Hydrochloric Acid → 1,4-Dihydro-6-methylquinoxaline-2,3-dione

Participants

Reaction Conditions

Reaction Steps

To a stirred solution of 3,4-diaminotoluene (0.302 g, 0.247 mmol, Aldrich) in 2N HCl (4 mL, 8 mmol), oxalic acid dihydrate (0.330 g, 0.261 mmol, Fisher) was added in one portion. The resulting deep purple solution was refluxed for 13 h, to give a purple suspension. This was cooled to 25° C., filtered, washed with water (5 mL), and dried in vacuo (0.1 mm Hg) to give a blue-grey powder. This was taken up in 2N NaOH (34 mL, 68 mmol), giving a brown solution, which was filtered. The brown filtrate was acidified to pH 1.0 by addition of 2N HCl (42 mL, 84 mmol), resulting in a tan suspension. Filtration of the suspension and washing of the filter cake with water (5 mL) gave the title compound as a grey powder (225.5 mg, 43%); mp 318° C. (the block was preheated to 300° C.); 1H NMR (DMSO-d6) δ2.32 (s, 3H), 6.90-6.99 (m, 3H), 11.22 (s, 1H), 11.90 (s, 1H).

Provenance & Evidence