Triphenylphosphine oxide

Triphenylphosphine oxide

Names
Preferred IUPAC name Triphenyl-λ5-phosphanone
Other names Triphenylphosphine oxide
Identifiers
CAS Number	791-28-6 Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:36601 Y
ChemSpider	12549 Y
ECHA InfoCard	100.011.217
PubChem CID	13097
RTECS number	SZ1676000
InChI InChI=1S/C18H15OP/c19-20(16-10-4-1-5-11-16,17-12-6-2-7-13-17)18-14-8-3-9-15-18/h1-15H Y Key: FIQMHBFVRAXMOP-UHFFFAOYSA-N Y InChI=1/C18H15OP/c19-20(16-10-4-1-5-11-16,17-12-6-2-7-13-17)18-14-8-3-9-15-18/h1-15H Key: FIQMHBFVRAXMOP-UHFFFAOYAB
SMILES O=P(c1ccccc1)(c2ccccc2)c3ccccc3
Properties
Chemical formula	C18H15OP
Molar mass	278.29 g/mol
Appearance	white crystals
Melting point	154 to 158 °C (309 to 316 °F; 427 to 431 K)
Boiling point	360 °C (680 °F; 633 K)
Solubility in water	low
Solubility in other solvents	polar organic solvents
Structure
Molecular shape	tetrahedral
Hazards
Main hazards	slight
R-phrases (outdated)	22-36/37/38
S-phrases (outdated)	26
Related compounds
Related compounds	P(C6H5)3S; P(C6H5)3; POCl3; PCl5
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Y  (what is YN ?)
Infobox references

P(C₆H₅)₃; POCl₃; PCl₅

Triphenylphosphine oxide (often abbreviated TPPO) is the chemical compound with the formula OP(C₆H₅)₃, also written as Ph₃PO or PPh₃O (Ph = C₆H₅). This colourless crystalline compound is a common side product in reactions involving triphenylphosphine. It is a popular reagent to induce the crystallizing of chemical compounds.

Ph₃PO is tetrahedral molecule related to POCl₃. The oxygen center is relatively basic. The rigidity of the backbone and the basicity of the oxygen center make this species a popular agent to crystallize otherwise difficult to crystallize molecules. This trick is applicable to molecules that have acidic hydrogen atoms, e.g. phenols.

Ph₃PO is a by-product of many useful reactions in organic synthesis including the Wittig, Staudinger, and Mitsunobu reactions. It is also formed when PPh₃Cl₂ is employed to convert alcohols into alkyl chlorides.

Triphenylphosphine can be regenerated from the oxide by treatment with trichlorosilane.

Triphenylphosphine oxide can be difficult to remove from reaction mixtures by means of chromatography. It is poorly soluble in hexane and cold diethyl ether. Trituration or chromatography of crude products with these solvents often leads to a good separation of triphenylphosphine oxide. One tip for its removal is to form its Mg(II) complex, which is poorly soluble in toluene or dichloromethane and can be filtered off. See WO 1998007724.

Ph₃PO is an excellent ligand for "hard" metal centers. A typical complex is the tetrahedral species NiCl₂(OPPh₃)₂.