Preparation method of 5-amino-3-cyano-1-(2, 6-dichloro-4-trifluoromethylphenyl)pyrazole

Abstract

The invention provides a preparation method of 5-amino-3-cyano-1-(2, 6-dichloro-4-trifluoromethylphenyl)pyrazole. The preparation method comprises the following steps of by taking p-trifluoromethylaniline as a raw material, carrying out diazotization reaction to form a ring with ethyl 2, 3-dicyanopropionate under a weakly acidic condition, and introducing a proper amount of chlorine into the cyclization compound for chlorination, and adjusting the pH value for decarboxylation to obtain the product 5-amino-3-cyano-1-(2, 6-dichloro-4-trifluoromethylphenyl)pyrazole. The preparation method of the5-amino-3-cyano-1-(2, 6-dichloro-4-trifluoromethyl phenyl)pyrazole is simple to operate, good in chlorination selectivity, few in side reaction, high in product yield, mild in reaction condition and beneficial to industrialization; the average yield of the method is not lower than 95%, and the product purity is 99.50% or above.

Description

technical field [0001] The invention relates to a preparation method of 5-amino-3-cyano-1-(2,6-dichloro-4-trifluoromethylphenyl)pyrazole, belonging to the technical field of compound synthesis. Background technique [0002] Arylpyrazoles are important intermediates of N-phenylpyrazole pesticides such as fipronil, ethiprole, butene-fipronil. The action principle of N-phenylpyrazole pesticides such as fipronil and ethiprole is to interfere with the chloride ion channel through the chloride channel regulated by γ-aminobutyric acid, destroy the activity of the normal central nervous system, and cause insect death. Since its entry into the pesticide market, fipronil has been well received by the market due to its excellent insecticidal effect. For many years, the global annual sales volume has ranked among the top ten insecticides and pesticides, becoming one of the best-selling pesticides. Others such as ethiprole (Ethpronil) and butylene fipronil are also excellent insecticide...

AI Technical Summary

Problems solved by technology

However, the product content of the process can only reach 98%, and the yield can only reach about 90%;

[0007] In CN201911238649.6, the synthesis method using 2,6-dichloro-4-trifluoromethylaniline as a raw material, the main disadvantage of this process is that the reaction mechanism is complicated, there are many side reactions, and the content of the obtained product can only reach 95%, and The yield is low, such as considering the yield of 2,6-dichloro-4-trifluoromethylaniline, the yield of the whole reaction will be lower

[0008] In CN201911238649.6, 2,6-dichloro-4-trifluoromethylaniline is used as raw material to form a salt with 2,6-dichloro-4-trifluoromethylaniline in an acid solution, and then quickly add 2 , Ethyl 3-dicyanopropionate, adding sodium nitrite at room temperature, then stirring and adding water to separate layers, and finally ring-closing reaction in ammonia water medium to obtain the finished product, but the reaction time of this process is long, and the product content reaches 96%. The yield is more than 83%, and if the yield of 2,6-dichloro-4-trifluoromethylaniline is also considered, the yield of the whole reaction will be even lower

[0009] In CN101289401B, it is proposed to use 3,4,5-trifluorotoluene as a raw material to prepare 2,6-dichloro-4-trifluoromethylaniline directly through ammonia, but the ammonia conditions of this technical scheme are harsh, and the reaction pressure is between Above 10MPa, the quantitative production risk factor is large, and the selectivity of the chlorination reaction is poor, there are many side reactions, and the product is difficult to purify

[0010] In CN1137090C, the highly toxic sodium cyanide is used, and there is a great potential safety hazard in production

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