An Introduction to Higher-Valent Organoiodine Compounds

Very often, the isocyanate is not isolated but is allowed to hydrolyze to the amine under the reaction conditions  

Higher-valent organoiodine compounds represent a major contribution of modern halogen chemistry to organic synthesis. The first such compound, dichloroiodobenzene (PhICl2), however, was prepared well over a century ago  

Given the variety of iodine valence states in organoiodine compounds, the A nomenclature (see Section 1.26) will prove useful for our discussion. Dichloroiodobenzene is thus a A -iodane, the superscript being essentially the valence of the atom in question. As shown below, a number of other A -iodanes such as iodobenzene diacetate are also readily accessible from iodobenzene the pentavalent iodine compound iodoxybenzene is shown below in a different color to distinguish it from the other trivalent compounds. 

Peroxyacid treatment, followed by heating in water, converts iodobenzene to iodoxyben-zene, a pentavalent iodine compound, as shown above. 

To varying degrees, all these compounds have found use as reagents in organic synthesis. In addition, substituted iodobenzenes have led to additional sophisticated reagents. Below we examine the mechanisms of action of a few of these. 

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