Author : Trung Dang Bao
Publisher :
ISBN 13 :
Total Pages : 296 pages
Book Rating : 4.:/5 (19 download)
Book Synopsis Nanoparticules (Bi)métalliques Dans Le Glycérol by : Trung Dang Bao
Download or read book Nanoparticules (Bi)métalliques Dans Le Glycérol written by Trung Dang Bao and published by . This book was released on 2018 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt: Metal nanoparticles (MNPs) applied in catalysis represent an attractive field due to their interesting physical and chemical properties. Besides, the addition of another metal to the host metal in the same entity (bimetallic nanoparticles, BMNPs) can trigger changes in electronic properties (charge transfer, orbital hybridization, etc.) and/or geometric features (alloy, core-shell, heterodimers, etc.), inducing modifications in their catalytic behavior, in terms of activity, selectivity, robustness, or even leading to new reactivity. Concerning the solvent, glycerol, showing a complex supramolecular structure, favors the dispersion of metal nanoparticles, avoiding their agglomeration and then facilitating the recycling of catalytic phase. Small and spherical zero-valent copper nanoparticles (CuNPs) immobilized in glycerol were synthesized using poly(vinylpyrrolidone) (PVP) as stabilizer under hydrogen pressure. CuNPs dispersed in glycerol proved to be a robust and versatile catalyst for a diversity of C-N bond formation reactions, synthesis of di- (via cross-dehydrogenative coupling), tri- (via aldehydeamine- alkyne A3 coupling) and tetra-substituted propargylic amines (via ketone-amine-alkyne KA2 coupling) as well as different types of heterocycles, in particular indolizines, benzofurans and quinolines, by tandem A3-cycloisomerization processes using ortho-functionalized benzaldehydes as substrates. Interestingly, the catalytic glycerol phase could be recycled more than five times in C-N bond formation and A3 coupling reactions, preserving their reactivity, without detecting a significant copper content in the extracted organic products. Bimetallic palladium-copper nanoparticles (PdCuNPs) dispersed in glycerol were prepared by co-reduction methodology. Depending on the different metal ratios used, Pd nanoparticles coated by Cu (Pd/Cu = 1/1), random alloy (Pd/Cu = 1/2) or mainly mixture of monometallic nanoparticles (Pd/Cu = 2/1) were obtained. By a sequential way of synthesis, a mixture of monometallic nanoparticles was mainly observed. In terms of reactivity, the effect of one metal to other one, on catalytic activity and selectivity was evaluated. The structure of the different PdCuNPs was also confirmed by the observed reactivity in the selective formation of alkenes by hydrogenation of alkynes, proving that Pd1Cu1 and Pd1Cu2 correspond to bimetallic structures. Besides, the influence of Pd incorporated into Cu on azide-alkyne cycloaddition (CuAAC) was also studied. Interestingly, Pd1Cu1 in glycerol were applied in one-pot processes acting as multitask catalytic system, involving CuAAC and Pd-catalyzed C-C cross couplings (Sonogashira, Suzuki-Miyaura and Heck). Thanks to the different rates between CuAAC and C-C couplings, these tandem processes permitted to obtain the desired products in high yields. Furthermore, Rh-catalyzed hydroaminomethylation of olefins, in order to synthesize amines, could be carried out in glycerol, generally showing a better reactivity compared to common organic solvents. These preliminary encouraging results permit to plan the design of a new biphasic system, including the recycling of the catalytic phase.
