Water → 4-Chloroisatoic anhydride

Participants

Reaction Steps

4-Chloroanthranilic acid (10.0 g, 56.5 mmol) was dissolved at room temperature with stirring in 190 mL of distilled water containing 8.98 g (84.7 mmol) Na2CO3. When the 4-chloroanthranilic acid was completely dissolved, a 20% w/v solution of phosgene in toluene (84 mL) was added dropwise via a dropping funnel over 45 minutes. The resulting suspension was stirred at room temperature overnight under nitrogen. The product was collected by filtration and washed well with water. The resulting gray-white solid was dried in a vacuum oven at 60° C. overnight to provide 7-chloro-1,4-dihydro-2H-3,1-benzoxazine-2,4-dione (10.3 g, 52.3 mmol, 93%): 1H NMR (DMSO-d6): δ 11.93 (br s, 1H), 7.17 (d, J=1.5 Hz, 1H), 7.28 (dd, J=1.6 and 8.2 Hz, 1H), 7.91 (d, J=8.2 Hz, 1H).

Provenance & Evidence