Ultrasound and Radiation-Induced Catalytic Oxidation of 1-Phenylethanol to Acetophenone with Iron-Containing Particulate Catalysts

Abstract

Iron-containing particulate catalysts of 0.1–1 µm size were prepared by wet and ball-milling procedures from common salts and characterized by FTIR, TGA, UV-Vis, PXRD, FEG-SEM, and XPS analyses. It was found that when the wet method was used, semi-spherical magnetic nanoparticles were formed, whereas the mechanochemical method resulted in the formation of nonmagnetic microscale needles and rectangles. Catalytic activity of the prepared materials in the oxidation of 1-phenylethanol to acetophenone was assessed under conventional heating, microwave (MW) irradiation, ultrasound (US), and oscillating magnetic field of high frequency (induction heating). In general, the catalysts obtained by wet methods exhibit lower activities, whereas the materials prepared by ball milling afford better acetophenone yields (up to 83%). A significant increase in yield (up to 4 times) was observed under the induction heating if compared to conventional heating. The study demonstrated that MW, US irradiations, and induction heating may have great potential as alternative ways to activate the catalytic system for alcohol oxidation. The possibility of the synthesized material to be magnetically recoverable has been also verified.

C-Heterogenized Re Nanoparticles as Effective Catalysts for the Reduction of 4-Nitrophenol and Oxidation of 1-Phenylethanol

“…The reduction of 4-NP (E 0 = −0.76 V) by NaBH 4 (E 0 = −1.33 V) is thermodynamically feasible, but kinetically restricted in the absence of a catalyst [41,42] in aqueous NaBH 4 . Our results confirm that the reaction does not proceed in a pure aqueous NaBH 4 solution.…”

“…In the present catalytic system, contrary to what was observed by other authors [41], no induction time was noticed. Such a reported induction period was linked [41] to the level of dissolved oxygen in the reaction medium, [42][43][44][45][46] and it ended once the level fell below a critical value that was dependent upon the metal nanoparticles used as the catalyst.…”

Sonochemical fabrication of inorganic nanoparticles for applications in catalysis

“… [93] Compared with the 70% desulfurization rate in a 6 h oxidative process, the ultrasound-assisted oxidation could reach a 90% desulfurization rate in 3.5 h. In the Han’s study, [94] the photocatalytic CdO took place of the polyoxometalate to apply in the ultrasound-assisted oxidative technology of organic sulfur removal from the diesel as well, and under the optimal condition, this oxidative approach was efficient for sulfur removal and reached a 99.47% desulfurization degree. Alternatively, iron materials have been also used in the ultrasound-induced catalytic oxidation, for example, the oxidation of 1-phenylethanol to acetophenone was carried out in the Ribeiro’s study, [95] and the activation of iron-containing particulate catalysts under the ultrasound could significantly increase the overall effectiveness of catalytic system.…”

A Keggin-type polyoxometalate-based metal–organic complex as a highly efficient heterogeneous catalyst for the selective oxidation of alkylbenzenes

“…4,5 Hence, activating C-H bonds in materials and converting these useless materials into valuable compounds is an important, economic and green step in synthetic chemistry. 6,7 Up to now, a few catalysts such as noble metals (Pd, Ru), 1,8 non-noble metal catalysts, 9,10 earth abundant metal catalysts, 11,12 and organic molecules 13,14 have been selected for the conversion of alkylbenzenes; however, some of these are neither recyclable nor inexpensive. Therefore, an economical and efficient heterogeneous catalyst without any additives is more desirable.…”