Catalytic Oxidation of Aliphatic Alcohols by Hydrogen Peroxide Using Merrifield Resin-Supported Binuclear Dioxidovanadium(v) Complexes of Hydrazone Ligands as a Catalyst
摘要
Catalytic oxidation of a number of straight-chain/cyclic aliphatic alcohols was examined in the presence of hydrogen peroxide and Merrifield resin-supported binuclear dioxidovanadium(V) complexes of hydrazone ligands in the absence of any additional solvent. The dioxidovanadium(V) complexes K2[(VO2-sal)2-dmh)]2− (1), K2[(VO2-Csal)2-dmh]2− (2), and K2[(VO2-Bsal)2-dmh]2− (3) were synthesized in the form of their K+-salt by reacting hydrazone based ligands H2(sal)2-dmh (I), H2(Csal)2-dmh (II), and H2(Bsal)2-dmh (III), with the vanadium precursor VO(acac)2, respectively. Imidazole functionalized Merrifield resin was used to heterogenize the dioxidovanadium complexes 1–3. XPS analysis reveals that the vanadium loading in the Merrifield resin is a few percent, and the oxidation state of the vanadium center in the grafted complexes is +5. A maximum substrate conversion of 95% (in the presence of 4), 90% (in the presence of 5), and 92% (in the presence of 6) is observed during the oxidation of ethanol, and acetic acid is the solo product. In general, cyclic alcohols are less reactive than acyclic ones. Whereas, alcohols with a higher number of carbon chains are less reactive than alcohols with fewer carbon atoms.
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