Making Copper(0) Nanoparticles in Glycerol: A Straightforward Synthesis for a Multipurpose Catalyst

Abstract

Dedicatedt ot he Laboratoire HØtØrochimieF ondamentale et AppliquØeo nt he occasiono fi ts 50 th anniversary.Supporting information for this article is availableunder https://doi.org/10.1002/adsc.201700535.Abstract: Small zero-valent copper nanoparticles (CuNPs) have been straightforwardly preparedf rom Cu(I) andC u(II) precursors in glycerol andi nt he presence of polyvinylpyrrolidone as stabilizer. Thanks to the negligible vaporp ressure of the solvent, these original nano-systems could be directly characterized in glycerol as well as in the solids tate, exhibiting relevantly homogeneous colloidal dispersions,a lso evena fter catalysis. CuNPs coming from the well-defined coordinationc omplex di-m-hydroxobis[(N,N,N',N'-tetramethylethylenediamine)copper(II)] chloride {[Cu(k 2 -N,N-TMEDA)(m-OH)] 2 Cl 2 } have been highly efficient in C-C andC -heteroatom bond formation processes. This newc atalytic system has proved its performance in C-Nc ouplings and in the synthesis of differently substitutedp ropargylic amines throughc ross-dehydrogenative couplings, multi-component reactions such as A 3 (aldehydealkyne-amine) and KA 2 (ketone-alkyne-amine) couplings,a sw ell as in the formationo fh eterocycles such as benzofurans,i ndolizines,a nd quinolines under smoothc onditions.N os ignificant copper amount was detected in the extracted organic compounds from the catalytic phase by inductively coupled plasma-atomic emission spectroscopic (ICP-AES)analyses,p roving ah ighly efficient immobilization of copper nanoparticles in glycerol. From am echanisticp oint of view,s pectroscopic data (infrareda nd ultraviolet-visible spectra) agreew ith asurface-like catalytic reactivity.

A walk around the application of nanocatalysts for cross-dehydrogenative coupling of C–H bonds

“…27 Recently, the group of Favier-Gómez's reported the synthesis of ultrane zero-valent copper nanoparticles (NPs) with mean diameters from about 1.7 to 2.4 nm by decomposition of [Cu(k 2 -N,N,N 0 ,N 0 -TMEDA)(m-OH)] 2 Cl 2 (TMEDA ¼ tetramethylethylenediamine) under hydrogen gas atmosphere (3 atm), in the presence of polyvinylpyrrolidone (PVP) as stabilizer in glycerol (Scheme 13). 28 The catalytic activity was evaluated in the oxidative coupling of tertiary amines 25 with terminal alkynes 26 in the presence of TBHP as an oxidant in glycerol. The obtained results from this study showed that the desired coupling products 27 were formed in moderate to excellent isolated yields (Scheme 14).…”

Glycerol: An Optimal Hydrogen Source for Microwave-Promoted Cu-Catalyzed Transfer Hydrogenation of Nitrobenzene to Aniline

“…CuNPs are an efficient source of Cu, but their potential applicability is restricted by copper's inherent instability under atmospheric conditions (Gawande et al, 2016). Cu(0)NPs have been efficiently prepared in glycerol (Dang-Bao et al, 2017), and some polyolstabilized CuNPs have been used in the reduction of nitrobenzene (Saha and Ranu, 2008;Duan et al, 2012;Santhanalakshmi and Parimala, 2012). Although several applications for copper catalysis in transfer hydrogenation have already been reported in the literature (Štefane and Požgan, 2014;Fan et al, 2018;Zhang and Li, 2019), the use of CuNPs for nitrobenzene reduction via transfer hydrogenation has not received much attention, to the best of our knowledge (Feng et al, 2014).…”

A Novel Recyclable Ni/Cu/Fe Termetallic Nanocatalyst for the Synthesis of Propargylamines through the A3‐Coupling Reactions

“…The results showed that reaction was significantly affected by temperature. A remark- able increase in yield of propargylamine product was observed at 100°C compared to other temperature levels ( Table 1, entries [14][15][16]. Therefore, the optimized conditions for the A 3coupling reaction are NiO/OA-CuFe 2 O 4 nanocatalyst (50 mg), toluene, and 100°C for an apropirate time ( Table 1, entry 5).…”

“…Furthermore, two kinds of terminal alkynes such as phenylacetylene and 1-hexyne were examined for the synthesis of various propargylamine products. As shown in Table 2, for all kinds of aldehydes and amines in the reaction with 1-hexyne, propargylamine products were obtained in longer reaction times ( Table 2, entries [14][15][16][17][18][19].…”

“…However, these reagents are mostly highly moisture-sensitive, and require strictly controlled reaction conditions. One way to form the propargylamines is to apply the transition-metal catalysts in three-component coupling of aldehydes or ketones, amines, and alkynes (A 3coupling [9,13] or KA 2 -coupling [14][15][16] reaction). However, the KA 2 reaction has been largely underdeveloped because of the extremely lower reactivity of ketones.…”