Arezoo Beirangi - Department of Chemistry, Karaj Branch, Islamic Azad University, Karaj, Iran
Somayeh Soleimani-Amiri - Department of Chemistry, Karaj Branch, Islamic Azad University, Karaj, Iran
Behrooz Mirza - Department of Chemistry, Karaj Branch, Islamic Azad University, Karaj, Iran

The iron-based magnetic nano-particles (Fe3O4@C-ONa) were synthesized as an efficient, available, environmentally friendly and recyclable catalyst and characterized by FT-IR, XRD, SEM, and VSM techniques. Then, the synthesized magnetic nanoparticles were applied as a heterogeneous and green catalyst in Knoevenagel condensation between meldrum's acid and salicylaldehyde derivatives in water as a green solvent for the synthesis of coumarin-3-carboxylicacid derivatives. In order to achieve the best conditions, the desired reaction was investigated at various temperatures,diverse solvents, and different amounts of the catalyst, under ultrasonic radiation as well as without ultrasonic radiations.The reaction in presence of Fe3O4@C-ONa (20 w%), at 80 °C in water as solvent, was identified as the best conditions.While the reaction with the help of ultrasound showed the best result at the lower temperature (40 °C). After the reactioncompletion, the catalyst was easily removed from the reaction mixture by an external magnet and prepared for reuse afterwashing. This catalyst was applied six times without noticible change in catalyst activity. This protocol is a novel,efficient, inexpensive, affordable and environmentally friendly method that demonstrates significant advantages such ashigh yields, short reaction time, and ease of preparation of the catalyst and easy removable catalyst.

Knoevenagel condensation, synthesis of coumarin-3-carboxylic acid derivatives, ultrasonic radiation, magnetic nano-particles