A combined experimental and computational study of the mechanism of fructose dehydration to 5-hydroxymethylfurfural in dimethylsulfoxide using Amberlyst 70, PO43−/niobic acid, or sulfuric acid catalysts

We report on a combined experimental and theoretical study of the acid catalyzed dehydration of D-fructose in dimethylsulfoxide using; Amberlyst 70, PO43-/niobic acid, and sulfuric acid as catalysts

Jing Zhang; Anirban Das; Rajeev S. Assary; Larry A. Curtiss; Eric Weitz

2014

Scholarcy highlights

  • Occurring, abundant and accessible carbohydrates are viewed as promising and underexploited "green" and renewable resources which can be used to produce chemical feedstocks and liquid transportation fuels
  • Amberlyst 70 and PO43-/niobic acid as well as a homogeneous catalystsulfuric acid - were used in this study
  • Peaks at m/z of 145.0494, 163.0600, and 185.0420, were observed for the reacting system, and were not observed in the ESI-MS of the control sample. These results indicate that the above three mass peaks originate from three species produced during the acid catalyzed fructose dehydration reaction taking place in DMSO
  • A third species that is capable of keto-enol tautomerism 2-(hydroxymethyl)-5-(hydroxylmethylene)-tetrahydrofuran-3,4-diol and 4-Dihydroxy-5-hydroxymethyl-tetrahydro-furan-2-carbaldehyde was identified by theory and experimentally by MS; experimentally it was not possible in this study to distinguish between the keto and the enol forms
  • We report preliminary kinetic data, using Nuclear magnetic resonance spectroscopy that is consistent with the proposed intermediates
  • Materials-D-fructose, DMSO-d6, D2O, H2O17, phosphoric acid, 5-hydroxymethylfurfural, sulfuric acid, and biphenyl were obtained from Sigma–Aldrich and used without further purification
  • We observe the same intermediates along the reaction pathway to HMF when using PO43-/niobic acid, which has both Lewis acid and Brønsted acid sites. These results are consistent with there being a common mechanism for the acid catalyzed triple dehydration of fructose to produce HMF and, at least for the systems studied; this mechanism appears to be independent of the source of protons
  • In presence of oxygen, DMSO can decompose at moderate temperatures to produce acidic species that catalyze the dehydration fructose rationalizing the claim in the literature that DMSO can act as a catalyst for the fructose dehydration reaction

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