Hösch reaction

The Hösch reaction (also known as the Hoesch reaction or Houben-Hoesch reaction) is an organic reaction in which a nitrile reacts with an arene compound to form a aryl ketone. the reaction is a type of Friedel-Crafts acylation with hydrochloric acid and a Lewis acid catalyst.

An example is the synthesis of  1-(2,4, 6-Trihydroxyphenyl)ethanone from phloroglucinol :


 * [[Image:Houben-Hoesch reaction.svg|Houben-Hoesch reaction]]

A ketimine is isolated as an intermediate reaction product. The attacking electrophile is possibly a species of the type R-C+=NHCl-. The arene must be electron-rich i.e. phenol or aniline type. A related reaction is the Gattermann reaction in which hydrocyanic acid not a nitrile is used.

The reaction is named after Kurt Hoesch and J. Houben who reported about this new reaction type in respectively 1915 and 1926.