反应详情

3.335 g (14.5 mmol) of 6,7-dichloro-1,4-dihydroquinoxaline-2,3-dione was dissolved in 65 mL of conc. H2SO4 with stirring and cooling in an ice-H2O bath, then 2.20 g (21.76 mmol) of KNO3 (Baker, used as received) was added in portions over 10 min. with stirring. The resulting mixture was stirred at 22° C. under N2 for 20 h. then was slowly poured into ice-H2O (400 mL) with stirring. The precipitate was collected on a sintered funnel by vacuum filtration, washed with H2O (5×10 mL), and dried at 60° C. under 0.1 mmHg for 12 h affording 3.39 g (85%) of the crude 6,7-dichloro-5-nitro-1,4-dihydroquinoxaline-2,3-dione as a grey-yellow powder. Purity: >98.5% based on HPLC analysis.

1. temperaturecooling in an ice-H2O bath
2. stirringwith stirring
3. stirringThe resulting mixture was stirred at 22° C. under N2 for 20 h.
4. stirringwith stirring
5. filtrationThe precipitate was collected on a sintered funnel by vacuum filtration
6. washwashed with H2O (5×10 mL)
7. customdried at 60° C. under 0.1 mmHg for 12 h