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Preparation method of 3-(difluoromethyl)-1-methyl-1H-pyrazole-4-carboxylic acid ethyl ester

A technology of dimethylpyrazole and difluoromethyl, which is applied in the field of preparation of ethyl 3--1-methyl-1H-pyrazole-4-carboxylate, can solve the problem of insufficient purity and the existence of isomers, etc. question

Active Publication Date: 2020-06-05
徐州圣元化工有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] At present, this compound shows more and more application value. However, there are many synthetic literature reports of this compound, among which condensation and cyclization are mostly used for synthesis, but it has disadvantages such as isomers and insufficient purity.

Method used

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  • Preparation method of 3-(difluoromethyl)-1-methyl-1H-pyrazole-4-carboxylic acid ethyl ester
  • Preparation method of 3-(difluoromethyl)-1-methyl-1H-pyrazole-4-carboxylic acid ethyl ester
  • Preparation method of 3-(difluoromethyl)-1-methyl-1H-pyrazole-4-carboxylic acid ethyl ester

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Embodiment 1

[0032]

[0033] 100g (1.04mol, 1eq) of 1,3-dimethylpyrazole and 400mL of ethanol were put into the reaction flask, and 166.4g (1.04mol, 1.00eq) of bromine was added dropwise with stirring at 5-10°C. React at 5-10°C for 4 hours, sample GC to detect the remaining raw materials 1 HNMR (400MHz, CDCl3): 7.97(s, 1H), 3.95(s, 3H), 2.77(s, 3H).

Embodiment 2

[0035]

[0036] Into the reaction flask, put 100g (1.04mol, 1eq) of 1,3-dimethylpyrazole, 800mL water and 400mL ethanol, add 132.1g (0.52mol, 0.5eq) of iodine in batches under stirring at room temperature, and then control the temperature at 84.8g (0.624mol, 0.6eq) of 25% hydrogen peroxide was added dropwise at 15-20°C. Stir at room temperature for 20 hours, sample GC to detect the remaining raw materials 1 HNMR (400MHz, CDCl 3 ):7.80(s,1H),3.95(s,3H),2.15(s,3H).

[0037] The second step: the synthesis of 4-(bromo / iodo)-1-methyl-1H-pyrazole-3-carbaldehyde

Embodiment 3

[0039]

[0040] 150g (0.857mol, 1eq) of 4-bromo-1,3-dimethyl-1H-pyrazole and 750mL of dichloromethane were put into the reaction flask, and 14g (0.086mol, 0.1 eq) Raise the temperature to 35-40°C and add NBS243.9g (1.37mol, 1.6eq) in batches. Subsequently, the temperature was controlled at 65-70° C. for 7 hours. Sampling GC to detect that the remaining raw material is 1 HNMR (400MHz, CDCl 3 ):9.75(s,1H),7.91(s,1H),3.95(s,3H).

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Abstract

The invention discloses a preparation method of 3-(difluoromethyl)-1-methyl-1H-pyrazole-4-carboxylic acid ethyl ester, and belongs to the technical field of organic synthesis. The preparation method comprises the following steps: with 1,3-dimethylpyrazole as a raw material, carrying out halogenation to obtain 4-halogenated-1,3,5-tetrahydronaphthalene; carrying out a reaction under the conditions of a bromination reagent and AIBN and hydrolysis with hexamethylenetetramine to obtain 4-halogen-1-methyl-1H-pyrazole-3-formaldehyde, then performing a reaction with a fluorination reagent to obtain 4-halogen-3-difluoromethyl-1-methylpyrazole; finally carrying out a reaction on the 4-halogen-3-difluoromethyl-1-methylpyrazole and a Grignard reagent to obtain 3-(difluoromethyl)-1-methyl-1H-pyrazole-4-carboxylic acid ethyl ester. The method is simple and convenient to operate and high in reaction yield, the purity of the obtained product can reach 99.5% or above, and the method has a potential process amplification prospect.

Description

technical field [0001] The invention relates to a preparation method of ethyl 3-(difluoromethyl)-1-methyl-1H-pyrazole-4-carboxylate, belonging to the technical field of organic synthesis. Background technique [0002] 3-(Difluoromethyl)-1-methyl-1H-pyrazole-4-carboxylic acid ethyl ester, English name: 3-difluoro methyl-1-methyl-1H-pyrazole-4-carboxylic acid ethyl ester, CAS : 141573-95-7, boiling point 288.4°C. 3-(Difluoromethyl)-1-methyl-1H-pyrazole-4-carboxylic acid ethyl ester can be used to prepare difluoromethylpyrazole carboxamides, which can be used as succinate dehydrogenase Inhibitory fungicides. Succinate dehydrogenase inhibitory fungicides are highly effective fungicides with high activity against a wide range of phytopathogenic fungi and are used for fungi in various cultivated plants such as cotton, vegetables, barley, corn, etc. and seeds Prevention and control has become a hot spot developed by major pesticide companies in recent years. [0003] At present...

Claims

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Application Information

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IPC IPC(8): C07D231/14
CPCC07D231/14
Inventor 陈红於万里
Owner 徐州圣元化工有限公司
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