Potassium Nitrate → 6,7-Difluoro-5-nitro-1,4-dihydro-2,3-quinoxalinedione

Temperature

55 °C

To a suspension of 6,7-difluoro-1,4-dihydro-2,3-quinoxalinedione (837 mg, 4.23 mmol) in trifluoracetic acid (30 mL) was added KNO3 (512 mg, 5.07 mmol). The mixture was stirred at 55° C. for 20 h at the end of this time, 256 mg (2.50 mmol) of KNO3 was added and the reaction mixture was stirred at 55° C. for 20 h, then another 256 mg (2.50 mmol) of KNO3 was added and the mixture was stirred at 55° C. for 20 h. The reaction mixture was then rota-evaporated to dryness. To the residual solid was added ice-cold water (about 15 mL), the solid was collected by vacuum filtration, washed with ice-cold water (5×5 mL), and dried at 40° C. under 1 mm Hg for 14 h, giving 700 mg (68%) of the title compound as a yellow powder. Mp 288°-90° C. (dec.). IR (KBr) 3424, 3226, 1752, 1717, 1554, 1356, 1304 cm-1. 1H NMR (DMSO-d6): 12.249 (s, 1H), 11.864 (bs, 1H), 7.330 (dd, 1H, J=10.5, 7.8 Hz). Analysis for C8H3F2N3O4, calcd: C, 39.50, H, 1.24, N, 17.29; found: C, 39.42, H, 1.26, N, 17.08.

1. additionwas added
2. stirringthe mixture was stirred at 55° C. for 20 h
3. customThe reaction mixture was then rota-evaporated to dryness
4. additionTo the residual solid was added ice-cold water (about 15 mL)
5. filtrationthe solid was collected by vacuum filtration
6. washwashed with ice-cold water (5×5 mL)
7. customdried at 40° C. under 1 mm Hg for 14 h

ORD record

ord-98236e8bdda749808565aad28f02abb1

Source dataset

uspto-grants-1996_05

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05514680