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

authors	Martins, NMR; Martins, LMDRS; Amorim, CO; Amaral, VS; Pombeiro, AJL
nationality	International
journal	CATALYSTS
author keywords	alcohol oxidation; ferrite magnetic nanoparticles; microwave irradiation; solvent-free; recycle
keywords	ASSISTED PEROXIDATIVE OXIDATION; LIQUID-PHASE OXIDATION; BENZYL ALCOHOL; AEROBIC OXIDATION; SELECTIVE OXIDATION; RECOVERABLE CATALYST; HYDROGEN-PEROXIDE; COFE2O4 NANOPARTICLES; FE3O4 NANOPARTICLES; CARBON NANOSPHERES
abstract	A series of first-row-transition-metal ferrite magnetic nanoparticles (NPs) MFe2O4 [M = Mn2+ (1), Fe2+ (2), Co-2+ (3), Ni2+ (4), Cu2+ (5) or Zn2+ (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. MnFe2O4 (1), CoFe2O4 (3) and CuFe2O4 (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 degrees 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.
publisher	MDPI AG
issn	2073-4344
year published	2017
volume	7
issue	7
digital object identifier (doi)	10.3390/catal7070222
web of science category	Chemistry, Physical
subject category	Chemistry
unique article identifier	WOS:000406702400030