Aerobic oxidation of monoterpenic alcohols catalyzed by ruthenium hydroxide supported on silica-coated magnetic nanoparticles

Ruthenium hydroxide supported on silica-coated magnetic nanoparticles was shown to be an efficient heterogeneous catalyst for the liquid-phase oxidation of a wide range of alcohols using molecular oxygen as a sole oxidant in the absence of co-catalysts or additives. The material was prepared through the loading of the amino modified support with ruthenium(III) ions from an aqueous solution of ruthenium(III) chloride followed by treatment with sodium hydroxide to form ruthenium hydroxide species. Characterizations suggest that ruthenium hydroxide is highly dispersed on the support surface, with no ruthenium containing crystalline phases being detected. Various carbonylic monoterpenoids important for fragrance and pharmaceutical industries can be obtained in good to excellent yields starting from biomass-based monoterpenic alcohols, such as isoborneol, perillyl alcohol, carveol, and citronellol. The catalyst undergoes no metal leaching and can be easily recovered by the application of an external magnet and re-used.

A magnetic material comprised of ruthenium hydroxide supported on silica-coated Fe3O4 nanoparticles is an effective catalyst for the liquid-phase aerobic oxidation of a wide range of alcohols into corresponding aldehydes and ketones. The oxidation of biomass-based monoterpenic alcohols gives carbonylic terpenoids useful for fragrance and pharmaceutical industries.Figure optionsDownload high-quality image (48 K)Download as PowerPoint slideHighlights
► Ruthenium hydroxide was supported on silica-coated magnetic Fe3O4 nanoparticles.
► The material is active in the oxidation of various alcohols with molecular oxygen.
► Commercially important monoterpenoids were obtained in good to excellent yields.
► The catalyst undergoes no metal leaching and can be magnetically recovered.