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 [Organic Syntheses, Coll. Vol. 2, p.522 (1943); Vol. 15, p.70 (1935). http://www.orgsynth.org/orgsyn/pdfs/CV2P0522.pdf] :

: A ketimine is isolated as an intermediate reaction product. The attacking electrophile is possibly [JerryMarch] 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 ["Eine neue Synthese aromatischer Ketone. I. Darstellung einiger Phenol-ketone" Berichte der deutschen chemischen Gesellschaft Volume 48, Issue 1, Date: Januar-Juni 1915, Pages: 1122-1133 Kurt Hoesch DOI|10.1002/cber.191504801156] and J. Houben ["Über die Kern-Kondensation von Phenolen und Phenol-äthern mit Nitrilen zu Phenol- und Phenol-äther-Ketimiden und -Ketonen (I.)" Berichte der deutschen chemischen Gesellschaft (A and B Series) Volume 59, Issue 11, Date: 8. Dezember 1926, Pages: 2878-2891 J. Houben DOI|10.1002/cber.19260591135] who reported about this new reaction type in respectively 1915 and 1926.

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