Easy, inexpensive and effective oxidative iodination of deactivated arenes in sulfuric acid

Electrophilic Iodination of Organic Compounds Using Elemental Iodine or Iodides

“…A mixture of 2-iodotoluene (66) and 4-iodotoluene (67) was ordinarily obtained, while iodination of isopropylbenzene or tert-butylbenzene gave only the 4-iodo isomer. 26,55,71,72 Dimethyl (68, 71, 75), trimethyl (79,82,86), and tetramethyl benzene derivatives (89, 92, 95) were also readily iodinated by a variety of iodinating systems (Table 6) and progressive iodination to poly(iodo-substituted) compounds was selectively achieved.…”

“…A very strong oxidant in an anhydrous and strongly acidic medium is ordinarily necessary for this kind of functionalisation when molecular iodine or the iodide anion is used as the source of iodine, while meta regioselectivity of iodination was observed in these reactions. A variety of benzene derivatives bearing a strongly deactivated aromatic ring were selectively and efficiently iodinated by iodine in concentrated sulfuric acid in the presence of strong oxidants like sodium percarbonate (SPC), 19 manganese(IV) oxide or potassium permanganate 78 (entry 4), sodium iodate or sodium periodate 79,80 (entries 5 and 6), diluted fluorine 81 (entry 8) or urea-hydrogen peroxide adduct 67 (entry 9), while for oxidative iodination by potassium iodide and potassium bromate in the presence of hydrochloric acid 22c was applied (entry 7). For the synthesis of 4-iodo-2,3,5,6tetrafluorobenzaldehyde from the corresponding highly deactivated tetrafluorobenzaldehyde precursor, an aryl carbanion was primarily formed and treated later with molecular iodine.…”

A Comparison of Microwave-Accelerated and Conventionally Heated Iodination Reactions of Some Arenes and Heteroarenes, Using ortho-Periodic Acid as the Oxidant†

“…However, we have established that for the iodination reactions carried out in very strongly polar and acidic media, e.g. in anhydrous AcOH/Ac 2 O/concd H 2 SO 4 solutions [ 10 ] or in 90% (v/v) sulfuric acid [ 15 ], the strict temperature control during the irradiation by microwaves is hardly possible, due to the easy overheating of such reaction mixtures, which very often ends up in overboiling.…”

Direct Green Iodination of Phenol over Solid Acids

“…Extensive use of strong acids in combination with various iodinating agents (HNO 3 /H 2 SO 4 , HIO 3 ; H 2 SO 4 /HIO 4 ; CF 3 SO 3 H/NIS) was reported [2][3][4][5][6][7][8][9].…”