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Preparation method of 3-difluoromethyl-1-methyl-1H-pyrazolyl-4-carboxylic acid

A technology of difluoromethyl and dimethylaminoacrylonitrile, which is applied in the field of synthesis of fine chemical intermediates, can solve the problems of high price of ethyl difluoroacetoacetate, unsuitability for industrial production, and high cost of industrial production, and achieve cost Low cost, low equipment requirements, and short process routes

Active Publication Date: 2014-11-26
YIFAN AGRI CHEM PLANT ZHEJIANG PROV
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Problems solved by technology

The process conditions are relatively harsh, and the isomers are not easy to separate, so it is not suitable for industrial production
[0007] WO2009106619 uses ethyl difluoroacetoacetate, acetic anhydride, triethyl orthoformate, and methylhydrazine as raw materials to synthesize 3-difluoromethyl-1-methyl-1H-pyrazole-4-carboxylic acid in 3 steps. The price of ethyl fluoroacetoacetate is relatively expensive, and the isomers are not easy to separate, and the industrial production cost is relatively high
[0008] Wang Yu et al prepared 2-difluoroacetyl-3-(dimethylamino)ethyl acrylate, difluoroacetic acid, hydrazine hydrate, and dimethyl sulfate to synthesize 3-difluoromethacrylate from acetylene alcohol as the starting material. Methyl-1-methyl-1H-pyrazole-4-carboxylic acid, the total reaction yield is 52%, the route is long, and the industrialization cost is higher

Method used

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  • Preparation method of 3-difluoromethyl-1-methyl-1H-pyrazolyl-4-carboxylic acid
  • Preparation method of 3-difluoromethyl-1-methyl-1H-pyrazolyl-4-carboxylic acid
  • Preparation method of 3-difluoromethyl-1-methyl-1H-pyrazolyl-4-carboxylic acid

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Embodiment 1

[0033] Example 1: Preparation of 3-difluoromethyl-1-methyl-1H-pyrazole-4-carboxylic acid (I)

[0034] 1) Preparation of N,N-dimethylaminoacrylonitrile (IV): Put 9.8g (92mmol) of sodium cyanoacetate and 50mL of toluene into a 100mL four-necked flask, and control the temperature at 40°C Add 55g (228mmol) of the imide salt shown in the formula (Ⅲ) dropwise, about 3 hours after the dropwise addition, keep the temperature for 6 hours, add 60mL of 5% sodium hydroxide aqueous solution to the feed solution, and stir for 5 minutes , layered extraction, the obtained toluene layer was dried with anhydrous sodium sulfate, concentrated to obtain 9.2g of N,N-dimethylaminoacrylonitrile shown in formula (IV), and the content of the product detected by GC (gas chromatography) was 94.2 %, the yield is 98.3%. 1 H-NMR (CDCl 3 , 500 MHz): δ=2.87 (6H, s, CH3), 3.60 (1H, d, CH), 6.91 (1H, d, CH);

[0035] In above-mentioned embodiment, replace toluene with any one in benzene, dichloromethane, she...

Embodiment 2

[0043] Example 2: Preparation of 3-difluoromethyl-1-methyl-1H-pyrazole-4-carboxylic acid (I)

[0044] 1) Preparation of N,N-dimethylaminoacrylonitrile (Ⅳ): Put 4.9g (46mmol) sodium cyanoacetate and 40mL ethanol into a 100mL four-neck flask, and add 27g (113mmol) dropwise at a temperature of about 30°C, such as The imine salt shown in formula (Ⅲ) was added dropwise in about 2 hours, and the reaction was incubated for 8 hours. 50 ml of 5% aqueous sodium hydroxide solution was added to the feed liquid, stirred for 5 minutes, extracted with toluene, and the obtained toluene The layer was dried over anhydrous sodium sulfate and concentrated to obtain 4.1 g of N,N-dimethylaminoacrylonitrile represented by formula (IV). The product content was 95.1% and the yield was 97.4% as detected by GC (gas chromatography). 1 H-NMR (CDCl 3 , 500 MHz): δ=2.85 (6H, s, CH3), 3.61 (1H, d, CH), 6.93 (1H, d, CH);

[0045] 2) Preparation of 2-((dimethylamino)methylene)-4,4-difluoro-3-carbonylbutyroni...

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Abstract

The invention relates to a preparation method of 3-difluoromethyl-1-methyl-1H-pyrazolyl-4-carboxylic acid, which comprises the following steps: reacting sodium cyanoacetate and imide salt to obtain N,N-dimethylaminoacrylonitrile, and reacting with difluoroacetyl chloride to obtain 2-((dimethylamino)methylene)-4,4-difluoro-3-carbonylbutyronitrile; reacting with methyl hydrazine to obtain 1-methyl-3-difluoromethyl-4-pyrazolylnitrile; and finally, reacting the 1-methyl-3-difluoromethyl-4-pyrazolylnitrile with sodium hydroxide to obtain the 3-difluoromethyl-1-methyl-1H-pyrazolyl-4-carboxylic acid. The method has the advantages of simple and accessible raw materials, low price, short process route, mild reaction conditions, low facility requests, high total reaction yield (more than 52%) and high product purity (more than 99.2%). The method has the characteristics of simple and reasonable technique, mild reaction conditions, high yield and low cost, can easily implement industrialization, and has wide application prospects.

Description

technical field [0001] The invention belongs to the technical field of synthesis of fine chemical intermediates, and in particular relates to a preparation method of 3-difluoromethyl-1-methyl-1H-pyrazole-4-carboxylic acid. Background technique [0002] 3-Difluoromethyl-1-methyl-1H-pyrazole-4-carboxylic acid (shown in formula (I)) is a synthetic compound of fluflufen, bixafen and pyraclofen, etc. It is a key intermediate of new amide fungicides, and its synthesis methods have been reported in many ways. [0003] [0004] A route introduced by EP2008996 is to synthesize 3-difluoromethyl-1-methyl-1H-pyrazole-4-carboxylic acid in 5 steps with raw materials such as dichloroacetyl chloride, vinyl ether compounds, and methylhydrazine. Although there are certain advantages in cost control, the reaction conditions are relatively harsh, in which dichloroacetyl chloride and vinyl ether compounds need to react at -40~-20°C; during the process of introducing carboxyl groups, the reac...

Claims

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Application Information

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IPC IPC(8): C07D231/14
CPCC07D231/14
Inventor 吴克崇吴贯中谭成侠潘旭闽
Owner YIFAN AGRI CHEM PLANT ZHEJIANG PROV
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