5 g of mesoporous wood activated carbon is added, stirred at 35 ° C for 1 h for decolorization, filtered, the filtrate is distilled under reduced pressure at 60 ° C and -0.095 MPa until no fraction is produced, 250 g of ethanol is added, the temperature is raised to 70 ° C, stirred to dissolve, cooled to 0 ° C at a rate of 15 ° C / h, stirred for crystallization for 1 h, filtered, washed with 0 ° C ethanol until the filter cake is off-white, and 61.5 g of crude product of kresoxim-methyl is obtained;

[0072] Step c, adding 180g of ethanol to the above-mentioned crude product of oxathiocarb, heating to 50°C, stirring to dissolve, cooling to 0°C at a rate of 10°C / h, stirring and crystallizing for 1h, filtering, eluting with 0°C ethanol until the filter cake is white, and drying to obtain 54.2g of oxathiocarb product, with a yield of 86.1% and a content of 98.0%.

[0073] Example 4

[0074] A method for preparing kresoxim-methyl comprises the following steps:

[0075] Step a, add the above 400g crystallization mother liquor into the reactor, wherein the mother liquor contains 0.197mol of (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester, 0.122mol of (E)-2-(2'-methylphenyl)-methoxyiminoacetic acid methyl ester, and 0.060mol of (E)-2-[(2',2'-dibromomethyl)phenyl]-methoxyiminoacetic acid methyl ester, desolventize the crystallization mother liquor at 60°C and -0.095MPa under reduced pressure and extract no fraction, add 400g of dichloroethane to dissolve, and obtain a dark blue solution, control the feed liquid temperature at 40°C, add 3.6g of hydrogen peroxide (0.030mol) with a mass concentration of 28%, stir for 1h, and stand for separation. phase, add 5g (0.004mol) of sodium sulfite solution with a mass concentration of 10% to the obtained oil phase, stand for phase separation, desolventize and extract no fraction under 60°C and -0.095MPa conditions, add 270g of acetonitrile, 32.2g (content 99%, 0.295mol) of o-methylphenol, and 2.6g (content 98%, 0.0097mol) of dodecyltrimethylammonium chloride, control the feed liquid temperature at 60°C, and add 52.2g (content 30%, 0.29mol) of sodium methoxide-methanol solution dropwise under stirring, and after the addition is completed, keep the temperature in the middle and control until the content of (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester is less than 0.5%, stop the reaction, and obtain a reaction solution;

[0076] Step b, the reaction solution is desolventized at 90 ° C and -0.095 MPa until no fraction is produced, 100 g of water and 300 g of dichloroethane are added, stirred, heated to 60 ° C, adjusted to 8-9 after dissolving, stirred for 0.5 h, re-measured pH is 8-9, allowed to stand for phase separation, 50 g of dichloroethane is added to the aqueous phase for extraction, the extract phase and the oil phase are combined, 4.5 g of mesoporous wood activated carbon is added, stirred at 70 ° C for decolorization for 0.5 h, filtered, the filtrate is distilled under reduced pressure at 70 ° C and -0.095 MPa until no fraction is produced, 250 g of ethanol is added, the temperature is raised to 55 ° C, stirred to dissolve, cooled to 10 ° C at a rate of 10 ° C / h, stirred for crystallization for 2 h, filtered, washed with -10 ° C ethanol until the filter cake is off-white, and 58.3 g of crude product of kresoxim-methyl is obtained;

[0077] Step c, adding 180g of ethanol to the above-mentioned crude product of oxathiocarb, heating to 60°C, stirring to dissolve, cooling to 0°C at a rate of 10°C / h, stirring and crystallizing for 1h, filtering, eluting with 0°C ethanol until the filter cake is white, and drying to obtain 51.6g of oxathiocarb product, with a yield of 82.4% and a content of 98.5%.

[0078] Example 5

[0079] A method for preparing kresoxim-methyl comprises the following steps:

[0080] Step a, add the above 400g crystallization mother liquor into the reactor, wherein the mother liquor contains 0.197mol of (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester, 0.122mol of (E)-2-(2'-methylphenyl)-methoxyiminoacetic acid methyl ester, and 0.060mol of (E)-2-[(2',2'-dibromomethyl)phenyl]-methoxyiminoacetic acid methyl ester, desolventize the crystallization mother liquor at 60°C and -0.095MPa under reduced pressure and extract no fraction, add 300g of dichloroethane to dissolve, and obtain a dark blue solution, control the feed liquid temperature at 40°C, add 4.8g of 28% mass concentration of hydrogen peroxide (0.039mol) dropwise, stir for 1h, stand for phase separation, and then add 400g of dichloroethane to the reaction mixture. 5 g (0.004 mol) of a sodium sulfite solution with a mass concentration of 10% was added to the obtained oil phase, and the mixture was allowed to stand for phase separation. The mixture was desolventized at 60° C. and -0.095 MPa until no fraction was produced. 270 g of acetonitrile, 32.2 g (content 99%, 0.295 mol) of o-methylphenol and 3.8 g (content 99%, 0.012 mol) of tetrabutylammonium bromide were added. The temperature of the feed liquid was controlled at 30° C. A total of 27.5 g (content 99%, 0.197 mol) of potassium carbonate was added in five portions with stirring at an interval of 0.5 h. After the addition was completed, the temperature was kept constant until the content of (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester was less than 0.5%, and the reaction was stopped to obtain a reaction liquid.

[0081] Step b, the reaction solution is desolventized at 90 ° C and -0.095 MPa until no fraction is produced, 141 g of water and 250 g of dichloroethane are added, stirred, heated to 60 ° C, adjusted to 8-9 after dissolving, stirred for 0.5 h, re-measured pH is 8-9, allowed to stand for phase separation, 100 g of dichloroethane is added to the aqueous phase for extraction, the extract phase and the oil phase are combined, 3.5 g of mesoporous wood activated carbon are added, stirred at 60 ° C for decolorization for 1 h, filtered, the filtrate is distilled under reduced pressure at 70 ° C and -0.095 MPa until no fraction is produced, 220 g of ethanol is added, the temperature is raised to 65 ° C, stirred to dissolve, cooled to -10 ° C at a rate of 10 ° C / h, stirred for crystallization for 2 h, filtered, washed with -10 ° C ethanol until the filter cake is off-white, and 70.5 g of crude product of kresoxim-methyl is obtained;

[0082] Step c, adding 200g of ethanol to the above-mentioned crude product of oxathiocarb, heating to 60°C, stirring to dissolve, cooling to -5°C at a rate of 10°C / h, stirring and crystallizing for 1h, filtering, eluting with -5°C ethanol until the filter cake is white, and drying to obtain 60.1g of oxathiocarb product, with a yield of 95.7% and a content of 98.2%.

[0083] Comparative Example 1

[0084] This comparative example provides a method for preparing kresoxim-methyl, which is different from Example 1 in that the step of hydrogen peroxide oxidation and impurity removal in step a is omitted, and specifically comprises the following steps:

[0085] Step a, add the above 400g crystallization mother liquor into the reactor, wherein the mother liquor contains 0.197mol of (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester, 0.122mol of (E)-2-(2'-methylphenyl)-methoxyiminoacetic acid methyl ester, and 0.060mol of (E)-2-[(2',2'-dibromomethyl)phenyl]-methoxyiminoacetic acid methyl ester, desolvate the crystallization mother liquor under reduced pressure at 60°C and -0.095MPa, and extract the fraction without fraction, add 270g of N,N-dimethylformamide, 30.0g of o-cresol g (content 99%, 0.275 mol), 5.3 g (content 98%, 0.0197 mol) of dodecyltrimethylammonium chloride, control the feed liquid temperature at 30°C, add 49.6 g (content 30%, 0.276 mol) of sodium methoxide-methanol solution dropwise under stirring, and after the addition is complete, control the temperature during insulation until the content of (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester remains unchanged, detect the remaining 3.0%, add 10.5 g (content 30%, 0.058 mol) of sodium methoxide-methanol solution, and keep the temperature for 2 h to reach the reaction end point to obtain a reaction solution;

[0086] Step b, the reaction solution is desolventized at 90 ° C and -0.095 MPa until no fraction is produced, 140 g of water and 282 g of dichloroethane are added, stirred, heated to 70 ° C, adjusted to 8-9 after dissolving, stirred for 0.5 h, re-measured pH is 8-9, allowed to stand for phase separation, 85 g of dichloroethane is added to the aqueous phase for extraction, the extract phase and the oil phase are combined to obtain a black oil phase, 4.4 g of mesoporous wood activated carbon is added, 60 ° C is stirred for decolorization for 0.5 h, filtered, the filtrate is distilled under reduced pressure at 70 ° C and -0.095 MPa until no fraction is produced, 200 g of methanol is added, the temperature is raised to 60 ° C, stirred to dissolve, cooled to -10 ° C at a rate of 15 ° C / h, stirred for crystallization for 1 h, filtered, washed with -10 ° C methanol until the filter cake is off-white, and 55.2 g of crude product of kystrobin is obtained;

[0087] Step c, adding 200g of methanol to the above-mentioned crude product of oxathiocarb, heating to 60°C, stirring to dissolve, cooling to 0°C at a rate of 10°C / h, stirring and crystallizing for 1h, filtering, eluting with 0°C methanol until the filter cake is white, and drying to obtain 48.2g of oxathiocarb product, with a total yield of 74.8% and a content of 95.7%.

[0088] Comparative Example 2

[0089] This comparative example provides a method for preparing kresoxim-methyl, which is different from Example 1 in that the hydrogen peroxide oxidation impurity removal in Example 1 is replaced by mesoporous wood activated carbon impurity removal, and specifically comprises the following steps:

[0090] Step a, add the above 400g crystallization mother liquor into the reactor, wherein the mother liquor contains 0.197mol of (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester, 0.122mol of (E)-2-(2'-methylphenyl)-methoxyiminoacetic acid methyl ester, and 0.060mol of (E)-2-[(2',2'-dibromomethyl)phenyl]-methoxyiminoacetic acid methyl ester, add 4g of mesoporous wood activated carbon to the crystallization mother liquor, control the feed liquid temperature at 60°C, stir and decolorize for 1h, filter and remove carbon, and then desolventize and extract no fraction under the conditions of 60°C and -0.095MPa under reduced pressure, add 270g of N,N-dimethylformamide, 3 g of o-methylphenol, and 100g of methyl ether. 0.0g (content 99%, 0.275mol), 5.3g (content 98%, 0.0197mol) of dodecyltrimethylammonium chloride, control the feed liquid temperature at 30°C, add 49.6g (content 30%, 0.276mol) of sodium methoxide-methanol solution dropwise under stirring, after the addition is completed, keep warm and control until the content of (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester remains unchanged (HPLC content 4.3%), add 12.4g (content 30%, 0.069mol) of sodium methoxide-methanol solution, keep warm for 2h, control the content of (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester to <0.5%, and obtain a reaction solution;

[0091] Step b, the reaction solution is desolventized at 90 ° C and -0.095 MPa until no fraction is produced, 140 g of water and 282 g of dichloroethane are added, stirred, heated to 70 ° C, adjusted to 8-9 after dissolving, stirred for 0.5 h, re-measured pH is 8-9, allowed to stand for phase separation, 85 g of dichloroethane is added to the aqueous phase for extraction, the extract phase and the oil phase are combined, 4.4 g of mesoporous wood activated carbon is added, stirred at 60 ° C for decolorization for 0.5 h, filtered, the filtrate is distilled under reduced pressure at 70 ° C and -0.095 MPa until no fraction is produced, 200 g of methanol is added, the temperature is raised to 60 ° C, stirred to dissolve, cooled to -10 ° C at a rate of 15 ° C / h, stirred for crystallization for 1 h, filtered, washed with -10 ° C methanol until the filter cake is off-white, and 58.9 g of crude product of kresoxim-methyl is obtained;

[0092] Step c, adding 200g of methanol to the above-mentioned crude product of oxathiocarb, heating to 60°C, stirring to dissolve, cooling to 0°C at a rate of 15°C / h, stirring and crystallizing for 1h, filtering, eluting with 0°C methanol until the filter cake is white, and drying to obtain 56.6g of oxathiocarb product, with a total yield of 89.2% and a content of 97.2%.

[0093] Comparative Example 3

[0094] This comparative example provides a method for preparing kresoxim-methyl, which is different from Example 1 only in that the mesoporous wood activated carbon in step b is replaced with microporous wood activated carbon, and specifically comprises the following steps:

[0095] Step a is exactly the same as in Example 1;

[0096] Step b, the reaction solution is desolventized at 90 ° C and -0.095 MPa until no fraction is produced, 140 g of water and 282 g of dichloroethane are added, stirred, heated to 70 ° C, adjusted to pH 8-9 after dissolving, stirred for 0.5 h, re-measured pH is 8-9, allowed to stand for phase separation, 85 g of dichloroethane is added to the aqueous phase for extraction, the extract phase and the oil phase are combined, 4.4 g of microporous wood activated carbon is added, stirred at 60 ° C for decolorization for 0.5 h, filtered, the filtrate is distilled under reduced pressure at 70 ° C and -0.095 MPa until no fraction is produced, 200 g of methanol is added, the temperature is raised to 60 ° C, stirred to dissolve, cooled to -10 ° C at a rate of 15 ° C / h, stirred for crystallization for 1 h, filtered, washed with -10 ° C methanol until the filter cake is off-white, and 69.7 g of crude product of kresoxim-methyl is obtained;

[0097] Step c, adding 200g of methanol to the above-mentioned crude product of oxathiocarb, heating to 60°C, stirring to dissolve, cooling to 0°C at a rate of 15°C / h, stirring and crystallizing for 1h, filtering, eluting with 0°C methanol until the filter cake is off-white, and drying to obtain 59.3g of oxathiocarb product, with a total yield of 93.8% and a content of 97.5%.

[0098] Comparative Example 4

[0099] This comparative example provides a method for preparing kresoxim-methyl, which is different from Example 1 only in that the reaction solvent of the condensation reaction in step a is replaced by toluene, and the catalyst is replaced by tert-butylamine, and specifically comprises the following steps:

[0100] Step a, add the above 400g crystallization mother liquor into the reactor, wherein the mother liquor contains 0.197mol of (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester, 0.122mol of (E)-2-(2'-methylphenyl)-methoxyiminoacetic acid methyl ester, and 0.060mol of (E)-2-[(2',2'-dibromomethyl)phenyl]-methoxyiminoacetic acid methyl ester, desolventize the crystallization mother liquor under 60°C and -0.095MPa conditions without fraction extraction, add 300g of dichloroethane to dissolve, and obtain a dark blue solution, control the feed liquid temperature at 25°C, add 6g of 28% mass concentration of hydrogen peroxide (0.049mol) dropwise, stir for 2h, stand for phase separation, and add 10% mass concentration of sodium sulfite solution to the obtained oil phase for 5min. g (0.004 mol), allowed to stand for phase separation, desolventized at 60°C and -0.095 MPa to remove fractions, added with 270 g toluene, 30.0 g o-methylphenol (content 99%, 0.275 mol), and 6 g tert-butylamine, the feed liquid temperature was controlled at 30°C, and 49.6 g sodium methoxide-methanol solution (content 30%, 0.276 mol) was added dropwise with stirring. After the addition was completed, the temperature was kept constant until the content of (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester was less than 0.5%, and the content of kresoxim-methyl was less than 5%. Tests showed that the bromine in (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester was replaced by methoxy to become the impurity (E)-2-(2'-methoxymethylphenyl)-methoxyiminoacetic acid methyl ester.

[0101] Comparative Example 5

[0102] This comparative example provides a method for preparing kresoxim-methyl, which is different from Example 1 only in that the crystallization solvents in step b and step c are replaced with ester solvents, and specifically comprises the following steps:

[0103] Step a is exactly the same as in Example 1;

[0104] Step b, the reaction solution is desolventized at 90 ° C and -0.095 MPa until no fraction is produced, 140 g of water and 282 g of dichloroethane are added, stirred, heated to 70 ° C, adjusted to 8-9 after dissolving, stirred for 0.5 h, re-measured pH is 8-9, allowed to stand for phase separation, 85 g of dichloroethane is added to the aqueous phase for extraction, the extract phase and the oil phase are combined, 4.4 g of mesoporous wood activated carbon is added, 60 ° C is stirred for decolorization for 0.5 h, filtered, the filtrate is distilled under reduced pressure at 70 ° C and -0.095 MPa until no fraction is produced, 200 g of ethyl acetate is added, the temperature is raised to 60 ° C, stirred to dissolve, cooled to -10 ° C at a rate of 15 ° C / h, stirred for crystallization for 1 h, filtered, and the filter cake is washed with -10 ° C ethyl acetate to obtain 53.7 g of a brown-yellow crude product of kresoxim-methyl;

[0105] Step c, adding 200g of butyl acetate to the above-mentioned crude product of kresoxim-methyl, heating to 60°C, stirring to dissolve, cooling to 0°C at a rate of 15°C / h, stirring and crystallizing for 1h, filtering, eluting the filter cake with 0°C butyl acetate, and drying to obtain 38.2g of yellow kresoxim-methyl product, with a total yield of 58.4% and a content of 94.2%.

[0106] In summary, the present invention uses the crystallization mother liquor of (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester as a raw material to prepare a high-purity kresoxim-methyl product, realizes the resource utilization of the crystallization mother liquor of (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester, significantly reduces the cost of raw materials, and also significantly reduces the increase of environmental protection costs caused by treating the crystallization mother liquor as hazardous waste, meets the requirements of green chemical industry, and is of great significance for promoting the sustainable development of kresoxim-methyl.

[0107] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modification, equivalent substitution or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing kresoxim-methyl, characterized in that: The reaction raw material is the crystallization mother liquor of (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester obtained by separating (E)-2-(2'-methylphenyl)-methoxyiminoacetic acid methyl ester through bromination reaction. The preparation method comprises the following steps: Step a, removing the solvent from the crystallization mother liquor of (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester, adding alkyl halide to dissolve, then adding hydrogen peroxide to carry out oxidation reaction, standing and separating the liquids to obtain a first oil phase; adding a reducing substance to the first oil phase to remove residual hydrogen peroxide, then removing the solvent again, adding a polar solvent to dissolve, to obtain a pretreatment liquid, Step b, adding o-methylphenol, alkali and quaternary ammonium salt catalyst to the pretreatment liquid, heating to carry out condensation reaction, desolventizing the reaction liquid, then adding alkyl halide and water to dissolve, adjusting the pH of the system to weak alkalinity, standing and separating the liquids to obtain a second oil phase; Step c, adding mesoporous activated carbon to the second oil phase for decolorization, solid-liquid separation, desolventizing the obtained filtrate, adding an alcohol solvent for dissolution, cooling and crystallizing to obtain kresoxim-methyl.

2. The method for preparing kresoxim-methyl according to claim 1, wherein In step a, the alkyl halide is one or both of dichloromethane and dichloroethane; and / or In step a, the oxidation reaction temperature is 20°C-40°C and the time is 1h-2h; and / or In step a, the reducing substance is a sodium sulfite solution with a mass concentration of 8% to 12%; and / or In step a, the polar solvent is at least one of N,N-dimethylformamide, acetonitrile or dimethyl sulfoxide.

3. The method for preparing kresoxim-methyl according to claim 1 or 2, characterized in that: In step a, the amount of the alkyl halide added is 0.75-1 times the mass of the crystallization mother liquor of (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester; and / or In step a, the molar ratio of H2O2 in the hydrogen peroxide to (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester in the crystallization mother liquor of (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester is 0.05:1-0.25:1; and / or In step a, the amount of the polar solvent added is 0.6-0.7 times the mass of the crystallization mother liquor of (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester.

4. The method for preparing kresoxim-methyl according to claim 1, wherein In step b, the base is at least one of sodium methoxide, potassium carbonate, potassium methoxide, sodium ethoxide, potassium ethoxide or sodium carbonate; and / or In step b, the quaternary ammonium salt catalyst is at least one of tetrabutylammonium bromide, benzyltriethylammonium chloride, dodecyltrimethylammonium chloride or hexadecyltrimethylammonium chloride; and / or In step b, the alkyl halide is one or both of dichloromethane and dichloroethane.

5. The method for preparing kresoxim-methyl according to claim 1, wherein In step b, the condensation reaction temperature is 30°C-60°C; and / or In step b, the weak alkalinity refers to a pH of 8-9.

6. The method for preparing kresoxim-methyl according to claim 1, characterized in that: In step b, the molar ratio of the o-methylphenol, the base, the quaternary ammonium salt catalyst and the (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester in the crystallization mother liquor of the (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester is (1-1.5):(0.75-1.5):(0.01-0.1):1; and / or In step b, the amount of the alkyl halide added is 3-6 times the mass of the (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester in the crystallization mother liquor of the (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester; and / or In step b, the amount of water added is 0.8-2.5 times the mass of (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester in the crystallization mother liquor of (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester.

7. The method for preparing kresoxim-methyl according to claim 1, characterized in that: In step c, the amount of mesoporous activated carbon added is 0.2%-1% of the mass of the second oil phase; and / or In step c, the decolorization temperature is 35°C-70°C, and the decolorization time is 0.5h-1h; and / or In step c, the alcohol solvent is at least one of methanol or ethanol; and / or In step c, the amount of the alcohol solvent added is 3-5 times the mass of the (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester in the (E)-2-(2'-bromomethylphenyl)-methoxyiminoacetic acid methyl ester reaction solution.

8. The method for preparing kresoxim-methyl according to claim 1, characterized in that: In step c, the dissolving temperature is 40°C-80°C; and / or In step c, a programmed cooling method is adopted, the temperature is lowered to -10°C-10°C at a rate of 10°C / h-15°C / h, and the temperature is kept for crystallization for 1h-2h.

9. The method for preparing kresoxim-methyl according to claim 1, characterized in that: The method also includes step d: adding the kresoxim-methyl into an alcohol solvent to dissolve, cooling and crystallizing, solid-liquid separation, washing, and drying to obtain refined kresoxim-methyl.

10. The method for preparing kresoxim-methyl according to claim 9, characterized in that: In step d, the alcohol solvent is at least one of methanol or ethanol; and / or In step d, the mass ratio of the alcohol solvent to kresoxim-methyl is 2.8:1-3.3:1; and / or In step d, the temperature is lowered to -10°C-10°C at a rate of 10°C / h-15°C / h by programmed cooling, and the temperature is kept for crystallization for 1h-2h.