反应详情

温度

0 °C

To a solution of 5-methyl-4H-3,1-benzoxazin-2,4-dione (20 g, 113 mmol) in 150 mL of concentrated H2SO4, cooled to −15° C., was added 7.83 g of 90% w/w HNO3 (in 30 mL of conc. H2SO4) dropwise at such a rate to keep the internal temperature below 5° C. After the addition was complete, the reaction was stirred at 0° C. for an additional 20 minutes then quenched by pouring the reaction mixture over crushed ice. Following further dilution with water, the resulting precipitate was filtered, washed with water, resuspended in water then filtered and washed again with water affording 15.1 g (60%) of 5-methyl-6-nitro-4H-3,1-benzoxazin-2,4-dione, after drying: Anal. Calc'd. for C9H6N2O5: C, 48.66; H, 2.72; N, 12.61. Found: C, 48.19; H, 2.54; N, 12.51.

1. customthe internal temperature below 5° C
2. additionAfter the addition
3. customthen quenched
4. additionby pouring the reaction mixture
5. customover crushed ice
6. filtrationthe resulting precipitate was filtered
7. washwashed with water
8. filtrationthen filtered
9. washwashed again with water affording 15.1 g (60%) of 5-methyl-6-nitro-4H-3,1-benzoxazin-2,4-dione
10. customafter drying