Photoinduced Carbonyl Coupling of Aldehydes on Anatase TiO2(101)

Carbonyl coupling of aldehydes is critical to many synthetic processes, including the development of alternative fuels and useful synthetic chemicals. We report a general photoinduced process for carbonyl coupling of aldehydes as a route to ketone synthesis. In contrast to thermal carbonyl coupling of aldehydes with O2 to ketones via carboxylate-type intermediates at high temperature, carbonyl coupling of aldehydes (CH3CHO, CH3CH2CHO, PhCHO) to produce ketones on anatase–TiO2(101) can be promoted by UV light below room temperature with high efficiency on the Ti5c sites, while aldehydes can also be decomposed during UV light irradiation. The mechanistic model constructed in this study elucidates the crucial role of TiO2 as a photocatalyst for synthetic reactions and provides a new pathway in conversion of aldehydes to ketones.