For questions about the synthesis, properties, or reactivities of organic compounds containing phosphorus; or about reactions in which such compounds are used.
Phosphorus in organic chemistry
Organic chemistry mainly focuses on the elements carbon, hydrogen, oxygen, nitrogen, and the halides. However, the use of other p-block elements in organic chemistry has grown tremendously over the past century. organophosphorus-compounds is part of a series of tags intended to collect questions about these elements.
(See also: organosulfur-compounds, organosilicon-compounds)
Both phosphorus(III) and phosphorus(V) compounds are used extensively in organic chemistry. Several examples (not exhaustive) follow:
A key characteristic of phosphorus is that it forms an extremely strong double bond with oxygen; the formation of a P=O bond is often used as a thermodynamic driving force in reactions. For example, the Wittig reaction and its variants (Horner–Wadsworth–Emmons, etc.); the Mitsunobu reaction; the Staudinger reduction; and the Vilsmeier formylation all feature the formation of a P=O bond.
On top of that, phosphines are strongly nucleophilic due to the high-energy (mostly) 3s lone pair on phosphorus. This has led to their use as nucleophilic catalysts in various reactions, such as the Baylis–Hillman reaction and some isomerisations (e.g. Trost, JACS 1992, 114, 7933).
Phosphines find an extremely important use in transition metal-catalysed coupling reactions, as ligands which coordinate to the metal catalyst. Triphenylphosphine, PPh3, was the original member of the family, but a wide variety of phosphines with ever-increasing complexity have been designed in order to effect difficult transformations. The careful tuning of electronic and steric properties allows for exquisite control of the course of reactions.
Outside of organic chemistry
Organophosphorus compounds, in particular phosphate esters, are key to the functioning of the human body. Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) are polymers formed from nucleotides, which contain a phosphate group. Adenosine triphosphate (ATP), the energy "currency" of the body, is likewise a triple phosphate ester; energy is derived from the hydrolysis of the phosphate ester. Phosphorylation is an extremely important method by which gene expression and protein function can be controlled; cell signalling relies heavily on enzymes which add and remove phosphate groups from biomolecules.
A less palatable use of organophosphorus compounds is as nerve agents. These are capable of covalently binding to acetylcholinesterase, an enzyme in the nervous system responsible for the breakdown of acetylcholine (a key neurotransmitter). Less toxic organophosphorus compounds are also used as insecticides and herbicides.
