反应详情

温度

5 °C

To a solution of 2,2,3-trimethyl-3,4-dihydro-2H-1-benzopyran-4-one (81 g, 0.426 mol) in concentrated sulfuric acid (695 ml) at 0° C. was added a solution containing concentrated sulfuric acid (30 ml) and nitric acid (65%, 175 ml) while maintaining the temperature below 5° C. After stirring for three hours at 5° C., the mixture was added to ice/water and the crude product recovered by filtration. This product was dried and washed with diisopropyl ether to give 44 g of 6-nitro-2,2,3-trimethyl-3,4-dihydro-2H-1-benzopyran-4-one, m.p. 78° C.

1. temperaturewhile maintaining the temperature below 5° C
2. filtrationthe crude product recovered by filtration
3. customThis product was dried
4. washwashed with diisopropyl ether