Potassium Nitrate → 6-Nitro-5,7-dibromo-1,4-dihydro-2,3-quinoxalinedione

HRID 54331Notes

Reaction equation

[Br:1][C:2]1[CH:11]=[C:10]([Br:12])[CH:9]=[C:8]2[C:3]=1[NH:4][C:5](=[O:14])[C:6](=[O:13])[NH:7]2.[N+:15]([O-])([O-:17])=[O:16].[K+]>OS(O)(=O)=O>[N+:15]([C:11]1[C:2]([Br:1])=[C:3]2[C:8](=[CH:9][C:10]=1[Br:12])[NH:7][C:6](=[O:13])[C:5](=[O:14])[NH:4]2)([O-:17])=[O:16]

Participants

Conditions

Temperature: 0 °C

Procedure

The method of Cheeseman, supra. was adapted. 5,7-Dibromo-1,4-dihydroquinoxaline-2,3-dione (74 mg, 0.23 mMol) was dissolved in concentrated H2SO4 (1 mL) at 0° C. for 30 mins., and then KNO3 (28 mg, 0.27 mMol, Baker) was added to this solution. The mixture was stirred at 0° C. for 3 h and then at room temperature for 30 h. It was poured into ice water (8 g) and the precipitate was collected by filtration, was dissolved into 1N KOH (5 mL), and the red precipitate was removed by filtration. The solution then was acidified to pH=2 with 4N HCl to obtain a cream precipitate, which was collected by filtration, then was dried in the air at 50° C. for 4 h, affording the pure 6-nitro-5,7-dibromo-1,4-dihydro-2,3-quinoxalinedione (71 mg, 84.5% ), as a yellow powder; mp: 318°-20° C. (dec.). IR (KBr, cm-1): 3468, 3131, 3062, 2931, 1712, 1593, 1537. NMR (1H, DMSO-d6): δ7.392 (s, 1H), 11.566 (s, 1H), 12.274 (s, 1H). HRMS: calcd. for C8H3N3O4Br2 m/z: 362.8489, found: 362.8478.

Workup

waitat room temperature for 30 h
filtrationthe precipitate was collected by filtration
dissolutionwas dissolved into 1N KOH (5 mL)
customthe red precipitate was removed by filtration
customto obtain a cream precipitate, which
filtrationwas collected by filtration
customwas dried in the air at 50° C. for 4 h

Sources & evidence

ORD record: ord-7cc064efbc184d5e956491c84f9a2877
Source dataset: uspto-grants-1997_04
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US05622952

Reaction notes

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