Abstract:

A practical catalytic method to oxidize α-ionone with molecular oxygen under normal pressure and temperature using N-hydroxyphthalimide (NHPI) combined with Co(acac)2 was developed, and probable catalytic mechanism was proposed. Influences of the reaction conditions on conversion of α-ionone and the selectivity of the major product (5-keto-α-ionone) were investigated, the optimal technical parameters for 5-keto-α-ionone were optimized. The results show that the primary products are 5-keto-α-ionone, epoxy-α- ionone, as well as rearrangement products 4-keto-β-ionone and epoxy-β-ionone, which are characterized by infrared spectra, proton nuclear magnetic resonance spectra, mass spectra and elemental analyzer; The yield of 5-keto-α-ionone and the conversion of α-ionone are 53.4% and 95.0%, respectively, when 25 % NHPI, 1.0% Co(acac)2 (in mole ratio) and no solvent is employed under O2 pressure for 1.0MPa and the reaction temperature at 70℃ for 10h, the procedure shows good reproducibility in the parallel experiments.