[Synthesis]
General procedure for the synthesis of 5-iodo-2-nitrophenol and 3-iodo-4-nitrophenol from 3-iodophenol: 3.0 mL of fuming nitric acid (75 mmol) in 12 mL of glacial acetic acid was added slowly and dropwise to a 60 mL solution of glacial acetic acid containing 15.03 g (68.3 mmol) of 3-iodophenol over a 25-minute period, and the reaction flask was placed in an ice bath to cool. The reaction mixture was continued to be stirred at room temperature for 30 min, after which the reaction solution was decanted into ice water. The reaction mixture was concentrated under vacuum, dissolved in 150 mL of water and subsequently extracted with dichloromethane (2 x 300 mL). The combined organic phases were dried with anhydrous magnesium sulfate and concentrated to give 17 g of crude product. Separation by silica gel medium pressure chromatography (eluent ratio 1:2 ethyl acetate:hexane) afforded 3-iodo-4-nitrophenol (6.93 g, 26.1 mmol, 38% yield) with a melting point of 121-123 °C; 1H NMR (CDCl3, 300 MHz) δ 7.98 (d, 1H, J = 9 Hz), 7.54 (d, 1H, J = 3 Hz) , 6.92 (dd, 1H, J = 9, 3 Hz), 5.54 (bs, 1H); IR (KBr) ν 3150 (wide), 1600, 1580, 1512, 1404, 1336, 1298, 1212, 1121, 1023, 870 cm?1; and 3-iodo-6-nitrophenol (3.07 g, 11.6 mmol. 17% yield) with a melting point of 92-94 °C after recrystallization from dichloromethane/hexane (literature value 96 °C; Hodgson, HH et al., 1927); 1H NMR (CDCl3, 300 MHz) δ 10.53 (s, 1H), 7.76 (d, 1H, J = 9.0 Hz), 7.59 (d, 1H, J = 2.0 Hz), 7.33 ( dd, 1H, J = 9.0, 2.0 Hz); 13C NMR (CDCl3) δ 105.2 (C-3), 125.6 (C-5), 129.2 (C-2), 129.7 (C-4), 133.4 (C-6), 154.6 (C-1); IR (KBr) ν 3430 (broad), 1604, 1571, 1518, 1463, 1317, 1225, 1172, 1055, 888 cm?1; elemental analysis (C6H4INO3) calculated values: C, 27.19; H, 1.52; N, 5.29. measured values: C, 27.36; H, 1.57; N, 5.15. |