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Method for preparing 2-cyano-3, 6-dichloropyridine

A technology of dichloropyridine and trichloropyridine, applied in the field of 2-cyano-3, can solve the problems of environmental hazards, low total yield, increased post-processing burden, etc., and achieves the advantages of reducing waste acid hazards and reducing operational risks. Effect

Active Publication Date: 2010-03-17
NANJING REDSUN BIOCHEM CO LTD +1
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Problems solved by technology

[0003] The preparation of 2-cyano-3,6-dichloropyridine mainly contains the following two methods: US4766219, with 2,3,6-trichloropyridine as raw material , the product is obtained by fluorination and cyanation of 2-position chlorine. Fluorination generally requires highly active fluoride, such as potassium fluoride, and cyanide requires highly toxic potassium cyanide or sodium cyanide. The total yield of the two-step reaction The efficiency is not high due to the restriction of the reaction conditions, and the residual unreacted substances cause great harm to the environment and increase the burden of post-processing
However, this principle has not been applied to the preparation process of 2-cyano-3,6-dichloropyridine, and the research selects a safe and cheap source of cyanide to prepare 2-cyano under mild, green and efficient reaction conditions. - The process method of 3,6-dichloropyridine has great practical application value

Method used

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  • Method for preparing 2-cyano-3, 6-dichloropyridine

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Effect test

Embodiment 1

[0021] 2,3,6-trichloropyridine (1092mg, 6mmol), potassium ferrocyanide trihydrate (557mg, 1.32mmol), sodium carbonate (636mg, 6mmol), palladium acetate (20mg, 0.03mmol) were dissolved in 100mLN, N - In dimethylformamide, under nitrogen protection. Heat to 120°C for 3 hours. After the reaction, the temperature returned to room temperature, and the reaction solution was diluted with 100 mL of ethyl acetate. Filter, and wash the filtrate twice with 80 mL of water and 80 mL of 5% ammonia water respectively. The organic phase was dried over anhydrous magnesium sulfate. The volatile substances were removed by rotary evaporation to obtain the product 2-cyano-3,6-dichloropyridine. The yield was 86%, and the purity was 97%.

Embodiment 2

[0023] 2,3,6-trichloropyridine (1820mg, 10mmol), potassium ferrocyanide (736mg, 2mmol), sodium carbonate (318mg, 3mmol), palladium acetate (6.7mg, 0.01mmol) were dissolved in 200mL 1,4- Dioxane, argon protection. Heat to 100°C for 3 hours. After the reaction, the temperature returned to room temperature, and the reaction solution was diluted with 200 mL of chloroform. Filter, and wash the filtrate twice with 150 mL of water and 100 mL of 5% ammonia water respectively. The organic phase was dried over sodium sulfate. The volatile substances were removed by rotary evaporation to obtain the product 2-cyano-3,6-dichloropyridine. The yield was 85%, and the purity was 96%.

Embodiment 3

[0025] 2,3,6-Trichloropyridine (1820mg, 10mmol), potassium ferrocyanide (3680mg, 10mmol), sodium carbonate (1060mg, 10mmol), palladium acetate (67.4mg, 0.1mmol) were dissolved in 300mL dimethylmethylene In sulfone, nitrogen protection. Heat to 135°C for 4 hours. After the reaction, the temperature returned to room temperature, and the reaction solution was diluted with 300 mL of ethyl acetate. Filter, and wash the filtrate twice with 200 mL of water and 150 mL of 5% ammonia water respectively. The organic phase was dried over anhydrous magnesium sulfate. The volatile substances were removed by rotary evaporation to obtain the product 2-cyano-3,6-dichloropyridine. The yield was 92%, and the purity was 95%.

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Abstract

The invention belongs to the field of chemical industry and discloses a method for preparing 2-cyano-3,6-dichloropyridine, which comprises the following steps: in an organic solvent, using 2,3,6-trichloropyridine and potassium ferrocyanide as raw materials, sodium carbonate and palladium diacetate as catalysts, and reacting for 2-20 hours at 40-200 DEG C under the protection of inert gases to prepare the 2-cyano-3,6-dichloropyridine, wherein the mol ratio of 2,3,6-trichloropyridine to potassium ferrocyanide to sodium carbonate to palladium diacetate is 1:0.1-1:0.1-1:0.001-0.01. The method usesthe potassium ferrocyanide which is convenient and easy to obtain as the source of cyanogens so as to avoid using the virulent cyanides, reduce the hazard of waste acids and the operational danger and also reduce the load for post-treatment. The method has the advantage of simpleness, mildness and environmental protection and is suitable for industrial production.

Description

technical field [0001] The invention belongs to the field of chemical industry and relates to a preparation method of 2-cyano-3,6-dichloropyridine. Background technique [0002] As an intermediate, 2-cyano-3,6-dichloropyridine can be used to prepare other intermediates or directly prepare pesticides, especially insecticides. [0003] The preparation of 2-cyano-3,6-dichloropyridine mainly contains the following two methods: US4766219, with 2,3,6-trichloropyridine as raw material, the product is obtained by fluorination and cyanation of 2-position chlorine, fluorine Cyanide generally needs highly active fluoride, such as potassium fluoride, and cyanide needs highly toxic potassium cyanide or sodium cyanide. The substances in it cause great harm to the environment and increase the burden of post-processing. Although the product can also be directly obtained from 2,3,6-trichloropyridine by one-step cyanation, the yield is very low. Journal of Labeled Compounds and Radiopharma...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D213/84
Inventor 薛谊李维思江涛蒋剑华王述刚
Owner NANJING REDSUN BIOCHEM CO LTD
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