phosphination

Phosphination is the chemical process of forming phosphorus–carbon bonds by introducing phosphorus-containing groups into organic molecules. The term encompasses several reaction types that install a phosphorus substituent onto a substrate, most commonly across carbon–carbon multiple bonds or via cross-coupling to create C–P bonds.

Two broad classes are hydrofunctionalization and cross‑coupling. In hydrofunctionalization, a phosphorus–hydrogen bond adds across an unsaturated substrate such as an alkene or alkyne, yielding organophosphorus products after subsequent workup. This can proceed via radical or polar mechanisms and is often promoted by light or metal catalysts. In cross‑coupling, organophosphorus reagents or phosphorus-containing auxiliaries participate in catalytic cycles (often palladium, nickel, or copper) to forge new C–P bonds between substrates such as aryl, vinyl, or alkyl partners and phosphorus ligands.

Common reagents include secondary phosphines (R2PH), phosphines, phosphine oxides, and related phosphorus hydrides. Reactions may require ligands, photoredox catalysis, or electrochemical conditions. Some developments expand to phosphination of arenes or heteroarenes via C–H activation, or to radical phosphination of simple hydrocarbons.

Applications of phosphination span the synthesis of organophosphorus compounds used as ligands in homogeneous catalysis, flame retardants, agricultural chemicals, and materials science. The resulting P–C bonds also enable exploration of new reactivity in medicinal chemistry.

Safety and handling: phosphorus reagents can be air- and moisture-sensitive and some are toxic. Reactions may generate phosphorus-containing wastes that require careful disposal. Ongoing research aims to improve chemoselectivity, atom economy, and sustainable catalysts.