Li–Al layered double hydroxides as catalysts for the synthesis of flavanone
Flavanone was synthesized via a series reaction scheme involving the Claisen–Schmidt condensation between 2′-hydroxyacetophenone and benzaldehyde to form 2′-hydroxychalcone and the subsequent isomerization of 2′-hydroxychalcone to flavanone. Reactions were carried out in the presence of Li–Al layered double hydroxide solid catalyst. The results showed that surface basicity varies with calcination temperature and rehydration. These variations in basicity correlate with the observed catalytic behavior. It is believed that Li+–O2− groups contribute to the surface basicity and are instrumental in the abstraction of a proton from the 2′-hydroxyacetophenone in what is believed to be the first step in the reaction mechanism.
Graphical AbstractFigure optionsDownload full-size imageDownload as PowerPoint slideResearch Highlights► Li–Al layered double hydroxide is active for the synthesis of flavanone. ► There is an increase in basic sites upon rehydration, likely caused by hydroxylation of the surface. ► Li+–O2− groups are believed to be present on calcined layered double hydroxides and contribute to increased basicity. ► Catalytic activity correlates with surface basicity. ► Li+–O2− groups are believed to be instrumental in the abstraction of a proton from 2′-hydroxyacetophenone, which is likely the first step in the reaction mechanism.
Journal: Catalysis Communications - Volume 12, Issue 2, 15 November 2010, Pages 92–94