Appel reaction

What is Appel reaction?

The Lee et al. first reported the Appel reaction in 1966, building upon the earlier work of Horner et al. in 1959, which involved the halogenation of alcohol using triarylphosphine dihalides. The Appel reaction is a chemical transformation that converts primary and secondary alcohols into their corresponding chlorides, with a noteworthy preference for inversion of the configuration.

Appel reaction - Appel reagent - Appel agent
Appel reaction
  • R = aryl, alkyl
  • R’ = aryl, alkyl, H

This reaction has been thoroughly reviewed by Appel and is commonly referred to as the Appel reaction. Additionally, the combination of triphenylphosphine and carbon tetrachloride is recognized as the Appel reagent or Appel agent.


  • Downie, J. M.; Holmes, J. B. and Lee, J. B., Chem. Ind., 1966, 22, 900-901.
  • Preparation of Acyl Halides under Very Mild Conditions
    John B. Lee
    Journal of the American Chemical Society 1966 88 (14), 3440-3441
    DOI: 10.1021/ja00966a052
  • Horner, L., Oediger, H. and Hoffmann, H. (1959), Phosphororganische Verbindungen, XVII Reaktionen mit Triphenylphosphin-dihalogeniden Über den Reaktionsverlauf der Halogenübertragung und Wasserabspaltung mit Phosphorhalogeniden. [Organophosphorus compounds, XVII Reactions with triphenylphosphine dihalides On the reaction course of halogen transfer and water splitting with phosphorus halides.] Justus Liebigs Ann. Chem., 626: 26-34.
  • Appel, R. (1975), Tertiary Phosphane/Tetrachloromethane, a Versatile Reagent for Chlorination, Dehydration, and PN Linkage. Angew. Chem. Int. Ed. Engl., 14: 801-811.