Selective photocatalytic oxidation at TiO2/Ti anodes of 4-methoxybenzyl alcohol to the corresponding benzaldehyde in “green” conditions

The photosensitized electrochemical oxidation at a TiO2/Ti anode is, in itself, a “green” chemical strategy as the semiconductor remains unchanged during the experiments, the metal is safe, low energies are involved and experimental conditions are mild. In this context, the oxidation of 4-methoxybenzyl alcohol to 4-methoxybenzaldehyde has been carried out on the light of further “green chemistry” requirements: water as medium, NaCl as supporting electrolyte, exclusion of the reference electrode, Ti cathode (less expensive than the traditional Pt one) and Ti mesh (to optimize the cell geometry). In this study some chemical (alcohol conversion to aldehyde and material recovery) and electrochemical (current efficiency and density) parameters have been used to select the reaction conditions that are more suitable for this purpose. As concern the cell, the best geometry was realized with an immersion lamp, coaxial with a mesh cylindrical TiO2/Ti anode and a mesh Ti cathode.