Silica Encapsulated-Gold Nanoparticles as a Nano-reactor for Aerobic Oxidation of Benzyl alcohols and Tandem Oxidative A
- PDF / 1,278,984 Bytes
- 8 Pages / 595.276 x 790.866 pts Page_size
- 68 Downloads / 227 Views
Silica Encapsulated‑Gold Nanoparticles as a Nano‑reactor for Aerobic Oxidation of Benzyl alcohols and Tandem Oxidative A3 coupling Reactions in Water Shahram Zare Hosseinzadeh1 · Mirzaagha Babazadeh1 · Gholam Hossein Shahverdizadeh1 · Moosa Es’haghi1 · Rahim Hosseinzadeh‑Khanmiri1 Received: 30 December 2019 / Accepted: 21 February 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract In this work, the encapsulated-Au nanoparticles (NPs) into the silica hollow NPs were synthesized by microwave-assisted preparation of PEG-coated Au NPs, coating them with a layer of organically modified silica and removing the PEG around the Au NPs. The structure of these encapsulated NPs was characterized by TEM, SEM, XRD, FTIR, EDX, TGA, and ICPOES. These NPs have shown excellent activities in the aerobic oxidation of benzyl alcohol derivatives and tandem oxidative A3 coupling reactions as a catalyst and reactor in the water at room temperature. Graphic Abstract Synthesis of a new silica/gold nanoparticles as catalytic nano-reactor for carrying out A3-coupling reaction in the water at ambient temperature
Keywords Gold NPs · PEG coating · Silica hollow sphere · Aerobic oxidation of alcohols · A3 coupling
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10562-020-03183-2) contains supplementary material, which is available to authorized users. * Gholam Hossein Shahverdizadeh [email protected] 1
Department of Chemistry, Tabriz Branch, Islamic Azad University, Tabriz, Iran
1 Introduction Catalysis using gold NPs is recently interested in many reports and also review and books due to the disappearance of the idea that gold has no catalytic properties and understand the direct relationship between particle size in nanometer scale and catalytic activity of gold [1–4]. Catalysis by
13
Vol.:(0123456789)
gold NPs (colloid gold NPs) is a bridge between homogeneous and heterogeneous catalysis (convergence for both fields). When the size of gold particles grows to a microscale, their catalytic activities are completely quenched; accordingly, to avoid agglomeration of gold NPs, the gold NPs were synthesized on the supports and coated with a layer of polymers or surfactant [1, 5, 6]. One of the common ways for preparation of the gold NPs is initiated from HAuCl4 using trisodium citrate as a reducing agent and also as a surfactant for the stabilizing of the NPs, but this method has some limitation that unable to stabilize the NPs for long times in high concentrations (more than 200 ppm) [7, 8]. However, the polymer-coated gold NPs especially PEGcoated NPs were strongly stable in aqueous media in higher concentrations. Using each of these methods for the stabilizing of gold NPs, many types of gold catalysts have been synthesized to accelerate the organic transformations [9–13]. The organic reaction in water is a challenging topic in recent decades. Water is a promising solvent from economic and environmental points of view, but most of the organic
Data Loading...
