Transesterification catalyzed by lanthanum complex grafted upon hydrotalcite as a macroligand

• Lanthanum species grafted upon the surface of hydrotalcite was prepared.
• La/HT showed good catalytic performance for transesterification.
• The catalyst was able to reusable.

Lanthanum species grafted upon hydrotalcite(HT) catalyzed transesterification of various esters in methanol solution. In this system, HT acted as a macroligand for lanthanum species through the complexation of the surface hydroxyl group of HT. HT-like compound containing La(III) in its brucite layer and simple La(III) salts showed low and/or no catalytic activity for the transesterification. The combined system of lanthanum ion and HT (La/HT) was important for demonstrating the catalytic activity. Moreover, the activity of the La/HT catalyst increased by treatment with aqueous alkaline but decreased by the reaction in anhydrous methanol. Since the hydrophilicity around the surface of La/HT was essential in the reaction for the catalytic activity, the substrate containing hydrophilic function was easily transformed. The structure of the active La/HT catalyst generated upon the HT surface might be a dinuclear lanthanum complex having aqua and hydroxo ligands, which acted as general acid and base, respectively. This catalyst was able to reuse by handling with slightly alkaline water.

Lanthanum species grafted upon hydrotalcite (La/HT) has been prepared as catalyst for transesterification of esters in methanol. It showed good catalytic performance and was able to reuse by handling with slight alkaline water.Figure optionsDownload as PowerPoint slide