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Preparation process of 1-(3-chloropyridine-2-yl)-3-bromo-1H-pyrazole-5-formic acid

A preparation process, the technology of chloropyridine, which is applied in the direction of organic chemistry, can solve the problems of complex operation, difficult industrialization, harsh conditions, etc., and achieve the effect of accelerating the reaction, improving the purity, and mild reaction conditions

Inactive Publication Date: 2016-12-07
ABA CHEM NANTONG
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Problems solved by technology

[0005] Referring to relevant literature, there are three main routes for the synthesis of 1-(3-chloropyridin-2-yl)-3-bromo-1H-pyrazole-5-carboxylic acid: Route 1 is composed of 3-bromopyrrole and 2,3 -Condensation of dichloropyridine to obtain 3-bromo-1-(5-chloro-2-pyrrolyl)pyrrole, which is then treated with lithium diisopropylamide, and the lithium salt obtained is then quenched with carbon dioxide to prepare; line 2 is based on 2 , 3-dichloropyridine and diethyl maleate are prepared as starting materials; Line 3 is prepared with monomethyl maleate and 2,3-dichloropyridine as starting materials; The problem of low efficiency, some still have complex operation, harsh conditions, difficult to industrialize

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  • Preparation process of 1-(3-chloropyridine-2-yl)-3-bromo-1H-pyrazole-5-formic acid
  • Preparation process of 1-(3-chloropyridine-2-yl)-3-bromo-1H-pyrazole-5-formic acid

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Effect test

Embodiment 1

[0017] The preparation process of 1-(3-chloropyridin-2-yl)-3-bromo-1H-pyrazole-5-carboxylic acid in this embodiment, the specific steps of the preparation process are as follows:

[0018] (1) Add 70g of 2,3-dichloropyridine and 250ml of ethanol with a mass concentration of 95% to the reaction bottle, add dropwise 125ml of hydrazine hydrate with a mass concentration of 50% under vigorous stirring, and heat to reflux for 25 hours after the addition is completed. After cooling to room temperature, a large amount of white crystals precipitated, filtered and dried to obtain 3-chloro-2-hydrazinopyridine;

[0019] (2) Add 125ml of sodium ethoxide solution into the reaction flask, then add 28g of 3-chloro-2-hydrazinopyridine under reflux, add 42g of diethyl maleate dropwise, drop it for about 1.5h, and continue the reflux reaction for 2.5 h, then lower to room temperature, add 20ml of glacial acetic acid and 300ml of water, after recovering most of the solvent, add 45ml of ethanol wit...

Embodiment 2

[0024] The preparation process of 1-(3-chloropyridin-2-yl)-3-bromo-1H-pyrazole-5-carboxylic acid in this embodiment, the specific steps of the preparation process are as follows:

[0025] (1) Add 60g of 2,3-dichloropyridine and 200ml of ethanol with a mass concentration of 95% in the reaction bottle, add dropwise 100ml of hydrazine hydrate with a mass concentration of 50% under vigorous stirring, and heat to reflux for 20 hours after the addition is completed. After cooling to room temperature, a large amount of white crystals precipitated, filtered and dried to obtain 3-chloro-2-hydrazinopyridine;

[0026] (2) Add 100ml of sodium ethoxide solution into the reaction flask, then add 25g of 3-chloro-2-hydrazinopyridine under reflux, add 40g of diethyl maleate dropwise, drop it for about 1h, and continue the reflux reaction for 2h. Then drop to room temperature, add 15ml of glacial acetic acid and 250ml of water, after recovering most of the solvent, add 40ml of ethanol with a ma...

Embodiment 3

[0031] The preparation process of 1-(3-chloropyridin-2-yl)-3-bromo-1H-pyrazole-5-carboxylic acid in this embodiment, the specific steps of the preparation process are as follows:

[0032](1) Add 80g of 2,3-dichloropyridine and 300ml of ethanol with a mass concentration of 95% in the reaction bottle, add dropwise 150ml of hydrazine hydrate with a mass concentration of 50% under vigorous stirring, and heat to reflux for 30 hours after the addition is completed. After cooling to room temperature, a large amount of white crystals precipitated, filtered and dried to obtain 3-chloro-2-hydrazinopyridine;

[0033] (2) Add 150ml of sodium ethoxide solution into the reaction flask, then add 30g of 3-chloro-2-hydrazinopyridine under reflux, add 45g of diethyl maleate dropwise, drop it for about 2h, and continue the reflux reaction for 3h. Then cool down to room temperature, add 25ml of glacial acetic acid and 350ml of water, after recovering most of the solvent, add 50ml of ethanol with ...

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Abstract

The invention relates to a preparation process of 1-(3-chloropyridine-2-yl)-3-bromo-1H-pyrazole-5-formic acid. The preparation process comprises five steps including synthesis of 3-chloro-2-hydrazinopyridine, synthesis of 2-(3-chloropyridine-2-yl)-5-hydroxypyrazole-3-ethyl formate, synthesis of 3-bromo-1-(3-chloropyridine-2-yl)-4,5-dihydro-1H-pyrazole-5-ethyl formate, synthesis of 3-bromo-1-(3-chloropyridine-2-yl)-1H-pyrazole-5-ethyl formate and synthesis of the 1-(3-chloropyridine-2-yl)-3-bromo-1H-pyrazole-5-formic acid. The preparation process of the 1-(3-chloropyridine-2-yl)-3-bromo-1H-pyrazole-5-formic acid has the advantages that a sodium ethoxide solution is directly adopted; compared with the utilization of ethanol and metal sodium, a reaction is accelerated so that the reaction time is shortened; meanwhile, bromine remained in the reaction is removed by sodium hydrogen sulfite, so that the purity of the product is greatly improved; in the whole process, reaction conditions are relative moderate, so that the preparation process is suitable for industrial production and the yield of the product is greatly improved.

Description

technical field [0001] The invention relates to the technical field of pharmaceutical intermediates, in particular to a 1-(3-chloropyridine [0002] -2-yl)-3-bromo-1H-pyrazole-5-carboxylic acid preparation process. Background technique [0003] Invertebrates can cause severe crop yield reduction, and are extremely harmful in high-efficiency agriculture. How to produce a pesticide with high efficiency, low toxicity, low price and environmental safety is imminent. Chlorantraniliprole is a new type of o-formamidobenzamide insecticide discovered and developed by DuPont in 2000. It is a new type of ryanodine receptor insecticide with high efficiency, low toxicity and unique mechanism of action. -(3-Chloropyridin-2-yl)-3-bromo-1H-pyrazole-5-carboxylic acid is a key intermediate in the synthesis of chlorantraniliprole. The main mechanism of action of chlorantraniliprole is to induce the activation of insect ryanodine receptors and release the endogenous calcium ion pool. It has t...

Claims

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Application Information

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IPC IPC(8): C07D401/04
CPCC07D401/04
Inventor 吕剑牛跃辉吴争光
Owner ABA CHEM NANTONG
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