Potassium Hydroxide → 6-Bromo-5-chlorobenzo[c][1,2,5]oxadiazole 1-oxide

Participants

Reaction Conditions

Reaction Steps

4-Bromo-5-chloro-2-nitroaniline (13.3 g, 53 mmol) was dissolved in 250 mL ethanol, treated with potassium hydroxide (10 g, 88%, 160 mmol) and heated at 60° C. for 2 h. The mixture was cooled to 0-5° C. and treated with dropwise with commercial bleach solution (320 g, 5%, 210 mmol). The cooling was removed and the mixture was stirred for 2 h at 20° C. The mixture was diluted with 1.5 liter of water and the precipitated product was collected by filtration and washed well with water. The wet product was taken up in 250 mL ethyl acetate, washed twice with 50 mL water, 50 mL saturated NaCl, dried (Na2SO4) and evaporated. The residue was chromatographed on silica with a 0-40% ethyl acetate-hexane gradient to give the title compound (5.0 g, 38%): mp 123-125° C. 1H NMR (400 MHz, CDCl3) δ 7.91 (s, 1H), 7.68 (s, 1H); EIMS m/z 248.

Provenance & Evidence