Photochemical oxidation of benzylic alcohols at natural sunlight utilizing CuO@ZnFe-LDH/TEMPO and air as the oxidant

A CuO@ZnFe-LDH composite, prepared from the co-precipitation of Cu²⁺ with ZnFe-LDH, served as an environmentally friendly photocatalyst. This catalyst was implemented in the selective oxidation of various primary and secondary alcohols to aldehydes or ketones utilizing air as the oxidant, 2,2,6,6-tetramethylpiperidine 1-oxyl radical (TEMPO), and sunlight as the light source. The yields varied from low to excellent. It was notable that the oxidation process also allowed for very selective conversion of benzylic alcohols that had phenolic hydroxyl groups. Moreover, leaching of copper from the catalyst during the reaction was minimal. Also, CuO@ZnFe-LDH could be effectively reused, while maintaining its high catalytic activity.