Sulfuric Acid → 4,5-Dichloro-7-nitroisatin

Participants

Reaction Steps

To a solution of 4,5-dichloroisatin (13f, 430 mg, 2.0 mmol) in cone H2SO4 (5 mL) was added powdered KNO3 (300 mg, 2.5 mmol) at 0° C. in portions with stirring. The mixture was stirred at 22° C. for 16 h, poured into ice-H2O (50 mL). The precipitate was filtered, washed with H2O (5×10 mL) and dried to give 295 mg (54%) of 13 h as a yellow powder. The analytical sample was obtained by crystallization from benzene, mp 204°-5° C. IR 1776, 1768, 1749, 1614, 1473, 1340, 1227 cm-1 ; 1H NMR δ 11.932 (s, 1H), 8.535 (s, 1H). HRMS Calcd for C8H2Cl2N2O4 : 259.9391; Found: 259.9389.

Provenance & Evidence