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
