Carbon nanofibers decorated with oxo–rhenium complexes: Highly efficient heterogeneous catalyst for oxidation of amines with hydrogen peroxide

• Efficient and improved heterogeneous oxo–rhenium catalyst for oxidation of amines with hydrogen peroxide.
• Chemically functionalized carbon nanofibres as support for immobilization of homogeneous metal complex.
• Green oxidation methodology for oxidation of amines using hydrogen peroxide as oxidant.
• Easily recoverable and efficiently recyclable metal catalyst.

Pyridine functionalized carbon nanofibers (Py-CNFs) were synthesized, characterized and used for the grafting of oxo–rhenium complex i.e., methyltrioxorhenium (MTO) via acid-base ionic interaction. The grafting of MTO to Py-CNFs was confirmed by FTIR, UV–vis, SEM, TEM and TGA analyses. The determination of rhenium content by ICP-AES further suggested the successful immobilization of MTO to the support. The developed heterogeneous material i.e., MTO@Py-CNFs was found to be an efficient catalyst for the oxidation of various secondary as well as tertiary amines to corresponding nitrones or N-oxides, respectively by using hydrogen peroxide. The developed catalyst was readily recovered by centrifugation and reused for subsequent ten runs without any significant loss in catalytic activity.

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