Dimethylformamide → 7-Bromo-2-chloroquinoxaline

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

Thionyl chloride (407.5 mL; 5.59 mol), then N,N-dimethylformamide (34.6 mL; 0.45 mol) were added dropwise to a mixture of 7-bromo-2(1H)-quinoxalinone (500 g; 2.24 mol) in toluene (7.61 L). The reaction mixture was stirred at 80° C. for 17 hours then cooled to 35° C. and poured cautiously onto water. The bi-phasic mixture was stirred for 30 minutes and then decanted. The organic layer was evaporated to dryness and the residue crystallized in methyl-tert-butyl ether, filtered and the precipitate washed with methyl-tert-butyl ether and dried to give 407 g (74.7%) of 7-bromo-2-chloro-quinoxaline. Filtrate was evaporated and re-crystallized in methyl-tert-butyl ether to provide a second fraction of 72 g (13.2%) of 7-bromo-2-chloro-quinoxaline.

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