Solvent-Free Microwave-Induced Oxidation of Alcohols Catalyzed by Ferrite Magnetic Nanoparticles

Abstract

Abstract:A series of first-row-transition-metal ferrite magnetic nanoparticles (NPs) MFe 2 O 4 [M = Mn 2+ (1), Fe 2+ (2), Co 2+ (3), Ni 2+ (4), Cu 2+ (5) or Zn 2+ (6)] were prepared by the co-precipitation method and characterized by Fourier transform infrared (FTIR) spectroscopy, powder X-ray diffraction (XRD), scanning electron microscope -energy dispersive X-ray spectrometry (SEM-EDS), vibrating sample magnetometer (VSM) and X-ray photoelectron spectroscopy (XPS). Those NPs were used as catalysts for the microwave-assisted oxidation of various alcohols in solvent-free medium. MnFe 2 O 4 (1), CoFe 2 O 4 (3) and CuFe 2 O 4 (5) act as catalysts for the conversion of alcohols to the corresponding ketones or aldehydes with a yield range of 81 to 94% in 2 h at 120 • C using t-BuOOH as an oxidant. These catalysts can be readily isolated by using an external magnet and no significant loss of activity is observed when reused up to 10 consecutive runs. The effects of some parameters, such as temperature, time, type of oxidant and presence of organic radicals, on the oxidation reactions were also investigated. The presented literature overview highlights the advantages of our new 1-6 NPs catalytic systems in terms of efficiency and economy, mainly due the used microwave (MW) heating mode.

First-Row-Transition Ion Metals(II)-EDTA Functionalized Magnetic Nanoparticles as Catalysts for Solvent-Free Microwave-Induced Oxidation of Alcohols

“…Importantly, these improved features occur without loss of the magnetic properties ( Figure 6). Therefore, the catalytic performance of EDTA functionalized materials allowed reaching full conversion of 1-phenylethanol what was not achievable with the previous reported transition metal ferrites [14] applying the same solvent-free MW-assisted oxidation methodology.…”

“…Moreover, despite the higher temperature used (120 • C vs. 80 • C), MW-irradiation consumes much lower energy than conventional heating. Our transition-metal EDTA functionalized magnetite nanocatalysts constitute an optimization of the magnetic ferrites previously reported by us [14]. Among the ferrite materials, magnetite exhibited the most promising chemo-physical properties, such as higher magnetization, turning it the easiest material to manipulate using an external magnet.…”

“…With the growing concern to bring out a more environmentally friendly chemical process, the use of a solvent-free synthetic protocol is of great significance. In addition, the heating mode through MW irradiation that requires low power and possibility to enhance the activity of alcohol oxidation reactions [6,7,14,[34][35][36][37][38][39][40][41] is a feature to take into account. In order to find the optimized reaction conditions, 1-phenylethanol was selected as a model alcohol substrate to oxidize (Scheme 1).…”

Towards Mechanistic Understanding of Liquid‐Phase Cinnamyl Alcohol Oxidation with tert‐Butyl Hydroperoxide over Noble‐Metal‐Free LaCo1–xFexO3 Perovskites

“…This is consistent with similar phenomena observed by other groups and indicates that the primary role of the catalyst is to decompose TBHP into reactive oxygen species (ROS). [7,31,34,59] The essentially constant selectivity to cinnamaldehyde observed for all catalysts during the catalyst screening indicates that the same radical mechanism applies to all utilized perovskite catalysts.…”

Synergetic Effect of Calcium Doping on Catalytic Activity of Manganese Ferrite: DFT Study and Oxidation of Hydrocarbon

“…They observed the same trend in selectivity and conversion per unit time. Table 1 reflects the higher catalytic activity of Mn-ferrite and Ca-doped Mn-ferrite used for the oxidation of CH in solvent-free conditions compared to all reported catalysts being used for the oxidation of COH/RCOR [29][30][31]50]. Reaction progress (%) Fang & co-workers [49] performed electrocatalytic oxidation of CH to CHOH/RCOR using a functional electrocatalytic membrane reactor (ECMR) assembled with an MnO nanostructure that was loaded on a porous titanium membrane as an anode in a ternary system of CH, water and acetic acid.…”