1 research outputs found
Organocatalytic Dehydration of Fructose-Based Carbohydrates into 5‑Hydroxymethylfurfural in the Presence of a Neutral Inner Salt
A series of organic
sulfonate inner salts, viz., aprotic imidazolium-
and pyridinium-based zwitterions bearing sulfonate
groups (−SO3–), were synthesized
for the catalytic conversion of fructose-based carbohydrates into
5-hydroxymethylfurfural (HMF). The dramatic cooperation of both the
cation and anion of inner salts played a crucial role in the HMF formation.
The inner salts have excellent solvent compatibility, and 4-(pyridinium)butane
sulfonate (PyBS) affords the highest catalytic activity with 88.2
and 95.1% HMF yields at almost full conversion of fructose in low-boiling-point
protic solvent isopropanol (i-PrOH) and aprotic solvent
dimethyl sulfoxide (DMSO), respectively. The substrate tolerance of
aprotic inner salt was also studied through changing the substrate
type, demonstrating its excellent specificity for catalytic valorization
of fructose-moiety-containing C6 sugars, such as sucrose and inulin.
Meanwhile, the neutral inner salt is structurally stable and reusable;
after being recycled four times, the catalyst showed no appreciable
loss of its catalytic activity. The plausible mechanism has been elucidated
based on the dramatic cooperative effect of both the cation and sulfonate
anion of inner salts. The noncorrosive, nonvolatile, and generally
nonhazardous aprotic inner salt used in this study will benefit many
biochemical-related applications