Potassium Hydroxide → 1-Amino-5-nitro-6,7-dichloro-1,4-dihydro-2,3-quinoxalinedione

Participants

Reaction Steps

The procedure of Shin, S. C. and Lee, Y. Y., Taehan Hwahakhoe Chi 27(5):382-4 (1983) was adapted. A red solution of 6,7-dichloro-5-nitro-1,4-dihydro-2,3-quinoxalinedione (100 mg, 0.36 mMol, Cheeseman, supra) and 3N KOH (2 mL) in distilled water (5 mL) at 65° C. was dropwise added to a colorless solution of NH2OSO3H (75 mg, 0.66 mMol, Aldrich) in distilled water (0.5 mL) with stirring. A yellow precipitate came out after 10 mins. The mixture was stirred at 65° C. for 1 h and allowed to stand at room temperature overnight, then the precipitate was collected by filtration at 50° C. and was washed with distilled water (2 ml), then dried at 50° C. overnight, affording 85 mg (80% ) of crude 1-amino-5-nitro-6,7-dichloro-1,4-dihydro-2,3-quinoxalinedione, as a yellow amorphous solid (80% of desired 1-amino-5-nitro-6,7-dichloro-1,4-dihydro-2,3-quinoxalinedione with 20% starting material by NMR). A 85 mg sample of crude 1-amino-5-nitro-6,7-dichloro-1,4-dihydro-2,3-quinoxalinedione (free base Na+, 0.293 mMol) was dissolved into distilled water (10 mL) at 50° C., then was acidified with AcOH to pH=5. After removal of the insoluble material by filtration, the mixture was heated at 60°-70° C. until a clear solution was obtained, which was slowly cooled, whereupon a yellow precipitate came out. The precipitate was crystallized from hot EtOH and the yellow microcrystals were collected by filtration, washed with cold ethanol (2 mL), and dried in the air at 60° C. for 4 h, affording 31 mg (29%) of pure 1-amino-5-nitro-6,7-dichloro-1,4-dihydro-2,3-quinoxalinedione. Mp was measured: the color of 1-amino-5-nitro-6,7-dichloro-1,4-dihydro-2,3-quinoxalinedione changed to dark yellow at 275° C.; the decomposition of 1-amino-5-nitro-6,7-dichloro-1,4-dihydro-2,3-quinoxalinedione is obvious at 280° C. and it melted to a black liquid at 290°-1° C. IR (KBr, cm-1): 3442; 3315; 3231; 1747; 1723; 1680; 1632; 1547. NMR (1H, DMSO-d6): δ5.848 (s, 2H); 7.951 (s, 1H); 12.595 (s, 1H). HRMS: calcd for C8H4N4O4Cl2 (M+) m/z: 289.9623; found 289.9616.

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