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Title: Solvent effects on catalytic activity and selectivity in amine-catalyzed d-fructose isomerization
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.  more » « less
Award ID(s):
1805129
PAR ID:
10486454
Author(s) / Creator(s):
; ; ; ; ; ; ; ; ;
Publisher / Repository:
Elsevier
Date Published:
Journal Name:
Journal of Catalysis
Volume:
418
ISSN:
0021-9517
Page Range / eLocation ID:
13-21
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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