Nano-structured Magnesium Oxide as Efficient Recyclable Catalyst for Knoevenagel and Claisen-Schmidt Condensation Reactions

Nano-structured magnesium oxide was prepared by calcining its hydromagnesite phase, obtained by simple precipitation using magnesium acetate and ammonium carbonate under ambient condition. This MgO was used as active and reusable catalyst for the Knoevenagel condensation of aromatic aldehydes with malononitrile and ethylcyanoacetate under solvent-free conditions at room temperature. It also exhibits strong activity in solvent-free base catalyzed Claisen-Schmidt condensation of various substituted benzaldehydes with acetophenone. The basic sites of different strengths like surface hydroxyl groups, and low coordination O2- sites may be responsible for the above catalytic activity. The experimental results showed that the nano-MgO has high catalytic activity and can be recycled without significant loss of its activity.