Highly effective catalysts of natural polymer supported Salophen Mn(III) complexes for aerobic oxidation of cyclohexene

Three chitosan (abbreviated as CS) supported Salophen Mn(III) complexes were prepared in a simple way and characterized by FT-IR and XPS. Their abilities to catalyze allylic oxidation of cyclohexene with oxygen in the absence of solvents or reducing agents were studied. It has been revealed that the amino groups of CS coordinated with the Mn atoms of Salophen Mn(III) complexes to form CS–Salophen Mn(III) complexes, which have much better catalytic activities for allylic oxidation of cyclohexene than the corresponding unsupported Salophen Mn(III) complexes. Under reaction conditions of 343 K and ambient pressure of oxygen, after 12 h reaction, the cyclohexene oxidation catalyzed by CS–Salophen Mn(III) complex resulted in 11.03 × 104 turnover numbers (based on the manganese atom), which was about 44 times as large as that by unsupported Salophen Mn(III) complex. The influences of reaction temperature and reaction time on the oxidation of cyclohexene were also investigated.

Graphical abstractThree chitosan (abbreviated as CS) supported Salophen Mn(III) complexes were prepared in a simple way and characterized by FT-IR and XPS. Their abilities to catalyze allylic oxidation of cyclohexene with oxygen in the absence of solvents or reducing agents were studied. Under reaction conditions of 343 K and ambient pressure of O2, using CS–Salophen Mn(III) complex as catalyst, 11.03 × 104 turnover numbers was obtained, which was about 44 times as large as that by unsupported Salophen Mn(III) complex. Figure optionsDownload full-size imageDownload as PowerPoint slide