The direct iodination of arenes with chromium(VI) oxide as the oxidant

Article abstract of DOI:10.1246/bcsj.70.1665

An easy and cheap laboratory method is presented for the direct mono- and diiodination of a number of activated and deactivated arenes. The main iodination reactions occurred at the temperatures not exceeding 65°C for 0.5-12 h in the anhydrous, strongly acidic liquid system, I₂/AcOH/Ac₂O/H₂SO₄, in the presence of prior dissolved CrO₃ used as the oxidant. The yields of the pure iodinated products varied from 31% (for 3,5- diiodobenzoic acid) up to 90% (for 4-iodoanisole). So far, benzonitrile and some oxidizable aromatics, e.g. naphthalene, fluorene, xanthene, and thiophene, have been found to be unsuitable for the effective iodination. Nevertheless, this novel, simple method of direct iodination is worthy to be extended to other appropriate aromatics.