Reaction of chloropyridazin-3(2H)-ones with iodide ion. Part II

László Károlyházy, Gábor Krajsovszky, Lajos Farkas, Sándor Boros, Antal Csámpai, Péter Mátyusa

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The reactions of 5-chloro-6-phenyl-,4,5-dichloro-6-phenyl- and 5-chloro-6-(2,4-dichlorophenyl)-2-methylpyridazin-3(2H)-ones with 57% aqueous hydrogen iodide or sodium iodide in dimethyl formamide, respectively, are described. Upon treatment of chloro compounds with 57% hydrogen iodide, besides nucleophilic substitution of chloro- by iodo substituent, subsequent hydrodeiodination also occurred. Thus, e.g. 4,5-dichloro-2-methyl-6- phenylpyridazin-3(2H)-one gave first 5-chloro-4-iodo-2-methyl-6-phenylpyridazin- 3(2H)-one and in the next step, 5-chloro-2-methyl-6-phenylpyridazin-3(2H)-one. Similarly, treatment of 5-chloro-2-methyl-6-phenylpyridazin-3(2H)-one led to the formation of 5-iodo-2-methyl-6-phenylpyridazin-3(2H)-one and 2-methyl-6-phenylpyridazin-3(2H)-one. The structure of each new product was proved by 1H, 13C and partly by 15N NMR spectroscopy.

Original languageEnglish
Article number36991
Issue number2
Publication statusPublished - Nov 29 2010



  • 6-Phenyl-halopyridazin-3(2H)-ones
  • Dehalogenation
  • Nucleophilic substitution
  • Regiochemistry

ASJC Scopus subject areas

  • Organic Chemistry

Cite this

Károlyházy, L., Krajsovszky, G., Farkas, L., Boros, S., Csámpai, A., & Mátyusa, P. (2010). Reaction of chloropyridazin-3(2H)-ones with iodide ion. Part II. Arkivoc, 2011(2), [36991].