Cyclohexane and toluene oxidation catalyzed by 1,10-phenantroline Cu(II) complexes

In this work, we present the cyclohexane oxidation catalyzed by the mononuclear 1,10-phenantroline Cu(II) complexes: [Cu(phen)3]Cl2·7H2O (1), [Cu(phen)2Cl]Cl·5H2O (2), [Cu(phen)Cl2] (3), using hydrogen peroxide as oxidant, in acetonitrile:water (3.5:1) solution. The reactions were carried out at temperatures ranging from 25 °C to 70 °C. All complexes were able to oxidize cyclohexane into cyclohexanol and cyclohexanone with low to moderate yields. Adipic acid was also formed in the reaction. The highest conversion was obtained with the system [Cu(phen)2Cl]Cl/H2O2/70 °C, with 67% total yield. Furthermore, these complexes were also able to oxidize toluene at room temperature.

Graphical abstractMononuclear 1,10-phenantroline Cu(II) complexes: [Cu(phen)3]Cl2·7H2O (1), [Cu(phen)2Cl]Cl·5H2O (2), [Cu(phen)Cl2] (3) were used to oxidize cyclohexane, using hydrogen peroxide as oxidant. All complexes were able to produce cyclohexanol and cyclohexanone with low to moderate yields. Adipic acid was also formed in the reaction. The highest conversion was obtained with the system [Cu(phen)2Cl]Cl at 70 °C, with 67% of total yield. It was also possible to relate the catalytic activity in cyclohexane oxidation, as well as toluene oxidation, with the redox properties of the complexes: the most easily reducible, being also the most active.Figure optionsDownload full-size imageDownload as PowerPoint slide