Imidazolium ionic liquids as solvents for cerium(IV)-mediated oxidation reactions

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journal

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Author(s)

  • Hasan Mehdi
  • Andrea Bodor
  • Diána Lantos
  • Dirk E. De Vos
  • Koen Binnemans

Detail(s)

Original languageEnglish
Pages (from-to)517-524
Journal / PublicationJournal of Organic Chemistry
Volume72
Issue number2
Publication statusPublished - 19 Jan 2007
Externally publishedYes

Abstract

Use of imidazolium ionic liquids as solvents for organic transformations with tetravalent cerium salts as oxidizing agents was evaluated. Good solubility was found for ammonium hexanitratocerate(IV) (ceric ammonium nitrate, CAN) and cerium(IV) triflate in 1-alkyl-3-methylimidazolium triflate ionic liquids. Oxidation of benzyl alcohol to benzaldehyde in 1-ethyl-3-methylimidazolium triflate was studied by in-situ FTIR spectroscopy and 13C NMR spectroscopy on carbon-13-labeled benzyl alcohol. Careful control of the reaction conditions is necessary because ammonium hexanitratocerate(IV) dissolved in an ionic liquid can transform benzyl alcohol not only into benzaldehyde but also into benzyl nitrate or benzoic acid. The selectivity of the reaction of cerium(IV) triflate with benzyl alcohol in dry ionic liquids depends on the degree of hydration of cerium(IV) triflate: anhydrous cerium(IV) triflate transforms benzyl alcohol into dibenzyl ether, whereas hydrated cerium(IV) triflate affords benzaldehyde as the main reaction product. Reactions of ammonium hexanitratocerate(IV) with organic substrates other than benzyl alcohol have been explored. 1,4-Hydroquinone is quantitatively transformed into 1,4-quinone. Anisole and naphthalene are nitrated. For the cerium-mediated oxidation reactions in ionic liquids, high reaction temperatures are an advantage because under these conditions smaller amounts of byproducts are formed. © 2007 American Chemical Society.

Citation Format(s)

Imidazolium ionic liquids as solvents for cerium(IV)-mediated oxidation reactions. / Mehdi, Hasan; Bodor, Andrea; Lantos, Diána; Horváth, István T.; De Vos, Dirk E.; Binnemans, Koen.

In: Journal of Organic Chemistry, Vol. 72, No. 2, 19.01.2007, p. 517-524.

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journal