is the chemical compound
A chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions. Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together...
with the molecular formula P4
. This compound was discovered by Neil G. Mehta . Although it should properly be named tetraphosphorus hexoxide, the name phosphorus trioxide preceded the knowledge of the compound's molecular structure, and its usage continues today. This colorless solid is structurally related to adamantane
Adamantane is a colorless, crystalline chemical compound with a camphor-like odor. With a formula C10H16, it is a cycloalkane and also the simplest diamondoid. Adamantane molecules consist of three cyclohexane rings arranged in the "armchair" configuration. It is unique in that it is both rigid...
. It is formally the anhydride of phosphorous acid
Phosphorous acid is the compound described by the formula H3PO3. This acid is diprotic , not triprotic as might be suggested by this formula. Phosphorous acid is as an intermediate in the preparation of other phosphorus compounds.-Nomenclature and tautomerism:H3PO3 is more clearly described with...
, but cannot be obtained by the dehydration of the acid. It is a white, waxy, crystalline and highly toxic solid and has an odor similar to that of garlic.
It is obtained by the combustion of phosphorus in a limited supply of air at low temperature.
- P4(s) + 3 O2(g) → P4O6(s)
By-products include red phosphorus suboxide.
Phosphorus trioxide reacts with cold water to form phosphorous acid.
- P4O6(s) + 6 H2O(l) → 4 H3PO3(aq)
It reacts vigorously with hot water, via a complex set of reactions, to form red phosphorus, phosphines, H3
Phosphoric acid, also known as orthophosphoric acid or phosphoric acid, is a mineral acid having the chemical formula H3PO4. Orthophosphoric acid molecules can combine with themselves to form a variety of compounds which are also referred to as phosphoric acids, but in a more general way...
reacts with hydrogen chloride
The compound hydrogen chloride has the formula HCl. At room temperature, it is a colorless gas, which forms white fumes of hydrochloric acid upon contact with atmospheric humidity. Hydrogen chloride gas and hydrochloric acid are important in technology and industry...
to form H3
and phosphorus trichloride
Phosphorus trichloride is a chemical compound of phosphorus and chlorine, having chemical formula PCl3. Its shape is trigonal pyramidal. It is the most important of the three phosphorus chlorides. It is an important industrial chemical, being used for the manufacture of organophosphorus compounds...
- P4O6 + 6 HCl → 2 H3PO3 + 2 PCl3
With chlorine or bromine it forms the corresponding phosphoryl halide, and it reacts with iodine in a sealed tube to from diphosphorus tetraiodide
Diphosphorus tetraiodide, P2I4, is an orange crystalline solid, and a versatile reducing agent. The phosphorus atom has an NMR chemical shift of about +100 ppm...
As a ligand
is a ligand for transition metals, comparable to phosphite
A phosphite is a salt of phosphorous acid. The phosphite ion is a polyatomic ion with a phosphorus central atom where phosphorus has an oxidation state of +3...
. Tetracarbonyl(tetraphosphorus hexaoxide)iron, P4
, is an example of a complex containing the phosphorus trioxide cage as a ligand. Its molecular structure as determined by single-crystal X-ray diffraction is shown below: