A kind of selective synthesis method of 2-chloro-5-picoline and 2,3-dichloro-5-picoline

Abstract

The invention relates to a method for selectively synthesizing 2-chloro-5-picoline and 2,3-dichloro-5-picoline, using pyridone and chlorine as raw materials, and using chlorination reagents and Lewis acid catalysts to cooperate Catalysis, which has the characteristics of low production cost and low equipment investment, selectively synthesizes the target product and achieves 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...

Examples

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%.

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...

Examples

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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