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Unravelling the Mechanism of the Ru/C‐Catalysed Isohexide and Ether Isomerization by Hydrogen Isotope Exchange
Author(s) -
Engel Rebecca V.,
Niemeier Johannes,
Fink Anja,
Rose Marcus
Publication year - 2018
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.201800058
Subject(s) - chemistry , isomerization , dehydrogenation , hydride , catalysis , ether , kinetic isotope effect , hydrogen , photochemistry , reaction mechanism , isotopic labeling , medicinal chemistry , organic chemistry , deuterium , physics , quantum mechanics
In this article we show that the catalytic isomerization of isohexide sugar alcohols as well as their respective ethers can occur by a hydride‐based mechanism rather than a dehydrogenation/re‐hydrogenation. C−H bonds in α‐position to hydroxy and ether groups are activated using Ru/C as solid catalyst at temperatures as high as 160 °C and above. Hydrogen isotope exchange experiments proved that a full hydride exchange and isomerization is possible for isohexides but unexpectedly also for their methyl ethers. This is of great importance as it proves the co‐existence of the both mechanisms for reactions that were so far assumed to occur solely by a dehydrogenation/re‐hydrogenation. Hence, this co‐existence should be taken into account for kinetic investigations of such reaction systems especially in the conversion of biomass‐based chemicals under hydrogenation conditions.