Alkyliodiden

Alkyliodiden, or alkyl iodides, are a class of organoiodine compounds with the general structure R–I, where R is an alkyl group. They are typically colorless liquids or low-melting solids. The C–I bond is relatively weak and polarizable, making these compounds among the most reactive of the simple alkyl halides in substitution and elimination reactions.

Common preparation methods include the Appel reaction of alcohols with triphenylphosphine and iodine to form R–I; conversion of alcohols to iodides via hydroiodic acid with red phosphorus; and displacement of sulfonate leaving groups (tosylates/mesylates) with iodide salts (Finkelstein-type).

Reactivity: The C–I bond is a good leaving group; alkyl iodides undergo SN2 readily for primary and some secondary substrates; tertiary iodides tend toward SN1 with formation of carbocation intermediates. They are more reactive in nucleophilic substitutions than chlorides or bromides. They also participate in radical reactions, photochemical processes, and can serve as precursors to alkyl radicals under light or transition-metal catalysis.

Applications: Used as versatile alkylating agents in organic synthesis, in the preparation of pharmaceuticals, natural products, and materials. They are common precursors for further transformations such as cross-couplings (e.g., Ni- or Cu-catalyzed) and radical couplings.

Safety: Alkyl iodides are typically irritants and can be toxic; many are lachrymatory and odorous. They should be handled in a well-ventilated area with appropriate PPE, stored away from oxidizers, and disposed of as hazardous waste.