An efficient and simple process for the preparation of stable nanocopper(0) on alumina [Cu(0)/Al2O3] from the inorganic composite precursor copper aluminum hydrotalcite (Cu‐Al HT) by a chemical reduction method is described. Cu(0)/Al2O3 was employed as an efficient catalyst in the acceptor‐ and oxidant‐free dehydrogenation of various amines and alcohols to their corresponding dehydrogenated products in good to excellent yields. The stability of Cu(0)/Al2O3 was assessed by studying its recoverability and reusability in the dehydrogenation of amines and alcohols for up to five cycles.magnified image

Abstract:A high surface, magnetic Fe 3 O 4 @mesoporouspolyaniline core-shell nanocomposite was synthesized from magnetic iron oxide (Fe 3 O 4 ) nanoparticles and mesoporouspolyaniline (mPANI). The novel porous magnetic Fe 3 O 4 was obtained by solvothermal method under sealed pressure reactor at high temperature to achieve high surface area. The mesoporouspolyaniline shell was synthesized by in situ surface polymerization onto porous magnetic Fe 3 O 4 in the presence of polyvinylpyrrolidone (PVP) and sodium dodecylbenzenesulfonate (SDBS), as a linker and structure-directing agent, through blackberry nanostructures assembly.The material composition, stoichiometric ratio and reaction conditions play vital roles in the synthesis of these nanostructures as confirmed by variety of characterization techniques. The role of the mesoporouspolyaniline shell is to stabilize the porous magnetic Fe 3 O 4 nanoparticles, and provide direct access to the core Fe 3 O 4 nanoparticles. The catalytic activity of magnetic Fe 3 O 4 @mesoporousPANI nanocomposite was evaluated in the cross-coupling of aryl chlorides and phenols.

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An efficient catalyst system consisting of copper-aluminum hydrotalcite/rac-BINOL ligand has been developed for the oxidation of alcohols using air as a green oxidant at room temperature. Various alcohols could be transformed into their corresponding aldehydes or ketones in good to excellent yields using the set of optimal conditions. This composite catalytic system can also be recovered and reused for several cycles without a significant loss of catalytic activity.

A simple one-step approach for the preparation of highly monodispersed nano copper(0) stabilized on alumina [Cu(0)/Al 2 O 3 ] by thermal reduction of copper-aluminium hydrotalcite (Cu-Al HT) under a hydrogen atmosphere is described. The transformation of Cu-Al HT to Cu(0)/Al 2 O 3 occurrs via dehydroxylation of divalent and trivalent metal hydroxides and decarboxylation of carbonate anions present in the interlayers of hydrotalcite, as confirmed by XPS, XANES, XRD and TEM analysis. Cu(0)/Al 2 O 3 nano composites were used as an efficient catalyst in the C À C coupling of deactivated aryl chlorides. The high efficiency and reusability exhibited by Cu(0)/ Al 2 O 3 outline its potential as an alternative over traditional noble metal-based catalysts in C À C coupling reactions.