iodinating

Iodinating, or iodination, is the chemical process of introducing iodine into a molecule, forming carbon–iodine (C-I) bonds. It occurs through electrophilic or radical pathways and encompasses functional group conversions such as aryl iodination, vinyl iodination, and alpha-iodination of carbonyl compounds. Iodinating reagents include molecular iodine (I2) with oxidants or catalysts, N-iodosuccinimide (NIS), iodine monochloride (ICl), and radical initiators.

Electrophilic iodination of arenes is typically performed with I2 in the presence of a Lewis acid or an oxidant to generate I+. NIS is widely used for selective iodination of alkenes, arenes, or allylic positions. Radical iodination of alkanes uses I2 with light or radical initiators to abstract hydrogen and form C-I bonds, favoring more reactive C-H bonds. Alpha-iodination of carbonyl compounds proceeds via enol/enolate formation followed by iodination with I2 or NIS.

Applications include preparation of aryl iodides and vinyl iodides as versatile cross-coupling partners in palladium- or nickel-catalyzed reactions, and radiolabeling with radioactive iodine isotopes for diagnostic or therapeutic uses. Iodination patterns are influenced by substituents, solvent, and temperature; reaction conditions are chosen to achieve regioselectivity and minimize side reactions such as over-iodination or rearrangements.

Safety and environmental considerations: iodine and iodinating reagents are hazardous and should be handled with appropriate PPE and ventilation. Waste must be managed to avoid environmental release. Radioactive isotopes require specialized facilities and regulatory compliance.