Oxido- and Dioxido-Vanadium(V) Complexes Supported on Carbon Materials: Reusable Catalysts for the Oxidation of Cyclohexane

Abstract

Oxidovanadium(V) and dioxidovanadium(V) compounds, [VO(OEt)L] (1) and [Et3NH][VO2L] (2), were synthesized using an aroylhydrazone Schiff base (5-bromo-2-hydroxybenzylidene)-2-hydroxybenzohydrazide (H2L). They were characterized by elemental analysis, Fourier-transform infrared spectroscopy (FT-IR), (1H and 51V) nuclear magnetic resonance (NMR), electrospray ionization mass spectrometry (ESI-MS) and single crystal X-ray diffraction analyses. Both complexes were immobilized on functionalized carbon nanotubes and activated carbon. The catalytic performances of 1 and 2, homogenous and anchored on the supports, were evaluated for the first time towards the MW-assisted peroxidative oxidation (with tert-butylhydroperoxide, TBHP) of cyclohexane under heterogeneous conditions. The immobilization of 1 and 2 on functionalized carbon materials improved the efficiency of catalytic oxidation and allowed the catalyst recyclability with a well-preserved catalytic activity.

Triazaphosphaadamantane-functionalized terpyridine metal complexes: cyclohexane oxidation in homogeneous and carbon-supported catalysis

“…The use of MeCN in oxidation reaction has been often reported. 14,16 Different co-solvents such as acetone and water were tested.…”

“…12,13 This prompted several research groups, including ours, to explore alternative pathways to synthesize better catalysts for the selective oxidation of cyclohexane. 14–16…”

Diastereomeric dinickel(ii) complexes with non-innocent bis(octaazamacrocyclic) ligands: isomerization, spectroelectrochemistry, DFT calculations and use in catalytic oxidation of cyclohexane

“…This inert C–H bond oxyfunctionalization has long been dominated by transition metal catalysis. 49–53…”

A one-step method for preparing Cr-doped SiO2: An efficient catalyst for the direct oxidation of cyclohexane to ketone-alcohol oil

“…In addition, other reports using tert- butyl hydrogen peroxide, and H 2 O 2 as oxidants for the liquid-phase oxidation of cyclohexane have been described. 17–20 In particular, H 2 O 2 , a green oxidant since it produces H 2 O as the sole byproduct, has received considerable attention in the field of catalytic oxidation. Consequently, several heterogeneous catalysts with H 2 O 2 as the oxidant have been applied to the selective oxidation of cyclohexane, including Fe/H-MSN, 21 CuNi/Al 2 O 3 , 22 PdX/TiO 2 , 23 VPO-TUD-1, 24 CuFeAl 2 O 4 , 25 Cu-Cr 2 O 3 , 26 CuCr 2 O 4 , 27 Cu/ZSM-5, 28 and VPO/KIT-6.…”