(Chloromethylene)triphenylphosphorane

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| ImageFile = Ph3P=CHCl.svg

| ImageSize = 110 px

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| Name = (Chloromethylene)triphenyl{{SHY}}phosphorane

| PIN = (Chloromethylidene)tri(phenyl)-λ⁵-phosphane

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|Section1={{Chembox Identifiers

| CASNo = 29949-92-6

| ChemSpiderID = 366640

| PubChem = 414080

| StdInChI=1S/C19H16ClP/c20-16-21(17-10-4-1-5-11-17,18-12-6-2-7-13-18)19-14-8-3-9-15-19/h1-16H

| StdInChIKey = KIZBYQRDCHVQID-UHFFFAOYSA-N

| SMILES = C1=CC=C(C=C1)P(=CCl)(C2=CC=CC=C2)C3=CC=CC=C3

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|Section2={{Chembox Properties

| C = 19|H=16|P=1|Cl=1

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| Appearance = white solid

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|Section3={{Chembox Hazards

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(Chloromethylene)triphenylphosphorane is the organophosphorus compound with the formula Ph₃P=CHCl (Ph = phenyl). It is a white solid but is usually generated and used in situ as a reagent in organic synthesis. It is structurally and chemically related to methylenetriphenylphosphorane.

The reagent is prepared from the chloromethylphosphonium salt [Ph₃PCH₂Cl]Cl by treatment with strong base. The phosphonium compound is generated by treatment of triphenylphosphine with chloroiodomethane.{{cite journal |doi=10.1002/anie.197701801|title=(Chloromethylene)triphenylphosphorane|year=1977|last1=Appel|first1=Rolf|last2=Morbach|first2=Wolfgang|journal=Angewandte Chemie International Edition in English|volume=16|issue=3|pages=180–181}}

(Chloromethylene)triphenylphosphorane converts aldehydes to vinyl chlorides:

:RCHO + Ph₃P=CHCl → RCH=CHCl + Ph₃PO

These vinyl chlorides undergo dehydrochlorination to give alkynes:{{cite book |doi=10.1002/047084289X.rc134|chapter=Chloromethyltriphenylphosphonium Chloride|title=Encyclopedia of Reagents for Organic Synthesis|year=2001|last1=Marth|first1=Charles F.|isbn=0471936235}}

:RCH=CHCl + NaN(SiMe₃)₂ → RC≡CH + NaCl + HN(SiMe₃)₂