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Effects of Alkali-Metal Ions and Counter Ions in Sn-Beta-Catalyzed Carbohydrate Conversion.

Samuel G ElliotSøren TolborgRobert MadsenEsben TaarningSebastian Meier
Published in: ChemSusChem (2018)
Alkali-metal ions have recently been shown to strongly influence the catalytic behavior of stannosilicates in the conversion of carbohydrates. An effect of having alkali-metal ions present is a pronounced increase in selectivity towards methyl lactate. Mechanistic details of this effect have remained obscure and are herein addressed experimentally through kinetic experiments and isotope tracking. The presence of alkali-metal ions has a differential effect in competing reaction pathways and promotes the rate of carbon-carbon bond breakage of carbohydrate substrates, but decreases the rates of competing dehydration pathways. Further addition of alkali-metal ions inhibits the activity of Sn-Beta in all major reaction pathways. The alkali-metal effects on product distribution and on the rate of product formation are similar, thus pointing to a kinetic reaction control and to irreversible reaction steps in the main pathways. Additionally, an effect of the accompanying basic anions is shown, supposedly facilitating the cation exchange and eliciting a different concentration-dependent effect to that of neutral alkali-metal salts.
Keyphrases
  • quantum dots
  • aqueous solution
  • ionic liquid
  • water soluble
  • simultaneous determination
  • liquid chromatography
  • tandem mass spectrometry