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Selective synthesis method of 2-chloro-5-methylpyridine and 2, 3-dichloro-5-methylpyridine

A technology of methyl pyridine and a synthetic method, applied in the direction of organic chemistry and the like, can solve the problems of only 56% of the total reaction yield, only 60% of the conversion rate, slow research and development progress, etc., and achieves low production cost, easy operation, and equipment investment. less effect

Active Publication Date: 2020-06-26
JIANGSU YANGNONG CHEM GROUP +3
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

2,3-dichloro-5-trifluoromethylpyridine is a key intermediate in the production of various pesticides, and has a broad market prospect, but the research and development of the above-mentioned varieties is currently progressing slowly
Among them, the preparation of fluorinated raw material 2,3-dichloro-5-picoline has become the main problem restricting its development
At present, publicly reported methods for synthesizing 2,3-dichloro-5-picoline include: Pews R.G et al., (Pews R.G, Lysenko Z.Synthesis of halogenated pyridine[J].Org.Chem,1985,50(25 ): 5115-5119) adopt dichloroacetonitrile and methacrolein cyclization to directly synthesize 2,3-dichloro-5-picoline, but the conversion rate of reaction raw material dichloroacetonitrile has only about 60%, and the conversion rate of raw material is low lead to high production costs
Liu et al. (Liu Buye, Ding Kehong. Synthesis of 2,3-dichloro-5-picoline [J]. Shandong Chemical Industry, 2015, 044(024): 18-20) firstly synthesized by using propionaldehyde, chlorine and other raw materials Dichloropropionaldehyde, and then react with acrylonitrile to obtain 2,3-dichloro-5-methylpyridine through two-step reaction of addition and ring closure, but the total yield of the reaction is only 56%.

Method used

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  • Selective synthesis method of 2-chloro-5-methylpyridine and 2, 3-dichloro-5-methylpyridine
  • Selective synthesis method of 2-chloro-5-methylpyridine and 2, 3-dichloro-5-methylpyridine
  • Selective synthesis method of 2-chloro-5-methylpyridine and 2, 3-dichloro-5-methylpyridine

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Experimental program
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Effect test

Embodiment 1

[0019] At 20°C, add 66.7g (0.6mol) of pyridone, 333.5g of toluene, and 2.02g (0.012mol) of ferric chloride into a 500ml four-necked flask, and mix well. Then feed chlorine gas (5.5L / h) in the mixed solution for 3 hours, the reaction is completed, be warming up to 110°C, feed phosgene (9L / h) for 3 hours, react for 1 hour, and obtain product 78.52g through post-processing steps, Among them, 70.11g of 2-chloro-5-methylpyridine and 7.87g of 2,3-dichloro-5-methylpyridine. The yield of 2-chloro-5-methylpyridine to pyridone was 91.6%, and the yield of 2,3-dichloro-5-methylpyridine to pyridone was 8.1%.

Embodiment 2

[0021] At 20°C, add 66.7g (0.6mol) of pyridone, 333.5g of toluene, 9.8g (0.06mol) of ferric chloride into a 500ml four-necked flask, and feed phosgene (9L / h) for 3 hours; then Chlorine gas (9.5L / h) was passed into the mixed solution simultaneously for 3h, the reaction was completed, the temperature was raised to 110°C, phosgene (9L / h) was passed through again for 3 hours, and the reaction was carried out for 1 hour, and 93.95g of the product was obtained through the post-processing step. Among them, 14.16g of 2-chloro-5-methylpyridine and 79.03g of 2,3-dichloro-5-methylpyridine. The yield of 2-chloro-5-methylpyridine to pyridone was 18.5%, and the yield of 2,3-dichloro-5-methylpyridine to pyridone was 81.3%.

Embodiment 3

[0023] Change ferric trichloride, phosgene and chlorine consumption on the basis of embodiment 2, add ferric trichloride 4.87g (0.03mol), pass into phosgene (4.5L / h) 3 hours, pass into chlorine gas (7.5L / h) for 3 hours. After the reaction, 88.43 g of the product was obtained through post-processing steps, including 33.07 g of 2-chloro-5-picoline and 54.92 g of 2,3-dichloro-5-picoline. The yield of 2-chloro-5-methylpyridine to pyridone was 43.2%, and the yield of 2,3-dichloro-5-methylpyridine to pyridone was 56.5%.

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Abstract

The invention relates to a selective synthesis method of 2-chloro-5-methylpyridine and 2, 3-dichloro-5-methylpyridine. The method adopts pyridone and chlorine as the raw materials, employs a chlorination reagent and a Lewis acid catalyst for synergistic catalysis, has the characteristics of low production cost and low equipment investment, selectively synthesizes the target products, and reaches the purpose of controllable production.

Description

technical field [0001] The present invention relates to a selective synthesis method of 2-chloro-5-methylpyridine and 2,3-dichloro-5-methylpyridine, more specifically, relates to a 5-methyl-3,4- Dihydropyridine-2(1H)-one (referred to as: pyridone) and chlorine as raw materials, catalytic selective synthesis of 2-chloro-5-picoline and 2,3-dichloro-5-picoline method. Background technique [0002] The synthesis process route of 2-chloro-5-picoline usually has the following three methods: 3-picoline nitroxide chlorination method, propionaldehyde-morpholine method and propionaldehyde-benzylamine method. At present, industrial production mainly adopts the latter two routes. The process of preparing 2-chloro-5-picoline by propionaldehyde-morpholine method is usually divided into two steps: (1) pyridone and chlorine react to prepare intermediate product 5,6-dichloro-5-methylpiperidine- 2-ketone; (2) the intermediate product obtained in step 1 is reacted with a chlorination reagent...

Claims

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Application Information

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IPC IPC(8): C07D213/61
CPCC07D213/61
Inventor 王根林王刚王浩丁克鸿徐林许越郭玉秀张曦廖强陆仁标
Owner JIANGSU YANGNONG CHEM GROUP
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