(Chloromethylene)triphenylphosphorane

(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.

(Chloromethylene)triphenylphosphorane converts aldehydes to vinyl chlorides:
 * RCHO +  Ph3P=CHCl  →  RCH=CHCl  +  Ph3PO

These vinyl chlorides undergo dehydrochlorination to give alkynes:
 * RCH=CHCl +  NaN(SiMe3)2  →  RC≡CH  +  NaCl  +  HN(SiMe3)2

Related compounds

 * (Iodomethylene)triphenylphosphorane
 * (Dichloromethylene)triphenylphosphorane