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Metathesis Strategy for the Immobilization of Copper(II) onto Carboxymethyl­cellulose/Fe3O4 Nanohybrid Supports: Efficient and Recoverable Magnetic Catalyst for the CuAAC Reaction

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journal contribution
posted on 09.11.2016, 00:00 by Zhuan Zhang, Ping Song, Junbin Zhou, Yang Chen, Bijin Lin, Yiqun Li
To overcome the inherent obstacles facing the traditional surface modification of Fe3O4 magnetic nanoparticles with appropriate capping agents to anchor the catalytically active complexes, a novel retrievable copper­(II) catalyst immobilized on carboxymethyl­cellulose/Fe3O4 nanoparticles (CuII–CMC–Fe3O4) magnetic hybrid materials was successfully prepared through three steps of sequential metathesis and one step of oxidation. First, ferrous carboxymethyl­cellulose (CMC–FeII) was prepared by ionic exchange of ferrous chloride and sodium carboxymethyl­cellulose (CMC–Na). Second, the resulting CMC–FeII was treated with NaOH solution to form the corresponding hybrid material Na–CMC–Fe­(OH)2, which proceeded to be exposed to the air to afford the Na–CMC–Fe3O4. Finally, the as-prepared Na–CMC–Fe3O4 was immersed in copper sulfate solution to self-assembly-fabricate the CuII–CMC–Fe3O4 hybrid catalyst by ionic exchange of Cu­(II) with Na–CMC–Fe3O4. The morphology and structural feature of the catalyst were characterized by different microscopic and spectroscopic techniques such as FT-IR, ICP-AES, XRD, SEM, EDS, TEM, TGA, and DSC. The ensuring catalyst has been successfully applied in the CuAAC reaction of benzyl halides, sodium azide, and terminal alkynes to the synthesis of 1,2,3-triazoles. Furthermore, the CuII–CMC–Fe3O4 could be easily isolated and recovered by magnetic decantation and reused for five consecutive cycles without much loss in activity.