Oxidation of benzoin catalyzed by oxovanadium (IV) schiff base complexes

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dc.contributor.authorAlsalim, Tahseen A.
dc.contributor.authorHadi, Jabbar S.
dc.contributor.authorAli, Omar N.
dc.contributor.authorAbbo, Hanna S.
dc.contributor.authorTitinchi, Salam J.J.
dc.date.accessioned2017-06-13T02:57:41Z
dc.date.available2017-06-13T02:57:41Z
dc.date.issued2013
dc.description.abstractBACKGROUND: The oxidative transformation of benzoin to benzil has been accomplished by the use of a wide variety of reagents or catalysts and different reaction procedures. The conventional oxidizing agents yielded mainly benzaldehyde or/and benzoic acid and only a trace amount of benzil. The limits of practical utilization of these reagents involves the use of stoichiometric amounts of corrosive acids or toxic metallic reagents, which in turn produce undesirable waste materials and required high reaction temperatures. In recent years, vanadium complexes have attracted much attention for their potential utility as catalysts for various types of reactions. RESULTS: Active and selective catalytic systems of new unsymmetrical oxovanadium(IV) Schiff base complexes for the oxidation of benzoin is reported. The Schiff base ligands are derived between 2-aminoethanol and 2-hydroxy-1- naphthaldehyde (H2L1) or 3-ethoxy salicylaldehyde (H2L3); and 2-aminophenol and 3-ethoxysalicylaldehyde (H2L2) or 2-hydroxy-1-naphthaldehyde (H2L4). The unsymmetrical Schiff bases behave as tridentate dibasic ONO donor ligands. Reaction of these Schiff base ligands with oxovanadyl sulphate afforded the mononuclear oxovanadium(IV) complexes (VIVOLx.H2O), which are characterized by various physico-chemical techniques. The catalytic oxidation activities of these complexes for benzoin were evaluated using H2O2 as an oxidant. The best reaction conditions are obtained by considering the effect of solvent, reaction time and temperature. Under the optimized reaction conditions, VOL4 catalyst showed high conversion (>99%) with excellent selectivity to benzil (~100%) in a shorter reaction time compared to the other catalysts considered. CONCLUSION: Four tridentate ONO type Schiff base ligands were synthesized. Complexation of these ligands with vanadyl(IV) sulphate leads to the formation of new oxovanadium(IV) complexes of type VIVOL.H2O. Elemental analyses and spectral data of the free ligands and their oxovanadium(IV) complexes were found to be in good agreement with their structures, indicating high purity of all the compounds. Oxovanadium complexes were screened for the oxidation of benzoin to benzil using H2O2 as oxidant. The effect of time, solvent and temperature were optimized to obtain maximum yield. The catalytic activity results demonstrate that these catalytic systems are both highly active and selective for the oxidation of benzoin under mild reaction conditions.en_US
dc.description.accreditationWeb of Science
dc.identifier.citationAlsalim, T. A. (2013). Oxidation of benzoin catalyzed by oxovanadium (IV) schiff base complexes. Chemistry Central Journal, 7(3)en_US
dc.identifier.issn1752-153X
dc.identifier.urihttp://hdl.handle.net/10566/2975
dc.identifier.urihttp://dx.doiorg/10.1186/1752-153X-7-3
dc.language.isoenen_US
dc.privacy.showsubmitterFALSE
dc.publisherChemistry Centralen_US
dc.rights© 2013 Alsalim et al.; licensee Chemistry Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
dc.status.ispeerreviewedTRUE
dc.subjectTridentate ONO Schiff base ligandsen_US
dc.subjectOxovanadium(IV) complexesen_US
dc.subjectBenzoin oxidationen_US
dc.subjectBenzilen_US
dc.titleOxidation of benzoin catalyzed by oxovanadium (IV) schiff base complexesen_US
dc.typeArticleen_US

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