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Diphenylphosphine

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Diphenylphosphine
Ball-and-stick model
Ball-and-stick model
Names
Preferred IUPAC name Diphenylphosphane
Identifiers
CAS Number
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.011.447 Edit this at Wikidata
EC Number
  • 212-591-4
PubChem CID
UNII
CompTox Dashboard (EPA)
InChI
  • InChI=1S/C12H11P/c1-3-7-11(8-4-1)13-12-9-5-2-6-10-12/h1-10,13HKey: GPAYUJZHTULNBE-UHFFFAOYSA-N
  • InChI=1/C12H11P/c1-3-7-11(8-4-1)13-12-9-5-2-6-10-12/h1-10,13HKey: GPAYUJZHTULNBE-UHFFFAOYAN
SMILES
  • c2c(Pc1ccccc1)cccc2
Properties
Chemical formula C12H11P
Molar mass 186.19 g/mol
Appearance colorless liquid
Density 1.07 g/cm, liquid
Boiling point 280 °C (536 °F; 553 K)
Solubility in water Insoluble
Hazards
GHS labelling:
Pictograms GHS02: FlammableGHS07: Exclamation mark
Signal word Danger
Hazard statements H250, H315, H319, H335
Precautionary statements P210, P222, P261, P264, P271, P280, P302+P334, P302+P352, P304+P340, P305+P351+P338, P312, P321, P332+P313, P337+P313, P362, P370+P378, P403+P233, P405, P422, P501
Safety data sheet (SDS) External MSDS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa). checkY verify (what is  ?) Infobox references
Chemical compound

Diphenylphosphine, also known as diphenylphosphane, is an 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.

Synthesis

Diphenylphosphine can be prepared from triphenylphosphine by reduction to lithium diphenylphosphide, which can be protonated to give the title compound:

PPh3 + 2 Li → LiPPh2 + LiPh
LiPPh2 + H2O → Ph2PH + LiOH

Uses and reactions

In the laboratory, diphenylphosphine is a common intermediate. It can be deprotonated to give diphenylphosphide derivatives:

Ph2PH + BuLi → Ph2PLi + BuH

The preparation of phosphine ligands, Wittig-Horner reagents, and phosphonium salts 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) and BINAP. via its bistriflate derivatives. Both the (R)- and (S)-enantiomers, as well as the racemate, are commercially available. One of the wide applications include chemoselective hydrogenation, where BINAP is conjugated to rhodium.

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.

Ph2PH + PhCHO → Ph2P(O)CH2Ph

Compared to tertiary phosphines, diphenylphosphine is weakly basic. The pKa of the protonated derivative is 0.03:

Ph2PH2 ⇌ Ph2PH + H

Handling properties

Diphenylphosphine readily oxidizes.

Ph2PH + O2 → Ph2P(O)OH

An intermediate in this oxidation is diphenylphosphine oxide. 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.

References

  1. V. D. Bianco; S. Doronzo (1976). "Diphenylphosphine". Inorganic Syntheses. Vol. 16. pp. 161–188. doi:10.1002/9780470132470.ch43. ISBN 9780470132470.
  2. ^ Piotrowski, D. W. (2001). "Diphenylphosphine". Encyclopedia of Reagents for Organic Synthesis. New York: John Wiley & Sons. doi:10.1002/047084289X.rd427. ISBN 0471936235.
  3. Cai, Dongwei; J. F. Payack; D. R. Bender; D. L. Hughes; T. R. Verhoeven; P. J. Reider (1999). "(R)-(+)- and (S)-(−)-2,2′-bis(diphenylphosphino)-1,1′-binapthyl (BINAP)". Organic Syntheses. 76: 6.
  4. C. A. Streuli, "Determination of Basicity of Substituted Phosphines by Nonaqueous Titrimetry", Analytical Chemistry 1960, volume 32, pages 985-987.doi:10.1021/ac60164a027
  5. Svara, J.; Weferling, N.; Hofmann, T. "Phosphorus Compounds, Organic". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a19_545.pub2. ISBN 978-3527306732.
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