Alcohol Oxidation Assisted by Molybdenum Hydrazonato Catalysts Employing Hydroperoxide Oxidants

Abstract

Molybdenum(VI) catalysts were obtained from methanol or acetonitrile by the reaction of [MoO2(C5H7O2)2] and isonicotinoyl- or nicotinoyl-based aroylhydrazones. Reactions in methanol resulted in the formation of the mononuclear complexes [MoO2(L1–4)(MeOH)] (1a–4a), while the ones in acetonitrile provided polynuclear complexes [MoO2(L1–4)]n (1–4). Crystals of polynuclear compound, [MoO2(L3)]n∙H2O (3∙H2O), suitable for X-ray diffraction analysis were obtained by the solvothermal procedure at 110 °C. Complexes were characterized by infrared spectroscopy (IR-ATR), nuclear magnetic resonance (NMR), elemental analysis (EA), and thermogravimetric analysis (TGA). The prepared catalysts were tested in alcohol oxidation reactions. Carveol, cyclohexanol, and butan-2-ol were investigated substrates. Because the alcohol oxidations are very challenging due to various possible pathways, the idea was to test different oxidants, H2O2, TBHP in water and decane, to optimize the researched catalytic system.

Impedance Spectroscopy as a Powerful Tool for Researching Molybdenum-Based Materials with Schiff Base Hydrazones

“…The longest distances within the Mo coordination sphere are those positioned trans to the oxo ligands, i.e., the Mo1–N2 and Mo1–O6 bonds (Mo1A–N2A, Mo1A–O6A, and Mo1B–N2B; Mo1B–O6B in [MoO 2 (L 1 )(2-PrOH)]·(2-PrOH). The main geometrical features of the Mo(VI) complexes investigated here are comparable with those of Mo(VI) complexes with similar ligands reported in the literature [ 6 , 7 , 8 , 31 , 32 ]. The largest differences in the molecular geometries between the complexes can be observed in the relative position of the phenyl rings of the aldehyde and hydrazone residues ( Figure 1 b and Table S5 , Figure 2 ).…”

“…The principal interest in the chemistry of molybdenum(VI) complexes with Schiff-base ligands arises from their biological and pharmacological importance [ 1 , 2 ]. To a greater extent, molybdenum compounds have been widely applied and researched in different catalytic processes, such as sulfoxidation [ 3 , 4 ], olefin epoxidations [ 5 , 6 , 7 ], alcohol oxidations [ 8 ], etc. The capability of molybdenum to adapt and easily convert between different oxidation states signals further applications.…”

Molybdenum, Vanadium, and Tungsten-Based Catalysts for Sustainable (ep)Oxidation

“…One alcohol of biomass origin, carveol, is the most interesting. The oxidants tested have been H 2 O 2 and TBHP (water or decane) [57]. Results compiled in Table 9 showed different phenomena.…”

Molybdenum-, Vanadium-, and Tungsten-Containing Materials for Catalytic Applications

“…Since our research domain is the catalytic applications of oxo-molybdenum and oxo-vanadium coordination complexes [ 14 , 15 , 16 , 17 , 18 ] and POMs [ 19 , 20 , 21 ], such as molecular [ 19 , 20 ] or supported catalysts [ 21 ], with emphasis on biomass-based substrate valorisation [ 22 , 23 , 24 ], we proposed to edit this Special Issue with the aim of collecting research of other international groups within the domain to show the diversity of possible catalyzed reactions using metal complexes. High catalytic activity with relatively low metal loading is an asset, from relatively low cost to more sustainable processes.…”