Allylic oxidation of olefins to the corresponding α,β-unsaturated ketones catalyzed by chromium aluminophosphate-5 Original Research Article

Chromium substituted Aluminophosphate-5 (CrAPO-5) is a heterogeneous catalyst for the liquid phase oxidation of olefins with tert-butyl hydroperoxide (TBHP) to the corresponding α,β-unsaturated ketones at 80°C. The olefins used were: menthene, limonene, α- and β-pinene, terpinolene and 3-carene. Conversions of these terpene substrates were in a range of 85–96% with in some cases high selectivities to a single product. High selectivities towards TBHP were obtained in an experiment where the substrate was used as solvent, i.e. in a large excess with respect to the oxidant. Allylic oxidation with the more bulky pinane hydroperoxide was slower than with TBHP as a result of the increased steric constraints imposed on this hydroperoxide in the channels of the aluminophosphate lattice.