Oxalic acid dihydrate → HCID 178517016, compound

Participants

Reaction Steps

A solution of 5-amino-4-nitrobenzo[b]thiophene (0.50 g, 2.6 mmol) in 50 ml of 96% ethanol was hydrogenated at room temperature and atm. pressure in the presence of 5% palladium-on-carbon until the theoretical amount of hydrogen was absorbed. The catalyst was filtered off, and the filtrate was acidified with 1N hydrochloric acid and evaporated to dryness. The residue was refluxed with oxalic acid dihydrate (0.40 g, 3.1 mmol) in 25 ml of 4M hydrochloric acid for 2 h. The mixture was cooled, and the precipitated solid was isolated by filtration, washed with water, ethanol and ether, and dried. The crude product was dissolved in a minimum amount of 2N sodium hydroxide, treated with decolourising charcoal, and filtered. The filtrate was acidified with 4M hydrochloric acid and the resulting precipitate was collected by filtration, washed with water, ethanol and ether to give 0.22 g (39%) of the thienoquinoxaline; m.p. 186.6° C.; IR (KBr): 1680 cm-1 ; H-NMR (DMSO-d6 ): 7.13 (d,J=9 Hz, 1H, ArH), 7.62 (D,J=9 Hz, 1H, ArH), 7.72 (d,J=5 Hz, 1H, ArH), 7.95 (d,J=5 Hz, 1H, ArH); MS m/z: 218 (M+, 100%).

Provenance & Evidence