Preparation method for thiamethoxam

A technology of thiamethoxam and chloromethylthiazole, which is applied in the field of preparation of thiamethoxam, can solve the problems of thiamethoxam limiting the purity of compound A, weakening the stability of compound A, increasing the cost of final products, etc., and shortening the operation period. , The effect of reducing product cost and reducing the generation of three wastes

Inactive Publication Date: 2012-03-14
ANHUI RES INST OF CHEM IND
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0006] But above-mentioned these existing patent methods, its obvious defect is: first, the preparation of thiamethoxam is always limited by the purity of compound A, in the process of industrialization, most of the operation cycle is spent on the purification of compound A, lon

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  • Preparation method for thiamethoxam

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Effect test

Embodiment 1

[0030] Take 18.5g of 3-methyl-4-nitroiminotetrahydro-1,3,5-oxadiazine and 16.8g of 2-chloro-5-chloromethylthiazole dissolved in 180g of acetone, add 0.4g of potassium iodide, 11g Potassium carbonate was stirred at room temperature for 8 hours, and the reaction was complete as detected by TLC. At this time, the system remained in a yellow suspension state. Evaporate the solvent acetone under reduced pressure at 40-50°C, add 400g of dichloromethane to the residue for soaking, filter to remove inorganic salts, collect the filtrate, the organic phase is a dark yellow transparent solution, and evaporate the dichloromethane to dryness at a temperature of 30-40°C to obtain crude Product, the crude product was heated to boiling and recrystallized with 130g of toluene, refluxed for 0.5h, cooled to room temperature to crystallize, and suction filtered to obtain 24.5g of beige thiamethoxam with a converted yield of 84% and a purity of 98%. The mother liquor was yellowish brown.

Embodiment 2

[0032] Take 18.5g of 3-methyl-4-nitroiminotetrahydro-1,3,5-oxadiazine and 16.8g of 2-chloro-5-chloromethylthiazole dissolved in 180g of acetonitrile, add 0.4g of potassium iodide, 11g Potassium carbonate was stirred under reflux for 12 hours. TLC detected that the reaction was complete. At this time, the system remained in a dark yellow suspension state. Evaporate the acetonitrile solvent under reduced pressure at 60-70°C, add 400g of dichloromethane to the residue for soaking, evaporate the dichloromethane to dryness at a temperature of 30-40°C to obtain a crude product, heat the crude product to boiling, recrystallize with 130g of toluene, and reflux After 0.5h, cool to room temperature and filter with suction to obtain 23.2 g of khaki-colored thiamethoxam, with a reduced yield of 78% and a purity of 96%.

Embodiment 3

[0034] According to 2006Mu00715, 18.5 g of 3-methyl-4-nitroiminotetrahydro-1,3,5-oxadiazine, 27.6 g of potassium carbonate were dissolved in 100 mL of DMF, and 16.8 g of 2-chloro-5-chloromethyl was added dropwise Base thiazole, control the temperature at 60-65 ° C, stir the reaction for 4 hours, the reaction system turns black completely. This system is highly alkaline, and a large amount of compound 2-chloro-5-chloromethylthiazole deteriorates during the reaction, and the color of thiamethoxam is very dark, and the yield is very low.

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Abstract

The invention relates to a preparation method for thiamethoxam. The preparation method comprises the following specific steps of: dissolving 3-methyl-4-nitroimidotetrahydro-1,3,5-oxadiazine and 2-chlorine-5-chloromethyl thiazole into a polar aprotic organic solvent, adding potassium iodide serving as a catalyst and potassium carbonate serving as an acid binding agent, stirring at normal temperature or in a heating way for 8 hours, and detecting whether reaction is fully completed through TLC (Thin Layer Chromatography), wherein a reaction system always keeps in yellow suspension state; and evaporating the organic solvent out, adding methylene dichloride into residues for immersion cleaning, filtering inorganic salts out, obtaining an organic phase which is a deep yellow transparent solution, evaporating the methylene dichloride to dryness, and recrystallizing the crude product by using methylbenzene to obtain maize-yellow thiamethoxam, wherein the yield is 85 percent and the purity is 98 percent. The preparation method has the advantages: the affinity substitution process is stable and quick, the tendency of a side reaction is lowered greatly, the bottleneck of the requirement on the purity of the 2-chlorine-5-chloromethyl thiazole is overcome, the problem of black color of the product is solved completely, and the product yield is greatly increased.

Description

technical field [0001] The invention belongs to the technical field of insecticide preparation, and in particular relates to a preparation method of thiamethoxam. Background technique [0002] The chemical name of thiamethoxam is 3-(2-chloro-1,3-thiazol-5-ylmethyl)-5-methyl-1,3,5-oxadiazin-4-ylidene(nitro) Amine; molecular formula C8H10ClN5O3S; molecular weight 291.71; mainly used for Lepidoptera, Coleoptera, Thysanoptera pests. Such as the control of various aphids, leafhoppers, whiteflies, planthoppers, etc. [0003] The preparation of thiamethoxam from the compound 3-methyl-4-nitroiminotetrahydro-1,3,5-oxadiazine and 2-chloro-5-chloromethylthiazole has been widely reported, PCT2002034734, 2006Mu00715, WO0100623. [0004] [0005] However, the color of the product, side reactions, and final low yield are huge obstacles in the industrialization of this step of reaction. The synthesis and purification of compound B are relatively easy, and the synthesis and purificatio...

Claims

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Application Information

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IPC IPC(8): C07D417/06
Inventor 胡仁涛潘启玉
Owner ANHUI RES INST OF CHEM IND
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