Water soluble polymer–surfactant complexes-stabilized Pd(0) nanocatalysts: Characterization and structure–activity relationships in biphasic hydrogenation of alkenes and α,β-unsaturated ketones

Abstract

A suitable approach to stabilize palladium nanoparticles in water as a green reaction medium for catalytic hydrogenation reactions is described. Supramolecular self-assemblies, obtained through the mixture of modified polyethyleneimines as amphiphilic polymers and water-soluble ammonium salts as surfactants, were used as efficient protective agents in the synthesis of Pd(0) nanospecies. The size and dispersion of the nanoparticles prepared with these original self-assemblies were characterized by TEM, SAXS and DLS techniques. The performances of the catalysts according to the polymer-surfactant mixtures were investigated in the hydrogenation of alkenes and α,β-unsaturated ketones in pure biphasic water/substrate medium, under mild conditions (room temperature and 1 bar H 2). The 2 nanocatalysts showed efficient catalytic activities and selectivity towards C=C bonds. From investigations, the polymer-surfactant complexes act as cooperative protective agents and a pertinent structure-activity relationship was proposed based on the zeta-potential values and the catalytic activity of the resulting colloids.

Surfactant‐directed Pd‐nanoparticle assemblies as efficient nanoreactors for water remediation

“…[16][17][18] In addition to stabilizing the metal NPs, the surfactant ligands may induce specific physicochemical properties to the NPs, 8,19 thereby influencing the nanomaterials' solubility and catalytic properties. 8,20,21 For instance, Albuquerque et al used water-soluble polymer-surfactant PdNPs for the hydrogenation of alkenes and α,β-unsaturated ketones. 21 The catalytic efficiency was attributed to a dynamic effect of the protective layer in facilitating the access of substrates onto Pd surface.…”

“…8,20,21 For instance, Albuquerque et al used water-soluble polymer-surfactant PdNPs for the hydrogenation of alkenes and α,β-unsaturated ketones. 21 The catalytic efficiency was attributed to a dynamic effect of the protective layer in facilitating the access of substrates onto Pd surface. On the other hand, strongly and heavily adsorbed surfactants may also block the active sites of the metal NP surface with the result of decreasing the catalytic activity.…”

PVA‐encapsulated Palladium Nanoparticles: Eco‐friendly and Highly Selective Catalyst for Hydrogenation of Nitrobenzene in Aqueous Medium

“…In addition, the selectivity for aniline remains 100 % for each cycle. It suggests that the backbone of PVA aggregates has not changed, and it may still play a valuable role in controlling the selectivity for aniline …”

“…It suggestst hat the backboneo f PVAa ggregates has not changed, and it mays till play av aluable role in controlling the selectivity for aniline. [36,37] The catalytic activity of Pd/PVAi nh ydrogenation of nitrobenzene to aniline werec ompared in detail with some catalysts reported previously (Table S2).…”

On the Formation of Palladium (II) Iodide Nanoparticles: An In Situ SAXS/XAS Study and Catalytic Evaluation on an Aryl Alkenylation Reaction in Water Medium

“…The in situ XAS measurements were performed in transmission mode in PdK−edge and the data were collected after 30 min of reactant mixing (see SI for details on the XAS setup). We also performed the reduction of Pd(OAc) 2 with NaBH 4 , a strong reducing agent typically used for metal nanoparticle synthesis, in the presence of PVP, in the formation of Pd 0 ‐NPs, for the sake of comparison. The variations in the XANES spectra, observed in Figure , clearly show the dependence of the Pd 2+ ligand exchange on the amount of KI.…”