iodineIII

Iodine(III), here referred to as iodineIII, designates compounds in which iodine is in the +3 oxidation state. These species are a subset of hypervalent iodine reagents and are valued in organic synthesis for their relatively mild, chemoselective oxidizing power and their ability to transfer oxygen or other groups to substrates.

Prominent iodine(III) reagents include iodosylbenzene (PhIO), phenyliodine diacetate (PhI(OAc)2, often abbreviated PIDA), and phenyliodine bis(trifluoroacetate) (PhI(OC(O)CF3)2, often abbreviated PIFA). These compounds feature hypervalent iodine centers with three-center four-electron bonding and typically adopt T- or see-saw-shaped geometries. They are commonly prepared by oxidizing iodoarenes with peracids such as meta-chloroperbenzoic acid or Oxone, among other oxidants.

Applications of iodineIII reagents span a wide range of oxidative transformations in organic synthesis. They can oxidize alcohols to carbonyl compounds, promote oxidative dearomatization of phenols, enable various cyclizations and rearrangements, and serve as key steps in the synthesis of complex molecules. In some cases, iodineIII reagents are used in catalytic cycles, where a catalytic amount of iodoarene is regenerated by a terminal oxidant.

Safety and handling considerations are important. Iodine(III) reagents are strong oxidants and can be moisture-sensitive or shock-sensitive when dry. They should be stored and used with appropriate safety precautions, in suitable organic solvents, away from incompatible materials, and with proper personal protective equipment.

See also hypervalent iodine, PIDA, PIFA, iodosylbenzene.