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Difluoromethylation Preparation method for 2-(2,4-dichlorophenyl)-1,2-dihydrogen-5-methyl-3H-1,2,4-triazole-3-ketone

A technology of -3H-1 and difluoromethylation, applied in the direction of organic chemistry, can solve the problems of not being suitable for industrial production, peroxide accumulation, and high cost of polyether, and achieve low cost, high recovery rate, and benefit The effect of industrial production

Active Publication Date: 2013-07-03
JIANGSU BAOZONG & BAODA PHARMACHEM
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007]Although the yield of the reaction is greatly improved, reaching 87.8%, but The cost of polyether is high, its solubility in water is high, and it is difficult to recycle. It also has the hidden danger of peroxide accumulation, so it is not suitable for industrial production.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0016] 0.5 moles of 2-(2,4-dichlorophenyl)-1,2-dihydro-5-methyl-3H-1,2,4-triazol-3-one, 0.025 moles of PEG300, 0.4 Add moles of potassium carbonate to 1 kg of xylene, heat to 140°C, reflux and dehydrate for 4 hours, and continue heating to 185°C after the potassium salt is completely formed, quickly pass through difluorochloromethane, and continue to keep warm React for half an hour, then cool, add water to wash, separate phases, and remove xylene under reduced pressure. Add water, azeotrope to further remove residual xylene. Cool, filter, wash, and dry to obtain 2-(2,4-dichlorophenyl)-4-(difluoromethyl)-2,4-dihydro-5-methyl-3H-1,2, 4-triazol-3-one product, the content is 87.2%, and the yield is 84.5%.

Embodiment 2

[0018] 0.5 moles of 2-(2,4-dichlorophenyl)-1,2-dihydro-5-methyl-3H-1,2,4-triazol-3-one, 0.025 moles of polyethylene glycol Alcohol dimethyl ether, 0.4 moles of potassium carbonate is added to 1 kg of xylene, heated to 140°C, refluxed for 4 hours, until the potassium salt is completely formed, continue to heat to 185°C, and quickly pass in difluorochloromethane , After passing through, continue to keep warm for half an hour, then cool, add water to wash, separate phases, and remove xylene under reduced pressure. Add water, azeotrope to further remove residual xylene. Cool, filter, wash, and dry to obtain 2-(2,4-dichlorophenyl)-4-(difluoromethyl)-2,4-dihydro-5-methyl-3H-1,2, 4-triazol-3-one product, the content is 88.5%, and the yield is 86.3%.

Embodiment 3

[0020] 0.5 mol of 2-(2,4-dichlorophenyl)-1,2-dihydro-5-methyl-3H-1,2,4-triazol-3-one, 0.025 mol of triethylene glycol Add dimethyl ether and 0.4 moles of potassium carbonate to 1 kg of xylene, heat to 140°C, reflux and dehydrate for 4 hours, after the potassium salt is completely formed, continue heating to 185°C, and quickly feed difluorochloromethane, After passing through, continue to keep warm for half an hour, then cool, add water to wash, separate phases, and remove xylene under reduced pressure. Add water, azeotrope to further remove residual xylene. Cool, filter, wash, and dry to obtain 2-(2,4-dichlorophenyl)-4-(difluoromethyl)-2,4-dihydro-5-methyl-3H-1,2, 4-triazol-3-one product, the content is 90.3%, and the yield is 88.2%.

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Abstract

The invention discloses a difluoromethylation Preparation method for 2-(2,4-dichlorophenyl)-1,2-dihydrogen-5-methyl-3H-1,2,4-triazole-3-ketone. The method comprises the following steps: triadimefon is led to react with potassium carbonate to obtain potassium triadimefon using xylol as reaction solvent and in the presence of phase transfer catalyst; the potassium triadimefon is then let to react with chlorodifluoromethane at the temperature of 150-200 DEG C; and the 2-(2,4-dichlorophenyl)-1,2-dihydrogen-5-methyl-3H-1,2,4-triazole-3-ketone is prepared at a high yield. The method is simple and highly efficient, is safe in operation and high in yield, and facilitates industrial production.

Description

technical field [0001] The invention relates to the technical field of fine chemicals, specifically a 2-(2,4-dichlorophenyl)-1,2-dihydro-5-methyl-3H-1,2,4-triazole- Preparation method of 3-ketone by difluoromethylation. Background technique [0002] 2-(2,4-Dichlorophenyl)-4-(difluoromethyl)-2,4-dihydro-5-methyl-3H-1,2,4-triazol-3-one (CAS No: 111992-16-6) is an intermediate of the herbicide sulfentrazone. The current industrial preparation method is obtained from phenylhydrazine as a starting material through ring formation, fluoromethylation and chlorination. The reaction equation is as follows (US5468868 (FMC), US5438149 (FMC)): [0003] This route involves secondary chlorination and uses two kinds of solvent systems, which has the problems of serious equipment corrosion, complicated operation and low yield. [0004] The document US 4909831 (FMC) reported that 2,4-dichlorophenylhydrazine was used as the starting material to obtain it through two steps of cyclization a...

Claims

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Application Information

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IPC IPC(8): C07D249/12
Inventor 朱志勇王琳陈荣
Owner JIANGSU BAOZONG & BAODA PHARMACHEM
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