Solvent effects on catalytic activity and selectivity in amine-catalyzed d-fructose isomerization

Journal of Catalysis, vol. 418, pp. 13–21

Abstract

Rational catalyst design and optimal solvent selection are key to advancing biorefining. Here, we explored the organocatalytic isomerization of d-fructose to a valuable rare monosaccharide, d-allulose, as a function of solvent. The isomerization of d-fructose to d-allulose competes with its isomerization to d-glucose and sugar degradation. In both water and DMF, the catalytic activity of amines towards d-fructose is correlated with their basicity. Solvents impact the selectivity significantly by altering the tautomeric distribution of d-fructose. Our results suggest that the furanose tautomer of d-fructose is isomerized to d-allulose, and the fractional abundance of this tautomer increases as follows: water < MeOH < DMF ≈ DMSO. Reaction rates are also higher in aprotic than in protic solvents. The best d-allulose yield, 14 %, was obtained in DMF with 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) as the catalyst. The reaction kinetics and mechanism were explored using operando NMR spectroscopy.

Authors 10

1. Peter Drabo Aachen Chair of Heterogeneous Catalysis and Chemical Technology Institute for Technical and Macromolecular Chemistry

   RWTH Aachen University

   Affiliation as printed

   Chair of Heterogeneous Catalysis and Chemical Technology, Institute for Technical and Macromolecular Chemistry, RWTH Aachen University, Worringerweg 2, 52074 Aachen, Germany

2. Matthias Fischer Aachen Chair of Heterogeneous Catalysis and Chemical Technology Institute for Technical and Macromolecular Chemistry

   RWTH Aachen University

   Affiliation as printed

   Chair of Heterogeneous Catalysis and Chemical Technology, Institute for Technical and Macromolecular Chemistry, RWTH Aachen University, Worringerweg 2, 52074 Aachen, Germany

3. Meike Emondts Aachen DWI - Leibniz Institute for Interactive Materials

   DWI – Leibniz Institute for Interactive Materials

   Affiliation as printed

   DWI – Leibniz Institute for Interactive Materials, Forckenbeckstr. 50, 52074 Aachen, Germany

4. Jegor Hamm Aachen Chair of Heterogeneous Catalysis and Chemical Technology Institute for Technical and Macromolecular Chemistry

   RWTH Aachen University

   Affiliation as printed

   Chair of Heterogeneous Catalysis and Chemical Technology, Institute for Technical and Macromolecular Chemistry, RWTH Aachen University, Worringerweg 2, 52074 Aachen, Germany

5. Mats Engelke Aachen Chair of Heterogeneous Catalysis and Chemical Technology Institute for Technical and Macromolecular Chemistry

   RWTH Aachen University

   Affiliation as printed

   Chair of Heterogeneous Catalysis and Chemical Technology, Institute for Technical and Macromolecular Chemistry, RWTH Aachen University, Worringerweg 2, 52074 Aachen, Germany

6. Marc Simonis Aachen Chair of Heterogeneous Catalysis and Chemical Technology Institute for Technical and Macromolecular Chemistry

   RWTH Aachen University

   Affiliation as printed

   Chair of Heterogeneous Catalysis and Chemical Technology, Institute for Technical and Macromolecular Chemistry, RWTH Aachen University, Worringerweg 2, 52074 Aachen, Germany

7. Long Hao Qi

   Iowa State University · Ames National Laboratory

   Affiliation as printed

   U.S. DOE, Ames Laboratory, Iowa State University, Ames, IA 50011, United States

8. Susannah L. Scott

   University of California, Santa Barbara

   Affiliation as printed

   Department of Chemical Engineering, University of California, Santa Barbara, CA 93106, United States

9. Regina Palkovits corresponding Aachen Chair of Heterogeneous Catalysis and Chemical Technology Institute for Technical and Macromolecular Chemistry

   RWTH Aachen University

   Affiliation as printed

   Chair of Heterogeneous Catalysis and Chemical Technology, Institute for Technical and Macromolecular Chemistry, RWTH Aachen University, Worringerweg 2, 52074 Aachen, Germany

10. Irina V. Delidovich corresponding

    TU Wien

    Affiliation as printed

    Institute of Chemical, Environmental and Bioscience Engineering, TU Wien, Getreidemarkt 9, 1060 Vienna, Austria