Triphenylphosphine sulfide

Triphenylphosphine sulfide (IUPAC name: triphenyl-λ⁵-phosphanethione) is the organophosphorus compound with the formula (C₆H₅)₃PS, usually written Ph₃PS (where Ph = phenyl). It is a colourless solid, which is soluble in a variety of organic solvents.

Structurally, the molecule resembles the corresponding oxide, with idealized C₃ point group symmetry. It is weakly nucleophilic at the sulfur atom.

Applications

Organic synthesis

Triphenylphosphine sulfide is useful for the conversion of epoxides to the corresponding episulfides:

Ph₂C₂H₂O Ph₃PS → Ph₂C₂H₂S Ph₃PO

It also reacts with ketenes to form thioketenes:

Ph₂CCO Ph₃PS → Ph₂CCS Ph₃PO

Analytical chemistry

In analytical chemistry, triphenylphosphine is used for the analysis of certain kinds of sulfur compounds. Elemental sulfur (S₈), as occurs in some oils, and labile organosulfur compounds, such as organic trisulfides, react with triphenylphosphine to give Ph₃PS, which can be detected by gas chromatography.

References