We investigated the selective oxidation of styrenes to benzaldehydes by using a non-irradiated TiO2-H2O2 catalytic system. The oxidation promotes multi-step reactions from styrenes, including the cleavage of a C=C double bond and the addition of an oxygen atom selectively and stepwise to provide the corresponding benzaldehydes in good yields (up to 72%). These reaction processes were spectroscopically shown by fluorescent measurements under the presence of competitive scavengers. The absence of the signal from OH radicals indicates the participation of other oxidants such as hydroperoxy radicals (•OOH) and superoxide radicals (•O2-) into the selective oxidation from styrene to benzaldehyde.
Keywords: benzaldehydes; heterogeneous catalyst; hydrogen peroxide; non-irradiated oxidation; styrenes; titanium dioxide.