Synthesis of Micrometer-Sized Nanostructured Magnesium Oxide and Its High Catalytic Activity in the Claisen−Schmidt Condensation Reaction.

Micrometer-sized nanostructured flowerlike MgO nanostructures were synthesized by an ethylene-glycol-mediated self-assembly process. The synthesized samples were studied systematically by X-ray powder diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, Fourier-transform IR, and energy-dispersive X-ray analysis. The results show that the flowerlike MgO have uniform morphologies with an average diameter of 600 nm for micrometer-sized spheres and 16 nm for the ribbonlike nano building blocks. Compared to hierarchical structured cobalt oxide, a new morphology evolution process is observed for the MgO precursor, indicating a new kinetic control mechanism for morphology evolution. Because of its micrometer-sized nanostructure, the as-obtained MgO shows high catalytic activity, high stability, and easy recovery for the Claisen−Schmidt condensation between benzaldehyde and acetophenone.