Fatemeh Tamaddon* and Davood Azadi Pages 201 - 210 ( 10 )
Background: Supporting of choline chloride (CC):2urea as a deep eutectic solvent (DES) on nonomagnetite gives the core-shell of nanoFe3O4@CC:2urea which in DES coating inhibits the agglomeration of nanoFe3O4 and nanoFe3O4 facilitates reusability of DES. The ratio of nanoFe3O4 to DES in nanoFe3O4@CC:2urea was determined as 8:1. These synergic effects led to a high catalytic performance for nanoFe3O4@CC:2urea versus individual nanoFe3O4 or CC:2urea in synthesis of pyrazole derivatives by various synthetic strategies. Faster reactions with higher yields at room temperature occur with low loading of this recyclable hybrid catalyst.
Method: NanoFe3O4 and DESs were prepared by co-precipitation of FeCl3.6H2O and FeCl2.4H2O with NH3 and heating the mixture of CC and hydrogen donors to a homogeneous liquid. Then, nanoFe3O4@CC:2urea was prepared by sonication of nanoFe3O4 and dissolved CC:2urea in methanol. After characterization by FT-IR, SEM, TEM, TGA, and VSM, the efficacy of nanoFe3O4@CC:2urea was examined in one-pot synthesis of pyrazoles and pyranopyrazoles.
Results: NanoFe3O4@CC:2urea is a hybrid organic/inorganic catalyst which in DES coating inhibits the agglomeration of Fe3O4 nanoparticles and nanoFe3O4 improves the reusability of DES. These synergic effects deliver a high catalytic performance for nanoFe3O4@CC:2urea in synthesis of pyrazoles and pyranopyrazoles. Faster reactions with higher yields at room temperature occur with low loading of this magnetically separable and reusable catalyst.
Conclusion: In summary, synergic effects of CC:2urea and nanomagnetite in nanoFe3O4@CC:2urea lead to a reusable catalyst with superior catalytic activity in room temperature three- or four- component synthesis of pyrazoles and pyranopyrazoles. This magnetically separable DES provides higher yields of products, faster reactions, and milder conditions compared to previous reported methods.
Deep eutectic, nanoFe3O4, immobilization, pyrazoles, multicomponent reactions, synergic effect.
Department of Chemistry, Faculty of Science, Yazd University, Yazd 89195-741, Department of Chemistry, Faculty of Science, Yazd University, Yazd 89195-741