Iron complexes with aminopyridine ligands are promising for efficient and selective organic substrate oxidation using hydrogen peroxide as a green oxidant. These catalysts hydroxylate aromatic and aliphatic C-H groups, and epoxidize C=C bonds. These reactions are enhanced by addition of stoichiometric carboxylic acid, although the reasons for this enhancement are still under investigation. Peroxy- and acylperoxyiron(III) are formed en route, but are not the species responsible for oxidation. Oxoiron(IV) has been proposed as the active species, as is the case in certain other iron catalysts and enzymatic systems, but is largely unreactive here. Instead, oxoiron(IV) exists as an unwanted byproduct, but can be fortuitously reduced back to peroxyiron(III) precursors of the catalytically-competent intermediate(s). O-O heterolysis of observed iron(III) species has been proposed to generate the putative oxoiron(V) active species, although direct evidence for this species remains limited. Recently, interest has turned to peroxyacids especially peracetic acid, which appear to generate the same catalytic intermediates, but greatly improve catalytic efficiency. Ongoing work is focused on elucidating the differences in mechanistic pathway when H2O2 + acid is employed vs. peroxyacid.

Mechanistic studies of hydrogen peroxide activation with non-heme iron aminopyridine complexes: Fe(III), Fe(IV), and beyond

256th National Meeting (2018)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.