Chlorodiphenylphosphine

Chlorodiphenylphosphine

Names
Preferred IUPAC name Diphenylphosphinous chloride
Other names chlorodiphenylphosphine p-chlorodiphenylphosphine diphenyl phosphine chloride diphenylchlorophosphine
Identifiers
CAS Number	1079-66-9
ChemSpider	59567
Jmol interactive 3D	Image
InChI InChI=1S/C12H10ClP/c13-14(11-7-3-1-4-8-11)12-9-5-2-6-10-12/h1-10H Key: XGRJZXREYAXTGV-UHFFFAOYSA-N InChI=1/C12H10ClP/c13-14(11-7-3-1-4-8-11)12-9-5-2-6-10-12/h1-10H Key: XGRJZXREYAXTGV-UHFFFAOYAM
SMILES ClP(c1ccccc1)c2ccccc2
Properties
Chemical 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 otherwise noted, 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

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

Unlike the synthesis of chlorodiisopropylphosphine, reaction of two equivalents of the phenyl Grignard reagents with PCl₃ does not efficiently afford the monochloride.

Uses

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

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

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

1. Quin, L. D. A Guide to Organophosphorus Chemistry; Wiley IEEE: New York, 2000; pp 44-69. ISBN 0-471-31824-8
2. 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