A method for preparing highly efficient cis-fluorocylalothrin

Abstract

This invention relates to the field of pyrethroid synthesis methods, particularly a method for preparing highly efficient cis-cyhalothrin, especially focusing on the epimer separation and activity enhancement process. The method uses 3-phenoxy-4-fluorobenzaldehyde as a raw material, adds dichloroquine chloride (cis-acyl chloride) dropwise to prepare cis-cyhalothrin, and then uses cyclohexane, n-heptane, and isopropanol as solvents, and diisopropylamine-triethylamine and a novel ZnCl2-TPP metal complex as catalysts to carry out an epimerization reaction to obtain highly efficient cis-cyhalothrin. After adjusting the pH to neutral, the product is filtered to obtain a crude highly efficient cis isomer. The crude product is recrystallized from methanol and vacuum dried to obtain the technical grade of highly efficient cis-cyhalothrin. This invention provides an epimerization process in the preparation method of highly efficient cis-cyhalothrin, which has the advantages of high conversion efficiency, short conversion time, and high purity of the technical grade.

Description

Technical Field

[0001] This invention relates to the field of pyrethroid synthesis methods, and in particular to a method for preparing highly efficient cis-cyhalothrin, especially targeting the process of epimer separation and activity enhancement. Background Technology

[0002] Cypermethrin is a synthetic pyrethroid insecticide with contact and stomach poison effects. It has a broad insecticidal spectrum, rapid knockdown, and long residual effect, and plants exhibit good resistance to it. High-efficiency cypermethrin is suitable for crops including cotton, wheat, corn, vegetables, tomatoes, apples, grapes, rapeseed, and soybeans.

[0003] Existing methods for synthesizing cypermethrin, such as the method for producing cypermethrin using the 3-bromo-4-fluorotoluene process disclosed in patent announcement CN1090611C, involve using 3-bromo-4-fluorotoluene and phenol as raw materials. The condensation yields p-fluoro-m-phenyltoluene, which is then chlorinated to obtain p-fluoro-m-phenoxybenzyl chloride. The p-fluoro-m-phenoxybenzyl chloride is hydrolyzed with hexamethylenetetramine to obtain 3-phenoxy-4-fluorobenzaldehyde. DV chrysanthemin is added to a sodium cyanide solution and esterified to obtain cypermethrin. The cypermethrin prepared by the above method contains one chiral carbon atom, forming multiple pairs of optical enantiomers. The presence of cis, trans, and mixed enantiomers leads to significant differences in insecticidal activity, affecting the insecticidal quality of cypermethrin. Therefore, this invention provides a method for preparing highly efficient cis-cypermethrin. Summary of the Invention

[0004] To address the technical challenge of significant differences in insecticidal activity caused by the mixing of cis, trans, and different enantiomers in existing deltamethrin formulations, which affects the insecticidal quality of deltamethrin, this invention provides a method for preparing highly efficient cis-deltamethrin.

[0005] The present invention provides a method for preparing highly efficient cis-cyhalothrin, which is achieved through the following technical solution: A method for preparing highly efficient cis-cyhalothrin includes the following steps: Step 1: Synthesis of cis-cyhalothrin crude oil; Step 2, Synthesis of crude trans isomer: Cis-cyhalothrin crude oil is dissolved in a mixed solvent, a composite catalyst is added, the temperature is raised, the reaction is stirred, then the temperature is lowered, the pH value is adjusted, and the crude trans isomer is obtained after filtration. Step 3, recrystallization treatment of crude trans isomer: After mixing crude trans isomer with methanol, the mixture is heated, and after the crude trans isomer dissolves in methanol, the mixture is cooled, filtered, and vacuum dried to obtain high-efficiency cis-cyhalothrin with a cis-cyhalothrin content ≥95%.

[0006] Preferably, the above preparation method includes: Step 1: Synthesis of cis-cyhalothrin crude oil; Step 2, Synthesis of crude trans isomer: Cis-cyhalothrin crude oil is dissolved in a mixed solvent, a composite catalyst is added, the mass of the composite catalyst is equal to 7-9% of the mass of the cis-cyhalothrin crude oil, the temperature is raised to 40-60℃, the reaction is stirred for 80-160 min, then the temperature is lowered to 8-12℃, acetic anhydride is added dropwise to adjust the pH to neutral, and the crude trans isomer is obtained after filtration. Step 3, recrystallization treatment of crude trans isomer: Mix 100 parts of crude trans isomer with 115-130 parts of methanol, heat to 60-65℃, dissolve the crude trans isomer in methanol, cool to 0℃, filter, and vacuum dry to obtain high-efficiency cis-cyhalothrin with a cis-cyhalothrin content ≥95%.

[0007] This invention provides a method for preparing highly efficient cis-cyhalothrin. The epimerization process has the advantages of high conversion efficiency, short conversion time, and high purity of the active ingredient. Moreover, the prepared highly efficient cis-cyhalothrin contains ≥99.9% cis-cyhalothrin, has high purity, and exhibits excellent insecticidal activity.

[0008] Preferably, the mixed solvent is a mixed solvent formed by cyclohexane, n-heptane, and isopropanol; the mass ratio of the mixed solvent to the cis-cyhalothrin crude oil is (115-125):100.

[0009] More preferably, the mixed solvent is a mixed solvent formed by 20-40 parts of cyclohexane, 20-40 parts of n-heptane, and 80 parts of isopropanol; the mass ratio of the mixed solvent to the cis-cyhalothrin crude oil is (118-120):100.

[0010] Preferably, the composite catalyst is a composite catalyst formed by diisopropylamine-triethylamine and ZnCl2-TPP; the molar ratio of ZnCl2 to TPP in the composite catalyst is 1.8:1.

[0011] In this invention, diisopropylamine-triethylamine and ZnCl2-TPP are used as composite catalysts to improve the rate of epimerization reaction. According to bioassay, the insecticidal activity of the highly efficient cis-cyhalothrin prepared in this invention is twice that of ordinary cyhalothrin.

[0012] Preferably, in step three, recrystallization treatment of the crude trans isomer: 100 parts of the crude trans isomer and 120 parts of methanol are mixed, heated to 60°C, and the crude trans isomer is dissolved in methanol. The mixture is then cooled from 60°C to 0°C at a cooling rate of 0.1-1.0°C / min, filtered, and vacuum dried to obtain a high-efficiency cis-cyhalothrin with a cis-cyhalothrin content ≥95%.

[0013] Preferably, the synthesis method of cis-cyhalothrin crude oil in step one is as follows: 3-phenoxy-4-fluorobenzaldehyde, a sodium cyanide aqueous solution with a mass concentration of 18-24%, a cyclohexane solution, and a phase transfer catalyst are mixed to obtain a mixed solution. The sodium cyanide in the 18-24% sodium cyanide aqueous solution contains 1.0-1.5 times the molar amount of 3-phenoxy-4-fluorobenzaldehyde. The amount of phase transfer catalyst used is 0.1%-0.2% of the mass of 3-phenoxy-4-fluorobenzaldehyde. Cis-dichlorobenzyl chloride is added dropwise to the mixed solution at a uniform rate at 0-30°C. The molar ratio of dichlorobenzyl chloride to 3-phenoxy-4-fluorobenzaldehyde is (1.1-1.2):1, and the addition time is 4-5 minutes. After the addition of cis-dichlorocypermethrin chloride is completed, keep the temperature at 0-30℃ for 100-150 minutes. Once the sample passes the test, terminate the reaction. After washing with water and removing the solvent, cis-cyhalothrin crude oil can be obtained.

[0014] The preparation method of cis-cyhalothrin crude oil in this invention is relatively simple, and the obtained cyhalothrin crude oil has high content and high yield, relatively low energy consumption, and reduces the overall production cost.

[0015] More preferably, the method for synthesizing cis-cyhalothrin crude oil in step one is as follows: S1.1, firstly, 3-phenoxy-4-fluorobenzaldehyde, a sodium cyanide aqueous solution with a mass concentration of 18-24%, a cyclohexane solution, and a phase transfer catalyst are mixed evenly to obtain mixture A. The sodium cyanide aqueous solution with a mass concentration of 18-24% contains 1.0-1.5 times the molar amount of 3-phenoxy-4-fluorobenzaldehyde, and the amount of phase transfer catalyst is 0.1%-0.2% of the mass of 3-phenoxy-4-fluorobenzaldehyde. Mixture A is injected into the first microchannel reactor through the first inlet by a metering pump. S1.2, cis-dichlorocypermethrin chloride is injected into the first microchannel reactor through the second inlet using a metering pump, and mixed with mixture A. The reaction temperature is controlled at 20-40℃ to obtain mixture C; S1.3, the mixture C is continuously passed through 6-12 reaction plates connected in series in a microchannel reactor to obtain the reaction solution; The reaction solutions obtained in S1.4 and S1.3 flow out of the microchannel reactor and are washed at least three times with deionized water. After washing, the solvent is removed by vacuum distillation to obtain cis-cyhalothrin crude oil.

[0016] The preparation of cis-cyhalothrin crude oil using a microchannel reactor can reduce the synthesis time of cis-cyhalothrin crude oil, increase the production of cis-cyhalothrin crude oil per unit time, and the yield of the prepared cis-cyhalothrin crude oil is relatively high.

[0017] More preferably, the flow rate of mixture A in S1.1 is 3-5 g / min, and the flow rate of cis-dichlorobenzyl chloride in S1.2 is 0.6-1.0 g / min; the ratio of the molar amount of cis-dichlorobenzyl chloride flowing into the first microchannel reactor per unit time in S1.2 to the molar amount of 3-phenoxy-4-fluorobenzaldehyde flowing into the first microchannel reactor per unit time in mixture A is (1.1-1.2):1.

[0018] The preparation of cis-cyhalothrin crude oil using a microchannel reactor requires strict control of the flow rates of mixture A and cis-dichlorocypermethrin to ensure the final yield and output of cis-cyhalothrin crude oil. If the flow rates are too high, insufficient reaction will result in a significant decrease in the yield and output of cis-cyhalothrin crude oil. Conversely, if the flow rates are too low, although the yield and output of cis-cyhalothrin crude oil will be relatively good, the production efficiency of cis-cyhalothrin crude oil will be affected.

[0019] Preferably, the phase transfer catalyst is any one of tetradecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride, and octadecyltrimethylammonium chloride.

[0020] More preferably, the phase transfer catalyst is octadecyltrimethylammonium chloride.

[0021] By adopting the above technical solution, the crude oil containing cypermethrin has a higher content and a better yield.

[0022] In summary, the present invention has the following advantages: 1. The high-efficiency cis-cyhalothrin prepared in this invention has a cis-cyhalothrin content of ≥95.0%, high purity, and excellent insecticidal activity.

[0023] 2. The present invention provides a method for preparing high-efficiency cis-cyhalothrin, which has the advantages of high conversion efficiency, short conversion time, high purity of active ingredient, and relatively low energy consumption due to the epimerization process.

[0024] 3. The preparation method of cis-cyhalothrin crude oil in this invention is relatively simple. Octadecyltrimethylammonium bromide is preferably used as a phase transfer catalyst to prepare cyhalothrin crude oil with high content and high yield, thereby ensuring that the final high-efficiency cis-cyhalothrin content is obtained and reducing the overall production cost.

[0025] 4. In this invention, diisopropylamine-triethylamine and ZnCl2-TPP are used as composite catalysts, which improves the rate of epimerization reaction. According to bioassay, the insecticidal activity of the highly efficient cis-cyhalothrin prepared in this invention is twice that of ordinary cyhalothrin. Detailed Implementation

[0026] To further understand the inventiveness and technical advancements of this invention, the preferred embodiments of this invention will be discussed in detail below with reference to examples and comparative examples.

[0027] Example: A method for preparing highly efficient cis-cyhalothrin, comprising the following steps: Step 1: There are two methods for synthesizing cis-cyhalothrin crude oil; ①. The synthesis method of cis-cyhalothrin crude oil is as follows: 3-phenoxy-4-fluorobenzaldehyde, a sodium cyanide aqueous solution with a mass concentration of 18-24%, a cyclohexane solution, and a phase transfer catalyst are mixed to obtain a mixed solution. The phase transfer catalyst is any one of tetradecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride, and octadecyltrimethylammonium chloride. Preferably, the phase transfer catalyst is octadecyltrimethylammonium chloride. The sodium cyanide in the 18-24% sodium cyanide aqueous solution contains 1.0-1.5 times the molar amount of 3-phenoxy-4-fluorobenzaldehyde. The amount of phase transfer catalyst is 0.1%-0.2% of the mass of 3-phenoxy-4-fluorobenzaldehyde. Cis-dichlorobenzyl chloride is added dropwise to the mixed solution at a uniform rate at 0-30℃. The molar ratio of dichlorobenzyl chloride to 3-phenoxy-4-fluorobenzaldehyde is (1.1-1.2):1, and the addition time is 4-5 minutes. After the addition of cis-dichlorocypermethrin chloride is completed, keep it at 0-30℃ for 100-150 min. Take a sample and test it. If it passes the test, stop the reaction. After washing with water and removing the solvent, you can get cis-cyhalothrin crude oil. ②. The synthesis method of cis-cyhalothrin crude oil is as follows: S1.1, 3-phenoxy-4-fluorobenzaldehyde, a sodium cyanide aqueous solution with a mass concentration of 18-24%, a cyclohexane solution, and a phase transfer catalyst are mixed evenly to obtain mixture A. The sodium cyanide in the 18-24% sodium cyanide aqueous solution contains 1.0-1.5 times the molar amount of 3-phenoxy-4-fluorobenzaldehyde. The amount of phase transfer catalyst is 0.1%-0.2% of the mass of 3-phenoxy-4-fluorobenzaldehyde. The phase transfer catalyst is any one of tetradecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride, and octadecyltrimethylammonium chloride. Preferably, the phase transfer catalyst is octadecyltrimethylammonium chloride. Mixture A is injected into the first microchannel reactor through the first inlet by a metering pump. The flow rate of mixture A is 3-5 g / min. S1.2, cis-dichlorobenzyl chloride is injected into the first microchannel reactor via a metering pump through the second inlet and mixed with mixture A. The flow rate of cis-dichlorobenzyl chloride is 0.6-1.0 g / min, and the ratio of the molar amount of cis-dichlorobenzyl chloride flowing into the first microchannel reactor per unit time to the molar amount of 3-phenoxy-4-fluorobenzaldehyde in mixture A flowing into the first microchannel reactor per unit time is (1.1-1.2):1. The reaction temperature is controlled at 20-40℃ to obtain mixture C. S1.3, the mixture C is continuously passed through 6-12 reaction plates connected in series in a microchannel reactor to obtain the reaction solution; The reaction solutions obtained in S1.4 and S1.3 flow out of the microchannel reactor and are washed in deionized water at least three times. After washing, the solvent is removed by vacuum distillation to obtain cis-cyhalothrin crude oil. Step 2, Synthesis of the crude trans isomer: Cis-cyhalothrin crude oil is dissolved in a mixed solvent, wherein the mass ratio of the mixed solvent to the cis-cyhalothrin crude oil is (115-125):100. The mixed solvent is a mixture of cyclohexane, n-heptane, and isopropanol. Preferably, the phase transfer catalyst mixed solvent is a mixture of 20-40 parts cyclohexane, 20-40 parts n-heptane, and 80 parts isopropanol. A composite catalyst is added, which is a composite catalyst formed by diisopropylamine-triethylamine and ZnCl2-TPP, with a molar ratio of ZnCl2 to TPP of 1.8:1. The mass of the composite catalyst is equal to 7-9% of the mass of the cis-cyhalothrin crude oil. The temperature is raised to 40-60℃, and the reaction is stirred for 80-160 min. Then, the temperature is lowered to 8-12℃, and acetic anhydride is added dropwise to adjust the pH to neutral. After filtration, the crude trans isomer is obtained. Step 3, recrystallization treatment of crude trans isomer: Mix 100 parts of crude trans isomer with 120 parts of methanol, heat to 60℃, dissolve crude trans isomer in methanol, and then cool from 60℃ to 0℃ at a cooling rate of 0.1-1.0℃ / min. Filter and vacuum dry to obtain high-efficiency cis-cyhalothrin with a cis-cyhalothrin content ≥95%.

[0028] Example 1: A method for preparing a high-efficiency cis-cyhalothrin, comprising the following steps: Step 1: The synthesis method of cis-cyhalothrin crude oil is as follows; 55 g of 3-phenoxy-4-fluorobenzaldehyde (CAS: 68359-57-9, molecular weight 216.208, i.e., 0.2544 mol), 90 g of aqueous sodium cyanide solution with a mass concentration of 20% (CAS: 143-33-9, molecular weight 49.007, i.e., 0.3673 mol), 180 g of cyclohexane (CAS: 110-82-7), and 0.05 g of octadecyltrimethylammonium bromide (CAS: 1120-02-1) are mixed to obtain a mixed solution. 68 g of cis-permethroyl chloride (Company: TAGROS CHEMICALS INDIAPRIVATE LIMITED, Licence No.: 335 / 1998, molecular weight 227.516, i.e., 0.2988 mol) is uniformly added dropwise to the mixed solution at room temperature, and the dropping time is 4 hours. After the dropping of cis-permethroyl chloride is completed, the mixture is insulated at room temperature for 120 min. After sampling and passing the inspection, the reaction is terminated. After washing with water and passing the inspection, the solvent is removed, so that 110.0 g of crude cyfluthrin oil is obtained; Step 2, Synthesis of trans isomer crude product: Add 110 g of the crude cyfluthrin oil obtained in Step 1 into a 500 mL four-necked flask, then add 130 g of a mixed solvent, the mixed solvent is formed by mixing 80 g of isopropanol (CAS: 67-63-0), 25 g of cyclohexane (CAS: 110-82-7) and 25 g of n-heptane (CAS: 142-82-5), then add 8.8 g of a composite catalyst, the composite catalyst is a composite catalyst formed by 3.6 g of diisopropylamine-triethylamine (mass ratio of diisopropylamine to triethylamine = 1:1; diisopropylamine is produced by Zhejiang Jianye Chemical Co., Ltd., production license No.: (ZJ) WH An Xu Zheng Zi

[2024] -A-2255; triethylamine, 99.5%, anhydrous grade, water ≤ 50 ppm, Macklin) and 5.2 g of ZnCl₂-TPP (ZnCl₂ is provided by Anhui Dalin New Carbon Materials Co., Ltd., production license No.: (Wan) WH An Xu Zheng Zi

[2023] No. 06; TPP is triphenylphosphine, provided by Shandong Hongchuan Chemical Co., Ltd., production license No.: (Lu) WH An Xu Zheng Zi (2024) 050104), in the composite catalyst, the molar ratio of ZnCl₂ to TPP is 1.8:1. Heat the mixture to 50 °C, stir and react for 2 hours, then naturally cool to 10 °C, add acetic anhydride dropwise to adjust the pH value to neutral, and obtain 103.0 g of trans isomer crude product after filtration; Step 3, recrystallization treatment of crude trans isomer: Add 103.0g of crude trans isomer and 122.4g of methanol (CAS: 67-56-1) to a 500ml four-necked flask, heat to 60℃ to dissolve completely, then cool from 60℃ to 0℃ at a cooling rate of 0.5℃ / min, filter, and vacuum dry to obtain 101.4g of high-efficiency cis-cyhalothrin, with a cis-cyhalothrin content of 98.0%.

[0029] The difference between Example 2 and Example 1 is that in step three of the preparation method of high-efficiency cis-cyhalothrin, recrystallization treatment of the crude trans isomer: 103.0g of crude trans isomer and 122.4g of methanol were added to a 500ml four-necked flask, heated to 60℃ to fully dissolve, and then cooled from 60℃ to 0℃ at a cooling rate of 0.1℃ / min. After filtration and vacuum drying, 102.5g of high-efficiency cis-cyhalothrin was obtained. The cis-cyhalothrin content in the high-efficiency cis-cyhalothrin was 98.6%. The remaining steps were the same.

[0030] The difference between Example 3 and Example 1 is that in step three of the preparation method of high-efficiency cis-cyhalothrin, recrystallization treatment of the crude trans isomer: 103.0g of crude trans isomer and 122.4g of methanol were added to a 500ml four-necked flask, heated to 60℃ to fully dissolve, and then cooled from 60℃ to 0℃ at a cooling rate of 0.3℃ / min. After filtration and vacuum drying, 102.0g of high-efficiency cis-cyhalothrin was obtained. The cis-cyhalothrin content in the high-efficiency cis-cyhalothrin was 98.3%. The remaining steps were the same.

[0031] The difference between Example 4 and Example 1 is that in step three of the preparation method of high-efficiency cis-cyhalothrin, recrystallization treatment of the crude trans isomer: 103.0g of crude trans isomer and 122.4g of methanol were added to a 500ml four-necked flask, heated to 60℃ to dissolve completely, and then cooled from 60℃ to 0℃ at a cooling rate of 0.7℃ / min. After filtration and vacuum drying, 100.7g of high-efficiency cis-cyhalothrin was obtained. The cis-cyhalothrin content in the high-efficiency cis-cyhalothrin was 97.4%. The remaining steps were the same.

[0032] The difference between Example 5 and Example 1 is that in step three of the preparation method of high-efficiency cis-cyhalothrin, recrystallization treatment of the crude trans isomer: 103.0g of crude trans isomer and 122.4g of methanol were added to a 500ml four-necked flask, heated to 60℃ to fully dissolve, and then cooled from 60℃ to 0℃ at a cooling rate of 1℃ / min. After filtration, the product was vacuum dried to obtain 100.1g of high-efficiency cis-cyhalothrin. The cis-cyhalothrin content in the high-efficiency cis-cyhalothrin was 96.9%. The remaining steps were the same.

[0033] The difference between Example 6 and Example 1 is as follows: Step 1 of the preparation method of high-efficiency cis-cyhalothrin, the synthesis method of cis-cyhalothrin crude oil is as follows: 55g of 3-phenoxy-4-fluorobenzaldehyde, 90g of sodium cyanide aqueous solution with a mass concentration of 20%, 180g of cyclohexane, and 0.05g of hexadecyltrimethylammonium bromide (CAS: 57-09-0) are mixed to obtain a mixed solution. 68g of cis-dichlorocypermethrin chloride is added dropwise to the mixed solution at a uniform rate at room temperature for 4 hours. After the cis-dichlorocypermethrin chloride is added, the solution is kept at room temperature for 120min. After the sample is tested and found to be qualified, the reaction is terminated. After washing with water and finding to be qualified, the solvent is removed to obtain 109.1g of cis-cyhalothrin crude oil.

[0034] The difference between Example 7 and Example 1 is as follows: Step 1 of the preparation method of high-efficiency cis-cyhalothrin, the synthesis method of cis-cyhalothrin crude oil is as follows: 55g of 3-phenoxy-4-fluorobenzaldehyde, 90g of sodium cyanide aqueous solution with a mass concentration of 20%, 180g of cyclohexane, and 0.05g of tetradecyltrimethylammonium bromide (CAS: 1119-97-7) are mixed to obtain a mixed solution. 68g of cis-dichlorocypermethrin chloride is added dropwise to the mixed solution at a uniform rate at room temperature for 4 hours. After the cis-dichlorocypermethrin chloride is added, the solution is kept at room temperature for 120min. After the sample is tested and found to be qualified, the reaction is terminated. After washing with water and finding to be qualified, the solvent is removed to obtain 108.4g of cis-cyhalothrin crude oil.

[0035] The difference between Example 8 and Example 1 is as follows: In step two of the preparation method of high-efficiency cis-cyhalothrin, the synthesis of the crude trans isomer is as follows: 110g of the crude cis-cyhalothrin from step one was added to a 500ml four-necked flask, followed by 130g of a mixed solvent consisting of 90g isopropanol, 20g cyclohexane, and 20g n-heptane. 8.8g of a composite catalyst was added, which was a composite catalyst formed by 3.6g of diisopropylamine-triethylamine and 5.2g of ZnCl2-TPP, with a molar ratio of ZnCl2 to TPP of 1.8:1. The temperature was raised to 50℃, and the reaction was stirred for 2 hours. Then, the temperature was allowed to dropwise cool to 10℃, and acetic anhydride was added to adjust the pH to neutral. After filtration, 102.5g of the crude trans isomer was obtained. The remaining steps were the same.

[0036] The difference between Example 9 and Example 1 is as follows: In step two of the preparation method of high-efficiency cis-cyhalothrin, the synthesis of the crude trans isomer: 110g of the crude cis-cyhalothrin from step one was added to a 500ml four-necked flask, followed by 135g of a mixed solvent consisting of 80g isopropanol, 30g cyclohexane, and 25g n-heptane. 8.8g of a composite catalyst was added, which was a composite catalyst formed by 3.6g of diisopropylamine-triethylamine and 5.2g of ZnCl2-TPP, with a molar ratio of ZnCl2 to TPP of 1.8:1. The temperature was raised to 50℃, and the reaction was stirred for 2 hours. Then, the temperature was allowed to dropwise cool to 10℃, and acetic anhydride was added to adjust the pH to neutral. After filtration, 102.8g of the crude trans isomer was obtained. The remaining steps were the same.

[0037] The difference between Example 10 and Example 1 is that in step one of the preparation method of the high-efficiency cis-cyhalothrin, the synthesis method of cis-cyhalothrin crude oil is as follows: S1.1 First, mix 55g of 3-phenoxy-4-fluorobenzaldehyde, 90g of a 20% sodium cyanide aqueous solution, 180g of cyclohexane, and 0.55g of octadecyltrimethylammonium bromide to obtain a mixture A. Inject mixture A into the first microchannel reactor (provided by Shandong Weijing Chemical Technology Co., Ltd., i.e., the first module into which mixture A is pumped into the microchannel reactor) through the first inlet using a metering pump at a flow rate of 201g / 60min. S1.2, 68.03g of cis-dichlorocypermethrin chloride was injected into the first microchannel reactor through a metering pump at a flow rate of 42g / 60min via the second inlet, and mixed with the mixture A. The reaction temperature was controlled at 25℃ to obtain mixture C. S1.3, the mixture C is continuously passed through 8 reaction plates connected in series in a microchannel reactor to obtain the reaction solution; The reaction solutions obtained in S1.4 and S1.3 flow out of the microchannel reactor and are washed three times with deionized water. After washing, the solvent is removed by vacuum distillation to obtain 110.2g of cis-cyhalothrin crude oil.

[0038] The difference between Example 11 and Example 1 is that in step one of the preparation method of the high-efficiency cis-cyhalothrin, the synthesis method of cis-cyhalothrin crude oil is as follows: S1.1 First, mix 55g of 3-phenoxy-4-fluorobenzaldehyde, 90g of 20% sodium cyanide aqueous solution, 180g of cyclohexane, and 0.55g of octadecyltrimethylammonium bromide to obtain mixture A. Inject mixture A into the first microchannel reactor (provided by Shandong Weijing Chemical Technology Co., Ltd., i.e., the first module into which mixture A is pumped into the microchannel reactor) through the first inlet using a metering pump at a flow rate of 254g / 60min. S1.2, 67.93g of cis-dichlorocypermethrin chloride was injected into the first microchannel reactor through a metering pump at a flow rate of 53g / 60min via the second inlet, and mixed with mixture A. The reaction temperature was controlled at 25℃ to obtain mixture C. S1.3, the mixture C is continuously passed through 8 reaction plates connected in series in a microchannel reactor to obtain the reaction solution; The reaction solutions obtained in S1.4 and S1.3 flow out of the microchannel reactor and are washed three times with deionized water. After washing, the solvent is removed by vacuum distillation to obtain 109.6g of cis-cyhalothrin crude oil.

[0039] The difference between Example 12 and Example 1 is that in step one of the preparation method of the high-efficiency cis-cyhalothrin, the synthesis method of cis-cyhalothrin crude oil is as follows: S1.1 First, mix 55g of 3-phenoxy-4-fluorobenzaldehyde, 90g of a 20% sodium cyanide aqueous solution, 180g of cyclohexane, and 0.55g of octadecyltrimethylammonium bromide to obtain a mixture A. Inject mixture A into the first microchannel reactor (provided by Shandong Weijing Chemical Technology Co., Ltd., i.e., the first module into which mixture A is pumped into the microchannel reactor) through the first inlet using a metering pump at a flow rate of 300g / 60min. S1.2, 67.04 g of cis-dichlorocypermethrin chloride was injected into the first microchannel reactor through a metering pump at a flow rate of 62.7 g / 60 min via the second inlet, and mixed with mixture A. The reaction temperature was controlled at 25 °C to obtain mixture C. S1.3, the mixture C is continuously passed through 8 reaction plates connected in series in a microchannel reactor to obtain the reaction solution; The reaction solutions obtained in S1.4 and S1.3 flow out of the microchannel reactor and are washed three times with deionized water. After washing, the solvent is removed by vacuum distillation to obtain 108.2g of cis-cyhalothrin crude oil.

[0040] The difference between Comparative Example 1 and Example 1 is that in step three of the preparation method of high-efficiency cis-cyhalothrin, recrystallization treatment of the crude trans isomer: 103.0g of crude trans isomer and 122.4g of methanol were added to a 500ml four-necked flask, heated to 60℃ to dissolve completely, and then cooled from 60℃ to 0℃ at a cooling rate of 1.5℃ / min. After filtration and vacuum drying, 99.3g of high-efficiency cis-cyhalothrin was obtained. The cis-cyhalothrin content in the high-efficiency cis-cyhalothrin was 95.8%. The remaining steps were the same.

[0041] The difference between Comparative Example 2 and Example 1 is as follows: Step 1 of the preparation method of high-efficiency cis-cyhalothrin, the synthesis method of cis-cyhalothrin crude oil is as follows: 55g of 3-phenoxy-4-fluorobenzaldehyde, 90g of sodium cyanide aqueous solution with a mass concentration of 20%, 180g of cyclohexane, and 0.05g of dodecyltrimethylammonium bromide (CAS: 1119-94-4) are mixed to obtain a mixed solution. 68g of cis-dichlorocypermethrin chloride is added dropwise to the mixed solution at a uniform rate at room temperature for 4 hours. After the cis-dichlorocypermethrin chloride is added, the solution is kept at room temperature for 120min. After the sample is tested and found to be qualified, the reaction is terminated. After washing with water and finding to be qualified, the solvent is removed to obtain 105.8g of cis-cyhalothrin crude oil.

[0042] The difference between Comparative Example 3 and Example 1 is as follows: In step two of the preparation method of high-efficiency cis-cyhalothrin, the synthesis of the crude trans isomer: 110g of the crude cis-cyhalothrin from step one was added to a 500ml four-necked flask, followed by 130g of a mixed solvent consisting of 80g of isopropanol, 35g of cyclohexane, and 35g of n-heptane. 8.8g of diisopropylamine-triethylamine catalyst was added, the temperature was raised to 50°C, and the reaction was stirred for 2 hours. Then, the temperature was allowed to dropwise cool to 10°C, and acetic anhydride was added to adjust the pH to neutral. After filtration, 95.2g of the crude trans isomer was obtained. The remaining steps were the same.

[0043] The difference between Comparative Example 4 and Example 1 is as follows: In step two of the preparation method of high-efficiency cis-cyhalothrin, the synthesis of the crude trans isomer: 110g of the crude cis-cyhalothrin from step one was added to a 500ml four-necked flask, followed by 130g of a mixed solvent consisting of 80g of isopropanol, 35g of cyclohexane, and 35g of n-heptane. 8.8g of a ZnCl2-TPP catalyst was added, with a ZnCl2 to TPP molar ratio of 1.8:1. The temperature was raised to 50°C, and the reaction was stirred for 2 hours. Subsequently, the temperature was allowed to cool naturally to 10°C, and acetic anhydride was added dropwise to adjust the pH to neutral. After filtration, 98.1g of the crude trans isomer was obtained. The remaining steps were the same.

[0044] The difference between Comparative Example 5 and Example 1 is as follows: In step two of the preparation method of high-efficiency cis-cyhalothrin, the synthesis of the crude trans isomer: 110g of crude cis-cyhalothrin from step one was added to a 500ml four-necked flask, followed by 130g of isopropanol and 8.8g of a composite catalyst. The composite catalyst is a composite catalyst formed by 3.6g of diisopropylamine-triethylamine and 5.2g of ZnCl2-TPP, with a molar ratio of ZnCl2 to TPP of 1.8:1. The temperature was raised to 50℃, and the reaction was stirred for 2 hours. Then, the temperature was allowed to dropwise cool to 10℃, and acetic anhydride was added to adjust the pH to neutral. After filtration, 100.1g of crude trans isomer was obtained. The remaining steps were the same.

[0045] The difference between Comparative Example 6 and Example 1 is that step one of the preparation method of the high-efficiency cis-cyhalothrin, the synthesis method of cis-cyhalothrin crude oil, is as follows: S1.1 First, mix 55g of 3-phenoxy-4-fluorobenzaldehyde, 90g of a 20% sodium cyanide aqueous solution, 180g of cyclohexane, and 0.55g of octadecyltrimethylammonium bromide to obtain a mixture A. Inject mixture A into the first microchannel reactor (provided by Shandong Weijing Chemical Technology Co., Ltd., i.e., the first module into which mixture A is pumped into the microchannel reactor) through the first inlet using a metering pump at a flow rate of 402g / 60min. S1.2, 67.04 g of cis-dichlorocypermethrin chloride was injected into the first microchannel reactor through a metering pump at a flow rate of 84 g / 60 min via the second inlet, and mixed with the mixture A. The reaction temperature was controlled at 25 °C to obtain mixture C. S1.3, the mixture C is continuously passed through 8 reaction plates connected in series in a microchannel reactor to obtain the reaction solution; The reaction solutions obtained in S1.4 and S1.3 flow out of the microchannel reactor and are washed three times with deionized water. After washing, the solvent is removed by vacuum distillation to obtain 101.4g of cis-cyhalothrin crude oil.

[0046] Table 1: Comparison of cooling rate and yield of high-efficiency cis-cyhalothrin in Examples 1-5 and Comparative Example 1 Example 1 0.5 101.4 Example 2 0.1 102.5 Example 3 0.3 102.0 Example 4 0.7 100.7 Example 5 1.0 100.1 Comparative Example 1 1.5 99.3 According to Table 1, comparing Examples 1-5 with Comparative Example 1, the cooling rate from 60°C to 0°C during recrystallization affects the yield and content of the final high-efficiency cis-cyhalothrin technical. The cooling rate from 60°C to 0°C should be controlled at 0.5-1 / min, preferably 0.5°C / min.

[0047] Table 2: Comparison of Phase Transfer Catalyst Yield and Cis-Cypermethrin Crude Oil Yield in Examples 1, 6-7 and Comparative Example 2 Example 1 Octadecyltrimethylammonium bromide 110.0 Example 6 cetyltrimethylammonium bromide 109.1 Example 7 Tetradecyltrimethylammonium bromide 108.4 Comparative Example 2 Dodecyltrimethylammonium bromide 105.8 Comparing Table 2 with Examples 1, 6-7, and Comparative Example 2, it can be seen that using any one of tetradecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride, or octadecyltrimethylammonium chloride as a phase transfer catalyst during the synthesis of cis-cyhalothrin crude oil can ensure a good yield and output of cis-cyhalothrin crude oil. Preferably, octadecyltrimethylammonium chloride is used as the phase transfer catalyst, resulting in even better yield and output of cis-cyhalothrin crude oil, and reducing the cost of the final high-efficiency cis-cyhalothrin technical material.

[0048] Table 3: Comparison of catalyst and trans-isomer crude product yields in Example 1 and Comparative Examples 3-4 Example 1 <![CDATA[diisopropylamine-triethylamine catalyst + ZnCl₂-TPP catalyst]]> 103.0 Comparative Example 3 diisopropylamine-triethylamine catalyst 95.2 Comparative Example 4 <![CDATA[ZnCl₂-TPP catalyst]]> 98.1 As shown in Table 3, comparing Example 1 with Comparative Examples 3-4, the use of a composite catalyst formed by diisopropylamine-triethylamine and ZnCl2-TPP improves the rate of epimerization reaction, which can improve the yield and output of the trans isomer crude product, thereby giving the final prepared high-efficiency cis-cyhalothrin technical material better insecticidal activity.

[0049] Table 4: Comparison of Yields of Mixed Solvent and Crude Trans Isomer in Examples 1, 8-9 and Comparative Example 5 Example 1 80g isopropanol, 25g cyclohexane, 25g n-heptane 103.0 Example 8 90g isopropanol, 20g cyclohexane, 20g n-heptane 102.5 Example 9 80g isopropanol, 30g cyclohexane, 25g n-heptane 102.8 Comparative Example 5 130g of isopropanol 101.1 Based on Table 4, a comparison of Examples 1, 8-9 and Comparative Example 5 shows that the mixed solvent formed by 20-30 parts cyclohexane, 20-30 parts n-heptane, and 80 parts isopropanol can improve the yield and production of the trans isomer crude product compared to the scheme using isopropanol as the sole solvent, thereby giving the final prepared high-efficiency cis-cyhalothrin technical better insecticidal activity.

[0050] Table 5: Comparison of flow rates of mixture A and cis-dichlorocypermethrin with crude oil yield of cis-cyhalothrin in Examples 1, 10-12 and Comparative Example 6 Example 10 201.0 42.0 110.2 Example 11 254.0 53.0 109.6 Example 12 300.0 62.7 108.2 Comparative Example 6 402.0 84.0 101.4 Based on Table 5, a comparison between Examples 10-12 and Comparative Example 6 shows that the flow rate of mixture A is 180-300 g / 60 min and the flow rate of cis-dichlorocypermethrin is 37.8-62.7 g / 60 min. The reaction is relatively thorough and the production cycle is reduced, ensuring the yield and output of cis-cyhalothrin crude oil while improving production efficiency.

[0051] In summary, compared with the prior art, the preparation method of the high-efficiency cis-cyhalothrin of the present invention has a simple process flow. The preparation of cyhalothrin uses octadecyltrimethylammonium bromide as a catalyst, and the prepared cyhalothrin has high crude oil content and high yield.

[0052] It should be noted that this specific embodiment is merely an explanation of the technical solution of the present invention and is not intended to limit the present invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but as long as they are within the scope of the claims of the present invention, they are protected by patent law.

Claims

1. A method for preparing highly efficient cis-cyhalothrin, characterized in that: Includes the following steps: Step 1: Synthesis of cis-cyhalothrin crude oil; A mixture is prepared by mixing 3-phenoxy-4-fluorobenzaldehyde, an aqueous solution of sodium cyanide with a mass concentration of 18-24%, a cyclohexane solution, and a phase transfer catalyst. The sodium cyanide in the 18-24% aqueous solution contains 1.0-1.5 times the molar amount of 3-phenoxy-4-fluorobenzaldehyde. The amount of phase transfer catalyst is 0.1%-0.2% of the mass of 3-phenoxy-4-fluorobenzaldehyde. Cis-dichlorobenzyl chloride is added dropwise to the mixture at a uniform rate at 0-30℃. The molar ratio of dichlorobenzyl chloride to 3-phenoxy-4-fluorobenzaldehyde is (1.1-1.2):

1. The addition time is 4-5 hours. After the addition of cis-dichlorobenzyl chloride is completed, the mixture is kept at 0-30℃ for 100-150 minutes. After the sample is tested and found to be qualified, the reaction is terminated. After washing with water and finding to be qualified, the solvent is removed to obtain cis-fluorocypermethrin crude oil. The phase transfer catalyst is any one of tetradecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride, and octadecyltrimethylammonium chloride; Step 2, Synthesis of the crude cis isomer: The crude cis-cyhalothrin crude oil is dissolved in a mixed solvent, a composite catalyst is added, the temperature is raised, the reaction is stirred, then the temperature is lowered, the pH value is adjusted, and the crude cis isomer is obtained after filtration. Step 3, recrystallization treatment of crude cis isomer: Mix 100 parts of crude cis isomer with 115-130 parts of methanol, heat to 60-65℃, dissolve crude cis isomer in methanol, cool to 0℃, filter, and vacuum dry to obtain high-efficiency cis-cyhalothrin with a cis-cyhalothrin content ≥95%. The composite catalyst is a composite catalyst formed from diisopropylamine-triethylamine and ZnCl2-TPP; The mixed solvent is a mixture of 20-40 parts cyclohexane, 20-40 parts n-heptane, and 80 parts isopropanol. The mass ratio of the mixed solvent to the cis-fluorocypermethrin crude oil is (115-125):

100.

2. The method for preparing a high-efficiency cis-cyhalothrin according to claim 1, characterized in that: The mass ratio of the mixed solvent to the cis-fluorocypermethrin crude oil is (118-120):

100.

3. The method for preparing a high-efficiency cis-cyhalothrin according to claim 1, characterized in that: The molar ratio of ZnCl2 to TPP in the composite catalyst is 1.8:

1.

4. The method for preparing a high-efficiency cis-cyhalothrin according to claim 1, characterized in that: Step three, recrystallization treatment of the crude cis isomer: 100 parts of the crude cis isomer and 120 parts of methanol are mixed, heated to 60°C, and the crude cis isomer is dissolved in methanol. The mixture is then cooled from 60°C to 0°C at a cooling rate of 0.1-1.0°C / min, filtered, and vacuum dried to obtain a high-efficiency cis-cyhalothrin with a cis-cyhalothrin content ≥95%.

5. The method for preparing a high-efficiency cis-cyhalothrin according to claim 1, characterized in that: The method for synthesizing cis-cyhalothrin crude oil in step one is as follows: S1.1, firstly, 3-phenoxy-4-fluorobenzaldehyde, a sodium cyanide aqueous solution with a mass concentration of 18-24%, a cyclohexane solution, and a phase transfer catalyst are mixed evenly to obtain mixture A. The sodium cyanide aqueous solution with a mass concentration of 18-24% contains 1.0-1.5 times the molar amount of 3-phenoxy-4-fluorobenzaldehyde, and the amount of phase transfer catalyst is 0.1%-0.2% of the mass of 3-phenoxy-4-fluorobenzaldehyde. Mixture A is injected into the first microchannel reactor through the first inlet by a metering pump. S1.2, cis-dichlorocypermethrin chloride is injected into the first microchannel reactor through the second inlet using a metering pump, and mixed with mixture A. The reaction temperature is controlled at 20-40℃ to obtain mixture C; S1.3, the mixture C is continuously passed through 6-12 reaction plates connected in series in a microchannel reactor to obtain the reaction solution; The reaction solutions obtained in S1.4 and S1.3 flow out of the microchannel reactor and are washed at least three times with deionized water. After washing, the solvent is removed by vacuum distillation to obtain cis-cyhalothrin crude oil.

6. The method for preparing a high-efficiency cis-cyhalothrin according to claim 5, characterized in that: The flow rate of mixture A in S1.1 is 3-5 g / min, and the flow rate of cis-dichlorobenzyl chloride in S1.2 is 0.6-1.0 g / min; the ratio of the molar amount of cis-dichlorobenzyl chloride flowing into the first microchannel reactor per unit time in S1.2 to the molar amount of 3-phenoxy-4-fluorobenzaldehyde flowing into the first microchannel reactor per unit time in mixture A is (1.1-1.2):

1.

7. The method for preparing a high-efficiency cis-cyhalothrin according to claim 1, characterized in that: The phase transfer catalyst is octadecyltrimethylammonium chloride.