Preparation method of 3-(difluoromethyl)-1-methyl-1H-pyrazol-4-carboxylic acid

A technology of difluoromethyl and dimethylamino, applied in the field of preparation of 3--1-methyl-1H-pyrazole-4-carboxylic acid, can solve the problem of no yield report, unsuitable for industrial production, system High moisture content is required to achieve the effect of simple and safe process operation, reduced solvent recovery cost and environmental pollution risk, and high product yield

Active Publication Date: 2014-02-12
HUNAN CHEM RES INST
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although there are certain advantages in cost, the key step of the reaction between difluoroacetylhydrazide and propiolate requires high temperature react

Method used

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  • Preparation method of 3-(difluoromethyl)-1-methyl-1H-pyrazol-4-carboxylic acid
  • Preparation method of 3-(difluoromethyl)-1-methyl-1H-pyrazol-4-carboxylic acid
  • Preparation method of 3-(difluoromethyl)-1-methyl-1H-pyrazol-4-carboxylic acid

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0030] Add 19.6g (0.35mol) propynyl alcohol, 8.75g (0.105mol) sodium hydroxide, and 60mL water into a 1000mL three-necked flask with mechanical stirring, control the reaction temperature at -5 to 5°C with ice-salt water, and dissolve 408mL (0.98 mol) 2.4mol / L sodium hypochlorite solution was added dropwise into the reaction bottle within 1 hour, and the reaction was continued for 1 hour. After the reaction, adjust the pH to 1 with concentrated hydrochloric acid and then stir for one hour, extract with ethyl acetate, stand still and separate the phases, and distill the organic phase under reduced pressure to obtain 22.4 g of propiolic acid with a content of 98.7% (liquid chromatography). The rate is 90.2%.

[0031] Add 22.4g (0.316mol) propiolic acid, 0.067g (0.3% of the mass of propiolic acid) nano-scale titanium dioxide, 17.4g (0.379mol) ethanol, and 130mL toluene to the tank with mechanical stirring, condenser and water separator A 500mL three-necked flask was refluxed and ...

Embodiment 2

[0038] Add 19.6g (0.35mol) propynyl alcohol, 8.75g (0.105mol) sodium hydroxide, and 80mL water into a 1000mL three-neck flask with mechanical stirring, and control the reaction temperature at -5 to 5°C with ice-salt water, and dissolve 408mL (0.98 mol) 2.4mol / L sodium hypochlorite solution was added dropwise into the reaction bottle within 1 hour, and the reaction was continued for 1 hour. After the reaction, adjust the pH to 1 with concentrated hydrochloric acid, then stir for one hour, extract with ethyl acetate, stand still and separate the phases, and distill the organic phase under reduced pressure to obtain 22.7 g of propiolic acid with a content of 97.9% (liquid chromatography). The rate is 90.8%.

[0039] Add 22.7g (0.318mol) propiolic acid, 0.091g (0.4% of the mass of propiolic acid) nanoscale titanium dioxide, 17.5g (0.38mol) ethanol, and 130mL toluene into a 500mL vessel with mechanical stirring, condenser and water separator The three-necked flask was refluxed and...

Embodiment 3

[0046] Add 19.6g (0.35mol) propynyl alcohol, 8.75g (0.105mol) sodium hydroxide, and 80mL water into a 1000mL three-neck flask with mechanical stirring, and control the reaction temperature at -5 to 5°C with ice-salt water, and dissolve 408mL (0.98 mol) 2.4mol / L sodium hypochlorite solution was added dropwise into the reaction bottle within 1 hour, and the reaction was continued for 1 hour. After the reaction, adjust the pH to 1 with concentrated hydrochloric acid and then stir for one hour, extract with ethyl acetate, stand and separate the phases, and distill the organic phase under reduced pressure to obtain 22.7 g of propiolic acid with a content of 98.3% (liquid chromatography). The rate is 90.9%.

[0047] Add 22.7g (0.318mol) propiolic acid, 0.091g (0.4% of the mass of propiolic acid) nanoscale titanium dioxide, 17.6g (0.382mol) ethanol, and 160mL toluene into a 500mL vessel with mechanical stirring, condenser and water separator The three-necked flask was refluxed and w...

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Abstract

The invention discloses a preparation method of 3-(difluoromethyl)-1-methyl-1H-pyrazol-4-carboxylic acid. The reaction formula is shown in the specification. Difluoroacetic acid, which is relatively low in price and small in molar mass and is introduced at a post-synthesis phase is adopted, so that the preparation method of the 3-(difluoromethyl)-1-methyl-1H-pyrazol-4-carboxylic acid is low in cost, simple and safe in technological operation, high in product content, and high in product yield; the content is 98.1-98.9% (liquid chromatogram, external standard); the total yield is 52.2-56.9% (based on propargyl alcohol). Nanoscale titanium dioxide is adopted to carry out catalytic esterification, so that the reaction yield is high; the reaction time is short; the used raw materials and solvent are cheap and available; furthermore, an organic solvent is avoided in the four reaction steps, so that the solvent recovery cost and the environmental pollution risk are greatly reduced.

Description

technical field [0001] The invention 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 is an important intermediate for the synthesis of amide-type low-toxicity and high-efficiency fungicides such as flufenapyramide, bixafen, and nappyrid Its content and yield directly affect the production cost and product quality of downstream products such as flufenapyramide, bixafen, and napyril. The molecular formula of 3-(difluoromethyl)-1-methyl-1H-pyrazole-4-carboxylic acid: C 6 h 6 f 2 N 2 o 2 , molecular weight: 176.12, molecular structure formula: [0003] [0004] Currently, the preparation methods of 3-(difluoromethyl)-1-methyl-1H-pyrazole-4-carboxylic acid mainly include the following. [0005] EP2008996 discloses a method for synthesizing 3-(difluoromethyl)-1-methyl-1H-pyrazole-4-carboxylic acid in five steps with dichloroacetyl chloride...

Claims

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Application Information

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IPC IPC(8): C07D231/14
CPCC07D231/14
Inventor 王宇李利锋毛春晖赵东江杨彬陈明
Owner HUNAN CHEM RES INST
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