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Preparing method of 3,5,6-trichloropyridinol

A technology of trichloropyridine and tetrachloropyridine, which is applied in the field of preparation of 3,5,6-trichloropyridine, can solve the problems of whitening product color, poor product color, and difficulty in industrialization, and shorten the reaction time. , The effect of high product purity and short reaction time

Inactive Publication Date: 2018-08-14
EAST CHINA UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This method has defects such as serious pollution, low yield, and poor product quality. JP59-170066 proposes to use 6-chloro-2-hydroxypyridine as a raw material to generate 3,5,6-trichloropyridine through liquid phase chlorination reaction. Alcohol, this process uses a large amount of acetic acid as a solvent, which seriously corrodes the equipment, and the raw materials are not easy to obtain and industrialized. Therefore, JP87-39570 proposes to use 2,3,5,6-tetrachloropyridine as a raw material and prepare 3, A new process for 5,6-triclopyridine, in which 2,3,5,6-tetrachloropyridine can be prepared in one step by pyridine chlorination (see CN1374297A), and pentachloropyridine can also be prepared by pyridine chlorination first, and then Then reduce pentachloropyridine to generate 2,3,5,6-tetrachloropyridine (see US patent USP3993654, USP4703123 and Chinese patent CN1421436A)
For the process route of preparing 3,5,6-trichloropyridinol by hydrolysis of 2,3,5,6-tetrachloropyridine, JP-0168357 proposed improvement measures, which improved the purity and yield of the product, but There is still the disadvantage of poor product color. JP-01203364A removes the iron ions in the raw material by adjusting the pH value of acidification, so that the color of the product becomes white and the purity is improved, but the reaction time still needs more than 20 hours

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0016] Put 43.4 g (0.2 mol) of 2,3,5,6-tetrachloropyridine and 180 mL of water into a three-necked flask, stir and heat up to 95°C, and weigh 18.34 g (0.44 mol) of sodium hydroxide with a purity of 96%. , and use a small part of it to adjust the pH of the solution to 9.5~10, continue to stir for 30 min, and then filter while it is hot to remove insoluble impurities. Put the filtrate into a 500mL autoclave, add the remaining sodium hydroxide and cetyltriethylammonium chloride 0.0434 g, stir and raise the temperature to 105°C, react for 5.5 h, after the reaction, cool down to 25°C, add Adjust the pH to 4.5-4.0 with 50% sulfuric acid, filter, wash with water, and dry to obtain 35.5 g of a white powder product. According to gas chromatography analysis, the purity of 3,5,6-triclopyridine in this product is 99.18%.

Embodiment 2

[0018] Put 43.4 g (0.2 mol) of 2,3,5,6-tetrachloropyridine and 210 mL of water into a three-neck flask, stir and heat up to 95°C, weigh 30.0 g (0.455 mol) of potassium hydroxide with a purity of 85%, And use a small part of it to adjust the pH of the solution to 9.5~10, continue to stir for 30 min, and then filter while it is hot to remove insoluble impurities. Put the filtrate into a 500mL autoclave, add the remaining sodium hydroxide and cetyltrimethylammonium chloride 0.058 g, stir and heat up to 110 °C, react for 4.0 h, after the reaction, cool down to 25 °C, add Adjust the pH to 4.5-4.0 with 50% sulfuric acid, filter, wash with water, and dry to obtain 35.8g of a white powder product. According to gas chromatography analysis, the purity of 3,5,6-triclopyridine in this product is 99.26%.

Embodiment 3

[0020] Put 43.4 g (0.2 mol) of 2,3,5,6-tetrachloropyridine and 240 mL of water into a three-neck flask, stir and heat up to 95°C, weigh 39.53 g (0.60 mol) of potassium hydroxide with a purity of 85%, And use a small part of it to adjust the pH of the solution to 9.5~10, continue to stir for 30 min, and then filter while it is hot to remove insoluble impurities. Put the filtrate into a 500 mL autoclave, add the remaining potassium hydroxide and benzyltrimethylammonium chloride 0.18 g, stir and raise the temperature to 120 °C, react for 4.0 h, after the reaction, cool down to 25 °C, add 15 % hydrochloric acid to adjust the pH to 4.5-4.0, filter, wash with water, and dry to obtain 35.9 g of a white powder product. According to gas chromatography analysis, the purity of 3,5,6-triclopyridinol in the product is 99.08%.

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Abstract

The invention discloses a preparing method of 3,5,6-trichloropyridinol. In the method, 2,3,5,6-tetrachloropyridine is used as the raw material, filtering is conducted when it is hot under the condition of controlling the temperature and pH value of a 2,3,5,6-tetrachloropyridine solution, and a small amount of insoluble impurities in the raw material are effectively removed; by selecting a proper phase shift catalyst, hydrolysis is conducted in an alkaline water solution to obtain sodium 3,5,6-trichloropyridin-2-olate, and therefore the target product is obtained by conducting acidifying through inorganic acid. The method has the advantages of being short in reaction time, few in side reaction, white in product color and luster, high in purity and the like and is a method suitable for industrially preparing the 3,5,6-trichloropyridinol.

Description

technical field [0001] The present invention relates to a preparation method of 3,5,6-triclopyridine alcohol, in particular to a preparation method of 3,5,6-trichloropyridine through hydrolysis and acidification under certain pressure and the presence of a phase transfer catalyst. The pyridinol method. Background technique [0002] 3,5,6-Triclopyridinol is a key intermediate for the synthesis of a new broad-spectrum insecticide, chlorpyrifos. Various preparation methods have been reported in the literature. Japanese Patent JP Zhao 56-92866 proposes a method using trichloroacetyl chloride as The raw material is condensed and cyclized with acrylonitrile to generate 3,5,6-trichloropyridinol. This method has defects such as serious pollution, low yield, and poor product quality. JP59-170066 proposes to use 6-chloro-2-hydroxypyridine as a raw material to generate 3,5,6-trichloropyridine through liquid phase chlorination reaction. Alcohol, this process uses a large amount of ace...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D213/64
CPCC07D213/64
Inventor 薛为岚陈璇曾作祥迟航
Owner EAST CHINA UNIV OF SCI & TECH
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