Aromatics iodination

The aHphatic iodine derivatives are usually prepared by reaction of an alcohol with hydroiodic acid or phosphoms trHodide by reaction of iodine, an alcohol, and red phosphoms addition of iodine monochloride, monobromide, or iodine to an olefin replacement reaction by heating the chlorine or bromine compound with an alkaH iodide ia a suitable solvent and the reaction of triphenyl phosphite with methyl iodide and an alcohol. The aromatic iodine derivatives are prepared by reacting iodine and the aromatic system with oxidising agents such as nitric acid, filming sulfuric acid, or mercuric oxide. 

Aromatic iodination can be carried out with a number of reagents, including iodine monochloride, 1C1. What is the direction of polarization of IC1 Propose a mechanism for the iodination of an aromatic ring with 1C). 

Copper(ll) chloride, aromatic iodination and, 551 Coproslanol, structure of, 304 Coral, organohalides from, 352 Corn oil, composition of. 1062 Cornforlh. John Warcup. 1085 Coronene, structure of, 532 Cortisone, structure of. 107 Couper, Archibald Scott, 7 Coupled reactions. 1128-1129 ATP and, 1128-1129 Coupling (NMU), 460... 

The anodic chlorination in some cases allows one to achieve better regioselec-tivities than chemical alternatives (p/o ratio of chlorotoluene in chlorination of toluene anodic 2.2, chemical alternative 0.5-1.0) [215]. Anodic oxidation of iodine in trimethyl orthoformate afforded a positive iodine species, which led to a more selective aromatic iodination than known methods ]216]. Aryliodination is achieved in good yield, when an aryhodide is oxidized in HOAc, 25% AC2O, 5% H2SO4 in the presence of an arene ]217, 218]. Alkyl nitroaromatic compounds, nitroaromatic ketones, and nitroanihnes are prepared in good yields and regioselectivity by addition of the corresponding nucleophile to a nitroarene and subsequent anodic oxidation of the a-complex (Table 13, number 11) ]219, 220]. 

The formation of unstable trifluoroacetyl hypoiodite on reaction of BTI with elemental iodine has been used for aromatic iodination. This method has some advantages over other methods, since it is carried out at room temperature and work up is convenient. 

Another mild oxidant for aromatic iodination is ammonium hexanitratocerate(IV) (CAN)358. This reagent is useful in the synthesis of 5-iodouracil derivatives (equation 47)359. 

The existence of Is" " and Ig was deduced over 30 years ago by Masson (I) from his studies of aromatic iodination reactions, but it is only recently that his conclusions have been confirmed by physical measurements. The controversy over the nature of the blue solutions of iodine in various highly acidic media has now been resolved, and it has been shown conclusively that these solutions contain Ig" (2-4) and not I+ as suggested earlier (5). There is, moreover, no convincing evidence for the existence of Cl or Br as stable species in solution or in the solid state. There is, however, evidence for polyatomic cations of chlorine and bromine analogous to the iodine cations, i.e., Clg", Brg, and Brg. ... 

Aromatic iodination (2, 220). In a procedure for the preparation of iododurene,3 a mixture of 13.4 g. (0.1 mole) of durene, 4.56 g. (0.02 mole) of periodic acid dihydrate, and 10.2 g. (0.04 mole) of iodine is stirred magnetically under reflux and treated with a... 

Indirect iodination. Two examples illustrate introduction of aromatic iodine by displacement of the HgCl group. In one, mercuric acetate is dissolved in hot phenol to form the o-acetoxymercuric derivative, the solution is poured into hot water, and... 

Aromatic iodination [1, 497, after citation of ref. 12]. Polyalkylbenzenes having bulky groups are not reactive toward iodine alone but may react in the presence of an oxidizing agent. In a detailed study of agents used in this connection (silver perchlorate, mercuric oxide, iodic acid, potassium persulfate, etc.) Japanese investigators123 found the combination of iodine with periodic acid dihydrate to be the most satisfactory. 

Aromatic iodination. Activation of iodine is necessary for this reaction. For this purpose, mercuric nitrate appears to be quite effective. 

It is also good to realize that properties like fragment lipophilicity contributions are additive properties, but may be very much dependent on the structural environment (Fig. 22.5). Some substitutions may have a more dramatic effect than expected. Radioactive labelling with I is quite common for biological studies. One should be aware, however, that aromatic iodination increases the log P of the compound by approximately 1 log P unit, and thus a different tissue distribution may result. An aromatic fluoro substituent has very little effect on the lipophilicity, but mainly serves in drugs to avoid oxydative biotransformation. 

Aromatic iodination. Alkyl aryl ethei Lead(IV) acetate can be used in place of HgC... 

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