Oxalic acid dihydrate → 5,7-Dimethyl-1,4-dihydroquinoxaline-2,3-dione
Reaktionsgleichung
[NH2:1][C:2]1[C:7]([CH3:8])=[CH:6][C:5]([CH3:9])=[CH:4][C:3]=1[NH2:10].O.O.[C:13](O)(=[O:17])[C:14](O)=[O:15]>Cl>[CH3:8][C:7]1[CH:6]=[C:5]([CH3:9])[CH:4]=[C:3]2[C:2]=1[NH:1][C:13](=[O:17])[C:14](=[O:15])[NH:10]2Komponenten
4
Edukt 2
Produkt 1
Reagenzien, Katalysatoren, Lösungsmittel 1
Reaktionsbedingungen
- Temperatur
- 62.5 °C
Versuchsvorschrift
A mixture of 1,2-diamino-4,6-dimethylbenzene (424 mg, 3.11 mmole) and oxalic acid dihydrate (432 mg, 3.43 mmole, used as received) in 4N HCl (20 mL) was refluxed at 120-5° C. for 3 h, then cooled to room temperature. The mixture was centrifuged and the supernatant was removed. The yellow solid was washed with cold water (2×2 mL), collected by filtration, and dried in vacuo for 2 h, affording 516 mg of crude 5,7-dimethyl-1,4-dihydro-2,3-quinoxalinedione (87%) as a yellow powder. The crude product was taken up in 1 N NaOH (10 mL) and filtered. The filtrate was acidified to pH =3, affording the pure title compound (490 mg) as a light yellow powder; mp:345-347° C. (dec); IR (KBr, cm−1):3460, 3190, 2986, 1716, 1709, 1630. 1H NMR (DMSO-d6): δ11.858 (s, 1H), 11.173 (s, 1H), 6.766 (s, 1H), 6.745 (s, 1H), 2.280 (s, 3), 2.211 (s, 3). HRMS: calcd for C10H10(N2O2 (M+) m/z: 190.0714; found: 190.0744.