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Preparation method of fipronil formed by oxidization of phenyl pyrazole derivatives

A technology of phenylpyrazole and its derivatives, which is applied in the field of preparation of fipronil, can solve the problems of high moisture content, poor reaction selectivity, and high ratio of by-product sulfuryl compounds in the recovery of trifluoroacetic acid, and achieve good industrial application prospects, reaction The effect of mild conditions and low production costs

Active Publication Date: 2010-01-20
YANGZHOU TIANHE PHARM CO LTD
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Problems solved by technology

The preparation method of the fipronil that EPO295117 introduces is by 5-amino-3-cyano group-1-(2,6-dichloro-4-trifluoromethylphenyl)-4-trifluoromethylthiopyrazole Dichloromethane as a solvent, and then oxidized with m-chloroperbenzoic acid to generate 5-amino-3-cyano-1-(2,6-dichloro-4-trifluoromethylphenyl)-4-trifluoromethane The base sulfinyl pyrazole is fipronil; its disadvantage is that the reaction time is long, it takes two days, the oxidant m-chloroperoxybenzoic acid is relatively expensive, and the reaction selectivity is poor, and the proportion of by-product sulfuryl compounds is relatively high
WO0130760 discloses the preparation method of oxidizing and synthesizing fipronil by using hydrogen peroxide in a trifluoroacetic acid medium; its disadvantage is that a large amount of expensive trifluoroacetic acid is used, and the recovered trifluoroacetic acid cannot be directly applied due to the high moisture content

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  • Preparation method of fipronil formed by oxidization of phenyl pyrazole derivatives

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Embodiment 1

[0017] Add 40 grams of 5-amino-3-cyano-1-(2,6-dichloro-4-trifluoromethylphenyl)-4-trifluoro Methylthiopyrazole, 150ml of formic acid with a volume concentration of 60-90%, stirred for 20 minutes, added 0.2 grams of vanadium pentoxide, slowly added 12 grams of hydrogen peroxide with a volume concentration of 20-60%, and controlled the temperature at 9-13 ℃, and react at this temperature for 5-6 hours. Sampling was done for HPLC detection. After the reaction was completed, 2.1 g of anhydrous sodium sulfite was added to continue the reaction for 1 hour. At a temperature of 30 to 50 ° C, the formic acid was evaporated under reduced pressure (vacuum degree of 0.04 to 0.095 MPa), 50 ml of methanol was added, and mole 10% aqueous sodium hydroxide solution to neutralize residual formic acid. Filtrate, take the precipitated solid, wash with water until neutral, and dry to obtain 38.2 g of crude fipronil.

[0018] Mix toluene and n-hexane at a volume ratio of 4:1 to form a mixed solve...

Embodiment 2

[0022] Under the temperature environment of -10 ~ 60 ℃, slowly add 24 grams of solid sodium perborate or solid sodium perborate and its hydrate, 0.2 grams of vanadium pentoxide into 60 grams of 80% formic acid, stir for 20 minutes, at 9 40 g of 5-amino-3-cyano-1-(2,6-dichloro-4-trifluoromethylphenyl)-4-trifluoromethylthiopyridine dissolved in 150 ml of formic acid was added dropwise at ~13°C azole, and react at this temperature for 2 to 3 hours. Sampling for HPLC detection. After the reaction is completed, add 2.1 g of anhydrous sodium sulfite to continue the reaction for 1 hour. At a temperature of 30 to 50 ° C, evaporate the formic acid under reduced pressure (vacuum degree of 0.04 to 0.095 MP), add 50 ml of methanol, and slowly add the molar concentration 10% aqueous sodium hydroxide solution to neutralize residual formic acid. Filtrate, take the precipitated solid, wash with water until neutral, and dry to obtain 37.5 g of crude fipronil with a content of 93%.

Embodiment 3

[0024] Add 40 grams of 5-amino-3-cyano-1-(2,6-dichloro-4-trifluoromethylphenyl)-4-trifluoro Methylthiopyrazole, 0.2 g of vanadium pentoxide and 150 ml of 80% formic acid were stirred and dissolved. Add 24.4 grams of m-chloroperoxybenzoic acid three times in the range of 9 to 13 ° C, and react at this temperature for 8-12 hours, take a sample to monitor HPLC, after the reaction is completed, add 2.1 grams of anhydrous sodium sulfite to continue the reaction for one hour, At a temperature of 30-50°C, distill the formic acid under reduced pressure (vacuum degree 0.04-0.095MP), add 50ml of methanol, and slowly add 10% sodium hydroxide solution to neutralize the remaining formic acid. Filter, wash the precipitated solid with water until neutral, and dry to obtain 38.1 g of crude fipronil with a content of 92.5%.

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Abstract

The invention relates to a preparation method of fipronil formed by oxidization of phenyl pyrazole derivatives, in particular to a method for catalyzing and oxidizing to generate the fipronil in methanoic acid medium by using 5-amino-3-cyano-1-(2,6-dichloro-4-trifluoromethylphenyl) pyrazole as raw materials. The invention adopts the technical scheme that the methanoic acid medium is oxidized to generate the fipronil, and methanoic acid is decompressed and distilled to be recovered. The invention has the advantages of simple process, environment protection, mild reaction condition, low production cost and the like, and has better industrial application prospect.

Description

technical field [0001] The present invention relates to a kind of preparation method of fipronil, especially by 5-amino-3-cyano-1-(2,6-dichloro-4-trifluoromethylphenyl)-4-trifluoromethylsulfide The technical field of synthetic technology for generating fipronil by oxidation of base pyrazole. Background technique [0002] Fipronil, also known as fipronil, chemical name 5-amino-3-cyano-1-(2,6-dichloro-4-trifluoromethylphenyl)-4-trifluoromethylthiopyrazole . White solid, melting point 200-201°C. The acute oral LD50 of rats is 97 mg / kg. Fipronil is a broad-spectrum insecticide, its mechanism of action interferes with the pathway of chloride ions through the chloride channel regulated by GABA, destroys the activity of the normal central nervous system and causes the death of individuals in sufficient doses. With contact killing, stomach poisoning and moderate systemic effects, it can control both underground pests and aboveground pests. The main control targets include aphids...

Claims

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Application Information

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IPC IPC(8): C07D231/44B01J23/22A01P7/04
Inventor 盛生昌李西宁周启伍朱林飞
Owner YANGZHOU TIANHE PHARM CO LTD
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