Triphénylphosphine

The triphénylphosphine (or triphénylphosphane), is a Composé organophosphoré of formula P (C₆H₅) ₃ - sometimes shortened in P Ph₃ gold Ph₃P. It is largely used in the made up synthesis of organometallic organics and . It is a relatively stable compound which exists in the shape of a crystalline solid to room temperature and which dissolves in the polar solvents not like the Benzène.

Preparation

Even if it is not expensive, the triphénylphosphine can be prepared in laboratory by treatment of the Trichlorure of phosphorus with bromide of phénylmagnésium or phényllithium. The industrial synthesis brings into play the Réaction of Friedel-Crafts between the Trichlorure of phosphorus and the Benzène. The triphénylphosphine can be recrystallized either in the hot ethanol or in the hot Isopropanol. This purification is sometimes advised to remove oxide of triphénylphosphine, of formula COp (C₆H₅) ₃, which was formed by slow oxidation by the air.

Principal organic reactions

P (C₆H₅) ₃ is largely used in organic synthesis. Reaction of the P (C₆H₅) ₃ on the Halogénoalcane S led to phosphoric salts also called salts of phosphonium.

These salts react with bases S strong (standard Organométallique S for example the Organolithien S, ions Amidure S - NH₂^- or Hydrure H^-, of the less strong bases being able to be used in certain case) to form ylides of phosphorus, also called phosphoranes .

These molecules are used in particular in the reaction of Wittig, where, créees in situ , they react with carbonyl compounds, Aldéhyde S or Cétone S, to form ethylene derivatives, even Alcène S.

reaction of Wittig reaction of Wittig

The reaction of P (C₆H₅) ₃ on the chlorines gives Cl₂P (C₆H₅) ₃, creates in situ to transform the alcohols into chlorinated derivatives, forming consequently occasion HCl and an oxide of tryphénylphosphine O=P (C₆H₅) ₃.

Reactions with the inorganic compounds and the organometallic ones

The triphénylphosphine is often used like Ligand of a metal cation to form a complex coordination. It binds to the majority of the metals of transition, in particular to metals of the medium and the end of the block D like the palladium, the Platine, the Ruthénium, the Nickel and the Osmium. Example: the Tetrakis (triphenylphosphine) of palladium (0). The corresponding triphénylamines have a weak affinity for the metals of transition. This difference is explained by more the small size of the atom of Azote, which involves larger steric gene limiting the approach of the Ligand towards the metal center.

The compounds of the type metal-p (C₆H₅) ₃ are characterized by spectroscopy NMR ³¹P.

The triphénylphosphine collects the Soufre starting from many sulfur compounds, including elementary sulfur. The phosphorated product is SP (C₆H₅) ₃. This reaction can be used to analyze the sulfur rates.

Use in organophosphoric chemistry

The triphénylphosphine is usually employed like precursor for others organophosphines. Lithium in THF and sodium (Na) or potassium (K) in NH₃ ammonia react to give (C₆H₅) ₂PM (M = Li, Na, K). One of the defects of these reactions is to generate as much phényllithium (or sodium, or potassium) C₆H₅M, but these species can be selectively converted into Benzène by attentive use of acid. The treatment of alkaline metal diphénylphosphure by an agent of Alkylation X-ray gives PRC₆H₅) ₂. This method can be used to prepare Ligand S like SME (C₆H₅) ₂ (methyldiphenylphosphine). The reaction with the dihalogénoalcanes corresponding gives (a) (diphénylphosphino) alkanes. For example, the Dibromide of ethylene and Ph₂PM react to give (C₆H₅) ₂PCH₂CH₂P (C₆H₅) ₂, called 1,2-(a) (diphénylphosphino) ethane or dppe. The addition of acid, even weak like the Chloride ammonium, converts (C₆H₅) ₂PM into (C₆H₅) ₂PH, or diphénylphosphine.

The Sulfonation of P (C₆H₅) ₃ gives the sorting (3-sulfophényl) phosphine, P (C₆H₄-3-SO₃^-) ₃. This anion phosphine is usually isolated like salt from trisodium and is known like TPPTS . Contrary to P (C₆H₅) ₃, TPPTS is water soluble, like its metal derivatives. Complexes TPPTS of rhodium are used in certain industrial reactions of Hydroformylation because of a separable water-soluble catalyst of the organic compounds.

Other reactions implying of the triphénylphosphines:

Reaction of Call
Reaction of Mitsunobu
Reaction of Wittig
Reaction of Staudinger
like ligand in the Reaction of Heck
In the production of the Catalyst of Wilkinson and the Complex of Vaska

External bonds

International Chemical Safety Card 0700
J.T. Baker MSDS

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