Chlorodiphenylphosphine

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Chlorodiphenylphosphine
Ph2PCl.png
Chlorodiphenylphosphine-3D-balls.png
Identifiers
CAS number 1079-66-9 YesY
ChemSpider 59567 YesY
Jmol-3D images Image 1
Properties
Molecular formula C12H10ClP
Molar mass 220.63776 g mol-1
Appearance clear to light yellow liquid
Density 1.229 g cm-3
Boiling point 320 ˚C
Solubility in water Reacts
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

Chlorodiphenylphosphine is an organophosphorus compound with the formula (C6H5)2PCl, abbreviated Ph2PCl. It is a colourless oily liquid with a pungent odor that is often described as being garlic-like and detectable even in the ppb range. It is useful reagent for introducing the Ph2P group into molecules, which includes many ligands.[1] Like other halophosphines, Ph2PCl is reactive with many nucleophiles such as water and easily oxidized even by air.

Synthesis and reactions[edit]

Chlorodiphenylphosphine is produced on a commercial scale from benzene and phosphorus trichloride (PCl3). Benzene reacts with phosphorus trichloride at extreme temperatures around 600 °C to give dichlorophenylphosphine (PhPCl2). Redistribution of PhPCl2 in the gas phase at high temperatures results in chlorodiphenylphosphine.[1][2]

2 PhPCl2 → Ph2PCl + PCl3

Alternatively such compounds are prepared by redistribution reactions starting with triphenylphosphine and phosphorus trichloride. Synthesis of Ph2PCl by the direct reaction of phenylmagnesium bromide and phosphorus trichloride is not practiced. On the other hand, PCl3 can be usefully converted to its monoamide, which in turn undergoes alkylation or arylation. Subsequent removal of the amide gives :[3]

PCl3 + 2 (iPr)2NH → (iPr)2NH2Cl + (iPr)2NPCl2
(iPr)2NPCl2 + 2 PhMgBr → (iPr)2NPPh2 + 2 MgBrCl
(iPr)2NPPh2 + 2 HCl → (iPr)2NH2Cl + PPh2Cl

Uses[edit]

Ph2PCl, along with other chlorophosphines, is used in the synthesis of various phosphines. A typical route uses Grignard reagents:[2]

Ph2PCl + MgRX → Ph2PR + MgClX

The phosphines produced from reactions with Ph2PCl are further developed and used as pesticides (such as EPN), stabilizers for plastics (Sandostab P-EPQ), various halogen compound catalysts, flame retardants (cyclic phosphinocarboxylic anhydride), as well as UV-hardening paint systems (used in dental materials) making Ph2PCl an important intermediate in the industrial world.[1][2]

Precursor to diphenylphosphido derivatives[edit]

Chlorodiphenylphosphine is used in the synthesis of sodium diphenylphosphide via its reaction with sodium metal in refluxing dioxane.[4]

Ph2PCl + 2 Na → Ph2PNa + NaCl

Diphenylphosphine can be synthesized in the reaction of Ph2PCl and LiAlH4, the latter usually used in excess.[5]

4 Ph2PCl + LiAlH4 → 4 Ph2PH + LiCl + AlCl3

Both Ph2PNa and Ph2PH are also used in the synthesis of organophosphine ligands.

Characterization[edit]

The quality of chlorodiphenylphosphine is often checked by 31P NMR spectroscopy.[6]

Compound 31P chemical shift

(ppm vs 85% H3PO4)

PPh3 -6
PPh2Cl 81.5
PPhCl2 165
PCl3 218

References[edit]

  1. ^ a b c Quin, L. D. A Guide to Organophosphorus Chemistry; Wiley IEEE: New York, 2000; pp 44-69. ISBN 0-471-31824-8
  2. ^ a b c Svara, J.; Weferling, N.; Hofmann, T. "Phosphorus Compounds, Organic," In 'Ullmann's Encyclopedia of Industrial Chemistry, 7th ed.; Wiley-VCH: 2008; doi:10.1002/14356007.a19_545.pub2; Accessed: February 18, 2008.
  3. ^ A. Bollmann, K. Blann, J. T. Dixon, F. M. Hess, E. Killian, H. Maumela, D. S. McGuinness, D. H. Morgan, A. Neveling, S. Otto, M. Overett, A. M. Z. Slawin, P. Wasserscheid, S. Kuhlmann, “Ethylene Tetramerization: A New Route to Produce 1-Octene in Exceptionally High Selectivities” J. Am. Chem. Soc. 2004, 126, 14712-14713 plus supporting information. doi: 10.1021/ja045602n
  4. ^ Roy, Jackson W; Thomson, RJ; MacKay.m.f, . (1985). "The Stereochemistry of Organometallic Compounds. XXV. The Stereochemistry of Displacements of Secondary Methanesulfonate and p-Toluene-sulfonate esters by Diphenylphosphide Ions. X-ray Crystal Structure of (5α-Cholestan-3α-yl)diphenylphosphine Oxide". Australian Journal of Chemistry 38 (1): 111–18. doi:10.1071/CH9850111. 
  5. ^ Stepanova, Valeria A.; Dunina, Valery V.; Smoliakova, Irina P. (2009). "Reactions of Cyclopalladated Complexes with Lithium Diphenylphosphide". Organometallics 28 (22): 6546–6558. doi:10.1021/om9005615. 
  6. ^ O. Kühl "Phosphorus-31 NMR Spectroscopy" Springer, Berlin, 2008. ISBN 978-3-540-79118-8