P2S5

P2S5, or diphosphorus pentasulfide, is a binary inorganic compound composed of phosphorus and sulfur. It is one of several phosphorus sulfides studied for their reactivity and potential uses in synthesis. The compound can be prepared by direct combination of elemental phosphorus and sulfur at elevated temperature under dry, inert conditions, or by controlled processing of related phosphorus sulfides.

Chemically, P2S5 is a covalent molecular compound. It is sensitive to moisture and hydrolyzes readily in water or damp air, a property that informs its handling and storage. When it hydrolyzes, it yields phosphoric acid and hydrogen sulfide according to the overall reaction: P2S5 + 8 H2O → 2 H3PO4 + 5 H2S.

In organic synthesis, P2S5 has been employed as a thionating agent, capable of converting carbonyl groups into thiones and enabling related sulfur-transfer transformations. It has also served as a precursor to other phosphorus–sulfur compounds and has historical use in the preparation of sulfur-containing phosphorus reagents.

Safety and handling notes are important: P2S5 is corrosive and toxic, and its hydrolysis releases hydrogen sulfide, a toxic gas with a characteristic foul odor. It should be stored and handled under dry, inert conditions, using appropriate protective equipment and ventilation.

See also: phosphorus sulfides, P4S10, thionating reagents.