Immobilization of Rh(I)-N-Xantphos and Fe(II)-C-Scorpionate onto Magnetic Nanoparticles: Reusable Catalytic System for Sequential Hydroformylation/Acetalization

Abstract

Two heterogeneous catalysts, MNP@SiO2-N-Xantphos/Rh(I) and MNP@SiO2-NH-C-scorpionate/Fe(II), were prepared by reaction of chloro-functionalized MNP@SiO2 with N-Xantphos and amino-functionalized MNP@SiO2 with iron(II)/C-allyl-scorpionate through nucleophilic substitution and hydroaminomethylation reactions, respectively. All catalysts were characterized using standard spectroscopic means, transmission electron microscopy (TEM), thermogravimetry (TG), and inductively coupled plasma optical emission spectrometry (ICP-OES). An active and highly selective one-pot hydroformylation/acetalization homogeneous system for the transformation of terminal and highly substituted olefins (including terpenes) onto ethyl acetals is described. A synergic effect of bimetallic Rh(I)/P and Fe(II)/C-scorpionate catalysts is disclosed for the first time. The further sequential use of the heterogeneous catalysts, MNP@SiO2-N-Xantphos/Rh(I) and MNP@SiO2-NH-C-scorpionate/Fe(II) in hydroformylation/acetalization reactions allows the direct transformation of olefin onto ethyl acetals, keeping the activity and selectivity. Both catalysts were easily recovered by magnetic separation and reused with negligible loss of activity/selectivity, after six reutilization cycles.

10th Anniversary of Catalysts: Molecular Catalysis

“…For example, the Special Issue summarizes efforts in the area of homogeneous catalysts concerning iridium catalysts containing NHC ligands applied to the asymmetric transfer hydrogenation of ketones [4], synthesis of quinoxalines from glycerol and diamines [5], cross coupling for natural product synthesis [6], and palladium-catalyzed reductive carbonylation of nitro-styrene [7]. This Special Issue also introduces efforts entitled "Immobilization of Rh(I)-N-Xantphos and Fe(II)-C-scorpionate onto magnetic nanoparticles [8]" and "5-(2-Pyridyl)tetrazolate complex of molybdenum(VI)" as precursors for reusable molybdenum oxide-based hybrid heterogeneous catalyst [9]. Moreover, this Special Issue introduces efforts concerning ring opening polymerization using Al and Zn complex catalysts [10], isospecific propylene polymerization by zirconium catalysts [11], and analysis of catalyst solution for ethylene copolymerization using XAS spectroscopy in solution [12].…”