2Aminoethanesulfonic acid immobilized on epichlorohydrin functionalized Fe3O4@WO3 (Fe3O4@WO3EAESO3H (III)): A heterogeneous and reusable nanocatalyst for synthesis of α,α bis (substitutedbenzylidene) cycloalkanones in solventfree conditions

A green, efficient, chemoselective, facile and clean procedure is described and discussed for the synthesis of α, α bis (substitutedbenzylidene) cycloalkanones in solventfree conditions. The condensation reaction was carried out through the reaction of aromatic aldehydes with cycloalkanones in the presence of Fe lt;sub gt;3 lt;/sub gt;O lt;sub gt;4 lt;/sub gt;@WO lt;sub gt;3 lt;/sub gt; (Fe lt;sub gt;3 lt;/sub gt;O lt;sub gt;4 lt;/sub gt;@WO lt;sub gt;3 lt;/sub gt;EAESO lt;sub gt;3 lt;/sub gt;H ( lt;strong gt;III lt;/strong gt;)) nanoparticles as the catalyst. The nanostructured catalyst with the spherical shape, particle size in the range of 723 nm and superparamagnetic behavior may be referred as an excellent replacement for Brønsted acids. The reaction proceeds rapidly at room temperature, giving high yields of products. No selfcondensation product was produced. Easy separation of the catalyst from the reaction mixture by means of an external magnetic field and reusing up to seven times without loss of activity are the salient features of the present method.