A New Nanomagnetic Pd-Co Bimetallic Alloy as Catalyst in the Mizoroki-Heck and Buchwald–Hartwig Amination Reactions in Aqueous Media

Abstract

A Pd-Co bimetallic alloy encapsulated in melamine-based dendrimer supported on magnetic nanoparticles denoted as γ-Fe2O3@MBD/Pd-Co was synthesized by a facile co-complexation-reduction method and characterized sufficiently. The catalytic evaluation of γ-Fe2O3@MBD/Pd-Co showed promising results in the Mizoroki-Heck and Buchwald-Hartwig amination reactions of various iodo-, bromo- and challenging chloroarenes in aqueous media. The synergetic cooperative effect of both Pd and Co and dispersion of the catalyst in water due to the encapsulation of γ-Fe2O3 by melamine-based dendrimer lead to high catalytic performance compared with the monometallic counterparts. The dispersion of the magnetic catalyst also facilitates the recovery and reuse of the catalyst by ten consecutive extraction and final magnetic isolation with no loss of catalytic activity, keeping its structure unaltered. Remarkably, this is the first paper on the use of palladium-cobalt bimetallic catalyst for Buchwald-Hartwig amination reaction and the first magnetically recyclable Pd/Co bimetallic catalyst in the Mizoroki-Heck coupling reactions.

Heterogenization of Cobalt on Nanostructured Magnetic Covalent Triazine Framework: Effective Catalyst for Buchwald-Hartwig N-Arylation, Reduction, and Oxidation Reactions

“…Finally, the product is formed by base-assisted elimination of X-H from intermediate (III) by subsequent reductive elimination and catalyst regeneration. 60 In the oxidation process, TBHP cleaves to yield the peroxo compound and tert-butanol (t-BuOH) resulting in the peroxo surface species. In these species, the O− O bond is polarized, which allows the labile hydroxyl group to attack the nucleophilic aldehyde and produce benzoic acid.…”