反应详情

温度

50 °C

To stirred conc H2SO4 (70 mL) at 0° C. was added 45 (6.0 g, 41.8 mmol) in portions. To the resulting dark brown solution was added dropwise 70% HNO3 (3.5 mL, 54 mmol) at 0° C. After the addition, the reaction mixture was stirred at 50° C. under N2 for 2.5 h, cooled to room temperature and poured into crushed ice (about 700 g). The mixture was basified to pH 9 by the addition of 40% aq. NaOH dropwise with stirring and cooling (ice-water bath). The precipitate was filtered, washed with water (4×100 mL) and MeOH (3×25 mL), and dried to give 5.28 g (67%) of 46 as a yellow powder, mp 214°-5° C. (lit. 214°-6° C., Cress et al., J. Org. Chem. 93-6 (1976)). 1H NMR (DMSO-d6) δ2.445 (s, 3H), 8.011 (bs, 2H), 8.340 (s, 1H).

1. additionAfter the addition
2. temperaturecooled to room temperature
3. additionpoured
4. stirringwith stirring
5. filtrationThe precipitate was filtered
6. washwashed with water (4×100 mL) and MeOH (3×25 mL)
7. customdried