triphenylphosphine dichloride
{{chembox
| Verifiedfields = changed
| Watchedfields = changed
| verifiedrevid = 430032953
| Name = Triphenylphosphine dichloride
| ImageFile = Dichlorotriphenylphosphine-2D.png
| ImageSize = 150px
| ImageName = Structural formula
| ImageFileL1 = Dichlorotriphenylphosphine-molecular-from-xtal-1998-3D-balls.png
| ImageNameL1 = Ball-and-stick model
| ImageFileR1 = Dichlorotriphenylphosphine-molecular-from-xtal-1998-3D-vdW.png
| ImageNameR1 = Space-filling model
| PIN = Dichlorotri(phenyl)-λ5-phosphane
| OtherNames =Dichlorotriphenylphosphorane
|Section1={{Chembox Identifiers
| CASNo = 2526-64-9
| CASNo_Ref = {{cascite|correct|CAS}}
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = 6CL2293LZ3
| PubChem = 260420
| ChemSpiderID_Ref = {{chemspidercite|changed|chemspider}}
| ChemSpiderID = 228579
| SMILES = ClP(Cl)(c1ccccc1)(c1ccccc1)c1ccccc1
| StdInChI_Ref = {{stdinchicite|changed|chemspider}}
| StdInChI = 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
| StdInChIKey_Ref = {{stdinchicite|changed|chemspider}}
| StdInChIKey = ASWXNYNXAOQCCD-UHFFFAOYSA-N
}}
|Section2={{Chembox Properties
| Formula = {{chem2|(C6H5)3PCl2}}
| C=18|H=15|Cl=2|P=1
| Appearance = Colorless solid
| Solubility = Reacts
| MeltingPtC = 176
| MeltingPt_ref =,{{cite journal | author = Victor Grignard, J. Savard | journal = Comptes rendus de l'Académie des sciences | year = 1931 | volume = 192 | pages = 592–5}} 85-100 °C,e-EROS Encyclopedia of Reagents for Organic Synthesis, {{doi|10.1002/047084289X.rt371}} 85 °C (decomposes)https://www.sigmaaldrich.com/GB/en/sds/aldrich/378755?userType=anonymous
}}
| Section7 = {{Chembox Hazards
| LD50 =
| LC50 =
| MainHazards = May cause severe skin and eye injury and cancer. If the chemical is let to enter the drains, there is a risk of explosion.
| GHSPictograms = {{GHS02}}{{GHS05}}{{GHS08}}
| GHSSignalWord = Danger
| HPhrases = {{H-phrases|H228|H314|H350}}
| PPhrases = {{P-phrases|P210|P240|P241|P260|P264|P280|P301+P330+P331|P302+P361+P354|P304+P340|P305+P354+P338|P316|P321|P363|P370+P378|P405|P501}}
}}
|Section8={{Chembox Related
| OtherCompounds = {{ubl|Phosphoranes|Triphenylphosphine|Phosphorus trichloride|Phosphorus pentachloride|Phosphorus halides|Tetraphenylphosphonium chloride}}
}}
}}
Triphenylphosphine dichloride is an organophosphorus compound with the chemical formula {{chem2|(C6H5)3PCl2}}, often abbreviated as {{chem2|Ph3PCl2}}, where Ph is phenyl. It 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, {{chem2|Ph3PCl2}} adopts an ionic phosphonium salt structure, {{chem2|[Ph3PCl]+Cl-}} (chlorotriphenylphosphonium chloride),{{cite journal | journal = Chemical Communications | year = 1996 | pages = 2521–2522 | doi = 10.1039/CC9960002521 |author1=S. M. Godfrey |author2=C. A. McAuliffe |author3=R. G. Pritchard |author4=J. M. Sheffield | title = 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 | issue = 22}} whereas in non-polar solvents like diethyl ether it exists as a non-solvated trigonal bipyramidal molecule.{{cite journal | journal = Chem. Commun. | year = 1998 | pages = 921–922 | doi = 10.1039/a800820e |author1=S. M. Godfrey |author2=C. A. McAuliffe |author3=J. M. Sheffield | title = 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 | issue = 8}} Two {{chem2|[Ph3PCl]+}} species can also adopt an unusual dinuclear ionic structure—both interacting with a {{chem2|Cl-}} via long Cl–Cl contacts.
File:Chlorotriphenylphosphonium-chloride-2D.png
File:Chlorotriphenylphosphonium-chloride-DCM-solvate-from-xtal-3D-balls.png
File:Chlorotriphenylphosphonium-chloride-DCM-solvate-from-xtal-3D-vdW.png
Synthesis
Triphenylphosphine dichloride is usually prepared fresh by the addition of chlorine to triphenylphosphine.
:{{chem2|Ph3P + Cl2 → Ph3PCl2}}
Both reagents are typically used in solution to ensure the correct stoichiometry.
{{chem2|Ph3PCl2}} can also be obtained by the reaction of iodobenzene dichloride ({{chem2|PhICl2}}) and triphenylphosphine.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}}
Alternatively, {{chem2|Ph3PCl2}} can be obtained by chlorination of triphenylphosphine oxide with, for example, phosphorus trichloride, as in Grignard's original 1931 synthesis.