Activated carbon functionalized with Mn(II) Schiff base complexes as efficient alkene oxidation catalysts: Solid support matters

A new synthetic methodology to covalently anchor Mn-II-Schiff-base catalysts onto activated carbon (ACox) has been applied, resulting in heterogeneous Mn-II-L@ACox materials. These catalysts are effective and selective towards epoxides with H2O2, in the presence of CH3COONH4, as co-catalyst, providing TONs equivalent-to/or higher than the homologous Mn-II-L@SiO2 catalysts for certain substrates. Moreover MnII-L@ACox catalysts are re-usable and kinetically faster than the corresponding Mn-II-L@SiO2 catalysts resulting in considerably higher TOFs. Combining catalytic and EPR spectroscopic data we propose a catalytic reaction mechanism which elucidates the co-catalytic function of CH3COONH4 which is of key importance for the successful performance of the studied Mn-II-catalysts. (C) 2014 Elsevier B.V. All rights reserved.