Benzoyl Peroxide → 6-(Bromomethyl)quinoxaline

Temperature

85 °C

In a 100 ml flask, 6-methyl-quinoxaline (1.25 g, 8.68 mmol) was dissolved together with N-bromosuccinimide (2.32, 13.0 mmol) and benzoyl peroxide (0.15 g, 0.62 mml) in 31 g of chlorobenzene. The mixture was heated up to 85° C. to give a pale yellow solution that slowly turned red. The solution was maintained at 85° C. for two hours to give a red solution of 6-bromomethyl-quinoxaline. The solution was then cooled down to room temperature with the formation of a precipitate mainly composed of succinimide. The solution was then mixed with an equal volume (˜31 ml) of pentane to ease the precipitation of succinimides (NHS as well as any unreacted NBS). After filtration, the orange solid obtained (1.4 g) was extracted few times with pentane (4 times, 50 ml each) to recover any remaining 6-bromomethyl-quinoxaline. The extracts were combined with the yellow solution of bromomethyl-quinoxaline and vacuum dried to give a yellow solid (1.92 g) that was suspended in an alkaline solution prepared by dissolving 2.0 g of sodium hydroxide pellets in 30 g of water. The catalyst (5% Pd/C) was added to the alkaline mixture (0.2 g) and the suspension was heated up to 85-95° C. and sparged with air for 48 hours. The black suspension was filtered to give an amber solution that was neutralized with dilute sulfuric acid to give a yellow powder (1.28 g, 85% yield) that precipitated from solution (6-quinoxaline-carboxylic acid).

1. customto give a pale yellow solution that slowly turned red
2. temperatureThe solution was maintained at 85° C. for two hours

ORD record

ord-074afac1cd2040d6b0eaa61764ff88d1

Source dataset

uspto-grants-2003_05

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06562972B1