Preparation of 2-iodo-4-chloroaniline_Kain Industrial Additive

Background and overview^[1][2]

Iodinated aminoaryl compounds such as 2-iodo-4-chloroaniline have considerable value as synthetic intermediates and can be used in various industrial settings, including the pharmaceutical industry. For example, 2-iodoaniline is a known precursor for the synthesis of a large number of indoles, including 2,3-disubstituted indoles, some of which are reported to be useful as potential migraine drugs. Many methods for the iodination of aminoaryl compounds have been reported in the literature, but they either result in low to moderate yields or require the use of expensive reagents that require separate preparation.

Preparation^[1]

2-Iodo-4-chloroaniline is prepared as follows: add an aqueous solution of potassium iodide (50g, 0.301mol), iodine (76g, 0.299mol) and water (100mL) over 45 minutes. Stir 4-chloroaniline (35 g, 0.276 mol, 50 μm average particle size), sodium bicarbonate (37 g, 0.440 mol) and water (210 mL) under stirring. The mixture was stirred for 3-5 hours. The solid was collected by filtration, washed with water, and dried to give 2-iodo-4-chloroaniline (69.6 g, 100% yield, 98.5% purity). ¹H NMR (CDCl3): δ7.56 (d, 1H, J = 2.4Hz), 7.12 (dd, 1H, J = 2.4Hz, 8.6Hz), 6.75 (d, 1H, J = 8.6Hz), 5.37 (br s, 2H).

Main reference materials

[1] (US20050215812) Processes for the preparation of iodinated amino-aryl compounds