Cuprous oxide agglomerates composed of 4-10 nm Cu2O nanoparticles were deposited on multiwalled carbon nanotubes (MWCNTs) and on ZnO/MWCNTs to give binary [Cu2O/MWCNT] and ternary [Cu2O/ZnO/MWCNT] composites. Di-aqua-bis[2-(methoxyimino)propanoato]copper Cu[O2CCCH3NOMe](2)·2H2O 1 in DMF was used as single source precursor for the deposition of nanoscaled Cu2O. The precursor decomposes either in air or under argon to yield CuO2 by in situ redox reaction. Thermogravimetric coupled mass spectroscopic analysis (TG-MS) of 1 revealed that methanol formed during the decomposition of 1 acts as a potential in situ reducing agent. Scanning electron microscopy (SEM) of the binary [Cu2O/MWCNT] nano-composite shows an increase of cuprous oxide loading depending on the precursor amount, along the periphery of the MWCNTs as well as formation of larger particle agglomerates. Transmission electron microscopy (TEM) of the sample shows crystalline domains of size 4-10 nm surrounded by an amorphous region within the larger particles. SEM and TEM of ternary [Cu2O/ZnO/MWCNT] clearly reveal that Cu2O nanoparticles are primarily deposited on ZnO rather than on MWCNTs. The catalytic activities of the [Cu2O/MWCNT] and [Cu2O/ZnO/MWCNT] binary and ternary composites were studied for the selective partial oxidation of ethanol to acetaldehyde with molecular oxygen. While using binary [Cu2O/MWCNT] (13.8 wt% Cu) as catalyst, acetaldehyde was obtained with a yield of 87% at 355 °C (selectivity 96% and conversion 91%). When nanoscale ZnO is present, the resulting [Cu2O/ZnO/MWCNT] composite shows preferential hydrogen and CO2 formation due to the fact that the dehydrogenation and total oxidation pathway is more favoured compared to the binary composite. Significant morphological changes of the catalyst during the catalytic process were observed. 相似文献
Electrochemically mediated atom transfer radical cyclization (eATRC) has been developed as an easy and clean method allowing the synthesis of halogenated cyclic compounds. This method has been successfully applied to the copper‐catalyzed atom transfer radical cyclization of some N‐allyl‐α,α‐dichloroamides in acetonitrile (CH3CN) using a copper complex with tris(2‐pyridylmethyl)amine (TPMA) with a metal loading of 1%. The catalyst is introduced as [Cu(II)TPMA]2+ and is activated and continuously regenerated to its active copper(I) form by reduction at a platinum (Pt) electrode. During the ATRC process a new copper(II) complex, namely, [ClCu(II)TPMA]+, whose reduction potential is ca. 0.350 V more negative than that of the starting [Cu(II)TPMA]2+, is formed. Therefore, the choice of the applied potential is critical and should be done taking care that all copper(II) species are reduced to copper(I). The compounds undergo very high conversions (79–100%) in a few hours of electrolysis, producing a cyclic γ‐lactam (yield 60–98%) as a mixture of two isomers, with a good cis‐diastereoselectivity [dr (cis/trans)=59/41–83/17]. [Cu(II)PMDETA]2+ (PMDETA=N,N,N′,N′′,N′′‐pentamethyldiethylenetriamine), which is much cheaper, albeit less reactive than [Cu(II)TPMA]2+, was also investigated but the results were not satisfactory.