Triphenylphosphine dichloride

Triphenylphosphine dichloride
Ball-and-stick model	Space-filling model
Names
	Preferred IUPAC name Dichlorotri(phenyl)-λ5-phosphane
	Other names Dichlorotriphenylphosphorane
Identifiers
CAS Number	2526-64-9 ;
3D model (JSmol)	Interactive image;
ChemSpider	228579 ;
ECHA InfoCard	100.107.819
PubChem CID	260420;
UNII	6CL2293LZ3 ;
CompTox Dashboard (EPA)	DTXSID50293708 ;
	InChI InChI=1S/C18H15Cl2P/c19-21(20,16-10-4-1-5-11-16,17-12-6-2-7-13-17)18-14-8-3-9-15-18/h1-15H Key: ASWXNYNXAOQCCD-UHFFFAOYSA-N ;
	SMILES ClP(Cl)(c1ccccc1)(c1ccccc1)c1ccccc1;
Properties
Chemical formula	C18H15Cl2P
Molar mass	333.19 g/mol
Melting point	176 °C (349 °F; 449 K) 85-100 °C
Solubility in water	Reacts
Related compounds
Related compounds	Phosphoranes; Triphenylphosphine; Phosphorus trichloride; Phosphorus pentachloride; Phosphorus halides; Tetraphenylphosphonium chloride
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Triphenylphosphine dichloride, (C₆H₅)₃PCl₂, 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.^[2]

Structure

In polar solvents such as acetonitrile, Ph₃PCl₂ adopts an ionic phosphonium salt structure, [Ph₃PCl⁺]Cl⁻,^[3] whereas in non-polar solvents like diethyl ether it exists as a non-solvated trigonal bipyramidal molecule.^[4] Two [Ph₃PCl⁺] species can also adopt an unusual dinuclear ionic structure—both interacting with a Cl⁻ via long Cl–Cl contacts.^[3]

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.^[2]

Ph₃PCl₂ can also be obtained by the reaction of iodobenzene dichloride (PhICl₂) and triphenylphosphine.^[5]

Alternatively, Ph₃PCl₂ can be obtained by chlorination of triphenylphosphine oxide with, for example, phosphorus trichloride, as in Grignard's original 1931 synthesis.^[1]

References

^ ^a ^b Victor Grignard, J. Savard (1931). Comptes rendus de l'Académie des sciences. 192: 592–5. {{cite journal}}: Missing or empty |title= (help)
^ ^a ^b ^c e-EROS Encyclopedia of Reagents for Organic Synthesis, doi:10.1002/047084289X.rt371
^ ^a ^b 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 [R3PCl]Cl but an unusual dinuclear ionic species, [Ph3PCl+⋯Cl–⋯+CIPPH3]Cl containing long Cl–Cl contacts". Chemical Communications (22): 2521–2522. doi:10.1039/CC9960002521.
^ 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.
^ Carle, M. S., Shimokura, G. K. and Murphy, G. K. (2016), Iodobenzene Dichloride in the Esterification and Amidation of Carboxylic Acids: In-Situ Synthesis of Ph3PCl2. Eur. J. Org. Chem., 2016: 3930–3933. {{DOI:10.1002/ejoc.201600714}}

[Grignard-1] Victor Grignard, J. Savard (1931). Comptes rendus de l'Académie des sciences. 192: 592–5. {{cite journal}}: Missing or empty |title= (help)

[e-EROS-2] -EROS Encyclopedia of Reagents for Organic Synthesis, doi:10.1002/047084289X.rt371

[Godfrey_1996-3] 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 [R3PCl]Cl but an unusual dinuclear ionic species, [Ph3PCl+⋯Cl–⋯+CIPPH3]Cl containing long Cl–Cl contacts". Chemical Communications (22): 2521–2522. doi:10.1039/CC9960002521.

[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.

[5] Carle, M. S., Shimokura, G. K. and Murphy, G. K. (2016), Iodobenzene Dichloride in the Esterification and Amidation of Carboxylic Acids: In-Situ Synthesis of Ph3PCl2. Eur. J. Org. Chem., 2016: 3930–3933. {{DOI:10.1002/ejoc.201600714}}

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