SyntheticPage 483
Published Feb 11, 2011
A mixture of nitrobenzene (1.25 g, 10 mmol) and sulfuric acid (96%, 10 ml) was stirred on an oil bath at room temperature while trichloroisocyanuric acid (5.0 g, 20 mmol) was carefully added. After 15 min of stirring a short air condenser was set on the flask and the temperature of the oil bath slowly increased to 180°C during the period of 2 h. The reaction mixture was left stirring for 4 h at that temperature. The organic layer solidified during cooling and was extracted directly from the sulfuric acid with dichloromethane (40 ml), the extract washed with water (3 × 40 ml), dried over anhydrous Na2CO3 and evaporated in vacuo (Caution: The waste acid is still concentrated and should be carefully quenched and disposed). The resulting 2.58 g of greenish crystals were triturated in hot methanol and filtered when cold to give white crystalline 2,3,4,5,6-pentachloronitrobenzene (1.86 g, 62 %).