Low melting sugar–urea–salt mixtures as solvents for organic reactions—estimation of polarity and use in catalysis
- 1 January 2006
- journal article
- Published by Royal Society of Chemistry (RSC) in Green Chemistry
- Vol. 8 (12), 1051-1055
- https://doi.org/10.1039/b603660k
Abstract
Mixtures of sugars, sugar alcohols or citric acid with urea and inorganic salts form stable melts if heated to 70 °C. The polarity of the melts was estimated using solvatochromic dyes and found to be in the range of DMF or water, depending on the sensitivity of the dye for hydrogen bonds. To explore the use of the melts as solvents in catalysis, Rh-catalyzed hydrogenations and Pd-catalyzed Suzuki reactions were performed. The hydrogenation of a double bond is sensitive to the composition of the melt, and no effect of the chiral melts on the stereochemical outcome of the reaction was observed. The Suzuki coupling proceeds rapidly, cleanly and quantitatively in all examined melts. The results recommend the non-toxic sugar–urea–salt melts as more sustainable reaction media for chemical transformations.Keywords
This publication has 35 references indexed in Scilit:
- Palladium-Catalyzed Suzuki Cross-Coupling Reactions in Ambient Temperature Ionic Liquids: Evidence for the Importance of Palladium Imidazolylidene ComplexesOrganometallics, 2003
- Rapid microwave-promoted Suzuki cross coupling reaction in waterGreen Chemistry, 2003
- Heterogeneously catalysed selective hydrogenation reactions in ionic liquidsGreen Chemistry, 2003
- Neoteric solvents for asymmetric hydrogenation: supercritical fluids, ionic liquids, and expanded ionic liquidsThis work was presented at the Green Solvents for Catalysis Meeting held in Bruchsal, Germany, 13–16th October 2002.Green Chemistry, 2003
- A Comparison of Ruthenium‐Catalysed Arene Hydrogenation Reactions in Water and 1‐Alkyl‐3‐methylimidazolium Tetrafluoroborate Ionic LiquidsAdvanced Synthesis & Catalysis, 2003
- Aryl−Aryl Bond Formation One Century after the Discovery of the Ullmann ReactionChemical Reviews, 2002
- Palladium-Catalyzed Cross-Coupling Reactions of Organoboron CompoundsChemical Reviews, 1995
- Solvatochromic Dyes as Solvent Polarity IndicatorsChemical Reviews, 1994
- The solvatochromic comparison method. I. The .beta.-scale of solvent hydrogen-bond acceptor (HBA) basicitiesJournal of the American Chemical Society, 1976
- Syntheses of complexes of rhodium (III)Journal of Inorganic and Nuclear Chemistry, 1966