triphenylphosphine

Triphenylphosphine (Ph3P) is an organophosphorus compound that serves as a versatile reagent and ligand in organic synthesis and coordination chemistry. Its chemical formula is C18H15P, and it is typically encountered as a white to pale yellow solid that is soluble in nonpolar organic solvents and largely insoluble in water. The molecule features a phosphorus center bonded to three phenyl rings in a tetrahedral geometry, classifying it as a tertiary phosphine.

As a ligand, triphenylphosphine is one of the most widely used in homogeneous catalysis. It is a relatively strong σ-donor and can stabilize low-oxidation-state metal centers, enabling a range of transformations such as cross-coupling, hydrofunctionalization, and hydrogenation. Commercial catalysts often incorporate Ph3P ligands, for example Pd(PPh3)4 or related complexes. In synthesis, Ph3P participates in the Staudinger reaction with organic azides to form iminophosphoranes, a key step in azide-to-amine conversions. Ph3P is also employed to generate phosphorane ylides in Wittig reactions, enabling carbon–carbon double-bond formation.

Preparation and handling: Triphenylphosphine is commercially available and can be prepared by reduction of triphenylphosphine oxide. It is relatively air-stable but slowly oxidizes in air to Ph3P=O; storage under inert atmosphere or in a dry, ventilated space is common. It is typically handled as a dry, inert-dust form in the lab, with standard precautions to avoid inhalation and skin contact. Safety considerations include potential irritation; appropriate disposal follows standard chemical waste guidelines.