反应详情

69.35 g of the mixture of 4,4-dicyano-3-methyl-3-butenal-dimethylacetal and 1,1-dicyano-4-methoxy-2-methyl-1,3-butadiene obtained in Step (a) was slowly added to 113 g of concentrated sulfuric acid over a period of 3 hours so that the temperature would not exceed 30° C. After stirring at room temperature for 20 minutes, the temperature was increased to 50° C., and stirring was carried out at the same temperature for 2 hours. After the reaction mixture was left to stand to cool, it was slowly poured into water ice (500 ml), the obtained crystals were collected by filtration and the crystals were washed with 100 ml of water. The crystals were air-dried for 1 week and further dried at 70° C. under reduced pressure for 8 hours to obtain 34.2 g (two step yield: 68%) of crude crystals of 3-cyano-4-methylpyridone.

1. customexceed 30° C
2. temperaturethe temperature was increased to 50° C.
3. stirringstirring
4. waitwas carried out at the same temperature for 2 hours
5. waitAfter the reaction mixture was left
6. temperatureto cool
7. filtrationthe obtained crystals were collected by filtration
8. washthe crystals were washed with 100 ml of water
9. customThe crystals were air-dried for 1 week
10. customfurther dried at 70° C. under reduced pressure for 8 hours