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Triphenylphosphine dichloride

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Triphenylphosphine dichloride
Structural formula
Ball-and-stick model
Ball-and-stick model
Space-filling model
Space-filling model
Names
IUPAC name Dichlorotriphenyl-λ-phosphane
Other names Dichlorotriphenylphosphorane
Identifiers
CAS Number
ECHA InfoCard 100.107.819 Edit this at Wikidata
CompTox Dashboard (EPA)
Properties
Chemical formula C18H15Cl2P
Molar mass 333.19 g/mol
Melting point 176 °C, 85-100 °C
Related compounds
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

Triphenylphosphine dichloride, Ph3PCl2, is a chlorinating agent widely used in organic chemistry. Applications include the conversion of alcohols and ethers to alkyl chlorides, the cleavage of epoxides to vicinal dichlorides and the chlorination of carboxylic acids to acyl chlorides.

Structure

In polar solvents such as acetonitrile or dichloromethane solutions, Ph3PCl2 adopts an ionic phosphonium salt structure, Cl, whereas in non-polar solvents like diethyl ether it exists as a non-solvated trigonal bipyramidal molecule. Two species can also adopt an unusual dinuclear ionic structure—both interacting with a Cl via long Cl–Cl contacts.

Synthesis

Triphenylphosphine dichloride is usually prepared fresh by the addition of chlorine to triphenylphosphine.

Ph3P + Cl2 → Ph3PCl2

Both reagents are typically used in solution to ensure the correct stoichiometry.

Alternatively, Ph3PCl2 can be obtained by chlorination of triphenylphosphine oxide with, for example, phosphorus trichloride, as in Grignard's original 1931 synthesis.

References

  1. ^ V. Grignard, J. Savard (1931). Compt. Rend. 192: 592–5. {{cite journal}}: Missing or empty |title= (help)
  2. ^ e-EROS Encyclopedia of Reagents for Organic Synthesis, doi:10.1002/047084289X.rt371
  3. ^ S. M. Godfrey, C. A. McAuliffe, R. G. Pritchard, J. M. Sheffield (1996). "An X-ray crystallorgraphic study of the reagent Ph3PCl2; not charge-transfer, R3P–Cl–Cl, trigonal bipyramidal or Cl but an unusual dinuclear ionic species, Cl containing long Cl–Cl contacts". Chem. Commun. (22): 2521−2522. doi:10.1039/CC9960002521.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  4. S. M. Godfrey, C. A. McAuliffe, J. M. Sheffield (1998). "Structural dependence of the reagent Ph3PCl2 on the nature of the solvent, both in the solid state and in solution; X-ray crystal structure of trigonal bipyramidal Ph3PCl2, the first structurally characterised five-coordinate R3PCl2 compound". Chem. Commun. (8): 921−922. doi:10.1039/a800820e.{{cite journal}}: CS1 maint: multiple names: authors list (link)
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