Unexpected chemoselectivity in the rhodium-catalyzed transfer hydrogenation of α,β-unsaturated ketones in ionic liquids

Zoltán Baán, Zoltán Finta, G. Keglevich, I. Hermecz

Research output: Contribution to journalArticle

46 Citations (Scopus)

Abstract

Chalcone and some other α,β-unsaturated ketones were subjected to transfer hydrogenation catalyzed by the dimer [Rh(cod)Cl]2 and the Wilkinson's catalyst in imidazolium-, ammonium- and phosphonium-based ionic liquids. In certain ionic liquids, the reduction of chalcone gave 1,3-diphenylpropan-1-one chemoselectively, in contrast with molecular solvents, which resulted in the formation of 1,3-diphenylpropan-1-ol. An accelerated reaction rate was observed in [emim][BuSO4] and [emin][HeSO 4]. The observed chemoselectivity could be maintained applying a 5 molar equivalent excess of [bmim][BF4] to chalcone in 2-PrOH. This phenomenon suggests that there is an interaction between the chalcone carbonyl group and the ionic liquid which prevents reduction of the carbonyl group. The catalyst [Rh(cod)Cl]2 dissolved in an ionic liquid was successfully recycled at least three times, in contrast with Wilkinson's catalyst, which lost its activity on recycling.

Original languageEnglish
Pages (from-to)1937-1940
Number of pages4
JournalGreen Chemistry
Volume11
Issue number12
DOIs
Publication statusPublished - 2009

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Chalcone
Ionic Liquids
rhodium
Rhodium
ketone
Ketones
Ionic liquids
Hydrogenation
catalyst
Catalysts
Ammonium Compounds
Dimers
reaction rate
Reaction rates
Recycling
ammonium
recycling
ionic liquid

ASJC Scopus subject areas

  • Environmental Chemistry
  • Pollution

Cite this

Unexpected chemoselectivity in the rhodium-catalyzed transfer hydrogenation of α,β-unsaturated ketones in ionic liquids. / Baán, Zoltán; Finta, Zoltán; Keglevich, G.; Hermecz, I.

In: Green Chemistry, Vol. 11, No. 12, 2009, p. 1937-1940.

Research output: Contribution to journalArticle

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AU - Hermecz, I.

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N2 - Chalcone and some other α,β-unsaturated ketones were subjected to transfer hydrogenation catalyzed by the dimer [Rh(cod)Cl]2 and the Wilkinson's catalyst in imidazolium-, ammonium- and phosphonium-based ionic liquids. In certain ionic liquids, the reduction of chalcone gave 1,3-diphenylpropan-1-one chemoselectively, in contrast with molecular solvents, which resulted in the formation of 1,3-diphenylpropan-1-ol. An accelerated reaction rate was observed in [emim][BuSO4] and [emin][HeSO 4]. The observed chemoselectivity could be maintained applying a 5 molar equivalent excess of [bmim][BF4] to chalcone in 2-PrOH. This phenomenon suggests that there is an interaction between the chalcone carbonyl group and the ionic liquid which prevents reduction of the carbonyl group. The catalyst [Rh(cod)Cl]2 dissolved in an ionic liquid was successfully recycled at least three times, in contrast with Wilkinson's catalyst, which lost its activity on recycling.

AB - Chalcone and some other α,β-unsaturated ketones were subjected to transfer hydrogenation catalyzed by the dimer [Rh(cod)Cl]2 and the Wilkinson's catalyst in imidazolium-, ammonium- and phosphonium-based ionic liquids. In certain ionic liquids, the reduction of chalcone gave 1,3-diphenylpropan-1-one chemoselectively, in contrast with molecular solvents, which resulted in the formation of 1,3-diphenylpropan-1-ol. An accelerated reaction rate was observed in [emim][BuSO4] and [emin][HeSO 4]. The observed chemoselectivity could be maintained applying a 5 molar equivalent excess of [bmim][BF4] to chalcone in 2-PrOH. This phenomenon suggests that there is an interaction between the chalcone carbonyl group and the ionic liquid which prevents reduction of the carbonyl group. The catalyst [Rh(cod)Cl]2 dissolved in an ionic liquid was successfully recycled at least three times, in contrast with Wilkinson's catalyst, which lost its activity on recycling.

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