Diphenylphosphine
Encyclopedia
Diphenylphosphine, also known as diphenylphosphane, is organophosphorus compound with the formula (C6H5)2PH. This foul smelling, colorless liquid is easily oxidized in air. It is a precursor to organophosphorus ligands for use as catalysts.
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The preparation of phosphine ligand
s, Wittig-Horner reagents
, and phosphonium salt
s are commonly accomplished by alkylating diphenylphosphine. The hydrogen atom connected to phosphorus undergoes Michael-like addition to activated alkenes, providing products with which to produce phosphine ligands such as 1,2-bis(diphenylphosphino)ethane
(Ph2PC2H4PPh2). Diphenylphosphine and especially diphenylphosphide derivatives are nucleophiles, so they add to carbon – heteroatom double bonds. For example, in the presence of concentrated hydrochloric acid at 100 °C, diphenylphosphine adds to the carbon atom in benzaldehyde
to give (phenyl-(phenylmethyl)phosphoryl)benzene.
The use of the diphenylphosphine–borane complex, Ph2PH•BH3 avoids the problem of phosphine oxidation by protecting the phosphine from oxidation and is available through chemical vendors.
Synthesis
Diphenylphosphine can be prepared cheaply from triphenylphosphineTriphenylphosphine
Triphenylphosphine is a common organophosphorus compound with the formula P3 - often abbreviated to PPh3 or Ph3P. It is widely used in the synthesis of organic and organometallic compounds. PPh3 exists as relatively air stable, colorless crystals at room temperature...
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- PPh3 + 2 Li → LiPPh2 + LiPh
- LiPPh2 + H2O → Ph2PH + LiOH
Uses and reactions
In the laboratory, diphenylphosphine is a common intermediate. It readily deprotonated to give diphenylphosphide derivatives:- Ph2PH + nBuLi → Ph2PLi + nBuH
The preparation of phosphine ligand
Ligand
In coordination chemistry, a ligand is an ion or molecule that binds to a central metal atom to form a coordination complex. The bonding between metal and ligand generally involves formal donation of one or more of the ligand's electron pairs. The nature of metal-ligand bonding can range from...
s, Wittig-Horner reagents
Horner-Wadsworth-Emmons reaction
The Horner-Wadsworth-Emmons reaction is the chemical reaction of stabilized phosphonate carbanions with aldehydes to produce predominantly E-alkenes....
, and phosphonium salt
Phosphonium salt
A phosphonium salt is a salt containing the phosphonium ion such as phosphonium iodide . More commonly, phosphonium refers to a quaternary organic derivative such as tetraphenylphosphonium chloride, 4P+ Cl- and tetramethylphosphonium iodide, [P4]+I−.Alkyltriphenylphosphonium salts are widely...
s are commonly accomplished by alkylating diphenylphosphine. The hydrogen atom connected to phosphorus undergoes Michael-like addition to activated alkenes, providing products with which to produce phosphine ligands such as 1,2-bis(diphenylphosphino)ethane
1,2-Bis(diphenylphosphino)ethane
1,2-Bisethane is a commonly used bidentate ligand in coordination chemistry. Dppe is almost invariably chelated, although there are examples of unidentate and of bridging behavior.-Preparation:...
(Ph2PC2H4PPh2). Diphenylphosphine and especially diphenylphosphide derivatives are nucleophiles, so they add to carbon – heteroatom double bonds. For example, in the presence of concentrated hydrochloric acid at 100 °C, diphenylphosphine adds to the carbon atom in benzaldehyde
Benzaldehyde
Benzaldehyde is an organic compound consisting of a benzene ring with a formyl substituent. It is the simplest aromatic aldehyde and one of the most industrially useful. This colorless liquid has a characteristic pleasant almond-like odor...
to give (phenyl-(phenylmethyl)phosphoryl)benzene.
- Ph2PH + PhCHO → Ph2P(O)CH2Ph
Handling properties
During the handling of diphenylphosphine, care must be taken to avoid oxidation of diphenylphosphine.- Ph2PH + O2 → Ph2P(O)OH
The use of the diphenylphosphine–borane complex, Ph2PH•BH3 avoids the problem of phosphine oxidation by protecting the phosphine from oxidation and is available through chemical vendors.