Preparation method of aryl pyrazole nitrile

Abstract

The invention discloses a preparation method of aryl pyrazole nitrile, which comprises the following steps: carrying out diazotization reaction on 2, 6-dichloro-4-trifluoromethylaniline and sodium nitrite under acidic conditions to obtain a diazonium substance, immediately carrying out coupling reaction on the diazonium substance and ethyl 2, 3-dicyanopropionate, and regulating to weakly acidic conditions for cyclization after the coupling reaction is finished, regulating to weakly alkaline conditions for decarboxylation, after decarboxylation, neutralizing until the pH value is 7, filtering to remove salt, and then carrying out desolventizing, rectifying, refining and the like to obtain aryl pyrazole nitrile, urea alkane and diethyl carbonate. According to the method, the diazotization reaction and the coupling reaction are almost carried out at the same time by improving the preparation process, so that the acid consumption of the whole reaction is reduced by more than half due to monomolecular acid released by the coupling reaction, and the waste inorganic salt generated after synthesis is also reduced by more than half.

Description

technical field [0001] The invention relates to the technical field of chemical substance synthesis, in particular to a preparation method of arylpyrazolenitrile. Background technique [0002] The chemical name of arylpyrazole nitrile is 5-amino-3-cyano-1-(2,6-dichloro-4-trifluoromethylphenyl)pyrazole, also known as pyrazole ring, and its structural formula is as follows: [0003] [0004] Arylpyrazole is a special intermediate for 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 the death of insects. Due to this unique mechanism of action, this type of pesticide has significant characteristics different from conventional insecticides: this series of insecticides are effective against pests...

AI Technical Summary

Problems solved by technology

[0005] The synthesis of existing arylpyrazole nitrile adopts diazotization of 2,6-dichloro 4-trifluoromethylaniline, and the obtained diazonium salt is coupled with ethyl 2,3-dicyanopropionate, and the coupling The compound obtains arylpyrazole nitrile through cyclization and decarboxylation, but the existing synthesis process, such as the technique in CN201710605773.6, can produce a large amount of acidic and alkaline waste water, which increases the processing difficulty of steps such as subsequent crystallization, separation and drying.

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