Oxidovanadium(V) Complexes Anchored on Carbon Materials as Catalysts for the Oxidation of 1-Phenylethanol

• Published in: ChemCatChem 2016-07, Vol.8 (13), p.2254-2266
• Main Authors: Sutradhar, Manas, Martins, Luísa M. D. R. S., Carabineiro, Sónia A. C., Guedes da Silva, M. Fátima C., Buijnsters, Josephus G., Figueiredo, José L., Pombeiro, Armando J. L.
• Format: Article
• Language: English
• Subjects: carbon; heterogeneous catalysis; immobilization; microwave chemistry; vanadium
• ISSN: 1867-3880; 1867-3899
• DOI: 10.1002/cctc.201600316

Six oxidovanadium(V) aroylhydrazone complexes derived from (3,5‐di‐tert‐butyl‐2‐hydroxybenzylidene)‐2‐hydroxybenzohydrazide (H2L1) and (3,5‐di‐tert‐butyl‐2‐hydroxybenzylidene)‐2‐aminobenzohydrazide (H2L2), namely, [VOL1(OEt)][VOL1(OEt) (EtOH)] (1), [VOL2(OEt)] (2), [Et3NH][VO2L1] (3), [VO2(HL2)]⋅2 EtOH (4), [(VOL1)2(μ‐O)] (5), and [(VOL2)2(μ‐O)] (6), were synthesized and characterized by elemental analysis, IR, 1H NMR, and 51V NMR spectroscopies, ESI‐MS and, for 1–5, single‐crystal XRD. The compounds have VO3+ (1 and 2), VO2+ (3 and 4), and V2O34+ (5 and 6) cores. They are active homogeneous catalysts in the microwave‐assisted, solvent‐free peroxidative oxidation of 1‐phenylethanol to acetophenone by tBuOOH. The immobilization of the oxidovanadium complexes (1, 2, 4, and 5) on oxidized carbon materials improved the oxidation efficiency and allowed catalyst reuse with the preservation of activity. Raise the anchor! Three sets of six oxidovanadium(V) complexes that bear three different vanadium cores (VO3+, VO2+, and V2O34+) are anchored onto carbon supports, and the assemblies are tested for the microwave‐assisted oxidation of secondary alcohols under mild conditions. The heterogeneous systems, in the absence of any added solvent or additive, are highly selective (above 98 %) and recyclable.