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Preparation method of fipronil intermediate

A technology for fipronil and intermediates, which is applied in the field of preparation of fipronil intermediates, can solve the problems of many reaction by-products, high reaction pressure, difficult purification and the like, and achieves high product yield, short reaction steps, and side reactions. less effect

Active Publication Date: 2020-02-28
SUZHOU KAIYUAN MINSHENG SCI & TECH CORP
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Problems solved by technology

[0003] At present, literatures and patents have reported various synthesis methods of 2,6-dichloro-4-trifluoromethylaniline, and these methods mainly have two major technical problems: one is that the reaction pressure is high, the yield is low, and it is difficult to realize industrialization; Second, there are many reaction by-products, which are difficult to purify. The product obtained is liquid with a purity of only about 90%.
This technical scheme uses bromotrifluoromethane gas as the trifluorinating reagent, which needs to be reacted in a pressure vessel, but bromotrifluoromethane has a strong corrosive effect on general metals, and has higher requirements for large-scale production equipment

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  • Preparation method of fipronil intermediate
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  • Preparation method of fipronil intermediate

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preparation example Construction

[0030] The preparation method of the fipronil intermediate of the concrete implementation of the present invention comprises:

[0031] In the first step, 4-methylaniline is chlorinated to obtain 2,6-dichloro-4-trichloromethylaniline;

[0032] The second step is to prepare 2,6-dichloro-4-trifluoromethylaniline by fluorinating 2,6-dichloro-4-trichloromethylaniline, which is the finished product of fipronil intermediate.

[0033] The specific process of the first step is as follows: In the reaction vessel, take the solvent, 4-methylaniline and catalyst and mix them uniformly, then add a chlorination reagent to carry out the chlorination reaction, and the reaction product is desolvated and purified to obtain 2,6 -Dichloro-4-trichloromethylaniline.

[0034] Specifically, in the first step:

[0035] The solvent is an inert solvent, and the inert solvent is ethylene dichloride, chloroform, or carbon tetrachloride.

[0036] The equivalent ratio of 4-methylaniline, catalyst, and chl...

Embodiment 1

[0053] Add 107.1g (1mol, 1.0eq) of 4-methylaniline into a 1000ml four-necked flask, 3.3g (0.02mol, 0.02eq) of catalyst azobisisobutylcyanide, and 500g of solvent dichloroethane, start stirring, and heat to 30°C, 426g (6mol, 6.0eq) of chlorinated reagent chlorine gas was passed in at 30°C-50°C, after passing through, the reaction was kept at 30°C-50°C for 4 hours. Controlled by HPLC, when 4-methylaniline is less than 1%, stop the reaction, precipitate under reduced pressure, crystallize at lower temperature, and obtain 273.8g of 2,6-dichloro-4-trichloromethylaniline by suction filtration, purity: 99.2 %, yield: 98%. This 2,6-dichloro-4-trichloromethylaniline's nuclear magnetic hydrogen spectrogram is as figure 1 shown.

[0054] Add 2,6-dichloro-4-trichloromethylaniline 273.8g (0.98mol, 1.0eq) and solvent DMF 550g into a 2000ml four-necked bottle, start stirring, and add the fluorinated reagent potassium fluoride 68.3 after the raw materials are dissolved g (1.18mol, 1.2eq), ...

Embodiment 2

[0058] Add 107.1g (1mol, 1.0eq) of 4-methylaniline, 4.8g (0.02mol, 0.02eq) of catalyst dibenzoyl peroxide, and 450g of solvent chloroform into a 1000ml four-necked flask, start stirring, and heat to 30°C. At 30°C-50°C, 462 g (6.5 mol, 6.0 eq) of chlorine gas, a chlorinating reagent, was passed through, and the mixture was incubated at 30°C-50°C for 5 hours. Controlled by HPLC, when 4-methylaniline is less than 1%, stop the reaction, precipitate under reduced pressure, crystallize at lower temperature, and filter with suction to obtain 271g of 2,6-dichloro-4-trichloromethylaniline, purity: 99.0% , Yield: 97%. The H NMR spectrum of the 2,6-dichloro-4-trichloromethylaniline is consistent with that of Example 1.

[0059] Add 271g (0.97mol, 1.0eq) of 2,6-dichloro-4-trichloromethylaniline and 500g of solvent DMSO into a 2000ml four-necked bottle, start stirring, and add 84.5g of fluorinated reagent potassium fluoride after the raw materials are dissolved (1.46mol, 1.5eq), the cata...

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Abstract

The invention relates to a preparation method of a fipronil intermediate. The preparation method comprises the following steps: carrying out a chlorination reaction on 4-methylaniline to obtain 2,6-dichloro-4-trichloromethylaniline; and subjecting 2,6-dichloro-4-trichloromethylaniline to a fluorination reaction to prepare 2,6-dichloro-4-trifluoromethylaniline which is the finished product of the fipronil intermediate. The invention provides the brand-new preparation method of 2,6-dichloro-4-trifluoromethylaniline, and the method has the advantages of easy availability of initial raw materials,short reaction steps, clear mechanism, few side reactions and high product yield, and is beneficial for realization of industrialization. With the method, average yield is not lower than 90%, and product purity is 99.0% or above.

Description

technical field [0001] The invention relates to a preparation method of a fipronil intermediate, which is specifically 2,6-dichloro-4-trifluoromethylaniline, and belongs to the technical field of intermediate compound preparation. Background technique [0002] As far as the applicant knows, 2,6-dichloro-4-trifluoromethylaniline is an important intermediate for the synthesis of the insecticide fipronil, and its appearance is white or off-white crystals with a melting point of 35°C-37°C . [0003] At present, literatures and patents have reported various synthesis methods of 2,6-dichloro-4-trifluoromethylaniline, and these methods mainly have two major technical problems: one is that the reaction pressure is high, the yield is low, and it is difficult to realize industrialization; The 2nd, reaction by-product is many, is difficult to purify, and the product that obtains is liquid, and purity only has about 90%. [0004] The U.S. patent application with the publication number...

Claims

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Application Information

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IPC IPC(8): C07C209/74C07C211/52C07C209/84
CPCC07C209/74C07C209/84C07C211/52
Inventor 曾淼徐剑锋赵飞孙思程晓文
Owner SUZHOU KAIYUAN MINSHENG SCI & TECH CORP
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