Method for preparing pirfenidone
A technology of pirfenidone and reverse method, which is applied in the field of preparation of anti-fibrosis drugs, can solve the problems of low yield and troublesome operation, and achieve the effects of high yield, easy operation and reduced production cost
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Embodiment 1
[0020] Mix 21.6g of 2-amino-5-picoline, 20.7g of diazotization reagent sodium nitrite and 40g of cold water at 5°C in a blender to make a paste, then add ice to cool the paste to 0°C, Then slowly pour the paste into a constantly stirring hydrochloric acid solution with a concentration of 12% by mass, and stir at 0° C. for 1 hour to make the reaction complete. Then heated to 95°C for 30 minutes and then cooled to 20°C, then adjusted to pH 7 with 50% sodium hydroxide solution by mass percent, then heated to 60°C, extracted with 150ml×5 ethyl acetate, and combined the organic layers , dried over anhydrous sodium sulfate, filtered, and the filtrate was concentrated under reduced pressure to obtain 18.4 g of a light yellow solid crude product; then 55 ml of absolute ethanol was added, heated to reflux for 1 h, cooled to 2°C, crystallized for 6 h, suction filtered, and washed with absolute ethanol , and dried at 50°C for 8 hours to obtain 15.3 g of light yellow crystal 2-hydroxy-5-m...
Embodiment 2
[0023] Mix 32.4g of 2-amino-5-picoline, 32.0g of diazotization reagent sodium nitrite and 60g of cold water at 0°C in a blender to make a paste, then add ice to cool the paste to -5 ℃, and then slowly pour the paste into a constantly stirring hydrochloric acid solution with a concentration of 10% by mass, and stir and react at 0 ℃ for 1 h to make the reaction complete. Then heated to 95°C for 30 minutes and then cooled to 20°C, then adjusted to pH 7 with 50% sodium hydroxide solution by mass percent, then heated to 60°C, extracted with 200ml×4 dichloromethane, and combined the organic layers , dried over anhydrous sodium sulfate, filtered, and the filtrate was concentrated under reduced pressure to obtain 25.3 g of a light yellow solid crude product; then 100 ml of ethyl acetate was added, heated to reflux for 1 h, cooled to 0°C, crystallized for 6 h, suction filtered, and washed with ethyl acetate , and dried at 50°C for 8 hours to obtain 22.1 g of light yellow crystal 2-hydr...
Embodiment 3
[0026] Mix 43.2g of 2-amino-5-picoline, 41.4g of diazotization reagent sodium nitrite and 85g of 10°C cold water in a blender to make a paste, then add ice to cool the paste to 5°C , and then slowly pour the paste into a constantly stirring hydrochloric acid solution with a concentration of 15% by mass, stir and react at 0° C. for 1 h to make the reaction complete. Then heated to 95°C for 30 minutes and then cooled to 20°C, then adjusted to pH 7 with 50% sodium hydroxide solution by mass percent, then heated to 60°C, extracted with 250ml×5 ethyl acetate, and combined the organic layers , dried over anhydrous sodium sulfate, filtered, and the filtrate was concentrated under reduced pressure to obtain 36.6g of a light yellow solid crude product; then 100ml of acetone was added, heated to reflux for 1h, cooled to 5°C, crystallized for 6h, suction filtered, washed with acetone, and dried at 50°C After 8 hours, 28.4 g of light yellow crystal 2-hydroxy-5-methylpyridine was obtained,...
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