Acyl-substituted ferrocenes as driers for solvent-borne alkyd paints

Ferrocenes bearing acyl substituents in the cyclopentadienyl rings [Fe(eta(5)-C5H4COR)(eta(5)-C5H5)] and [Fe(eta(5)-C5H4COR)(2)] (R = CH3, CF3 and Ph) were examined as new driers for solvent-borne alkyd binder. All studied ferrocenes were found to be active catalysts for cross-linking reaction of the alkyd. These iron(II) compounds give solid polymeric films with hardness and drying time comparable to the commercial cobalt(II) drier. Acetyl- and benzoyl-substituted ferrocenes show an excellent synergic effect with the cobalt drier giving hard polymeric films within short drying time. The kinetics of the alkyd autoxidation was followed by FTIR spectroscopy. Spin-trapping ESR technique has proven the important role of the ferrocenium cation upon decomposition of hydroperoxides by ferrocene-based driers. The peroxy and alkoxy radicals, appearing in drying process, were resolved by the new spin trap methyl-N-mesityl nitrone. (C) 2011 Elsevier B.V. All rights reserved.