Synthesis, characterization and catalytic potentials of polymer anchored copper(II), oxovanadium(IV) and dioxomolybdenum(VI) complexes of 2-(α-hydroxymethyl)benzimidazole

• Published in: Reactive & functional polymers Vol. 63; no. 1; pp. 71 - 83
• Main Authors: Maurya, Mannar R., Sikarwar, Sweta, Joseph, Trissa, Manikandan, Palanichamy, Halligudi, S.B.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01-04-2005; Elsevier Science
• Subjects: 2-(α-hydroxymethyl)benzimidazole; Applied sciences; Exact sciences and technology; Organic polymers; Oxidation of styrene and ethyl benzene; Oxidative bromination of salicylaldehyde; Physicochemistry of polymers; Polymer anchored-complexes; Properties and characterization; Special properties (catalyst, reagent or carrier); Polymer anchored-complexes; Oxidation of styrene and ethyl benzene; 2-(α-hydroxymethyl)benzimidazole; Oxidative bromination of salicylaldehyde; Vanadium IV Complexes; Styrene(chloromethyl) polymer; Catalyst selectivity; Temperature effect; Benzimidazole derivative polymer; Experimental study; Molybdenum VI Complexes; Chemical substitution; Styrene derivative polymer; Aldol; Ethylbenzene; Chemical modification; Benzimidazole derivatives; Copper II Complexes; Preparation; Crosslinked polymer; Styrene; Oxidation; Catalyst activity; Catalyst support
• ISSN: 1381-5148
• DOI: 10.1016/j.reactfunctpolym.2005.02.008

2-(α-Hydroxymethyl)benzimidazole (Hhmbmz) has been covalently anchored to chloromethylated polystyrene cross-linked with 5% divinylbenzene. This chelating resin reacts with cupric acetate, vanadyl sulphate and [MoO
2(acac)
2] (Hacac
=
acetylacetone) in presence of Hhmbmz to give complexes PS-[Cu(hmbmz)
2], PS-[VO(hmbmz)
2] and PS-[MoO
2(hmbmz)
2] (where, PS-hmbmz
=
deprotonated 2-(α-hydroxymethyl) benzimidazole covalently linked with polymer), respectively. These complexes were characterized by elemental analyses, FT-IR, EPR and electronic spectra, SEM and TGA-DTA methods. EPR results indicate that complexes are well dispersed in the polymeric support. Complexes PS-[Cu(hmbmz)
2] and PS-[VO(hmbmz)
2] have been used as catalysts for the oxidation of styrene and ethyl benzene while PS-[VO(hmbmz)
2] and PS-[MoO
2(hmbmz)
2] for the oxidative bromination of salicylaldehyde. Oxidation of styrene gives three major products, styrene oxide, benzaldehyde and benzoic acid while ethyl benzene gives acetophenone as the major product. Oxidative bromination of salicylaldehyde using H
2O
2/KBr gives 5-bromosalicylaldehyde selectively in quantitative yield. EPR spectra of both freshly prepared and recovered catalysts are identical, which indicate that the metal-Schiff base moiety is intact and the coordination environments are not altered during the reaction.