The Transfer Hydrogenation of Cinnamaldehyde Using Homogeneous Cobalt(II) and Nickel(II) (E)-1-(Pyridin-2-yl)-N-(3-(triethoxysilyl)propyl)methanimine and the Complexes Anchored on Fe3O4 Support as Pre-Catalysts: An Experimental and In Silico Approach

Abstract

The imino pyridine Schiff base cobalt(II) and nickel(II) complexes (C1 and C2) and their functionalised γ-Fe3O4 counterparts (Fe3O4@C1 and Fe3O4@C2) were synthesised and characterised using IR, elemental analysis, and ESI-MS for C1 and C2, and single crystal X-ray diffraction for C1, while the functionalised materials Fe3O4@C1 and Fe3O4@C2 were characterized using IR, XRD, SEM, TEM, EDS, ICP-OES, XPS and TGA. Complexes C1, C2 and the functionalised materials Fe3O4@C1 and Fe3O4@C2 were tested as catalysts for the selective transfer hydrogenation of cinnamaldehyde and all four pre-catalysts showed excellent catalytic activity. Complexes C1 and C2 acted as homogeneous catalysts with high selectivity towards the formation of hydrocinnamaldehyde (88.7% and 92.6%, respectively) while Fe3O4@C1 and Fe3O4@C2 acted as heterogeneous catalysts with high selectivity towards cinnamyl alcohol (89.7% and 87.7%, respectively). Through in silico studies of the adsorption energies, we were able to account for the different products formed using the homogeneous and the heterogeneous catalysts which we attribute to the preferred interaction of the C=C moiety in the substrate with the Ni centre in C2 (−0.79 eV) rather than the C=O (−0.58 eV).

Highly efficient hydrogenation of furfural to valuable products catalysed by Rh (III), Pd (II), Ni (II), Fe (II) and Ru (II) half‐sandwich picolinamide and the SBA‐15 supported molecular complexes as pre‐catalysts

“…The O 1 s core level XPS spectra in the samples showed different O 1 s at different binding energies such as (C=O; SiO 2 ), (C–O) and metal oxide (Figure 7). 59,60 …”

“…58 The O 1 s core level XPS spectra in the samples showed different O 1 s at different binding energies such as (C=O; SiO 2 ), (C-O) and metal oxide (Figure 7). 59,60 Upon incorporation of complexes onto SBA-15, the O 1 s (C=O; SiO 2 ) binding energy also shifted from 533.3 eV in SBA-15 to 532.8 eV for C2@SBA-15 and 532.8 eV for C3@SBA-15, respectively. The O 1 s (C-O) also shifted from 532.2 eV in SBA-15 to 531.7 eV for C2@SBA-15 and 531.8 eV for C3@SBA-15, respectively.…”

Chem4Energy: a consortium of the Royal Society Africa Capacity-Building Initiative

“…In the literature, palladium nanoparticles stabilized with phenanthroline ligands on polyethylene have been reported as active hydrogenation catalysts, giving turnover numbers (TON) in the range of 422-448, conversions of 100% and 100% selectivity towards the hydrogenation of C = C bonds in different alkene substrates (reaction conditions: 10 mmol substrate, 5 mg catalyst, stir, H 2 balloon) [37]. In addition, nanosupports such as metal oxides can be used to incorporate homogeneous catalysts, which yields highly recyclable catalysts suitable for a biorefinery in a green catalysis process [38]. This work aims to demonstrate the synthesis and characterization of Pd(0) nanocatalysts stabilized with bidentate nitrogen binding ligands as novel catalysts for the hydrogenation of furfural to produce furfural alcohol, which is an intermediate on the route to several fine chemicals (figure 6).…”