Monodispersed and Stable Nano Copper(0) from Copper‐ Aluminium Hydrotalcite: Importance in CC Couplings of Deactivated Aryl Chlorides

Abstract

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.

14. Österreichische Chemietage

“…Figure 2 shows the XRD spectrum of Cu‐Al HT, CuO/Al 2 O 3 and Cu(0)/Al 2 O 3 . The peak positions of Cu‐Al HT and CuO/Al 2 O 3 were in accord with literature reports 20,22. The major diffraction peaks of chemically reduced Cu(0)/Al 2 O 3 catalyst were found at 2θ=43.5, 50.6, and 74.3 which are corresponding to the three crystalline planes, (1 1 1), (2 0 0) and (2 2 0), of the face‐centered cubic (fcc) Cu (JCPDS 4‐836, a =0.3615 nm), respectively.…”

“…Recently, Cu‐Al HT was exploited as single source precursor for the preparation of stable nanocopper particles on alumina by our group. The high efficiency of the catalyst was introduced for the first time in various CC bond forming reactions 20…”

Cu(0)@Al2O3/SiO2 NPs: an efficient reusable catalyst for the cross coupling reactions of aryl chlorides with amines and anilines

“…In the case of Cu(0)@Al 2 O 3 / SiO 2 , the binding energies were observed at 932.48, 952.11 eV which corresponds to Cu 2p 1/2 , Cu 2p 3/2 and conrms the copper in metallic phase, disappearance of satellite peaks at corresponding positions also strongly conrms the reduction of Cu(II) to Cu(0) state. 15,16 The HR-TEM Images of Cu(0)@Al 2 O 3 /SiO 2 catalyst with a Cu loading of 2.06 wt% are shown in Fig. 3.…”

“…Recently, Cu(0) NPs have been reported for successful C-C cross-coupling reactions. 16 So, in order to check the veracity of Cu(0) in the present C-N cross-coupling reaction, Cu(0) NPs impregnated on Al 2 O 3 /SiO 2 were prepared. Amusingly, screening of Cu(0)@Al 2 O 3 /SiO 2 gave sharp increase in the yield (up to 96%, Table 1, entry 14).…”

Trace amount CuII(ppm) and mixture design of CuII/PdIIcatalyzed Suzuki cross-coupling reactions based on the cooperative interaction of metal with a conjugated pyridylspirobifluorene

“…[14][15][16][17] Reports on Cu(0)-catalyzed Suzuki couplings of aryl halides with arylboronic acids were very limited in the past decades. 18,19 Interestingly, as far as we know, Cu(II)-catalyzed Suzuki-type C (aryl) -C (aryl) cross-coupling reactions have been scarcely reported until now, which possibly result from the Cu(II) ion inactivity of 3d 9 electrons for those catalytic systems. A larger p-conjugated organic ligand may enhance the catalytic activity of Cu(II) ions to promote the C-C coupling information based on the synergistic effect of metal ions and p-conjugated moieties, in which delocalized electrons of the organic ligand can be transferred to d-orbits of metal ions to elevate the catalytic performance of metal ions.…”