Theoretical investigation for isomerization of allylic alcohols over Au6 cluster

Abstract

Transformation of allylic alcohols to corresponding saturated carbonyl compounds is one of the important reactions for industrial processes. Lately, Au-supported catalysts exhibit the catalytic activity for the isomerization of allylic alcohols to saturated aldehydes. However, the detail catalytic mechanism of this reaction was not elucidated in detail. Thus, theoretical calculations were carried out for the isomerization of 2-hexen-1-ol over isolated Au 6 cluster in order to elucidate the reaction over Au catalysts. From these calculation results, it was found that the rate determining step of the reaction process was the hydrogen elimination from OH group of allylic alcohol, and the substrate was converted to 1-hexen-1-ol on Au 6 cluster. Finally, it was also confirmed that 1-hexen-1ol was converted to the corresponding aldehyde, and its activation barrier was much smaller than that of the deprotonation from OH group of allylic alcohol.

Advances in Gold Catalysis and Understanding the Catalytic Mechanism

“…This is ascribed to minimizing the size of Au particles from 2.5 nm on NiO to 0.9 nm on La–NiO, according to XAFS analysis. A DFT calculation using a Au 6 cluster suggested that the β‐hydride elimination at the C‐1 position and the hydrogen transfer to the C‐3 position would easily occur on the Au 6 cluster with low activation energies 92. The first deprotonation of the alcohol was found to have the highest activation energy, meaning that the deprotonation is the rate‐determining step.…”