The chemical element phosphorus is often used in fireworks but its most important application is as the starting material for organophosphorus compounds and fire resistant polymers. phosphorus hydride (PH), formed by the disproportionation of white phosphorus at elevated temperatures, is a poisonous and highly reactive gas that burns in air to form phosphine, with a foul odor.
The low vapor pressure of PH3 allows for its use in large scale reactions, although it must be handled carefully to avoid toxic effects. It is a key reactant in the production of metal phosphides by the reduction of the corresponding organophosphorus salts. The phosphorus hydride is also the starting material for the synthesis of many other organic compounds including the flame retardants hexachlorobenzene and tricloroethylene.
Recent Advances in Hydride Chemistry
A recently published paper describes the discovery of a two-dimensional phase of compressed “phosphine” with superconductivity below 30 K at 83 GPa. This phase is stabilized by layers of fluid hydrogen molecules that minimize Coulomb repulsion between adjacent 2D sheets of phosphorus atoms.
phosphorus hydride forms when white phosphorus is heated at high temperature in the presence of a catalyst such as magnesium bisphosphate. The reaction results in a mixture of phosphine and phosphoric acid, which can be further reacted to produce substituted phosphines.
phosphorus hydride is more electronegative than nitrogen, which makes it less able to expand its valence shell to hold more than eight electrons. This fact, along with the fact that phosphorus is more stable than nitrogen at higher temperatures, leads to the formation of an extensive array of compounds in which phosphorus has negative oxidation numbers. The radii of phosphorus and oxygen are comparable, so P-O double bonds are weaker than O-O double bonds.