Triphenylphosphine oxide
From Wikipedia, the free encyclopedia
| Triphenylphosphine oxide | |
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| IUPAC name | Triphenylphosphine oxide |
| Identifiers | |
| CAS number | [791-28-6] |
| RTECS number | SZ1676000 |
| SMILES | O=P(c1ccccc1)- (c2ccccc2)c3ccccc3 |
| Properties | |
| Molecular formula | C18H15OP |
| Molar mass | 278.28 g/mol |
| Appearance | white crystals |
| Melting point |
154-158 °C (427-429 K) |
| Boiling point |
360 °C (633 K) |
| Solubility in water | low |
| Solubility in other solvents | polar organic solvents |
| Structure | |
| Molecular shape | tetrahedral |
| Hazards | |
| Main hazards | slight |
| R-phrases | 22-36/37/38 |
| S-phrases | 26 |
| Related compounds | |
| Related compounds | POCl3, PCl5, P(C6H5)3 |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references |
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Triphenylphosphine oxide is the chemical compound with the formula OP(C6H5)3. Often chemists abbreviate the formula by writing Ph3PO or PPh3O (Ph = C6H5). This white crystalline compound is a common side product in reactions involving triphenylphosphine. It is a popular reagent to induce the crystallizing of chemical compounds.
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[edit] Structure and properties
Ph3PO is tetrahedral molecule related to POCl3.[1] 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.[2]
[edit] As a by-product of organic synthesis
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.
- Ph3PCl2 + ROH → Ph3PO + HCl + RCl
Triphenylphosphine can be regenerated from the oxide by treatment with trichlorosilane.
- Ph3PO + SiHCl3 → PPh3 + 1/n (OSiCl2)n + HCl
[edit] Coordination chemistry
Ph3PO is an excellent ligand for "hard" metal centers. A typical complex is the tetrahedral species NiCl2(OPPh3)2.[3]
Ph3PO is a common impurity in PPh3. The oxidation of PPh3 by oxygen, including air, is catalyzed by many metal ions:
- 2 PPh3 + O2 → 2 Ph3PO
[edit] References
- ^ D. E. C. Corbridge "Phosphorus: An Outline of its Chemistry, Biochemistry, and Technology" 5th Edition Elsevier: Amsterdam. ISBN 0-444-89307-5.
- ^ M. C. Etter and P. W. Baures (1988). "Triphenylphosphine oxide as a crystallization aid". J. Am. Chem. Soc. 110 (2): 639–640. doi:.
- ^ D. M. L. Goodgame and M. Goodgame (1965). "Near-Infrared Spectra of Some Pseudotetrahedral Complexes of Cobalt (II) and Nickel(II)". Inorg. Chem. 4 (2): 139–143. doi:.
