Fluorous biphase oxidation of ethyl benzene and benzyl alcohol catalyzed by perfluoroalkyl phthalocyanine complexes

Background: Ketones and aldehydes are important organic chemicals as intermediates for the pharmaceutical and fine-chemical industries. The existing oxidation reactions to obtain ketones and aldehydes are no longer sustainable because of the large amount of waste generated and use of stoichiometric reagents: a cleaner catalytic oxidation system needs to be developed. Results: The experimental results show that cobalt (II) tetra-(perfluorohexyl) phthalocyaninate delivered a high catalytic activity for the oxidation of ethyl benzene (35% conversion and 86% selectivity to acetophenone) at 90°C under ambient pressure of oxygen. The catalyst could be recycled for at least four runs. For the oxidation of benzyl alcohol to benzaldehyde, a conversion of 6% was achieved but with a selectivity of 100% at 90°C under 2 × 105 Pa O₂. Conclusion: Perfluoroalkyl metallophthalocyanines can be used for the fluorous biphasic oxidation of ethyl benzene and benzyl alcohol with molecular oxygen. The cobalt (II) tetra-(perfluorohexyl) phthalocyaninate exhibited the highest catalytic activity for the oxidation of ethyl benzene. The catalytic oxidation of benzyl alcohol using our method may be feasible in industrial applications.