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Preparation method for 2,3-dichloropyridine

A technology of dichloropyridine and trichloropyridine, which is applied in the field of preparation of 2,3-dichloropyridine, can solve the problems of high price of hydrodechlorination catalyst, poor recycling effect and low product yield, etc. Less dosage, easy recycling, good reaction selectivity

Inactive Publication Date: 2019-01-29
CHONGQING ZHONGBANG TECH CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0010] In summary, the current existing technology for preparing 2,3-dichloropyridine mainly has the following problems: the preparation steps are relatively cumbersome, the product yield is not high, the raw materials are not easy to obtain, the price is relatively expensive, and the There are many three wastes, the environment is not friendly, the hydrodechlorination catalyst used is expensive and the recycling effect is not good, etc.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0023] In a 1000ml stainless steel autoclave, add 50g of 2,3,6-trichloropyridine, 300g of methanol, 35g of triethylamine, and then add 0.05g of 10% palladium carbon, replace the air in the autoclave with nitrogen three times, then replace it with hydrogen three times Finally, pressurize to 4.0Mpa, control the temperature at 45-50°C, set the reaction speed at 300rmp / min, continuously add hydrogen during the reaction, maintain the reaction pressure at 3.0-4.0Mpa, and stop the reaction after 4 hours. The temperature was lowered, and samples were taken for liquid phase quantitative detection and analysis. The conversion rate of the raw material 2,3,6-trichloropyridine was 96.5%, and the selectivity of 2,3-dichloropyridine was 86.7%. After the reaction solution was filtered, rectification was performed to remove the reaction solvent, water was added to separate layers, and the organic phase was taken for rectification to obtain 33.1 g of white 2,3-dichloropyridine product with a pro...

Embodiment 2

[0025] In a 1000ml stainless steel autoclave, add 50g of 2,3,6-trichloropyridine, 300g of methanol, 27.4g of pyridine, and then add 0.2g of 10% palladium carbon. , pressurize to 2.5Mpa, control the temperature at 50-60°C, set the reaction speed at 400rmp / min, continuously add hydrogen during the reaction process, maintain the reaction pressure at 2.0-2.5Mpa, stop the reaction after 5 hours of reaction. The temperature was lowered, and samples were taken for liquid phase quantitative detection and analysis. The conversion rate of the raw material 2,3,6-trichloropyridine was 95.8%, and the selectivity of 2,3-dichloropyridine was 88.5%. After the reaction solution was filtered, rectification was performed to remove the reaction solvent, water was added to separate layers, and the organic phase was taken for rectification to obtain 33.4 g of white 2,3-dichloropyridine product with a product purity of 99.6%.

Embodiment 3

[0027] In a 1000ml stainless steel autoclave, add 50g of 2,3,6-trichloropyridine, 200g of isopropanol, 35g of triethylamine, and then add 0.05g of 10% palladium carbon. After replacement three times, pressurize to 3.0Mpa, control the temperature at 45-50°C, set the reaction speed at 300rmp / min, continuously add hydrogen during the reaction process, maintain the reaction pressure at 1.5-2.0Mpa, stop the reaction after 5h . The temperature was lowered, and samples were taken for liquid phase quantitative detection and analysis. The conversion rate of the raw material 2,3,6-trichloropyridine was 94.3%, and the selectivity of 2,3-dichloropyridine was 85.8%. After the reaction solution was filtered, rectification was performed to remove the reaction solvent, water was added to separate layers, and the organic phase was taken for rectification to obtain 31.8 g of white 2,3-dichloropyridine product with a product purity of 99.8%.

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Abstract

The invention discloses a preparation method for 2,3-dichloropyridine. The method provided by the invention is carried out through the following steps: with 2,3,6-trichloropyridine as a raw material,a basic compound as an acid-binding agent, palladium on carbon as a catalyst and hydrogen as a hydrogen source, carrying out a hydrodechlorination reaction in a pure organic solvent system at a temperature of 20 to 100 DEG C and a pressure of 1.0 to 8.0 Mpa under stirring with a rotating speed controlled to be 100 to 1000 rmp / min, and after the reaction is performed for 2 to 10 h, subjecting a reaction liquid to post-treatment so as to obtain a 2,3-dichloropyridine product. The preparation method provided by the invention has the following advantages: the conversion rate of the raw material is95% or above; the selectivity of the product can reach 88%; meanwhile, the usage amount of the catalyst is small; operation is simple; the requirements for equipment are low; a solvent is easy to recycle; the product is easy to separate; the quality of the product is high; few three wastes are produced; and the preparation method is a green process applicable to industrial production.

Description

technical field [0001] The invention belongs to the field of organic synthesis, and relates to a preparation method of 2,3-dichloropyridine, an important chemical intermediate in the fields of medicine and pesticides, in particular to a preparation method of 2,3-dichloropyridine. Background technique [0002] 2,3-Dichloropyridine is an important intermediate for the synthesis of chlorantraniliprole insecticide. The insecticide has the characteristics of high efficiency and low toxicity. The preparation and synthesis method of 2,3-Dichloropyridine directly affects its downstream products development and application. At present, the synthetic routes of 2,3-dichloropyridine mainly include the following: [0003] (1) Using nicotinamide as the raw material, DuPont Company of the United States reported in the patent CN1910152A that nicotinamide was used as the starting raw material, and the target product was obtained through Hofmann degradation, chlorination, diazotization and c...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D213/61
CPCC07D213/61
Inventor 王平赖明牟新斌蒋程李雪平
Owner CHONGQING ZHONGBANG TECH CO LTD
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