反应详情

温度

60 °C

A solution of 2-amino-3,5-dimethoxypyrazine (0.02 mole) in 300 ml. of 6M sulfuric acid at 0°-5° C. is treated with 0.022 mole sodium nitrite in 25 ml. of water at such a rate to insure that the termperature of the reaction mixture does not rise above 5° C. After standing 45 minutes at 0°-5°C., a little urea is added to destroy excess nitrous acid and the mixture then is treated with sodium hydroxide solution until strongly basic. The reaction mixture is warmed to 60° C. for 1 hour and then brought to pH 8.5. The mixture is concentrated to a third of the original volume and cooled in the refrigerator overnight. The product is separated by filtration and dried in vacuo, recrystallized from a suitable solvent to give 2-hydroxy-3,5-dimethoxypyrazine.

1. customdoes not rise above 5° C
2. customto destroy excess nitrous acid
3. additionthe mixture then is treated with sodium hydroxide solution until strongly basic
4. concentrationThe mixture is concentrated to a third of the original volume
5. temperaturecooled in the refrigerator overnight
6. customThe product is separated by filtration
7. customdried in vacuo
8. customrecrystallized from a suitable solvent