Oxidation of secondary amines to nitrones using magnetically separable tungstophosphoric acid supported on silica-encapsulated γ-Fe2O3 nanoparticles

Superparamagnetic tungstophosphoric acid supported on silica-encapsulated γ-Fe2O3 was used as an efficient catalyst for the direct oxidation of secondary amines to nitrones with hydrogen peroxide as the oxidant. The catalyst could be recycled up to four times without significant loss of activity.