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The selective hydrogenation of fluorinated arenes with polar functionalities is achieved, opening a versatile pathway for the production of valuable substituted fluorocyclohexane derivatives from readily available substrates. The use of supercritical carbon dioxide (scCO2) as a hydrophobic and green solvent in combination with Rh nanoparticles immobilized on molecularly modified silica as catalysts favours hydrogenation over hydrodefluorination. The approach compares favourably in terms of green chemistry metrics relative to traditional synthetic routes as exemplified for the useful building block 4-fluorocyclohexan-1-ol. [ABSTRACT FROM AUTHOR]

The preparation, characterization, and catalytic properties of Pd nanoparticles supported on mesoporous organic–inorganic hybrid materials are described for continuous-flow aerobic oxidation of alcohols using supercritical carbon dioxide (scCO2) as a mobile phase. The nanoparticles were generated “bottom-up” from molecular precursors that were precoordinated to the support through suitable anchor units. The most active material allows high single-pass conversions in scCO2 at temperatures as low as 60 °C. This high activity may be associated with the presence of small primary crystallites (approx. 2 nm) that conglomerate to ensembles about 25 nm in size, leading to a larger number of high-indexed planes in small volume units. These findings may provide useful guidelines for further catalyst design on the nanoscale for green oxidation methods. [Copyright &y& Elsevier]