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Mechanism of Brønsted Acid‐Catalyzed Glucose Dehydration
Author(s) -
Yang Liu,
Tsilomelekis George,
Caratzoulas Stavros,
Vlachos Dionisios G.
Publication year - 2015
Publication title -
chemsuschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.412
H-Index - 157
eISSN - 1864-564X
pISSN - 1864-5631
DOI - 10.1002/cssc.201403264
Subject(s) - chemistry , formic acid , levulinic acid , catalysis , protonation , reaction mechanism , dehydration reaction , rate determining step , brønsted–lowry acid–base theory , nuclear magnetic resonance spectroscopy , organic chemistry , photochemistry , ion
We present the first DFT‐based microkinetic model for the Brønsted acid‐catalyzed conversion of glucose to 5‐hydroxylmethylfurfural (HMF), levulinic acid (LA), and formic acid (FA) and perform kinetic and isotopic tracing NMR spectroscopy mainly at low conversions. We reveal that glucose dehydrates through a cyclic path. Our modeling results are in excellent agreement with kinetic data and indicate that the rate‐limiting step is the first dehydration of protonated glucose and that the majority of glucose is consumed through the HMF intermediate. We introduce a combination of 1) automatic mechanism generation with isotopic tracing experiments and 2) elementary reaction flux analysis of important paths with NMR spectroscopy and kinetic experiments to assess mechanisms. We find that the excess formic acid, which appears at high temperatures and glucose conversions, originates from retro‐aldol chemistry that involves the C6 carbon atom of glucose.