2,4-Diiodoaniline is generally prepared by the reactions of aniline with iodine in the presence of oxidants, with ICl vapor.
Step: Freshly distilled aniline (1mL, 11mmol) was dissolved in concentrated HCl (50 mL) and diluted with water to 0.5 L. Then KICl2 (5.2 g, 22 mmol) was added portionwise with vigorous stirring at ≈20 °C, this being followed by the gradual formation of a grayish precipitate. After completion of the reaction (3h), the precipitate was filtered off and recrystallized from benzene with addition of activated carbon. The yield of diiodoaniline was 2.14g (57%), m.p. 95 °C.
1H NMR (CDCl3), δ: 3.74 (br.s, 2 H, NH2); 6.49 (d, 1 H, C(6)H, J = 8.2 Hz); 7.36 (dd, 1 H, C(5)H, J1 = 1.0 Hz; J2 = 8.2 Hz); 7.87 (d, 1 H, C(3)H, J = 1 Hz).
