Fosfinen

Fosfinen, the Dutch term for phosphines, are phosphorus hydrides with phosphine (PH3) as the simplest member. They are colorless, highly toxic and flammable gases at room temperature. They often have a sharp odor, but detection by smell is unreliable, so exposure must be avoided. PH3 is a trigonal pyramidal molecule with a lone pair on phosphorus and is a weak base; many phosphines (PR3) are important ligands in catalysis.

In air, phosphines oxidize to phosphorus oxides, and PH3 can act as a reducing agent in various reactions. They are generally more soluble in organic solvents than in water and can be generated on demand in the laboratory or industrially.

Production and occurrence: Industrial phosphine is typically produced on site. A common preparation route uses the hydrolysis of calcium phosphide: Ca3P2 + 6 H2O → 2 PH3 + 3 Ca(OH)2. It can also arise as a byproduct in phosphorus processing. In the lab, phosphine can be generated by other controlled reactions and used immediately.

Uses: Phosphines are widely used as ligands in homogeneous catalysis; organophosphine ligands (PR3) support many catalysts in hydroformylation, hydrogenation, and related transformations. Phosphine gas is also employed as a phosphorus dopant in the semiconductor industry. Historically, phosphine was used as a fumigant in stored grain, but its use is now tightly regulated due to toxicity.

Safety: Phosphines are highly toxic and flammable. Inhalation or skin contact can be dangerous, and they form explosive mixtures with air. Handling requires proper ventilation, detectors, and storage under inert conditions.