Catalytic isomerisation of α-pinene oxide in the presence of ETS-10 supported ferrocenium ions.

Ferrocenium ions, [Fc] + , have been immobilised in the microporous titanosilicate ETS-10 by ion exchange of Na + /K + ions under hydrothermal conditions. The resultant hybrid inorganic-organometallic (ETS-10/[Fc] + ) material was characterised by elemental analysis, diffuse reflectance UV–Vis spectroscopy, FT-IR spectroscopy, powder X-ray diffraction, scanning electron microscopy, and thermogravimetric analysis. The ETS-10/[Fc] + sample was tested as a catalyst for the isomerisation of α-pinene oxide (PinOx) at 35 °C. With α,α,α-trifluorotoluene (TFT) as solvent, campholenic aldehyde (CPA) was the main product formed in 38% yield at 100% conversion and 30 min reaction. Other reaction products included trans -carveol, iso -pinocamphone and trans -pinocarveol. The same PinOx conversion and CPA yield could be reached within 1 min reaction time by increasing the reaction temperature (to 55 °C) and the Fe:PinOx molar ratio. Other solvents (hexane, CH 3 CN, toluene) led to poorer results than TFT. Characterisation of the used catalyst, together with an analysis of the catalytic activity of the liquid phase obtained after contact of ETS-10/[Fc] + with TFT, indicated that the ETS-10/[Fc] + sample was resistant toward leaching of iron-containing active species. When the recovered solid was reused in a second batch run, catalytic activity was lower than in the first run, while selectivity to CPA was higher. [ABSTRACT FROM AUTHOR]